3756 lines
100 KiB
C
3756 lines
100 KiB
C
/*
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* mm/mmap.c
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*
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* Written by obz.
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*
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* Address space accounting code <alan@lxorguk.ukuu.org.uk>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/mm.h>
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#include <linux/vmacache.h>
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#include <linux/shm.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/shmem_fs.h>
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#include <linux/profile.h>
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#include <linux/export.h>
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#include <linux/mount.h>
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#include <linux/mempolicy.h>
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#include <linux/rmap.h>
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#include <linux/mmu_notifier.h>
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#include <linux/mmdebug.h>
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#include <linux/perf_event.h>
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#include <linux/audit.h>
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#include <linux/khugepaged.h>
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#include <linux/uprobes.h>
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#include <linux/rbtree_augmented.h>
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#include <linux/notifier.h>
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#include <linux/memory.h>
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#include <linux/printk.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/moduleparam.h>
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#include <linux/pkeys.h>
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#include <linux/oom.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/tlb.h>
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#include <asm/mmu_context.h>
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#include "internal.h"
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#ifndef arch_mmap_check
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#define arch_mmap_check(addr, len, flags) (0)
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
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const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
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const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
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int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
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#endif
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#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
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const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
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const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
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int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
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#endif
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static bool ignore_rlimit_data;
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core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
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static void unmap_region(struct mm_struct *mm,
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struct vm_area_struct *vma, struct vm_area_struct *prev,
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unsigned long start, unsigned long end);
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/* description of effects of mapping type and prot in current implementation.
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* this is due to the limited x86 page protection hardware. The expected
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* behavior is in parens:
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*
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* map_type prot
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* PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
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* MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
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* w: (no) no w: (no) no w: (yes) yes w: (no) no
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* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
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*
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* MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
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* w: (no) no w: (no) no w: (copy) copy w: (no) no
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* x: (no) no x: (no) yes x: (no) yes x: (yes) yes
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*
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* On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
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* MAP_PRIVATE:
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* r: (no) no
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* w: (no) no
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* x: (yes) yes
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*/
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pgprot_t protection_map[16] __ro_after_init = {
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__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
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__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
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};
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#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
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static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
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{
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return prot;
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}
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#endif
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pgprot_t vm_get_page_prot(unsigned long vm_flags)
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{
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pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
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(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
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pgprot_val(arch_vm_get_page_prot(vm_flags)));
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return arch_filter_pgprot(ret);
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}
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EXPORT_SYMBOL(vm_get_page_prot);
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static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
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{
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return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
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}
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/* Update vma->vm_page_prot to reflect vma->vm_flags. */
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void vma_set_page_prot(struct vm_area_struct *vma)
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{
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unsigned long vm_flags = vma->vm_flags;
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pgprot_t vm_page_prot;
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vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
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if (vma_wants_writenotify(vma, vm_page_prot)) {
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vm_flags &= ~VM_SHARED;
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vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
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}
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/* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
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WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
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}
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/*
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* Requires inode->i_mapping->i_mmap_rwsem
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*/
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static void __remove_shared_vm_struct(struct vm_area_struct *vma,
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struct file *file, struct address_space *mapping)
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{
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if (vma->vm_flags & VM_DENYWRITE)
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atomic_inc(&file_inode(file)->i_writecount);
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if (vma->vm_flags & VM_SHARED)
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mapping_unmap_writable(mapping);
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flush_dcache_mmap_lock(mapping);
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vma_interval_tree_remove(vma, &mapping->i_mmap);
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flush_dcache_mmap_unlock(mapping);
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}
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/*
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* Unlink a file-based vm structure from its interval tree, to hide
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* vma from rmap and vmtruncate before freeing its page tables.
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*/
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void unlink_file_vma(struct vm_area_struct *vma)
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{
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struct file *file = vma->vm_file;
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if (file) {
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struct address_space *mapping = file->f_mapping;
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i_mmap_lock_write(mapping);
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__remove_shared_vm_struct(vma, file, mapping);
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i_mmap_unlock_write(mapping);
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}
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}
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/*
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* Close a vm structure and free it, returning the next.
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*/
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static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
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{
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struct vm_area_struct *next = vma->vm_next;
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might_sleep();
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if (vma->vm_ops && vma->vm_ops->close)
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vma->vm_ops->close(vma);
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if (vma->vm_file)
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fput(vma->vm_file);
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mpol_put(vma_policy(vma));
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vm_area_free(vma);
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return next;
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}
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static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
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struct list_head *uf);
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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
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unsigned long retval;
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unsigned long newbrk, oldbrk, origbrk;
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *next;
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unsigned long min_brk;
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bool populate;
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bool downgraded = false;
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LIST_HEAD(uf);
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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origbrk = mm->brk;
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#ifdef CONFIG_COMPAT_BRK
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/*
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* CONFIG_COMPAT_BRK can still be overridden by setting
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* randomize_va_space to 2, which will still cause mm->start_brk
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* to be arbitrarily shifted
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*/
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if (current->brk_randomized)
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min_brk = mm->start_brk;
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else
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min_brk = mm->end_data;
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#else
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min_brk = mm->start_brk;
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#endif
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if (brk < min_brk)
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goto out;
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/*
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* Check against rlimit here. If this check is done later after the test
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* of oldbrk with newbrk then it can escape the test and let the data
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* segment grow beyond its set limit the in case where the limit is
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* not page aligned -Ram Gupta
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*/
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if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
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mm->end_data, mm->start_data))
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goto out;
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newbrk = PAGE_ALIGN(brk);
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oldbrk = PAGE_ALIGN(mm->brk);
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if (oldbrk == newbrk) {
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mm->brk = brk;
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goto success;
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}
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/*
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* Always allow shrinking brk.
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* __do_munmap() may downgrade mmap_sem to read.
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*/
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if (brk <= mm->brk) {
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int ret;
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/*
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* mm->brk must to be protected by write mmap_sem so update it
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* before downgrading mmap_sem. When __do_munmap() fails,
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* mm->brk will be restored from origbrk.
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*/
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mm->brk = brk;
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ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
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if (ret < 0) {
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mm->brk = origbrk;
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goto out;
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} else if (ret == 1) {
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downgraded = true;
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}
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goto success;
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}
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/* Check against existing mmap mappings. */
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next = find_vma(mm, oldbrk);
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if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
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goto out;
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/* Ok, looks good - let it rip. */
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if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
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goto out;
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mm->brk = brk;
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success:
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populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
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if (downgraded)
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up_read(&mm->mmap_sem);
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else
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up_write(&mm->mmap_sem);
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userfaultfd_unmap_complete(mm, &uf);
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if (populate)
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mm_populate(oldbrk, newbrk - oldbrk);
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return brk;
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out:
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retval = origbrk;
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up_write(&mm->mmap_sem);
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return retval;
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}
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static long vma_compute_subtree_gap(struct vm_area_struct *vma)
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{
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unsigned long max, prev_end, subtree_gap;
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/*
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* Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
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* allow two stack_guard_gaps between them here, and when choosing
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* an unmapped area; whereas when expanding we only require one.
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* That's a little inconsistent, but keeps the code here simpler.
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*/
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max = vm_start_gap(vma);
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if (vma->vm_prev) {
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prev_end = vm_end_gap(vma->vm_prev);
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if (max > prev_end)
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max -= prev_end;
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else
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max = 0;
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}
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if (vma->vm_rb.rb_left) {
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subtree_gap = rb_entry(vma->vm_rb.rb_left,
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struct vm_area_struct, vm_rb)->rb_subtree_gap;
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if (subtree_gap > max)
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max = subtree_gap;
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}
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if (vma->vm_rb.rb_right) {
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subtree_gap = rb_entry(vma->vm_rb.rb_right,
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struct vm_area_struct, vm_rb)->rb_subtree_gap;
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if (subtree_gap > max)
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max = subtree_gap;
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}
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return max;
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}
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#ifdef CONFIG_DEBUG_VM_RB
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static int browse_rb(struct mm_struct *mm)
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{
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struct rb_root *root = &mm->mm_rb;
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int i = 0, j, bug = 0;
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struct rb_node *nd, *pn = NULL;
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unsigned long prev = 0, pend = 0;
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for (nd = rb_first(root); nd; nd = rb_next(nd)) {
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struct vm_area_struct *vma;
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vma = rb_entry(nd, struct vm_area_struct, vm_rb);
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if (vma->vm_start < prev) {
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pr_emerg("vm_start %lx < prev %lx\n",
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vma->vm_start, prev);
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bug = 1;
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}
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if (vma->vm_start < pend) {
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pr_emerg("vm_start %lx < pend %lx\n",
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vma->vm_start, pend);
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bug = 1;
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}
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if (vma->vm_start > vma->vm_end) {
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pr_emerg("vm_start %lx > vm_end %lx\n",
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vma->vm_start, vma->vm_end);
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bug = 1;
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}
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spin_lock(&mm->page_table_lock);
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if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
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pr_emerg("free gap %lx, correct %lx\n",
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vma->rb_subtree_gap,
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vma_compute_subtree_gap(vma));
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bug = 1;
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}
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spin_unlock(&mm->page_table_lock);
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i++;
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pn = nd;
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prev = vma->vm_start;
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pend = vma->vm_end;
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}
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j = 0;
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for (nd = pn; nd; nd = rb_prev(nd))
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j++;
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if (i != j) {
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pr_emerg("backwards %d, forwards %d\n", j, i);
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bug = 1;
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}
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return bug ? -1 : i;
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}
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static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
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{
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struct rb_node *nd;
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for (nd = rb_first(root); nd; nd = rb_next(nd)) {
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struct vm_area_struct *vma;
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vma = rb_entry(nd, struct vm_area_struct, vm_rb);
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VM_BUG_ON_VMA(vma != ignore &&
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vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
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vma);
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}
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}
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static void validate_mm(struct mm_struct *mm)
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{
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int bug = 0;
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int i = 0;
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unsigned long highest_address = 0;
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struct vm_area_struct *vma = mm->mmap;
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while (vma) {
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struct anon_vma *anon_vma = vma->anon_vma;
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struct anon_vma_chain *avc;
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if (anon_vma) {
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anon_vma_lock_read(anon_vma);
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list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
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anon_vma_interval_tree_verify(avc);
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anon_vma_unlock_read(anon_vma);
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}
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highest_address = vm_end_gap(vma);
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vma = vma->vm_next;
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i++;
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}
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if (i != mm->map_count) {
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pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
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bug = 1;
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}
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if (highest_address != mm->highest_vm_end) {
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pr_emerg("mm->highest_vm_end %lx, found %lx\n",
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mm->highest_vm_end, highest_address);
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bug = 1;
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}
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i = browse_rb(mm);
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if (i != mm->map_count) {
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if (i != -1)
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pr_emerg("map_count %d rb %d\n", mm->map_count, i);
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bug = 1;
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}
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VM_BUG_ON_MM(bug, mm);
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}
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#else
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#define validate_mm_rb(root, ignore) do { } while (0)
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#define validate_mm(mm) do { } while (0)
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#endif
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RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
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unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
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|
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/*
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* Update augmented rbtree rb_subtree_gap values after vma->vm_start or
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* vma->vm_prev->vm_end values changed, without modifying the vma's position
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* in the rbtree.
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*/
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static void vma_gap_update(struct vm_area_struct *vma)
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{
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/*
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* As it turns out, RB_DECLARE_CALLBACKS() already created a callback
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* function that does exacltly what we want.
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*/
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vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
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}
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static inline void vma_rb_insert(struct vm_area_struct *vma,
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struct rb_root *root)
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{
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/* All rb_subtree_gap values must be consistent prior to insertion */
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validate_mm_rb(root, NULL);
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rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
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}
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static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
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{
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/*
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* Note rb_erase_augmented is a fairly large inline function,
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* so make sure we instantiate it only once with our desired
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* augmented rbtree callbacks.
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*/
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rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
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}
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|
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static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
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struct rb_root *root,
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struct vm_area_struct *ignore)
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{
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/*
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* All rb_subtree_gap values must be consistent prior to erase,
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* with the possible exception of the "next" vma being erased if
|
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* next->vm_start was reduced.
