mirror of https://gitee.com/openkylin/linux.git
381 lines
8.6 KiB
C
381 lines
8.6 KiB
C
/*
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* Page fault handler for SH with an MMU.
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*
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* Copyright (C) 1999 Niibe Yutaka
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* Copyright (C) 2003 - 2009 Paul Mundt
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*
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* Based on linux/arch/i386/mm/fault.c:
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* Copyright (C) 1995 Linus Torvalds
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <linux/perf_event.h>
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#include <asm/io_trapped.h>
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#include <asm/system.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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static inline int notify_page_fault(struct pt_regs *regs, int trap)
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{
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int ret = 0;
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if (kprobes_built_in() && !user_mode(regs)) {
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, trap))
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ret = 1;
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preempt_enable();
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}
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return ret;
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}
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static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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{
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unsigned index = pgd_index(address);
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pgd_t *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pgd += index;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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return NULL;
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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_k, address);
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if (!pud_present(*pud_k))
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return NULL;
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if (!pud_present(*pud))
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set_pud(pud, *pud_k);
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pmd = pmd_offset(pud, address);
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pmd_k = pmd_offset(pud_k, address);
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if (!pmd_present(*pmd_k))
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return NULL;
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if (!pmd_present(*pmd))
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set_pmd(pmd, *pmd_k);
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else {
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/*
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* The page tables are fully synchronised so there must
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* be another reason for the fault. Return NULL here to
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* signal that we have not taken care of the fault.
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*/
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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return NULL;
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}
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return pmd_k;
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}
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/*
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* Handle a fault on the vmalloc or module mapping area
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*/
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static noinline int vmalloc_fault(unsigned long address)
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{
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pgd_t *pgd_k;
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pmd_t *pmd_k;
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pte_t *pte_k;
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/* Make sure we are in vmalloc/module/P3 area: */
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if (!(address >= VMALLOC_START && address < P3_ADDR_MAX))
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return -1;
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*
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* Do _not_ use "current" here. We might be inside
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* an interrupt in the middle of a task switch..
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*/
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pgd_k = get_TTB();
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pmd_k = vmalloc_sync_one(pgd_k, address);
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if (!pmd_k)
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return -1;
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pte_k = pte_offset_kernel(pmd_k, address);
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if (!pte_present(*pte_k))
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return -1;
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return 0;
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}
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static int fault_in_kernel_space(unsigned long address)
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{
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return address >= TASK_SIZE;
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*/
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asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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unsigned long writeaccess,
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unsigned long address)
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{
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unsigned long vec;
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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int si_code;
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int fault;
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siginfo_t info;
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tsk = current;
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mm = tsk->mm;
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si_code = SEGV_MAPERR;
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vec = lookup_exception_vector();
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*/
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if (unlikely(fault_in_kernel_space(address))) {
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if (vmalloc_fault(address) >= 0)
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return;
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if (notify_page_fault(regs, vec))
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return;
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goto bad_area_nosemaphore;
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}
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if (unlikely(notify_page_fault(regs, vec)))
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return;
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/* Only enable interrupts if they were on before the fault */
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if ((regs->sr & SR_IMASK) != SR_IMASK)
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local_irq_enable();
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
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/*
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* If we're in an interrupt, have no user context or are running
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* in an atomic region then we must not take the fault:
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*/
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if (in_atomic() || !mm)
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goto no_context;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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si_code = SEGV_ACCERR;
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if (writeaccess) {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto bad_area;
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}
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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survive:
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fault = handle_mm_fault(mm, vma, address, writeaccess ? FAULT_FLAG_WRITE : 0);
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGBUS)
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goto do_sigbus;
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BUG();
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}
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if (fault & VM_FAULT_MAJOR) {
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tsk->maj_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
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regs, address);
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} else {
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tsk->min_flt++;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
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regs, address);
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}
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up_read(&mm->mmap_sem);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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bad_area_nosemaphore:
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if (user_mode(regs)) {
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info.si_signo = SIGSEGV;
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void *) address;
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force_sig_info(SIGSEGV, &info, tsk);
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return;
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}
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no_context:
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/* Are we prepared to handle this kernel fault? */
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if (fixup_exception(regs))
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return;
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if (handle_trapped_io(regs, address))
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return;
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*
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*/
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bust_spinlocks(1);
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if (oops_may_print()) {
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unsigned long page;
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if (address < PAGE_SIZE)
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printk(KERN_ALERT "Unable to handle kernel NULL "
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"pointer dereference");
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else
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printk(KERN_ALERT "Unable to handle kernel paging "
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"request");
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printk(" at virtual address %08lx\n", address);
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printk(KERN_ALERT "pc = %08lx\n", regs->pc);
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page = (unsigned long)get_TTB();
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if (page) {
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page = ((__typeof__(page) *)page)[address >> PGDIR_SHIFT];
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printk(KERN_ALERT "*pde = %08lx\n", page);
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if (page & _PAGE_PRESENT) {
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page &= PAGE_MASK;
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address &= 0x003ff000;
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page = ((__typeof__(page) *)
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__va(page))[address >>
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PAGE_SHIFT];
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printk(KERN_ALERT "*pte = %08lx\n", page);
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}
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}
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}
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die("Oops", regs, writeaccess);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (is_global_init(current)) {
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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}
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printk("VM: killing process %s\n", tsk->comm);
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if (user_mode(regs))
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do_group_exit(SIGKILL);
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goto no_context;
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do_sigbus:
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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info.si_signo = SIGBUS;
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info.si_errno = 0;
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info.si_code = BUS_ADRERR;
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info.si_addr = (void *)address;
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force_sig_info(SIGBUS, &info, tsk);
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/* Kernel mode? Handle exceptions or die */
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if (!user_mode(regs))
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goto no_context;
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}
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/*
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* Called with interrupts disabled.
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*/
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asmlinkage int __kprobes
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handle_tlbmiss(struct pt_regs *regs, unsigned long writeaccess,
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unsigned long address)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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pte_t entry;
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/*
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* We don't take page faults for P1, P2, and parts of P4, these
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* are always mapped, whether it be due to legacy behaviour in
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* 29-bit mode, or due to PMB configuration in 32-bit mode.
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*/
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if (address >= P3SEG && address < P3_ADDR_MAX) {
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pgd = pgd_offset_k(address);
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} else {
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if (unlikely(address >= TASK_SIZE || !current->mm))
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return 1;
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pgd = pgd_offset(current->mm, address);
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}
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pud = pud_offset(pgd, address);
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if (pud_none_or_clear_bad(pud))
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return 1;
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pmd = pmd_offset(pud, address);
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if (pmd_none_or_clear_bad(pmd))
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return 1;
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pte = pte_offset_kernel(pmd, address);
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entry = *pte;
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if (unlikely(pte_none(entry) || pte_not_present(entry)))
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return 1;
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if (unlikely(writeaccess && !pte_write(entry)))
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return 1;
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if (writeaccess)
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entry = pte_mkdirty(entry);
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entry = pte_mkyoung(entry);
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set_pte(pte, entry);
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#if defined(CONFIG_CPU_SH4) && !defined(CONFIG_SMP)
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/*
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* SH-4 does not set MMUCR.RC to the corresponding TLB entry in
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* the case of an initial page write exception, so we need to
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* flush it in order to avoid potential TLB entry duplication.
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*/
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if (writeaccess == 2)
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local_flush_tlb_one(get_asid(), address & PAGE_MASK);
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#endif
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update_mmu_cache(NULL, address, pte);
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return 0;
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}
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