mirror of https://gitee.com/openkylin/linux.git
171 lines
4.2 KiB
C
171 lines
4.2 KiB
C
/*
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* linux/arch/arm/mm/mmap.c
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*/
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/shm.h>
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#include <linux/sched.h>
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#include <linux/io.h>
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#include <linux/personality.h>
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#include <linux/random.h>
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#include <asm/cputype.h>
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#include <asm/system.h>
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#define COLOUR_ALIGN(addr,pgoff) \
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((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
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(((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
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/*
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* We need to ensure that shared mappings are correctly aligned to
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* avoid aliasing issues with VIPT caches. We need to ensure that
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* a specific page of an object is always mapped at a multiple of
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* SHMLBA bytes.
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*
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* We unconditionally provide this function for all cases, however
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* in the VIVT case, we optimise out the alignment rules.
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*/
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unsigned long
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arch_get_unmapped_area(struct file *filp, unsigned long addr,
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unsigned long len, unsigned long pgoff, unsigned long flags)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long start_addr;
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#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_V6K)
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unsigned int cache_type;
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int do_align = 0, aliasing = 0;
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/*
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* We only need to do colour alignment if either the I or D
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* caches alias. This is indicated by bits 9 and 21 of the
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* cache type register.
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*/
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cache_type = read_cpuid_cachetype();
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if (cache_type != read_cpuid_id()) {
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aliasing = (cache_type | cache_type >> 12) & (1 << 11);
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if (aliasing)
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do_align = filp || flags & MAP_SHARED;
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}
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#else
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#define do_align 0
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#define aliasing 0
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#endif
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/*
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* We enforce the MAP_FIXED case.
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*/
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if (flags & MAP_FIXED) {
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if (aliasing && flags & MAP_SHARED &&
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(addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
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return -EINVAL;
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return addr;
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}
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if (len > TASK_SIZE)
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return -ENOMEM;
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if (addr) {
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if (do_align)
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addr = COLOUR_ALIGN(addr, pgoff);
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else
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr &&
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(!vma || addr + len <= vma->vm_start))
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return addr;
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}
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if (len > mm->cached_hole_size) {
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start_addr = addr = mm->free_area_cache;
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} else {
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start_addr = addr = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = 0;
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}
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/* 8 bits of randomness in 20 address space bits */
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if ((current->flags & PF_RANDOMIZE) &&
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!(current->personality & ADDR_NO_RANDOMIZE))
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addr += (get_random_int() % (1 << 8)) << PAGE_SHIFT;
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full_search:
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if (do_align)
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addr = COLOUR_ALIGN(addr, pgoff);
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else
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addr = PAGE_ALIGN(addr);
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for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
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/* At this point: (!vma || addr < vma->vm_end). */
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if (TASK_SIZE - len < addr) {
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/*
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* Start a new search - just in case we missed
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* some holes.
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*/
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if (start_addr != TASK_UNMAPPED_BASE) {
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start_addr = addr = TASK_UNMAPPED_BASE;
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mm->cached_hole_size = 0;
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goto full_search;
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}
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return -ENOMEM;
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}
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if (!vma || addr + len <= vma->vm_start) {
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/*
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* Remember the place where we stopped the search:
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*/
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mm->free_area_cache = addr + len;
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return addr;
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}
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if (addr + mm->cached_hole_size < vma->vm_start)
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mm->cached_hole_size = vma->vm_start - addr;
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addr = vma->vm_end;
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if (do_align)
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addr = COLOUR_ALIGN(addr, pgoff);
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}
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}
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/*
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* You really shouldn't be using read() or write() on /dev/mem. This
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* might go away in the future.
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*/
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int valid_phys_addr_range(unsigned long addr, size_t size)
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{
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if (addr < PHYS_OFFSET)
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return 0;
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if (addr + size > __pa(high_memory - 1) + 1)
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return 0;
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return 1;
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}
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/*
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* We don't use supersection mappings for mmap() on /dev/mem, which
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* means that we can't map the memory area above the 4G barrier into
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* userspace.
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*/
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int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
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{
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return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);
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}
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#ifdef CONFIG_STRICT_DEVMEM
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#include <linux/ioport.h>
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/*
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* devmem_is_allowed() checks to see if /dev/mem access to a certain
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* address is valid. The argument is a physical page number.
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* We mimic x86 here by disallowing access to system RAM as well as
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* device-exclusive MMIO regions. This effectively disable read()/write()
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* on /dev/mem.
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*/
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int devmem_is_allowed(unsigned long pfn)
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{
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if (iomem_is_exclusive(pfn << PAGE_SHIFT))
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return 0;
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if (!page_is_ram(pfn))
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return 1;
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return 0;
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}
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#endif
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