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*/
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validate_mm_rb(root, ignore);
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__vma_rb_erase(vma, root);
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}
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|
|
static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
|
|
struct rb_root *root)
|
|
{
|
|
/*
|
|
* All rb_subtree_gap values must be consistent prior to erase,
|
|
* with the possible exception of the vma being erased.
|
|
*/
|
|
validate_mm_rb(root, vma);
|
|
|
|
__vma_rb_erase(vma, root);
|
|
}
|
|
|
|
/*
|
|
* vma has some anon_vma assigned, and is already inserted on that
|
|
* anon_vma's interval trees.
|
|
*
|
|
* Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
|
|
* vma must be removed from the anon_vma's interval trees using
|
|
* anon_vma_interval_tree_pre_update_vma().
|
|
*
|
|
* After the update, the vma will be reinserted using
|
|
* anon_vma_interval_tree_post_update_vma().
|
|
*
|
|
* The entire update must be protected by exclusive mmap_sem and by
|
|
* the root anon_vma's mutex.
|
|
*/
|
|
static inline void
|
|
anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma_chain *avc;
|
|
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
|
|
}
|
|
|
|
static inline void
|
|
anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma_chain *avc;
|
|
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
|
|
}
|
|
|
|
static int find_vma_links(struct mm_struct *mm, unsigned long addr,
|
|
unsigned long end, struct vm_area_struct **pprev,
|
|
struct rb_node ***rb_link, struct rb_node **rb_parent)
|
|
{
|
|
struct rb_node **__rb_link, *__rb_parent, *rb_prev;
|
|
|
|
__rb_link = &mm->mm_rb.rb_node;
|
|
rb_prev = __rb_parent = NULL;
|
|
|
|
while (*__rb_link) {
|
|
struct vm_area_struct *vma_tmp;
|
|
|
|
__rb_parent = *__rb_link;
|
|
vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
|
|
|
|
if (vma_tmp->vm_end > addr) {
|
|
/* Fail if an existing vma overlaps the area */
|
|
if (vma_tmp->vm_start < end)
|
|
return -ENOMEM;
|
|
__rb_link = &__rb_parent->rb_left;
|
|
} else {
|
|
rb_prev = __rb_parent;
|
|
__rb_link = &__rb_parent->rb_right;
|
|
}
|
|
}
|
|
|
|
*pprev = NULL;
|
|
if (rb_prev)
|
|
*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
|
|
*rb_link = __rb_link;
|
|
*rb_parent = __rb_parent;
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long count_vma_pages_range(struct mm_struct *mm,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
unsigned long nr_pages = 0;
|
|
struct vm_area_struct *vma;
|
|
|
|
/* Find first overlaping mapping */
|
|
vma = find_vma_intersection(mm, addr, end);
|
|
if (!vma)
|
|
return 0;
|
|
|
|
nr_pages = (min(end, vma->vm_end) -
|
|
max(addr, vma->vm_start)) >> PAGE_SHIFT;
|
|
|
|
/* Iterate over the rest of the overlaps */
|
|
for (vma = vma->vm_next; vma; vma = vma->vm_next) {
|
|
unsigned long overlap_len;
|
|
|
|
if (vma->vm_start > end)
|
|
break;
|
|
|
|
overlap_len = min(end, vma->vm_end) - vma->vm_start;
|
|
nr_pages += overlap_len >> PAGE_SHIFT;
|
|
}
|
|
|
|
return nr_pages;
|
|
}
|
|
|
|
void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct rb_node **rb_link, struct rb_node *rb_parent)
|
|
{
|
|
/* Update tracking information for the gap following the new vma. */
|
|
if (vma->vm_next)
|
|
vma_gap_update(vma->vm_next);
|
|
else
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
|
|
/*
|
|
* vma->vm_prev wasn't known when we followed the rbtree to find the
|
|
* correct insertion point for that vma. As a result, we could not
|
|
* update the vma vm_rb parents rb_subtree_gap values on the way down.
|
|
* So, we first insert the vma with a zero rb_subtree_gap value
|
|
* (to be consistent with what we did on the way down), and then
|
|
* immediately update the gap to the correct value. Finally we
|
|
* rebalance the rbtree after all augmented values have been set.
|
|
*/
|
|
rb_link_node(&vma->vm_rb, rb_parent, rb_link);
|
|
vma->rb_subtree_gap = 0;
|
|
vma_gap_update(vma);
|
|
vma_rb_insert(vma, &mm->mm_rb);
|
|
}
|
|
|
|
static void __vma_link_file(struct vm_area_struct *vma)
|
|
{
|
|
struct file *file;
|
|
|
|
file = vma->vm_file;
|
|
if (file) {
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
if (vma->vm_flags & VM_DENYWRITE)
|
|
atomic_dec(&file_inode(file)->i_writecount);
|
|
if (vma->vm_flags & VM_SHARED)
|
|
atomic_inc(&mapping->i_mmap_writable);
|
|
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_interval_tree_insert(vma, &mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
}
|
|
|
|
static void
|
|
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, struct rb_node **rb_link,
|
|
struct rb_node *rb_parent)
|
|
{
|
|
__vma_link_list(mm, vma, prev, rb_parent);
|
|
__vma_link_rb(mm, vma, rb_link, rb_parent);
|
|
}
|
|
|
|
static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, struct rb_node **rb_link,
|
|
struct rb_node *rb_parent)
|
|
{
|
|
struct address_space *mapping = NULL;
|
|
|
|
if (vma->vm_file) {
|
|
mapping = vma->vm_file->f_mapping;
|
|
i_mmap_lock_write(mapping);
|
|
}
|
|
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
__vma_link_file(vma);
|
|
|
|
if (mapping)
|
|
i_mmap_unlock_write(mapping);
|
|
|
|
mm->map_count++;
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* Helper for vma_adjust() in the split_vma insert case: insert a vma into the
|
|
* mm's list and rbtree. It has already been inserted into the interval tree.
|
|
*/
|
|
static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
|
|
if (find_vma_links(mm, vma->vm_start, vma->vm_end,
|
|
&prev, &rb_link, &rb_parent))
|
|
BUG();
|
|
__vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
mm->map_count++;
|
|
}
|
|
|
|
static __always_inline void __vma_unlink_common(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev,
|
|
bool has_prev,
|
|
struct vm_area_struct *ignore)
|
|
{
|
|
struct vm_area_struct *next;
|
|
|
|
vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
|
|
next = vma->vm_next;
|
|
if (has_prev)
|
|
prev->vm_next = next;
|
|
else {
|
|
prev = vma->vm_prev;
|
|
if (prev)
|
|
prev->vm_next = next;
|
|
else
|
|
mm->mmap = next;
|
|
}
|
|
if (next)
|
|
next->vm_prev = prev;
|
|
|
|
/* Kill the cache */
|
|
vmacache_invalidate(mm);
|
|
}
|
|
|
|
static inline void __vma_unlink_prev(struct mm_struct *mm,
|
|
struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev)
|
|
{
|
|
__vma_unlink_common(mm, vma, prev, true, vma);
|
|
}
|
|
|
|
/*
|
|
* We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
|
|
* is already present in an i_mmap tree without adjusting the tree.
|
|
* The following helper function should be used when such adjustments
|
|
* are necessary. The "insert" vma (if any) is to be inserted
|
|
* before we drop the necessary locks.
|
|
*/
|
|
int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
|
|
struct vm_area_struct *expand)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
|
|
struct address_space *mapping = NULL;
|
|
struct rb_root_cached *root = NULL;
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct file *file = vma->vm_file;
|
|
bool start_changed = false, end_changed = false;
|
|
long adjust_next = 0;
|
|
int remove_next = 0;
|
|
|
|
if (next && !insert) {
|
|
struct vm_area_struct *exporter = NULL, *importer = NULL;
|
|
|
|
if (end >= next->vm_end) {
|
|
/*
|
|
* vma expands, overlapping all the next, and
|
|
* perhaps the one after too (mprotect case 6).
|
|
* The only other cases that gets here are
|
|
* case 1, case 7 and case 8.
|
|
*/
|
|
if (next == expand) {
|
|
/*
|
|
* The only case where we don't expand "vma"
|
|
* and we expand "next" instead is case 8.
|
|
*/
|
|
VM_WARN_ON(end != next->vm_end);
|
|
/*
|
|
* remove_next == 3 means we're
|
|
* removing "vma" and that to do so we
|
|
* swapped "vma" and "next".
|
|
*/
|
|
remove_next = 3;
|
|
VM_WARN_ON(file != next->vm_file);
|
|
swap(vma, next);
|
|
} else {
|
|
VM_WARN_ON(expand != vma);
|
|
/*
|
|
* case 1, 6, 7, remove_next == 2 is case 6,
|
|
* remove_next == 1 is case 1 or 7.
|
|
*/
|
|
remove_next = 1 + (end > next->vm_end);
|
|
VM_WARN_ON(remove_next == 2 &&
|
|
end != next->vm_next->vm_end);
|
|
VM_WARN_ON(remove_next == 1 &&
|
|
end != next->vm_end);
|
|
/* trim end to next, for case 6 first pass */
|
|
end = next->vm_end;
|
|
}
|
|
|
|
exporter = next;
|
|
importer = vma;
|
|
|
|
/*
|
|
* If next doesn't have anon_vma, import from vma after
|
|
* next, if the vma overlaps with it.
|
|
*/
|
|
if (remove_next == 2 && !next->anon_vma)
|
|
exporter = next->vm_next;
|
|
|
|
} else if (end > next->vm_start) {
|
|
/*
|
|
* vma expands, overlapping part of the next:
|
|
* mprotect case 5 shifting the boundary up.
|
|
*/
|
|
adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
|
|
exporter = next;
|
|
importer = vma;
|
|
VM_WARN_ON(expand != importer);
|
|
} else if (end < vma->vm_end) {
|
|
/*
|
|
* vma shrinks, and !insert tells it's not
|
|
* split_vma inserting another: so it must be
|
|
* mprotect case 4 shifting the boundary down.
|
|
*/
|
|
adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
|
|
exporter = vma;
|
|
importer = next;
|
|
VM_WARN_ON(expand != importer);
|
|
}
|
|
|
|
/*
|
|
* Easily overlooked: when mprotect shifts the boundary,
|
|
* make sure the expanding vma has anon_vma set if the
|
|
* shrinking vma had, to cover any anon pages imported.
|
|
*/
|
|
if (exporter && exporter->anon_vma && !importer->anon_vma) {
|
|
int error;
|
|
|
|
importer->anon_vma = exporter->anon_vma;
|
|
error = anon_vma_clone(importer, exporter);
|
|
if (error)
|
|
return error;
|
|
}
|
|
}
|
|
again:
|
|
vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
|
|
|
|
if (file) {
|
|
mapping = file->f_mapping;
|
|
root = &mapping->i_mmap;
|
|
uprobe_munmap(vma, vma->vm_start, vma->vm_end);
|
|
|
|
if (adjust_next)
|
|
uprobe_munmap(next, next->vm_start, next->vm_end);
|
|
|
|
i_mmap_lock_write(mapping);
|
|
if (insert) {
|
|
/*
|
|
* Put into interval tree now, so instantiated pages
|
|
* are visible to arm/parisc __flush_dcache_page
|
|
* throughout; but we cannot insert into address
|
|
* space until vma start or end is updated.
|
|
*/
|
|
__vma_link_file(insert);
|
|
}
|
|
}
|
|
|
|
anon_vma = vma->anon_vma;
|
|
if (!anon_vma && adjust_next)
|
|
anon_vma = next->anon_vma;
|
|
if (anon_vma) {
|
|
VM_WARN_ON(adjust_next && next->anon_vma &&
|
|
anon_vma != next->anon_vma);
|
|
anon_vma_lock_write(anon_vma);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
if (adjust_next)
|
|
anon_vma_interval_tree_pre_update_vma(next);
|
|
}
|
|
|
|
if (root) {
|
|
flush_dcache_mmap_lock(mapping);
|
|
vma_interval_tree_remove(vma, root);
|
|
if (adjust_next)
|
|
vma_interval_tree_remove(next, root);
|
|
}
|
|
|
|
if (start != vma->vm_start) {
|
|
vma->vm_start = start;
|
|
start_changed = true;
|
|
}
|
|
if (end != vma->vm_end) {
|
|
vma->vm_end = end;
|
|
end_changed = true;
|
|
}
|
|
vma->vm_pgoff = pgoff;
|
|
if (adjust_next) {
|
|
next->vm_start += adjust_next << PAGE_SHIFT;
|
|
next->vm_pgoff += adjust_next;
|
|
}
|
|
|
|
if (root) {
|
|
if (adjust_next)
|
|
vma_interval_tree_insert(next, root);
|
|
vma_interval_tree_insert(vma, root);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
}
|
|
|
|
if (remove_next) {
|
|
/*
|
|
* vma_merge has merged next into vma, and needs
|
|
* us to remove next before dropping the locks.
|
|
*/
|
|
if (remove_next != 3)
|
|
__vma_unlink_prev(mm, next, vma);
|
|
else
|
|
/*
|
|
* vma is not before next if they've been
|
|
* swapped.
|
|
*
|
|
* pre-swap() next->vm_start was reduced so
|
|
* tell validate_mm_rb to ignore pre-swap()
|
|
* "next" (which is stored in post-swap()
|
|
* "vma").
|
|
*/
|
|
__vma_unlink_common(mm, next, NULL, false, vma);
|
|
if (file)
|
|
__remove_shared_vm_struct(next, file, mapping);
|
|
} else if (insert) {
|
|
/*
|
|
* split_vma has split insert from vma, and needs
|
|
* us to insert it before dropping the locks
|
|
* (it may either follow vma or precede it).
|
|
*/
|
|
__insert_vm_struct(mm, insert);
|
|
} else {
|
|
if (start_changed)
|
|
vma_gap_update(vma);
|
|
if (end_changed) {
|
|
if (!next)
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
else if (!adjust_next)
|
|
vma_gap_update(next);
|
|
}
|
|
}
|
|
|
|
if (anon_vma) {
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
if (adjust_next)
|
|
anon_vma_interval_tree_post_update_vma(next);
|
|
anon_vma_unlock_write(anon_vma);
|
|
}
|
|
if (mapping)
|
|
i_mmap_unlock_write(mapping);
|
|
|
|
if (root) {
|
|
uprobe_mmap(vma);
|
|
|
|
if (adjust_next)
|
|
uprobe_mmap(next);
|
|
}
|
|
|
|
if (remove_next) {
|
|
if (file) {
|
|
uprobe_munmap(next, next->vm_start, next->vm_end);
|
|
fput(file);
|
|
}
|
|
if (next->anon_vma)
|
|
anon_vma_merge(vma, next);
|
|
mm->map_count--;
|
|
mpol_put(vma_policy(next));
|
|
vm_area_free(next);
|
|
/*
|
|
* In mprotect's case 6 (see comments on vma_merge),
|
|
* we must remove another next too. It would clutter
|
|
* up the code too much to do both in one go.
|
|
*/
|
|
if (remove_next != 3) {
|
|
/*
|
|
* If "next" was removed and vma->vm_end was
|
|
* expanded (up) over it, in turn
|
|
* "next->vm_prev->vm_end" changed and the
|
|
* "vma->vm_next" gap must be updated.
|
|
*/
|
|
next = vma->vm_next;
|
|
} else {
|
|
/*
|
|
* For the scope of the comment "next" and
|
|
* "vma" considered pre-swap(): if "vma" was
|
|
* removed, next->vm_start was expanded (down)
|
|
* over it and the "next" gap must be updated.
|
|
* Because of the swap() the post-swap() "vma"
|
|
* actually points to pre-swap() "next"
|
|
* (post-swap() "next" as opposed is now a
|
|
* dangling pointer).
|
|
*/
|
|
next = vma;
|
|
}
|
|
if (remove_next == 2) {
|
|
remove_next = 1;
|
|
end = next->vm_end;
|
|
goto again;
|
|
}
|
|
else if (next)
|
|
vma_gap_update(next);
|
|
else {
|
|
/*
|
|
* If remove_next == 2 we obviously can't
|
|
* reach this path.
|
|
*
|
|
* If remove_next == 3 we can't reach this
|
|
* path because pre-swap() next is always not
|
|
* NULL. pre-swap() "next" is not being
|
|
* removed and its next->vm_end is not altered
|
|
* (and furthermore "end" already matches
|
|
* next->vm_end in remove_next == 3).
|
|
*
|
|
* We reach this only in the remove_next == 1
|
|
* case if the "next" vma that was removed was
|
|
* the highest vma of the mm. However in such
|
|
* case next->vm_end == "end" and the extended
|
|
* "vma" has vma->vm_end == next->vm_end so
|
|
* mm->highest_vm_end doesn't need any update
|
|
* in remove_next == 1 case.
|
|
*/
|
|
VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
|
|
}
|
|
}
|
|
if (insert && file)
|
|
uprobe_mmap(insert);
|
|
|
|
validate_mm(mm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* If the vma has a ->close operation then the driver probably needs to release
|
|
* per-vma resources, so we don't attempt to merge those.
|
|
*/
|
|
static inline int is_mergeable_vma(struct vm_area_struct *vma,
|
|
struct file *file, unsigned long vm_flags,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
|
|
{
|
|
/*
|
|
* VM_SOFTDIRTY should not prevent from VMA merging, if we
|
|
* match the flags but dirty bit -- the caller should mark
|
|
* merged VMA as dirty. If dirty bit won't be excluded from
|
|
* comparison, we increase pressue on the memory system forcing
|
|
* the kernel to generate new VMAs when old one could be
|
|
* extended instead.
|
|
*/
|
|
if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
|
|
return 0;
|
|
if (vma->vm_file != file)
|
|
return 0;
|
|
if (vma->vm_ops && vma->vm_ops->close)
|
|
return 0;
|
|
if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
|
|
struct anon_vma *anon_vma2,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* The list_is_singular() test is to avoid merging VMA cloned from
|
|
* parents. This can improve scalability caused by anon_vma lock.
|
|
*/
|
|
if ((!anon_vma1 || !anon_vma2) && (!vma ||
|
|
list_is_singular(&vma->anon_vma_chain)))
|
|
return 1;
|
|
return anon_vma1 == anon_vma2;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* in front of (at a lower virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*
|
|
* We don't check here for the merged mmap wrapping around the end of pagecache
|
|
* indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
|
|
* wrap, nor mmaps which cover the final page at index -1UL.
|
|
*/
|
|
static int
|
|
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
if (vma->vm_pgoff == vm_pgoff)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
|
|
* beyond (at a higher virtual address and file offset than) the vma.
|
|
*
|
|
* We cannot merge two vmas if they have differently assigned (non-NULL)
|
|
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
|
|
*/
|
|
static int
|
|
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t vm_pgoff,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
|
|
{
|
|
if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
|
|
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
|
|
pgoff_t vm_pglen;
|
|
vm_pglen = vma_pages(vma);
|
|
if (vma->vm_pgoff + vm_pglen == vm_pgoff)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
|
|
* whether that can be merged with its predecessor or its successor.
|
|
* Or both (it neatly fills a hole).
|
|
*
|
|
* In most cases - when called for mmap, brk or mremap - [addr,end) is
|
|
* certain not to be mapped by the time vma_merge is called; but when
|
|
* called for mprotect, it is certain to be already mapped (either at
|
|
* an offset within prev, or at the start of next), and the flags of
|
|
* this area are about to be changed to vm_flags - and the no-change
|
|
* case has already been eliminated.
|
|
*
|
|
* The following mprotect cases have to be considered, where AAAA is
|
|
* the area passed down from mprotect_fixup, never extending beyond one
|
|
* vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
|
|
*
|
|
* AAAA AAAA AAAA AAAA
|
|
* PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
|
|
* cannot merge might become might become might become
|
|
* PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
|
|
* mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
|
|
* mremap move: PPPPXXXXXXXX 8
|
|
* AAAA
|
|
* PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
|
|
* might become case 1 below case 2 below case 3 below
|
|
*
|
|
* It is important for case 8 that the the vma NNNN overlapping the
|
|
* region AAAA is never going to extended over XXXX. Instead XXXX must
|
|
* be extended in region AAAA and NNNN must be removed. This way in
|
|
* all cases where vma_merge succeeds, the moment vma_adjust drops the
|
|
* rmap_locks, the properties of the merged vma will be already
|
|
* correct for the whole merged range. Some of those properties like
|
|
* vm_page_prot/vm_flags may be accessed by rmap_walks and they must
|
|
* be correct for the whole merged range immediately after the
|
|
* rmap_locks are released. Otherwise if XXXX would be removed and
|
|
* NNNN would be extended over the XXXX range, remove_migration_ptes
|
|
* or other rmap walkers (if working on addresses beyond the "end"
|
|
* parameter) may establish ptes with the wrong permissions of NNNN
|
|
* instead of the right permissions of XXXX.
|
|
*/
|
|
struct vm_area_struct *vma_merge(struct mm_struct *mm,
|
|
struct vm_area_struct *prev, unsigned long addr,
|
|
unsigned long end, unsigned long vm_flags,
|
|
struct anon_vma *anon_vma, struct file *file,
|
|
pgoff_t pgoff, struct mempolicy *policy,
|
|
struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
|
|
{
|
|
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
|
|
struct vm_area_struct *area, *next;
|
|
int err;
|
|
|
|
/*
|
|
* We later require that vma->vm_flags == vm_flags,
|
|
* so this tests vma->vm_flags & VM_SPECIAL, too.
|
|
*/
|
|
if (vm_flags & VM_SPECIAL)
|
|
return NULL;
|
|
|
|
if (prev)
|
|
next = prev->vm_next;
|
|
else
|
|
next = mm->mmap;
|
|
area = next;
|
|
if (area && area->vm_end == end) /* cases 6, 7, 8 */
|
|
next = next->vm_next;
|
|
|
|
/* verify some invariant that must be enforced by the caller */
|
|
VM_WARN_ON(prev && addr <= prev->vm_start);
|
|
VM_WARN_ON(area && end > area->vm_end);
|
|
VM_WARN_ON(addr >= end);
|
|
|
|
/*
|
|
* Can it merge with the predecessor?
|
|
*/
|
|
if (prev && prev->vm_end == addr &&
|
|
mpol_equal(vma_policy(prev), policy) &&
|
|
can_vma_merge_after(prev, vm_flags,
|
|
anon_vma, file, pgoff,
|
|
vm_userfaultfd_ctx)) {
|
|
/*
|
|
* OK, it can. Can we now merge in the successor as well?
|
|
*/
|
|
if (next && end == next->vm_start &&
|
|
mpol_equal(policy, vma_policy(next)) &&
|
|
can_vma_merge_before(next, vm_flags,
|
|
anon_vma, file,
|
|
pgoff+pglen,
|
|
vm_userfaultfd_ctx) &&
|
|
is_mergeable_anon_vma(prev->anon_vma,
|
|
next->anon_vma, NULL)) {
|
|
/* cases 1, 6 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
next->vm_end, prev->vm_pgoff, NULL,
|
|
prev);
|
|
} else /* cases 2, 5, 7 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
end, prev->vm_pgoff, NULL, prev);
|
|
if (err)
|
|
return NULL;
|
|
khugepaged_enter_vma_merge(prev, vm_flags);
|
|
return prev;
|
|
}
|
|
|
|
/*
|
|
* Can this new request be merged in front of next?
|
|
*/
|
|
if (next && end == next->vm_start &&
|
|
mpol_equal(policy, vma_policy(next)) &&
|
|
can_vma_merge_before(next, vm_flags,
|
|
anon_vma, file, pgoff+pglen,
|
|
vm_userfaultfd_ctx)) {
|
|
if (prev && addr < prev->vm_end) /* case 4 */
|
|
err = __vma_adjust(prev, prev->vm_start,
|
|
addr, prev->vm_pgoff, NULL, next);
|
|
else { /* cases 3, 8 */
|
|
err = __vma_adjust(area, addr, next->vm_end,
|
|
next->vm_pgoff - pglen, NULL, next);
|
|
/*
|
|
* In case 3 area is already equal to next and
|
|
* this is a noop, but in case 8 "area" has
|
|
* been removed and next was expanded over it.
|
|
*/
|
|
area = next;
|
|
}
|
|
if (err)
|
|
return NULL;
|
|
khugepaged_enter_vma_merge(area, vm_flags);
|
|
return area;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Rough compatbility check to quickly see if it's even worth looking
|
|
* at sharing an anon_vma.
|
|
*
|
|
* They need to have the same vm_file, and the flags can only differ
|
|
* in things that mprotect may change.
|
|
*
|
|
* NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
|
|
* we can merge the two vma's. For example, we refuse to merge a vma if
|
|
* there is a vm_ops->close() function, because that indicates that the
|
|
* driver is doing some kind of reference counting. But that doesn't
|
|
* really matter for the anon_vma sharing case.
|
|
*/
|
|
static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
return a->vm_end == b->vm_start &&
|
|
mpol_equal(vma_policy(a), vma_policy(b)) &&
|
|
a->vm_file == b->vm_file &&
|
|
!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
|
|
b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
/*
|
|
* Do some basic sanity checking to see if we can re-use the anon_vma
|
|
* from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
|
|
* the same as 'old', the other will be the new one that is trying
|
|
* to share the anon_vma.
|
|
*
|
|
* NOTE! This runs with mm_sem held for reading, so it is possible that
|
|
* the anon_vma of 'old' is concurrently in the process of being set up
|
|
* by another page fault trying to merge _that_. But that's ok: if it
|
|
* is being set up, that automatically means that it will be a singleton
|
|
* acceptable for merging, so we can do all of this optimistically. But
|
|
* we do that READ_ONCE() to make sure that we never re-load the pointer.
|
|
*
|
|
* IOW: that the "list_is_singular()" test on the anon_vma_chain only
|
|
* matters for the 'stable anon_vma' case (ie the thing we want to avoid
|
|
* is to return an anon_vma that is "complex" due to having gone through
|
|
* a fork).
|
|
*
|
|
* We also make sure that the two vma's are compatible (adjacent,
|
|
* and with the same memory policies). That's all stable, even with just
|
|
* a read lock on the mm_sem.
|
|
*/
|
|
static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
|
|
{
|
|
if (anon_vma_compatible(a, b)) {
|
|
struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
|
|
|
|
if (anon_vma && list_is_singular(&old->anon_vma_chain))
|
|
return anon_vma;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_mergeable_anon_vma is used by anon_vma_prepare, to check
|
|
* neighbouring vmas for a suitable anon_vma, before it goes off
|
|
* to allocate a new anon_vma. It checks because a repetitive
|
|
* sequence of mprotects and faults may otherwise lead to distinct
|
|
* anon_vmas being allocated, preventing vma merge in subsequent
|
|
* mprotect.
|
|
*/
|
|
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
struct vm_area_struct *near;
|
|
|
|
near = vma->vm_next;
|
|
if (!near)
|
|
goto try_prev;
|
|
|
|
anon_vma = reusable_anon_vma(near, vma, near);
|
|
if (anon_vma)
|
|
return anon_vma;
|
|
try_prev:
|
|
near = vma->vm_prev;
|
|
if (!near)
|
|
goto none;
|
|
|
|
anon_vma = reusable_anon_vma(near, near, vma);
|
|
if (anon_vma)
|
|
return anon_vma;
|
|
none:
|
|
/*
|
|
* There's no absolute need to look only at touching neighbours:
|
|
* we could search further afield for "compatible" anon_vmas.
|
|
* But it would probably just be a waste of time searching,
|
|
* or lead to too many vmas hanging off the same anon_vma.
|
|
* We're trying to allow mprotect remerging later on,
|
|
* not trying to minimize memory used for anon_vmas.
|
|
*/
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* If a hint addr is less than mmap_min_addr change hint to be as
|
|
* low as possible but still greater than mmap_min_addr
|
|
*/
|
|
static inline unsigned long round_hint_to_min(unsigned long hint)
|
|
{
|
|
hint &= PAGE_MASK;
|
|
if (((void *)hint != NULL) &&
|
|
(hint < mmap_min_addr))
|
|
return PAGE_ALIGN(mmap_min_addr);
|
|
return hint;
|
|
}
|
|
|
|
static inline int mlock_future_check(struct mm_struct *mm,
|
|
unsigned long flags,
|
|
unsigned long len)
|
|
{
|
|
unsigned long locked, lock_limit;
|
|
|
|
/* mlock MCL_FUTURE? */
|
|
if (flags & VM_LOCKED) {
|
|
locked = len >> PAGE_SHIFT;
|
|
locked += mm->locked_vm;
|
|
lock_limit = rlimit(RLIMIT_MEMLOCK);
|
|
lock_limit >>= PAGE_SHIFT;
|
|
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
|
|
return -EAGAIN;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
|
|
{
|
|
if (S_ISREG(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
if (S_ISBLK(inode->i_mode))
|
|
return MAX_LFS_FILESIZE;
|
|
|
|
/* Special "we do even unsigned file positions" case */
|
|
if (file->f_mode & FMODE_UNSIGNED_OFFSET)
|
|
return 0;
|
|
|
|
/* Yes, random drivers might want more. But I'm tired of buggy drivers */
|
|
return ULONG_MAX;
|
|
}
|
|
|
|
static inline bool file_mmap_ok(struct file *file, struct inode *inode,
|
|
unsigned long pgoff, unsigned long len)
|
|
{
|
|
u64 maxsize = file_mmap_size_max(file, inode);
|
|
|
|
if (maxsize && len > maxsize)
|
|
return false;
|
|
maxsize -= len;
|
|
if (pgoff > maxsize >> PAGE_SHIFT)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* The caller must hold down_write(¤t->mm->mmap_sem).
|
|
*/
|
|
unsigned long do_mmap(struct file *file, unsigned long addr,
|
|
unsigned long len, unsigned long prot,
|
|
unsigned long flags, vm_flags_t vm_flags,
|
|
unsigned long pgoff, unsigned long *populate,
|
|
struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
int pkey = 0;
|
|
|
|
*populate = 0;
|
|
|
|
if (!len)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Does the application expect PROT_READ to imply PROT_EXEC?
|
|
*
|
|
* (the exception is when the underlying filesystem is noexec
|
|
* mounted, in which case we dont add PROT_EXEC.)
|
|
*/
|
|
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
|
|
if (!(file && path_noexec(&file->f_path)))
|
|
prot |= PROT_EXEC;
|
|
|
|
/* force arch specific MAP_FIXED handling in get_unmapped_area */
|
|
if (flags & MAP_FIXED_NOREPLACE)
|
|
flags |= MAP_FIXED;
|
|
|
|
if (!(flags & MAP_FIXED))
|
|
addr = round_hint_to_min(addr);
|
|
|
|
/* Careful about overflows.. */
|
|
len = PAGE_ALIGN(len);
|
|
if (!len)
|
|
return -ENOMEM;
|
|
|
|
/* offset overflow? */
|
|
if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
|
|
return -EOVERFLOW;
|
|
|
|
/* Too many mappings? */
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
/* Obtain the address to map to. we verify (or select) it and ensure
|
|
* that it represents a valid section of the address space.
|
|
*/
|
|
addr = get_unmapped_area(file, addr, len, pgoff, flags);
|
|
if (offset_in_page(addr))
|
|
return addr;
|
|
|
|
if (flags & MAP_FIXED_NOREPLACE) {
|
|
struct vm_area_struct *vma = find_vma(mm, addr);
|
|
|
|
if (vma && vma->vm_start < addr + len)
|
|
return -EEXIST;
|
|
}
|
|
|
|
if (prot == PROT_EXEC) {
|
|
pkey = execute_only_pkey(mm);
|
|
if (pkey < 0)
|
|
pkey = 0;
|
|
}
|
|
|
|
/* Do simple checking here so the lower-level routines won't have
|
|
* to. we assume access permissions have been handled by the open
|
|
* of the memory object, so we don't do any here.
|
|
*/
|
|
vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
|
|
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
|
|
|
|
if (flags & MAP_LOCKED)
|
|
if (!can_do_mlock())
|
|
return -EPERM;
|
|
|
|
if (mlock_future_check(mm, vm_flags, len))
|
|
return -EAGAIN;
|
|
|
|
if (file) {
|
|
struct inode *inode = file_inode(file);
|
|
unsigned long flags_mask;
|
|
|
|
if (!file_mmap_ok(file, inode, pgoff, len))
|
|
return -EOVERFLOW;
|
|
|
|
flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
|
|
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
/*
|
|
* Force use of MAP_SHARED_VALIDATE with non-legacy
|
|
* flags. E.g. MAP_SYNC is dangerous to use with
|
|
* MAP_SHARED as you don't know which consistency model
|
|
* you will get. We silently ignore unsupported flags
|
|
* with MAP_SHARED to preserve backward compatibility.
|
|
*/
|
|
flags &= LEGACY_MAP_MASK;
|
|
/* fall through */
|
|
case MAP_SHARED_VALIDATE:
|
|
if (flags & ~flags_mask)
|
|
return -EOPNOTSUPP;
|
|
if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
/*
|
|
* Make sure we don't allow writing to an append-only
|
|
* file..
|
|
*/
|
|
if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
|
|
return -EACCES;
|
|
|
|
/*
|
|
* Make sure there are no mandatory locks on the file.
|
|
*/
|
|
if (locks_verify_locked(file))
|
|
return -EAGAIN;
|
|
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
|
|
|
|
/* fall through */
|
|
case MAP_PRIVATE:
|
|
if (!(file->f_mode & FMODE_READ))
|
|
return -EACCES;
|
|
if (path_noexec(&file->f_path)) {
|
|
if (vm_flags & VM_EXEC)
|
|
return -EPERM;
|
|
vm_flags &= ~VM_MAYEXEC;
|
|
}
|
|
|
|
if (!file->f_op->mmap)
|
|
return -ENODEV;
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
break;
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
switch (flags & MAP_TYPE) {
|
|
case MAP_SHARED:
|
|
if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
|
|
return -EINVAL;
|
|
/*
|
|
* Ignore pgoff.
|
|
*/
|
|
pgoff = 0;
|
|
vm_flags |= VM_SHARED | VM_MAYSHARE;
|
|
break;
|
|
case MAP_PRIVATE:
|
|
/*
|
|
* Set pgoff according to addr for anon_vma.
|
|
*/
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Set 'VM_NORESERVE' if we should not account for the
|
|
* memory use of this mapping.
|
|
*/
|
|
if (flags & MAP_NORESERVE) {
|
|
/* We honor MAP_NORESERVE if allowed to overcommit */
|
|
if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
|
|
vm_flags |= VM_NORESERVE;
|
|
|
|
/* hugetlb applies strict overcommit unless MAP_NORESERVE */
|
|
if (file && is_file_hugepages(file))
|
|
vm_flags |= VM_NORESERVE;
|
|
}
|
|
|
|
addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
|
|
if (!IS_ERR_VALUE(addr) &&
|
|
((vm_flags & VM_LOCKED) ||
|
|
(flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
|
|
*populate = len;
|
|
return addr;
|
|
}
|
|
|
|
unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
|
|
unsigned long prot, unsigned long flags,
|
|
unsigned long fd, unsigned long pgoff)
|
|
{
|
|
struct file *file = NULL;
|
|
unsigned long retval;
|
|
|
|
if (!(flags & MAP_ANONYMOUS)) {
|
|
audit_mmap_fd(fd, flags);
|
|
file = fget(fd);
|
|
if (!file)
|
|
return -EBADF;
|
|
if (is_file_hugepages(file))
|
|
len = ALIGN(len, huge_page_size(hstate_file(file)));
|
|
retval = -EINVAL;
|
|
if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
|
|
goto out_fput;
|
|
} else if (flags & MAP_HUGETLB) {
|
|
struct user_struct *user = NULL;
|
|
struct hstate *hs;
|
|
|
|
hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (!hs)
|
|
return -EINVAL;
|
|
|
|
len = ALIGN(len, huge_page_size(hs));
|
|
/*
|
|
* VM_NORESERVE is used because the reservations will be
|
|
* taken when vm_ops->mmap() is called
|
|
* A dummy user value is used because we are not locking
|
|
* memory so no accounting is necessary
|
|
*/
|
|
file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
|
|
VM_NORESERVE,
|
|
&user, HUGETLB_ANONHUGE_INODE,
|
|
(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
}
|
|
|
|
flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
|
|
|
|
retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
|
|
out_fput:
|
|
if (file)
|
|
fput(file);
|
|
return retval;
|
|
}
|
|
|
|
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
|
|
unsigned long, prot, unsigned long, flags,
|
|
unsigned long, fd, unsigned long, pgoff)
|
|
{
|
|
return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_OLD_MMAP
|
|
struct mmap_arg_struct {
|
|
unsigned long addr;
|
|
unsigned long len;
|
|
unsigned long prot;
|
|
unsigned long flags;
|
|
unsigned long fd;
|
|
unsigned long offset;
|
|
};
|
|
|
|
SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
|
|
{
|
|
struct mmap_arg_struct a;
|
|
|
|
if (copy_from_user(&a, arg, sizeof(a)))
|
|
return -EFAULT;
|
|
if (offset_in_page(a.offset))
|
|
return -EINVAL;
|
|
|
|
return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
|
|
a.offset >> PAGE_SHIFT);
|
|
}
|
|
#endif /* __ARCH_WANT_SYS_OLD_MMAP */
|
|
|
|
/*
|
|
* Some shared mappigns will want the pages marked read-only
|
|
* to track write events. If so, we'll downgrade vm_page_prot
|
|
* to the private version (using protection_map[] without the
|
|
* VM_SHARED bit).
|
|
*/
|
|
int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
|
|
{
|
|
vm_flags_t vm_flags = vma->vm_flags;
|
|
const struct vm_operations_struct *vm_ops = vma->vm_ops;
|
|
|
|
/* If it was private or non-writable, the write bit is already clear */
|
|
if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
|
|
return 0;
|
|
|
|
/* The backer wishes to know when pages are first written to? */
|
|
if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
|
|
return 1;
|
|
|
|
/* The open routine did something to the protections that pgprot_modify
|
|
* won't preserve? */
|
|
if (pgprot_val(vm_page_prot) !=
|
|
pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
|
|
return 0;
|
|
|
|
/* Do we need to track softdirty? */
|
|
if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
|
|
return 1;
|
|
|
|
/* Specialty mapping? */
|
|
if (vm_flags & VM_PFNMAP)
|
|
return 0;
|
|
|
|
/* Can the mapping track the dirty pages? */
|
|
return vma->vm_file && vma->vm_file->f_mapping &&
|
|
mapping_cap_account_dirty(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
/*
|
|
* We account for memory if it's a private writeable mapping,
|
|
* not hugepages and VM_NORESERVE wasn't set.
|
|
*/
|
|
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
|
|
{
|
|
/*
|
|
* hugetlb has its own accounting separate from the core VM
|
|
* VM_HUGETLB may not be set yet so we cannot check for that flag.
|
|
*/
|
|
if (file && is_file_hugepages(file))
|
|
return 0;
|
|
|
|
return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
|
|
}
|
|
|
|
unsigned long mmap_region(struct file *file, unsigned long addr,
|
|
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
|
|
struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
int error;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
unsigned long charged = 0;
|
|
|
|
/* Check against address space limit. */
|
|
if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
|
|
unsigned long nr_pages;
|
|
|
|
/*
|
|
* MAP_FIXED may remove pages of mappings that intersects with
|
|
* requested mapping. Account for the pages it would unmap.
|
|
*/
|
|
nr_pages = count_vma_pages_range(mm, addr, addr + len);
|
|
|
|
if (!may_expand_vm(mm, vm_flags,
|
|
(len >> PAGE_SHIFT) - nr_pages))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Clear old maps */
|
|
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
|
|
&rb_parent)) {
|
|
if (do_munmap(mm, addr, len, uf))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* Private writable mapping: check memory availability
|
|
*/
|
|
if (accountable_mapping(file, vm_flags)) {
|
|
charged = len >> PAGE_SHIFT;
|
|
if (security_vm_enough_memory_mm(mm, charged))
|
|
return -ENOMEM;
|
|
vm_flags |= VM_ACCOUNT;
|
|
}
|
|
|
|
/*
|
|
* Can we just expand an old mapping?
|
|
*/
|
|
vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
|
|
NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
|
|
if (vma)
|
|
goto out;
|
|
|
|
/*
|
|
* Determine the object being mapped and call the appropriate
|
|
* specific mapper. the address has already been validated, but
|
|
* not unmapped, but the maps are removed from the list.
|
|
*/
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma) {
|
|
error = -ENOMEM;
|
|
goto unacct_error;
|
|
}
|
|
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
vma->vm_flags = vm_flags;
|
|
vma->vm_page_prot = vm_get_page_prot(vm_flags);
|
|
vma->vm_pgoff = pgoff;
|
|
|
|
if (file) {
|
|
if (vm_flags & VM_DENYWRITE) {
|
|
error = deny_write_access(file);
|
|
if (error)
|
|
goto free_vma;
|
|
}
|
|
if (vm_flags & VM_SHARED) {
|
|
error = mapping_map_writable(file->f_mapping);
|
|
if (error)
|
|
goto allow_write_and_free_vma;
|
|
}
|
|
|
|
/* ->mmap() can change vma->vm_file, but must guarantee that
|
|
* vma_link() below can deny write-access if VM_DENYWRITE is set
|
|
* and map writably if VM_SHARED is set. This usually means the
|
|
* new file must not have been exposed to user-space, yet.
|
|
*/
|
|
vma->vm_file = get_file(file);
|
|
error = call_mmap(file, vma);
|
|
if (error)
|
|
goto unmap_and_free_vma;
|
|
|
|
/* Can addr have changed??
|
|
*
|
|
* Answer: Yes, several device drivers can do it in their
|
|
* f_op->mmap method. -DaveM
|
|
* Bug: If addr is changed, prev, rb_link, rb_parent should
|
|
* be updated for vma_link()
|
|
*/
|
|
WARN_ON_ONCE(addr != vma->vm_start);
|
|
|
|
addr = vma->vm_start;
|
|
vm_flags = vma->vm_flags;
|
|
} else if (vm_flags & VM_SHARED) {
|
|
error = shmem_zero_setup(vma);
|
|
if (error)
|
|
goto free_vma;
|
|
} else {
|
|
vma_set_anonymous(vma);
|
|
}
|
|
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
/* Once vma denies write, undo our temporary denial count */
|
|
if (file) {
|
|
if (vm_flags & VM_SHARED)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
if (vm_flags & VM_DENYWRITE)
|
|
allow_write_access(file);
|
|
}
|
|
file = vma->vm_file;
|
|
out:
|
|
perf_event_mmap(vma);
|
|
|
|
vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
|
|
if (vm_flags & VM_LOCKED) {
|
|
if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
|
|
is_vm_hugetlb_page(vma) ||
|
|
vma == get_gate_vma(current->mm))
|
|
vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
|
|
else
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
}
|
|
|
|
if (file)
|
|
uprobe_mmap(vma);
|
|
|
|
/*
|
|
* New (or expanded) vma always get soft dirty status.
|
|
* Otherwise user-space soft-dirty page tracker won't
|
|
* be able to distinguish situation when vma area unmapped,
|
|
* then new mapped in-place (which must be aimed as
|
|
* a completely new data area).
|
|
*/
|
|
vma->vm_flags |= VM_SOFTDIRTY;
|
|
|
|
vma_set_page_prot(vma);
|
|
|
|
return addr;
|
|
|
|
unmap_and_free_vma:
|
|
vma->vm_file = NULL;
|
|
fput(file);
|
|
|
|
/* Undo any partial mapping done by a device driver. */
|
|
unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
|
|
charged = 0;
|
|
if (vm_flags & VM_SHARED)
|
|
mapping_unmap_writable(file->f_mapping);
|
|
allow_write_and_free_vma:
|
|
if (vm_flags & VM_DENYWRITE)
|
|
allow_write_access(file);
|
|
free_vma:
|
|
vm_area_free(vma);
|
|
unacct_error:
|
|
if (charged)
|
|
vm_unacct_memory(charged);
|
|
return error;
|
|
}
|
|
|
|
unsigned long unmapped_area(struct vm_unmapped_area_info *info)
|
|
{
|
|
/*
|
|
* We implement the search by looking for an rbtree node that
|
|
* immediately follows a suitable gap. That is,
|
|
* - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
|
|
* - gap_end = vma->vm_start >= info->low_limit + length;
|
|
* - gap_end - gap_start >= length
|
|
*/
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long length, low_limit, high_limit, gap_start, gap_end;
|
|
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
/* Adjust search limits by the desired length */
|
|
if (info->high_limit < length)
|
|
return -ENOMEM;
|
|
high_limit = info->high_limit - length;
|
|
|
|
if (info->low_limit > high_limit)
|
|
return -ENOMEM;
|
|
low_limit = info->low_limit + length;
|
|
|
|
/* Check if rbtree root looks promising */
|
|
if (RB_EMPTY_ROOT(&mm->mm_rb))
|
|
goto check_highest;
|
|
vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
|
|
if (vma->rb_subtree_gap < length)
|
|
goto check_highest;
|
|
|
|
while (true) {
|
|
/* Visit left subtree if it looks promising */
|
|
gap_end = vm_start_gap(vma);
|
|
if (gap_end >= low_limit && vma->vm_rb.rb_left) {
|
|
struct vm_area_struct *left =
|
|
rb_entry(vma->vm_rb.rb_left,
|
|
struct vm_area_struct, vm_rb);
|
|
if (left->rb_subtree_gap >= length) {
|
|
vma = left;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
|
check_current:
|
|
/* Check if current node has a suitable gap */
|
|
if (gap_start > high_limit)
|
|
return -ENOMEM;
|
|
if (gap_end >= low_limit &&
|
|
gap_end > gap_start && gap_end - gap_start >= length)
|
|
goto found;
|
|
|
|
/* Visit right subtree if it looks promising */
|
|
if (vma->vm_rb.rb_right) {
|
|
struct vm_area_struct *right =
|
|
rb_entry(vma->vm_rb.rb_right,
|
|
struct vm_area_struct, vm_rb);
|
|
if (right->rb_subtree_gap >= length) {
|
|
vma = right;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Go back up the rbtree to find next candidate node */
|
|
while (true) {
|
|
struct rb_node *prev = &vma->vm_rb;
|
|
if (!rb_parent(prev))
|
|
goto check_highest;
|
|
vma = rb_entry(rb_parent(prev),
|
|
struct vm_area_struct, vm_rb);
|
|
if (prev == vma->vm_rb.rb_left) {
|
|
gap_start = vm_end_gap(vma->vm_prev);
|
|
gap_end = vm_start_gap(vma);
|
|
goto check_current;
|
|
}
|
|
}
|
|
}
|
|
|
|
check_highest:
|
|
/* Check highest gap, which does not precede any rbtree node */
|
|
gap_start = mm->highest_vm_end;
|
|
gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
|
|
if (gap_start > high_limit)
|
|
return -ENOMEM;
|
|
|
|
found:
|
|
/* We found a suitable gap. Clip it with the original low_limit. */
|
|
if (gap_start < info->low_limit)
|
|
gap_start = info->low_limit;
|
|
|
|
/* Adjust gap address to the desired alignment */
|
|
gap_start += (info->align_offset - gap_start) & info->align_mask;
|
|
|
|
VM_BUG_ON(gap_start + info->length > info->high_limit);
|
|
VM_BUG_ON(gap_start + info->length > gap_end);
|
|
return gap_start;
|
|
}
|
|
|
|
unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long length, low_limit, high_limit, gap_start, gap_end;
|
|
|
|
/* Adjust search length to account for worst case alignment overhead */
|
|
length = info->length + info->align_mask;
|
|
if (length < info->length)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Adjust search limits by the desired length.
|
|
* See implementation comment at top of unmapped_area().
|
|
*/
|
|
gap_end = info->high_limit;
|
|
if (gap_end < length)
|
|
return -ENOMEM;
|
|
high_limit = gap_end - length;
|
|
|
|
if (info->low_limit > high_limit)
|
|
return -ENOMEM;
|
|
low_limit = info->low_limit + length;
|
|
|
|
/* Check highest gap, which does not precede any rbtree node */
|
|
gap_start = mm->highest_vm_end;
|
|
if (gap_start <= high_limit)
|
|
goto found_highest;
|
|
|
|
/* Check if rbtree root looks promising */
|
|
if (RB_EMPTY_ROOT(&mm->mm_rb))
|
|
return -ENOMEM;
|
|
vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
|
|
if (vma->rb_subtree_gap < length)
|
|
return -ENOMEM;
|
|
|
|
while (true) {
|
|
/* Visit right subtree if it looks promising */
|
|
gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
|
|
if (gap_start <= high_limit && vma->vm_rb.rb_right) {
|
|
struct vm_area_struct *right =
|
|
rb_entry(vma->vm_rb.rb_right,
|
|
struct vm_area_struct, vm_rb);
|
|
if (right->rb_subtree_gap >= length) {
|
|
vma = right;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
check_current:
|
|
/* Check if current node has a suitable gap */
|
|
gap_end = vm_start_gap(vma);
|
|
if (gap_end < low_limit)
|
|
return -ENOMEM;
|
|
if (gap_start <= high_limit &&
|
|
gap_end > gap_start && gap_end - gap_start >= length)
|
|
goto found;
|
|
|
|
/* Visit left subtree if it looks promising */
|
|
if (vma->vm_rb.rb_left) {
|
|
struct vm_area_struct *left =
|
|
rb_entry(vma->vm_rb.rb_left,
|
|
struct vm_area_struct, vm_rb);
|
|
if (left->rb_subtree_gap >= length) {
|
|
vma = left;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Go back up the rbtree to find next candidate node */
|
|
while (true) {
|
|
struct rb_node *prev = &vma->vm_rb;
|
|
if (!rb_parent(prev))
|
|
return -ENOMEM;
|
|
vma = rb_entry(rb_parent(prev),
|
|
struct vm_area_struct, vm_rb);
|
|
if (prev == vma->vm_rb.rb_right) {
|
|
gap_start = vma->vm_prev ?
|
|
vm_end_gap(vma->vm_prev) : 0;
|
|
goto check_current;
|
|
}
|
|
}
|
|
}
|
|
|
|
found:
|
|
/* We found a suitable gap. Clip it with the original high_limit. */
|
|
if (gap_end > info->high_limit)
|
|
gap_end = info->high_limit;
|
|
|
|
found_highest:
|
|
/* Compute highest gap address at the desired alignment */
|
|
gap_end -= info->length;
|
|
gap_end -= (gap_end - info->align_offset) & info->align_mask;
|
|
|
|
VM_BUG_ON(gap_end < info->low_limit);
|
|
VM_BUG_ON(gap_end < gap_start);
|
|
return gap_end;
|
|
}
|
|
|
|
|
|
#ifndef arch_get_mmap_end
|
|
#define arch_get_mmap_end(addr) (TASK_SIZE)
|
|
#endif
|
|
|
|
#ifndef arch_get_mmap_base
|
|
#define arch_get_mmap_base(addr, base) (base)
|
|
#endif
|
|
|
|
/* Get an address range which is currently unmapped.
|
|
* For shmat() with addr=0.
|
|
*
|
|
* Ugly calling convention alert:
|
|
* Return value with the low bits set means error value,
|
|
* ie
|
|
* if (ret & ~PAGE_MASK)
|
|
* error = ret;
|
|
*
|
|
* This function "knows" that -ENOMEM has the bits set.
|
|
*/
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA
|
|
unsigned long
|
|
arch_get_unmapped_area(struct file *filp, unsigned long addr,
|
|
unsigned long len, unsigned long pgoff, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr);
|
|
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = 0;
|
|
info.length = len;
|
|
info.low_limit = mm->mmap_base;
|
|
info.high_limit = mmap_end;
|
|
info.align_mask = 0;
|
|
return vm_unmapped_area(&info);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* This mmap-allocator allocates new areas top-down from below the
|
|
* stack's low limit (the base):
|
|
*/
|
|
#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
|
|
unsigned long
|
|
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
|
|
const unsigned long len, const unsigned long pgoff,
|
|
const unsigned long flags)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long addr = addr0;
|
|
struct vm_unmapped_area_info info;
|
|
const unsigned long mmap_end = arch_get_mmap_end(addr);
|
|
|
|
/* requested length too big for entire address space */
|
|
if (len > mmap_end - mmap_min_addr)
|
|
return -ENOMEM;
|
|
|
|
if (flags & MAP_FIXED)
|
|
return addr;
|
|
|
|
/* requesting a specific address */
|
|
if (addr) {
|
|
addr = PAGE_ALIGN(addr);
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (mmap_end - len >= addr && addr >= mmap_min_addr &&
|
|
(!vma || addr + len <= vm_start_gap(vma)) &&
|
|
(!prev || addr >= vm_end_gap(prev)))
|
|
return addr;
|
|
}
|
|
|
|
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
|
|
info.length = len;
|
|
info.low_limit = max(PAGE_SIZE, mmap_min_addr);
|
|
info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
|
|
info.align_mask = 0;
|
|
addr = vm_unmapped_area(&info);
|
|
|
|
/*
|
|
* A failed mmap() very likely causes application failure,
|
|
* so fall back to the bottom-up function here. This scenario
|
|
* can happen with large stack limits and large mmap()
|
|
* allocations.
|
|
*/
|
|
if (offset_in_page(addr)) {
|
|
VM_BUG_ON(addr != -ENOMEM);
|
|
info.flags = 0;
|
|
info.low_limit = TASK_UNMAPPED_BASE;
|
|
info.high_limit = mmap_end;
|
|
addr = vm_unmapped_area(&info);
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
#endif
|
|
|
|
unsigned long
|
|
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
|
|
unsigned long pgoff, unsigned long flags)
|
|
{
|
|
unsigned long (*get_area)(struct file *, unsigned long,
|
|
unsigned long, unsigned long, unsigned long);
|
|
|
|
unsigned long error = arch_mmap_check(addr, len, flags);
|
|
if (error)
|
|
return error;
|
|
|
|
/* Careful about overflows.. */
|
|
if (len > TASK_SIZE)
|
|
return -ENOMEM;
|
|
|
|
get_area = current->mm->get_unmapped_area;
|
|
if (file) {
|
|
if (file->f_op->get_unmapped_area)
|
|
get_area = file->f_op->get_unmapped_area;
|
|
} else if (flags & MAP_SHARED) {
|
|
/*
|
|
* mmap_region() will call shmem_zero_setup() to create a file,
|
|
* so use shmem's get_unmapped_area in case it can be huge.
|
|
* do_mmap_pgoff() will clear pgoff, so match alignment.
|
|
*/
|
|
pgoff = 0;
|
|
get_area = shmem_get_unmapped_area;
|
|
}
|
|
|
|
addr = get_area(file, addr, len, pgoff, flags);
|
|
if (IS_ERR_VALUE(addr))
|
|
return addr;
|
|
|
|
if (addr > TASK_SIZE - len)
|
|
return -ENOMEM;
|
|
if (offset_in_page(addr))
|
|
return -EINVAL;
|
|
|
|
error = security_mmap_addr(addr);
|
|
return error ? error : addr;
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_unmapped_area);
|
|
|
|
/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
|
|
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct rb_node *rb_node;
|
|
struct vm_area_struct *vma;
|
|
|
|
/* Check the cache first. */
|
|
vma = vmacache_find(mm, addr);
|
|
if (likely(vma))
|
|
return vma;
|
|
|
|
rb_node = mm->mm_rb.rb_node;
|
|
|
|
while (rb_node) {
|
|
struct vm_area_struct *tmp;
|
|
|
|
tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
|
|
|
|
if (tmp->vm_end > addr) {
|
|
vma = tmp;
|
|
if (tmp->vm_start <= addr)
|
|
break;
|
|
rb_node = rb_node->rb_left;
|
|
} else
|
|
rb_node = rb_node->rb_right;
|
|
}
|
|
|
|
if (vma)
|
|
vmacache_update(addr, vma);
|
|
return vma;
|
|
}
|
|
|
|
EXPORT_SYMBOL(find_vma);
|
|
|
|
/*
|
|
* Same as find_vma, but also return a pointer to the previous VMA in *pprev.
|
|
*/
|
|
struct vm_area_struct *
|
|
find_vma_prev(struct mm_struct *mm, unsigned long addr,
|
|
struct vm_area_struct **pprev)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
|
|
vma = find_vma(mm, addr);
|
|
if (vma) {
|
|
*pprev = vma->vm_prev;
|
|
} else {
|
|
struct rb_node *rb_node = mm->mm_rb.rb_node;
|
|
*pprev = NULL;
|
|
while (rb_node) {
|
|
*pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
|
|
rb_node = rb_node->rb_right;
|
|
}
|
|
}
|
|
return vma;
|
|
}
|
|
|
|
/*
|
|
* Verify that the stack growth is acceptable and
|
|
* update accounting. This is shared with both the
|
|
* grow-up and grow-down cases.
|
|
*/
|
|
static int acct_stack_growth(struct vm_area_struct *vma,
|
|
unsigned long size, unsigned long grow)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long new_start;
|
|
|
|
/* address space limit tests */
|
|
if (!may_expand_vm(mm, vma->vm_flags, grow))
|
|
return -ENOMEM;
|
|
|
|
/* Stack limit test */
|
|
if (size > rlimit(RLIMIT_STACK))
|
|
return -ENOMEM;
|
|
|
|
/* mlock limit tests */
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
unsigned long locked;
|
|
unsigned long limit;
|
|
locked = mm->locked_vm + grow;
|
|
limit = rlimit(RLIMIT_MEMLOCK);
|
|
limit >>= PAGE_SHIFT;
|
|
if (locked > limit && !capable(CAP_IPC_LOCK))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Check to ensure the stack will not grow into a hugetlb-only region */
|
|
new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
|
|
vma->vm_end - size;
|
|
if (is_hugepage_only_range(vma->vm_mm, new_start, size))
|
|
return -EFAULT;
|
|
|
|
/*
|
|
* Overcommit.. This must be the final test, as it will
|
|
* update security statistics.
|
|
*/
|
|
if (security_vm_enough_memory_mm(mm, grow))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
|
|
/*
|
|
* PA-RISC uses this for its stack; IA64 for its Register Backing Store.
|
|
* vma is the last one with address > vma->vm_end. Have to extend vma.
|
|
*/
|
|
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *next;
|
|
unsigned long gap_addr;
|
|
int error = 0;
|
|
|
|
if (!(vma->vm_flags & VM_GROWSUP))
|
|
return -EFAULT;
|
|
|
|
/* Guard against exceeding limits of the address space. */
|
|
address &= PAGE_MASK;
|
|
if (address >= (TASK_SIZE & PAGE_MASK))
|
|
return -ENOMEM;
|
|
address += PAGE_SIZE;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
gap_addr = address + stack_guard_gap;
|
|
|
|
/* Guard against overflow */
|
|
if (gap_addr < address || gap_addr > TASK_SIZE)
|
|
gap_addr = TASK_SIZE;
|
|
|
|
next = vma->vm_next;
|
|
if (next && next->vm_start < gap_addr &&
|
|
(next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
|
|
if (!(next->vm_flags & VM_GROWSUP))
|
|
return -ENOMEM;
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
}
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_sem in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address > vma->vm_end) {
|
|
unsigned long size, grow;
|
|
|
|
size = address - vma->vm_start;
|
|
grow = (address - vma->vm_end) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* vma_gap_update() doesn't support concurrent
|
|
* updates, but we only hold a shared mmap_sem
|
|
* lock here, so we need to protect against
|
|
* concurrent vma expansions.
|
|
* anon_vma_lock_write() doesn't help here, as
|
|
* we don't guarantee that all growable vmas
|
|
* in a mm share the same root anon vma.
|
|
* So, we reuse mm->page_table_lock to guard
|
|
* against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_end = address;
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
if (vma->vm_next)
|
|
vma_gap_update(vma->vm_next);
|
|
else
|
|
mm->highest_vm_end = vm_end_gap(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
khugepaged_enter_vma_merge(vma, vma->vm_flags);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
|
|
|
|
/*
|
|
* vma is the first one with address < vma->vm_start. Have to extend vma.
|
|
*/
|
|
int expand_downwards(struct vm_area_struct *vma,
|
|
unsigned long address)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *prev;
|
|
int error = 0;
|
|
|
|
address &= PAGE_MASK;
|
|
if (address < mmap_min_addr)
|
|
return -EPERM;
|
|
|
|
/* Enforce stack_guard_gap */
|
|
prev = vma->vm_prev;
|
|
/* Check that both stack segments have the same anon_vma? */
|
|
if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
|
|
(prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
|
|
if (address - prev->vm_end < stack_guard_gap)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* We must make sure the anon_vma is allocated. */
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* vma->vm_start/vm_end cannot change under us because the caller
|
|
* is required to hold the mmap_sem in read mode. We need the
|
|
* anon_vma lock to serialize against concurrent expand_stacks.
|
|
*/
|
|
anon_vma_lock_write(vma->anon_vma);
|
|
|
|
/* Somebody else might have raced and expanded it already */
|
|
if (address < vma->vm_start) {
|
|
unsigned long size, grow;
|
|
|
|
size = vma->vm_end - address;
|
|
grow = (vma->vm_start - address) >> PAGE_SHIFT;
|
|
|
|
error = -ENOMEM;
|
|
if (grow <= vma->vm_pgoff) {
|
|
error = acct_stack_growth(vma, size, grow);
|
|
if (!error) {
|
|
/*
|
|
* vma_gap_update() doesn't support concurrent
|
|
* updates, but we only hold a shared mmap_sem
|
|
* lock here, so we need to protect against
|
|
* concurrent vma expansions.
|
|
* anon_vma_lock_write() doesn't help here, as
|
|
* we don't guarantee that all growable vmas
|
|
* in a mm share the same root anon vma.
|
|
* So, we reuse mm->page_table_lock to guard
|
|
* against concurrent vma expansions.
|
|
*/
|
|
spin_lock(&mm->page_table_lock);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mm->locked_vm += grow;
|
|
vm_stat_account(mm, vma->vm_flags, grow);
|
|
anon_vma_interval_tree_pre_update_vma(vma);
|
|
vma->vm_start = address;
|
|
vma->vm_pgoff -= grow;
|
|
anon_vma_interval_tree_post_update_vma(vma);
|
|
vma_gap_update(vma);
|
|
spin_unlock(&mm->page_table_lock);
|
|
|
|
perf_event_mmap(vma);
|
|
}
|
|
}
|
|
}
|
|
anon_vma_unlock_write(vma->anon_vma);
|
|
khugepaged_enter_vma_merge(vma, vma->vm_flags);
|
|
validate_mm(mm);
|
|
return error;
|
|
}
|
|
|
|
/* enforced gap between the expanding stack and other mappings. */
|
|
unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
|
|
|
|
static int __init cmdline_parse_stack_guard_gap(char *p)
|
|
{
|
|
unsigned long val;
|
|
char *endptr;
|
|
|
|
val = simple_strtoul(p, &endptr, 10);
|
|
if (!*endptr)
|
|
stack_guard_gap = val << PAGE_SHIFT;
|
|
|
|
return 0;
|
|
}
|
|
__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
|
|
|
|
#ifdef CONFIG_STACK_GROWSUP
|
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_upwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *
|
|
find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma, *prev;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma_prev(mm, addr, &prev);
|
|
if (vma && (vma->vm_start <= addr))
|
|
return vma;
|
|
if (!prev || expand_stack(prev, addr))
|
|
return NULL;
|
|
if (prev->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(prev, addr, prev->vm_end, NULL);
|
|
return prev;
|
|
}
|
|
#else
|
|
int expand_stack(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
return expand_downwards(vma, address);
|
|
}
|
|
|
|
struct vm_area_struct *
|
|
find_extend_vma(struct mm_struct *mm, unsigned long addr)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long start;
|
|
|
|
addr &= PAGE_MASK;
|
|
vma = find_vma(mm, addr);
|
|
if (!vma)
|
|
return NULL;
|
|
if (vma->vm_start <= addr)
|
|
return vma;
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
return NULL;
|
|
start = vma->vm_start;
|
|
if (expand_stack(vma, addr))
|
|
return NULL;
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
populate_vma_page_range(vma, addr, start, NULL);
|
|
return vma;
|
|
}
|
|
#endif
|
|
|
|
EXPORT_SYMBOL_GPL(find_extend_vma);
|
|
|
|
/*
|
|
* Ok - we have the memory areas we should free on the vma list,
|
|
* so release them, and do the vma updates.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
unsigned long nr_accounted = 0;
|
|
|
|
/* Update high watermark before we lower total_vm */
|
|
update_hiwater_vm(mm);
|
|
do {
|
|
long nrpages = vma_pages(vma);
|
|
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += nrpages;
|
|
vm_stat_account(mm, vma->vm_flags, -nrpages);
|
|
vma = remove_vma(vma);
|
|
} while (vma);
|
|
vm_unacct_memory(nr_accounted);
|
|
validate_mm(mm);
|
|
}
|
|
|
|
/*
|
|
* Get rid of page table information in the indicated region.
|
|
*
|
|
* Called with the mm semaphore held.
|
|
*/
|
|
static void unmap_region(struct mm_struct *mm,
|
|
struct vm_area_struct *vma, struct vm_area_struct *prev,
|
|
unsigned long start, unsigned long end)
|
|
{
|
|
struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
|
|
struct mmu_gather tlb;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm, start, end);
|
|
update_hiwater_rss(mm);
|
|
unmap_vmas(&tlb, vma, start, end);
|
|
free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
|
|
next ? next->vm_start : USER_PGTABLES_CEILING);
|
|
tlb_finish_mmu(&tlb, start, end);
|
|
}
|
|
|
|
/*
|
|
* Create a list of vma's touched by the unmap, removing them from the mm's
|
|
* vma list as we go..
|
|
*/
|
|
static void
|
|
detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
struct vm_area_struct *prev, unsigned long end)
|
|
{
|
|
struct vm_area_struct **insertion_point;
|
|
struct vm_area_struct *tail_vma = NULL;
|
|
|
|
insertion_point = (prev ? &prev->vm_next : &mm->mmap);
|
|
vma->vm_prev = NULL;
|
|
do {
|
|
vma_rb_erase(vma, &mm->mm_rb);
|
|
mm->map_count--;
|
|
tail_vma = vma;
|
|
vma = vma->vm_next;
|
|
} while (vma && vma->vm_start < end);
|
|
*insertion_point = vma;
|
|
if (vma) {
|
|
vma->vm_prev = prev;
|
|
vma_gap_update(vma);
|
|
} else
|
|
mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
|
|
tail_vma->vm_next = NULL;
|
|
|
|
/* Kill the cache */
|
|
vmacache_invalidate(mm);
|
|
}
|
|
|
|
/*
|
|
* __split_vma() bypasses sysctl_max_map_count checking. We use this where it
|
|
* has already been checked or doesn't make sense to fail.
|
|
*/
|
|
int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
struct vm_area_struct *new;
|
|
int err;
|
|
|
|
if (vma->vm_ops && vma->vm_ops->split) {
|
|
err = vma->vm_ops->split(vma, addr);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
new = vm_area_dup(vma);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
if (new_below)
|
|
new->vm_end = addr;
|
|
else {
|
|
new->vm_start = addr;
|
|
new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
|
|
}
|
|
|
|
err = vma_dup_policy(vma, new);
|
|
if (err)
|
|
goto out_free_vma;
|
|
|
|
err = anon_vma_clone(new, vma);
|
|
if (err)
|
|
goto out_free_mpol;
|
|
|
|
if (new->vm_file)
|
|
get_file(new->vm_file);
|
|
|
|
if (new->vm_ops && new->vm_ops->open)
|
|
new->vm_ops->open(new);
|
|
|
|
if (new_below)
|
|
err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
|
|
((addr - new->vm_start) >> PAGE_SHIFT), new);
|
|
else
|
|
err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
|
|
|
|
/* Success. */
|
|
if (!err)
|
|
return 0;
|
|
|
|
/* Clean everything up if vma_adjust failed. */
|
|
if (new->vm_ops && new->vm_ops->close)
|
|
new->vm_ops->close(new);
|
|
if (new->vm_file)
|
|
fput(new->vm_file);
|
|
unlink_anon_vmas(new);
|
|
out_free_mpol:
|
|
mpol_put(vma_policy(new));
|
|
out_free_vma:
|
|
vm_area_free(new);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Split a vma into two pieces at address 'addr', a new vma is allocated
|
|
* either for the first part or the tail.
|
|
*/
|
|
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
|
|
unsigned long addr, int new_below)
|
|
{
|
|
if (mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
return __split_vma(mm, vma, addr, new_below);
|
|
}
|
|
|
|
/* Munmap is split into 2 main parts -- this part which finds
|
|
* what needs doing, and the areas themselves, which do the
|
|
* work. This now handles partial unmappings.
|
|
* Jeremy Fitzhardinge <jeremy@goop.org>
|
|
*/
|
|
int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
|
|
struct list_head *uf, bool downgrade)
|
|
{
|
|
unsigned long end;
|
|
struct vm_area_struct *vma, *prev, *last;
|
|
|
|
if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
|
|
return -EINVAL;
|
|
|
|
len = PAGE_ALIGN(len);
|
|
if (len == 0)
|
|
return -EINVAL;
|
|
|
|
/* Find the first overlapping VMA */
|
|
vma = find_vma(mm, start);
|
|
if (!vma)
|
|
return 0;
|
|
prev = vma->vm_prev;
|
|
/* we have start < vma->vm_end */
|
|
|
|
/* if it doesn't overlap, we have nothing.. */
|
|
end = start + len;
|
|
if (vma->vm_start >= end)
|
|
return 0;
|
|
|
|
/*
|
|
* If we need to split any vma, do it now to save pain later.
|
|
*
|
|
* Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
|
|
* unmapped vm_area_struct will remain in use: so lower split_vma
|
|
* places tmp vma above, and higher split_vma places tmp vma below.
|
|
*/
|
|
if (start > vma->vm_start) {
|
|
int error;
|
|
|
|
/*
|
|
* Make sure that map_count on return from munmap() will
|
|
* not exceed its limit; but let map_count go just above
|
|
* its limit temporarily, to help free resources as expected.
|
|
*/
|
|
if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
error = __split_vma(mm, vma, start, 0);
|
|
if (error)
|
|
return error;
|
|
prev = vma;
|
|
}
|
|
|
|
/* Does it split the last one? */
|
|
last = find_vma(mm, end);
|
|
if (last && end > last->vm_start) {
|
|
int error = __split_vma(mm, last, end, 1);
|
|
if (error)
|
|
return error;
|
|
}
|
|
vma = prev ? prev->vm_next : mm->mmap;
|
|
|
|
if (unlikely(uf)) {
|
|
/*
|
|
* If userfaultfd_unmap_prep returns an error the vmas
|
|
* will remain splitted, but userland will get a
|
|
* highly unexpected error anyway. This is no
|
|
* different than the case where the first of the two
|
|
* __split_vma fails, but we don't undo the first
|
|
* split, despite we could. This is unlikely enough
|
|
* failure that it's not worth optimizing it for.
|
|
*/
|
|
int error = userfaultfd_unmap_prep(vma, start, end, uf);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* unlock any mlock()ed ranges before detaching vmas
|
|
*/
|
|
if (mm->locked_vm) {
|
|
struct vm_area_struct *tmp = vma;
|
|
while (tmp && tmp->vm_start < end) {
|
|
if (tmp->vm_flags & VM_LOCKED) {
|
|
mm->locked_vm -= vma_pages(tmp);
|
|
munlock_vma_pages_all(tmp);
|
|
}
|
|
|
|
tmp = tmp->vm_next;
|
|
}
|
|
}
|
|
|
|
/* Detach vmas from rbtree */
|
|
detach_vmas_to_be_unmapped(mm, vma, prev, end);
|
|
|
|
/*
|
|
* mpx unmap needs to be called with mmap_sem held for write.
|
|
* It is safe to call it before unmap_region().
|
|
*/
|
|
arch_unmap(mm, vma, start, end);
|
|
|
|
if (downgrade)
|
|
downgrade_write(&mm->mmap_sem);
|
|
|
|
unmap_region(mm, vma, prev, start, end);
|
|
|
|
/* Fix up all other VM information */
|
|
remove_vma_list(mm, vma);
|
|
|
|
return downgrade ? 1 : 0;
|
|
}
|
|
|
|
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
|
|
struct list_head *uf)
|
|
{
|
|
return __do_munmap(mm, start, len, uf, false);
|
|
}
|
|
|
|
static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
|
|
{
|
|
int ret;
|
|
struct mm_struct *mm = current->mm;
|
|
LIST_HEAD(uf);
|
|
|
|
if (down_write_killable(&mm->mmap_sem))
|
|
return -EINTR;
|
|
|
|
ret = __do_munmap(mm, start, len, &uf, downgrade);
|
|
/*
|
|
* Returning 1 indicates mmap_sem is downgraded.
|
|
* But 1 is not legal return value of vm_munmap() and munmap(), reset
|
|
* it to 0 before return.
|
|
*/
|
|
if (ret == 1) {
|
|
up_read(&mm->mmap_sem);
|
|
ret = 0;
|
|
} else
|
|
up_write(&mm->mmap_sem);
|
|
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
return ret;
|
|
}
|
|
|
|
int vm_munmap(unsigned long start, size_t len)
|
|
{
|
|
return __vm_munmap(start, len, false);
|
|
}
|
|
EXPORT_SYMBOL(vm_munmap);
|
|
|
|
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
|
|
{
|
|
profile_munmap(addr);
|
|
return __vm_munmap(addr, len, true);
|
|
}
|
|
|
|
|
|
/*
|
|
* Emulation of deprecated remap_file_pages() syscall.
|
|
*/
|
|
SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
|
|
unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
|
|
{
|
|
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long populate = 0;
|
|
unsigned long ret = -EINVAL;
|
|
struct file *file;
|
|
|
|
pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
|
|
current->comm, current->pid);
|
|
|
|
if (prot)
|
|
return ret;
|
|
start = start & PAGE_MASK;
|
|
size = size & PAGE_MASK;
|
|
|
|
if (start + size <= start)
|
|
return ret;
|
|
|
|
/* Does pgoff wrap? */
|
|
if (pgoff + (size >> PAGE_SHIFT) < pgoff)
|
|
return ret;
|
|
|
|
if (down_write_killable(&mm->mmap_sem))
|
|
return -EINTR;
|
|
|
|
vma = find_vma(mm, start);
|
|
|
|
if (!vma || !(vma->vm_flags & VM_SHARED))
|
|
goto out;
|
|
|
|
if (start < vma->vm_start)
|
|
goto out;
|
|
|
|
if (start + size > vma->vm_end) {
|
|
struct vm_area_struct *next;
|
|
|
|
for (next = vma->vm_next; next; next = next->vm_next) {
|
|
/* hole between vmas ? */
|
|
if (next->vm_start != next->vm_prev->vm_end)
|
|
goto out;
|
|
|
|
if (next->vm_file != vma->vm_file)
|
|
goto out;
|
|
|
|
if (next->vm_flags != vma->vm_flags)
|
|
goto out;
|
|
|
|
if (start + size <= next->vm_end)
|
|
break;
|
|
}
|
|
|
|
if (!next)
|
|
goto out;
|
|
}
|
|
|
|
prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
|
|
prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
|
|
prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
|
|
|
|
flags &= MAP_NONBLOCK;
|
|
flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
struct vm_area_struct *tmp;
|
|
flags |= MAP_LOCKED;
|
|
|
|
/* drop PG_Mlocked flag for over-mapped range */
|
|
for (tmp = vma; tmp->vm_start >= start + size;
|
|
tmp = tmp->vm_next) {
|
|
/*
|
|
* Split pmd and munlock page on the border
|
|
* of the range.
|
|
*/
|
|
vma_adjust_trans_huge(tmp, start, start + size, 0);
|
|
|
|
munlock_vma_pages_range(tmp,
|
|
max(tmp->vm_start, start),
|
|
min(tmp->vm_end, start + size));
|
|
}
|
|
}
|
|
|
|
file = get_file(vma->vm_file);
|
|
ret = do_mmap_pgoff(vma->vm_file, start, size,
|
|
prot, flags, pgoff, &populate, NULL);
|
|
fput(file);
|
|
out:
|
|
up_write(&mm->mmap_sem);
|
|
if (populate)
|
|
mm_populate(ret, populate);
|
|
if (!IS_ERR_VALUE(ret))
|
|
ret = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* this is really a simplified "do_mmap". it only handles
|
|
* anonymous maps. eventually we may be able to do some
|
|
* brk-specific accounting here.
|
|
*/
|
|
static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma, *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
pgoff_t pgoff = addr >> PAGE_SHIFT;
|
|
int error;
|
|
|
|
/* Until we need other flags, refuse anything except VM_EXEC. */
|
|
if ((flags & (~VM_EXEC)) != 0)
|
|
return -EINVAL;
|
|
flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
|
|
|
|
error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
|
|
if (offset_in_page(error))
|
|
return error;
|
|
|
|
error = mlock_future_check(mm, mm->def_flags, len);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* Clear old maps. this also does some error checking for us
|
|
*/
|
|
while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
|
|
&rb_parent)) {
|
|
if (do_munmap(mm, addr, len, uf))
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* Check against address space limits *after* clearing old maps... */
|
|
if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
if (mm->map_count > sysctl_max_map_count)
|
|
return -ENOMEM;
|
|
|
|
if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
|
|
return -ENOMEM;
|
|
|
|
/* Can we just expand an old private anonymous mapping? */
|
|
vma = vma_merge(mm, prev, addr, addr + len, flags,
|
|
NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
|
|
if (vma)
|
|
goto out;
|
|
|
|
/*
|
|
* create a vma struct for an anonymous mapping
|
|
*/
|
|
vma = vm_area_alloc(mm);
|
|
if (!vma) {
|
|
vm_unacct_memory(len >> PAGE_SHIFT);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
vma_set_anonymous(vma);
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
vma->vm_pgoff = pgoff;
|
|
vma->vm_flags = flags;
|
|
vma->vm_page_prot = vm_get_page_prot(flags);
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
out:
|
|
perf_event_mmap(vma);
|
|
mm->total_vm += len >> PAGE_SHIFT;
|
|
mm->data_vm += len >> PAGE_SHIFT;
|
|
if (flags & VM_LOCKED)
|
|
mm->locked_vm += (len >> PAGE_SHIFT);
|
|
vma->vm_flags |= VM_SOFTDIRTY;
|
|
return 0;
|
|
}
|
|
|
|
int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long len;
|
|
int ret;
|
|
bool populate;
|
|
LIST_HEAD(uf);
|
|
|
|
len = PAGE_ALIGN(request);
|
|
if (len < request)
|
|
return -ENOMEM;
|
|
if (!len)
|
|
return 0;
|
|
|
|
if (down_write_killable(&mm->mmap_sem))
|
|
return -EINTR;
|
|
|
|
ret = do_brk_flags(addr, len, flags, &uf);
|
|
populate = ((mm->def_flags & VM_LOCKED) != 0);
|
|
up_write(&mm->mmap_sem);
|
|
userfaultfd_unmap_complete(mm, &uf);
|
|
if (populate && !ret)
|
|
mm_populate(addr, len);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vm_brk_flags);
|
|
|
|
int vm_brk(unsigned long addr, unsigned long len)
|
|
{
|
|
return vm_brk_flags(addr, len, 0);
|
|
}
|
|
EXPORT_SYMBOL(vm_brk);
|
|
|
|
/* Release all mmaps. */
|
|
void exit_mmap(struct mm_struct *mm)
|
|
{
|
|
struct mmu_gather tlb;
|
|
struct vm_area_struct *vma;
|
|
unsigned long nr_accounted = 0;
|
|
|
|
/* mm's last user has gone, and its about to be pulled down */
|
|
mmu_notifier_release(mm);
|
|
|
|
if (unlikely(mm_is_oom_victim(mm))) {
|
|
/*
|
|
* Manually reap the mm to free as much memory as possible.
|
|
* Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
|
|
* this mm from further consideration. Taking mm->mmap_sem for
|
|
* write after setting MMF_OOM_SKIP will guarantee that the oom
|
|
* reaper will not run on this mm again after mmap_sem is
|
|
* dropped.
|
|
*
|
|
* Nothing can be holding mm->mmap_sem here and the above call
|
|
* to mmu_notifier_release(mm) ensures mmu notifier callbacks in
|
|
* __oom_reap_task_mm() will not block.
|
|
*
|
|
* This needs to be done before calling munlock_vma_pages_all(),
|
|
* which clears VM_LOCKED, otherwise the oom reaper cannot
|
|
* reliably test it.
|
|
*/
|
|
(void)__oom_reap_task_mm(mm);
|
|
|
|
set_bit(MMF_OOM_SKIP, &mm->flags);
|
|
down_write(&mm->mmap_sem);
|
|
up_write(&mm->mmap_sem);
|
|
}
|
|
|
|
if (mm->locked_vm) {
|
|
vma = mm->mmap;
|
|
while (vma) {
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
munlock_vma_pages_all(vma);
|
|
vma = vma->vm_next;
|
|
}
|
|
}
|
|
|
|
arch_exit_mmap(mm);
|
|
|
|
vma = mm->mmap;
|
|
if (!vma) /* Can happen if dup_mmap() received an OOM */
|
|
return;
|
|
|
|
lru_add_drain();
|
|
flush_cache_mm(mm);
|
|
tlb_gather_mmu(&tlb, mm, 0, -1);
|
|
/* update_hiwater_rss(mm) here? but nobody should be looking */
|
|
/* Use -1 here to ensure all VMAs in the mm are unmapped */
|
|
unmap_vmas(&tlb, vma, 0, -1);
|
|
free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
|
|
tlb_finish_mmu(&tlb, 0, -1);
|
|
|
|
/*
|
|
* Walk the list again, actually closing and freeing it,
|
|
* with preemption enabled, without holding any MM locks.
|
|
*/
|
|
while (vma) {
|
|
if (vma->vm_flags & VM_ACCOUNT)
|
|
nr_accounted += vma_pages(vma);
|
|
vma = remove_vma(vma);
|
|
}
|
|
vm_unacct_memory(nr_accounted);
|
|
}
|
|
|
|
/* Insert vm structure into process list sorted by address
|
|
* and into the inode's i_mmap tree. If vm_file is non-NULL
|
|
* then i_mmap_rwsem is taken here.
|
|
*/
|
|
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
|
|
{
|
|
struct vm_area_struct *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
|
|
if (find_vma_links(mm, vma->vm_start, vma->vm_end,
|
|
&prev, &rb_link, &rb_parent))
|
|
return -ENOMEM;
|
|
if ((vma->vm_flags & VM_ACCOUNT) &&
|
|
security_vm_enough_memory_mm(mm, vma_pages(vma)))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* The vm_pgoff of a purely anonymous vma should be irrelevant
|
|
* until its first write fault, when page's anon_vma and index
|
|
* are set. But now set the vm_pgoff it will almost certainly
|
|
* end up with (unless mremap moves it elsewhere before that
|
|
* first wfault), so /proc/pid/maps tells a consistent story.
|
|
*
|
|
* By setting it to reflect the virtual start address of the
|
|
* vma, merges and splits can happen in a seamless way, just
|
|
* using the existing file pgoff checks and manipulations.
|
|
* Similarly in do_mmap_pgoff and in do_brk.
|
|
*/
|
|
if (vma_is_anonymous(vma)) {
|
|
BUG_ON(vma->anon_vma);
|
|
vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
|
|
}
|
|
|
|
vma_link(mm, vma, prev, rb_link, rb_parent);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Copy the vma structure to a new location in the same mm,
|
|
* prior to moving page table entries, to effect an mremap move.
|
|
*/
|
|
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
|
|
unsigned long addr, unsigned long len, pgoff_t pgoff,
|
|
bool *need_rmap_locks)
|
|
{
|
|
struct vm_area_struct *vma = *vmap;
|
|
unsigned long vma_start = vma->vm_start;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct vm_area_struct *new_vma, *prev;
|
|
struct rb_node **rb_link, *rb_parent;
|
|
bool faulted_in_anon_vma = true;
|
|
|
|
/*
|
|
* If anonymous vma has not yet been faulted, update new pgoff
|
|
* to match new location, to increase its chance of merging.
|
|
*/
|
|
if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
|
|
pgoff = addr >> PAGE_SHIFT;
|
|
faulted_in_anon_vma = false;
|
|
}
|
|
|
|
if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
|
|
return NULL; /* should never get here */
|
|
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
|
|
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
|
|
vma->vm_userfaultfd_ctx);
|
|
if (new_vma) {
|
|
/*
|
|
* Source vma may have been merged into new_vma
|
|
*/
|
|
if (unlikely(vma_start >= new_vma->vm_start &&
|
|
vma_start < new_vma->vm_end)) {
|
|
/*
|
|
* The only way we can get a vma_merge with
|
|
* self during an mremap is if the vma hasn't
|
|
* been faulted in yet and we were allowed to
|
|
* reset the dst vma->vm_pgoff to the
|
|
* destination address of the mremap to allow
|
|
* the merge to happen. mremap must change the
|
|
* vm_pgoff linearity between src and dst vmas
|
|
* (in turn preventing a vma_merge) to be
|
|
* safe. It is only safe to keep the vm_pgoff
|
|
* linear if there are no pages mapped yet.
|
|
*/
|
|
VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
|
|
*vmap = vma = new_vma;
|
|
}
|
|
*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
|
|
} else {
|
|
new_vma = vm_area_dup(vma);
|
|
if (!new_vma)
|
|
goto out;
|
|
new_vma->vm_start = addr;
|
|
new_vma->vm_end = addr + len;
|
|
new_vma->vm_pgoff = pgoff;
|
|
if (vma_dup_policy(vma, new_vma))
|
|
goto out_free_vma;
|
|
if (anon_vma_clone(new_vma, vma))
|
|
goto out_free_mempol;
|
|
if (new_vma->vm_file)
|
|
get_file(new_vma->vm_file);
|
|
if (new_vma->vm_ops && new_vma->vm_ops->open)
|
|
new_vma->vm_ops->open(new_vma);
|
|
vma_link(mm, new_vma, prev, rb_link, rb_parent);
|
|
*need_rmap_locks = false;
|
|
}
|
|
return new_vma;
|
|
|
|
out_free_mempol:
|
|
mpol_put(vma_policy(new_vma));
|
|
out_free_vma:
|
|
vm_area_free(new_vma);
|
|
out:
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Return true if the calling process may expand its vm space by the passed
|
|
* number of pages
|
|
*/
|
|
bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
|
|
{
|
|
if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
|
|
return false;
|
|
|
|
if (is_data_mapping(flags) &&
|
|
mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
|
|
/* Workaround for Valgrind */
|
|
if (rlimit(RLIMIT_DATA) == 0 &&
|
|
mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
|
|
return true;
|
|
|
|
pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
|
|
current->comm, current->pid,
|
|
(mm->data_vm + npages) << PAGE_SHIFT,
|
|
rlimit(RLIMIT_DATA),
|
|
ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
|
|
|
|
if (!ignore_rlimit_data)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
|
|
{
|
|
mm->total_vm += npages;
|
|
|
|
if (is_exec_mapping(flags))
|
|
mm->exec_vm += npages;
|
|
else if (is_stack_mapping(flags))
|
|
mm->stack_vm += npages;
|
|
else if (is_data_mapping(flags))
|
|
mm->data_vm += npages;
|
|
}
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
|
|
|
|
/*
|
|
* Having a close hook prevents vma merging regardless of flags.
|
|
*/
|
|
static void special_mapping_close(struct vm_area_struct *vma)
|
|
{
|
|
}
|
|
|
|
static const char *special_mapping_name(struct vm_area_struct *vma)
|
|
{
|
|
return ((struct vm_special_mapping *)vma->vm_private_data)->name;
|
|
}
|
|
|
|
static int special_mapping_mremap(struct vm_area_struct *new_vma)
|
|
{
|
|
struct vm_special_mapping *sm = new_vma->vm_private_data;
|
|
|
|
if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
|
|
return -EFAULT;
|
|
|
|
if (sm->mremap)
|
|
return sm->mremap(sm, new_vma);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct vm_operations_struct special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
.mremap = special_mapping_mremap,
|
|
.name = special_mapping_name,
|
|
};
|
|
|
|
static const struct vm_operations_struct legacy_special_mapping_vmops = {
|
|
.close = special_mapping_close,
|
|
.fault = special_mapping_fault,
|
|
};
|
|
|
|
static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
|
|
{
|
|
struct vm_area_struct *vma = vmf->vma;
|
|
pgoff_t pgoff;
|
|
struct page **pages;
|
|
|
|
if (vma->vm_ops == &legacy_special_mapping_vmops) {
|
|
pages = vma->vm_private_data;
|
|
} else {
|
|
struct vm_special_mapping *sm = vma->vm_private_data;
|
|
|
|
if (sm->fault)
|
|
return sm->fault(sm, vmf->vma, vmf);
|
|
|
|
pages = sm->pages;
|
|
}
|
|
|
|
for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
|
|
pgoff--;
|
|
|
|
if (*pages) {
|
|
struct page *page = *pages;
|
|
get_page(page);
|
|
vmf->page = page;
|
|
return 0;
|
|
}
|
|
|
|
return VM_FAULT_SIGBUS;
|
|
}
|
|
|
|
static struct vm_area_struct *__install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, void *priv,
|
|
const struct vm_operations_struct *ops)
|
|
{
|
|
int ret;
|
|
struct vm_area_struct *vma;
|
|
|
|
vma = vm_area_alloc(mm);
|
|
if (unlikely(vma == NULL))
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
vma->vm_start = addr;
|
|
vma->vm_end = addr + len;
|
|
|
|
vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
|
|
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
|
|
|
|
vma->vm_ops = ops;
|
|
vma->vm_private_data = priv;
|
|
|
|
ret = insert_vm_struct(mm, vma);
|
|
if (ret)
|
|
goto out;
|
|
|
|
vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
|
|
|
|
perf_event_mmap(vma);
|
|
|
|
return vma;
|
|
|
|
out:
|
|
vm_area_free(vma);
|
|
return ERR_PTR(ret);
|
|
}
|
|
|
|
bool vma_is_special_mapping(const struct vm_area_struct *vma,
|
|
const struct vm_special_mapping *sm)
|
|
{
|
|
return vma->vm_private_data == sm &&
|
|
(vma->vm_ops == &special_mapping_vmops ||
|
|
vma->vm_ops == &legacy_special_mapping_vmops);
|
|
}
|
|
|
|
/*
|
|
* Called with mm->mmap_sem held for writing.
|
|
* Insert a new vma covering the given region, with the given flags.
|
|
* Its pages are supplied by the given array of struct page *.
|
|
* The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
|
|
* The region past the last page supplied will always produce SIGBUS.
|
|
* The array pointer and the pages it points to are assumed to stay alive
|
|
* for as long as this mapping might exist.
|
|
*/
|
|
struct vm_area_struct *_install_special_mapping(
|
|
struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, const struct vm_special_mapping *spec)
|
|
{
|
|
return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
|
|
&special_mapping_vmops);
|
|
}
|
|
|
|
int install_special_mapping(struct mm_struct *mm,
|
|
unsigned long addr, unsigned long len,
|
|
unsigned long vm_flags, struct page **pages)
|
|
{
|
|
struct vm_area_struct *vma = __install_special_mapping(
|
|
mm, addr, len, vm_flags, (void *)pages,
|
|
&legacy_special_mapping_vmops);
|
|
|
|
return PTR_ERR_OR_ZERO(vma);
|
|
}
|
|
|
|
static DEFINE_MUTEX(mm_all_locks_mutex);
|
|
|
|
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
|
|
{
|
|
if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
|
|
/*
|
|
* We can safely modify head.next after taking the
|
|
* anon_vma->root->rwsem. If some other vma in this mm shares
|
|
* the same anon_vma we won't take it again.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us thanks to the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (__test_and_set_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
|
|
{
|
|
if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change from under us because
|
|
* we hold the mm_all_locks_mutex.
|
|
*
|
|
* Operations on ->flags have to be atomic because
|
|
* even if AS_MM_ALL_LOCKS is stable thanks to the
|
|
* mm_all_locks_mutex, there may be other cpus
|
|
* changing other bitflags in parallel to us.
|
|
*/
|
|
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
|
|
BUG();
|
|
down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This operation locks against the VM for all pte/vma/mm related
|
|
* operations that could ever happen on a certain mm. This includes
|
|
* vmtruncate, try_to_unmap, and all page faults.
|
|
*
|
|
* The caller must take the mmap_sem in write mode before calling
|
|
* mm_take_all_locks(). The caller isn't allowed to release the
|
|
* mmap_sem until mm_drop_all_locks() returns.
|
|
*
|
|
* mmap_sem in write mode is required in order to block all operations
|
|
* that could modify pagetables and free pages without need of
|
|
* altering the vma layout. It's also needed in write mode to avoid new
|
|
* anon_vmas to be associated with existing vmas.
|
|
*
|
|
* A single task can't take more than one mm_take_all_locks() in a row
|
|
* or it would deadlock.
|
|
*
|
|
* The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
|
|
* mapping->flags avoid to take the same lock twice, if more than one
|
|
* vma in this mm is backed by the same anon_vma or address_space.
|
|
*
|
|
* We take locks in following order, accordingly to comment at beginning
|
|
* of mm/rmap.c:
|
|
* - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
|
|
* hugetlb mapping);
|
|
* - all i_mmap_rwsem locks;
|
|
* - all anon_vma->rwseml
|
|
*
|
|
* We can take all locks within these types randomly because the VM code
|
|
* doesn't nest them and we protected from parallel mm_take_all_locks() by
|
|
* mm_all_locks_mutex.
|
|
*
|
|
* mm_take_all_locks() and mm_drop_all_locks are expensive operations
|
|
* that may have to take thousand of locks.
|
|
*
|
|
* mm_take_all_locks() can fail if it's interrupted by signals.
|
|
*/
|
|
int mm_take_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
|
|
BUG_ON(down_read_trylock(&mm->mmap_sem));
|
|
|
|
mutex_lock(&mm_all_locks_mutex);
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->vm_file && vma->vm_file->f_mapping &&
|
|
!is_vm_hugetlb_page(vma))
|
|
vm_lock_mapping(mm, vma->vm_file->f_mapping);
|
|
}
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (signal_pending(current))
|
|
goto out_unlock;
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_lock_anon_vma(mm, avc->anon_vma);
|
|
}
|
|
|
|
return 0;
|
|
|
|
out_unlock:
|
|
mm_drop_all_locks(mm);
|
|
return -EINTR;
|
|
}
|
|
|
|
static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
|
|
{
|
|
if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
|
|
/*
|
|
* The LSB of head.next can't change to 0 from under
|
|
* us because we hold the mm_all_locks_mutex.
|
|
*
|
|
* We must however clear the bitflag before unlocking
|
|
* the vma so the users using the anon_vma->rb_root will
|
|
* never see our bitflag.
|
|
*
|
|
* No need of atomic instructions here, head.next
|
|
* can't change from under us until we release the
|
|
* anon_vma->root->rwsem.
|
|
*/
|
|
if (!__test_and_clear_bit(0, (unsigned long *)
|
|
&anon_vma->root->rb_root.rb_root.rb_node))
|
|
BUG();
|
|
anon_vma_unlock_write(anon_vma);
|
|
}
|
|
}
|
|
|
|
static void vm_unlock_mapping(struct address_space *mapping)
|
|
{
|
|
if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
|
|
/*
|
|
* AS_MM_ALL_LOCKS can't change to 0 from under us
|
|
* because we hold the mm_all_locks_mutex.
|
|
*/
|
|
i_mmap_unlock_write(mapping);
|
|
if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
|
|
&mapping->flags))
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The mmap_sem cannot be released by the caller until
|
|
* mm_drop_all_locks() returns.
|
|
*/
|
|
void mm_drop_all_locks(struct mm_struct *mm)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct anon_vma_chain *avc;
|
|
|
|
BUG_ON(down_read_trylock(&mm->mmap_sem));
|
|
BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
|
|
|
|
for (vma = mm->mmap; vma; vma = vma->vm_next) {
|
|
if (vma->anon_vma)
|
|
list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
|
|
vm_unlock_anon_vma(avc->anon_vma);
|
|
if (vma->vm_file && vma->vm_file->f_mapping)
|
|
vm_unlock_mapping(vma->vm_file->f_mapping);
|
|
}
|
|
|
|
mutex_unlock(&mm_all_locks_mutex);
|
|
}
|
|
|
|
/*
|
|
* initialise the percpu counter for VM
|
|
*/
|
|
void __init mmap_init(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
|
|
VM_BUG_ON(ret);
|
|
}
|
|
|
|
/*
|
|
* Initialise sysctl_user_reserve_kbytes.
|
|
*
|
|
* This is intended to prevent a user from starting a single memory hogging
|
|
* process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
|
|
* mode.
|
|
*
|
|
* The default value is min(3% of free memory, 128MB)
|
|
* 128MB is enough to recover with sshd/login, bash, and top/kill.
|
|
*/
|
|
static int init_user_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_user_reserve);
|
|
|
|
/*
|
|
* Initialise sysctl_admin_reserve_kbytes.
|
|
*
|
|
* The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
|
|
* to log in and kill a memory hogging process.
|
|
*
|
|
* Systems with more than 256MB will reserve 8MB, enough to recover
|
|
* with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
|
|
* only reserve 3% of free pages by default.
|
|
*/
|
|
static int init_admin_reserve(void)
|
|
{
|
|
unsigned long free_kbytes;
|
|
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_admin_reserve);
|
|
|
|
/*
|
|
* Reinititalise user and admin reserves if memory is added or removed.
|
|
*
|
|
* The default user reserve max is 128MB, and the default max for the
|
|
* admin reserve is 8MB. These are usually, but not always, enough to
|
|
* enable recovery from a memory hogging process using login/sshd, a shell,
|
|
* and tools like top. It may make sense to increase or even disable the
|
|
* reserve depending on the existence of swap or variations in the recovery
|
|
* tools. So, the admin may have changed them.
|
|
*
|
|
* If memory is added and the reserves have been eliminated or increased above
|
|
* the default max, then we'll trust the admin.
|
|
*
|
|
* If memory is removed and there isn't enough free memory, then we
|
|
* need to reset the reserves.
|
|
*
|
|
* Otherwise keep the reserve set by the admin.
|
|
*/
|
|
static int reserve_mem_notifier(struct notifier_block *nb,
|
|
unsigned long action, void *data)
|
|
{
|
|
unsigned long tmp, free_kbytes;
|
|
|
|
switch (action) {
|
|
case MEM_ONLINE:
|
|
/* Default max is 128MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_user_reserve_kbytes;
|
|
if (0 < tmp && tmp < (1UL << 17))
|
|
init_user_reserve();
|
|
|
|
/* Default max is 8MB. Leave alone if modified by operator. */
|
|
tmp = sysctl_admin_reserve_kbytes;
|
|
if (0 < tmp && tmp < (1UL << 13))
|
|
init_admin_reserve();
|
|
|
|
break;
|
|
case MEM_OFFLINE:
|
|
free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
|
|
|
|
if (sysctl_user_reserve_kbytes > free_kbytes) {
|
|
init_user_reserve();
|
|
pr_info("vm.user_reserve_kbytes reset to %lu\n",
|
|
sysctl_user_reserve_kbytes);
|
|
}
|
|
|
|
if (sysctl_admin_reserve_kbytes > free_kbytes) {
|
|
init_admin_reserve();
|
|
pr_info("vm.admin_reserve_kbytes reset to %lu\n",
|
|
sysctl_admin_reserve_kbytes);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static struct notifier_block reserve_mem_nb = {
|
|
.notifier_call = reserve_mem_notifier,
|
|
};
|
|
|
|
static int __meminit init_reserve_notifier(void)
|
|
{
|
|
if (register_hotmemory_notifier(&reserve_mem_nb))
|
|
pr_err("Failed registering memory add/remove notifier for admin reserve\n");
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(init_reserve_notifier);
|