514 lines
12 KiB
C
514 lines
12 KiB
C
/*
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* linux/arch/arm/mm/fault.c
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*
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* Copyright (C) 1995 Linus Torvalds
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* Modifications for ARM processor (c) 1995-2004 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/signal.h>
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#include <linux/mm.h>
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#include <linux/hardirq.h>
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#include <linux/init.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <linux/page-flags.h>
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#include <linux/sched.h>
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#include <linux/highmem.h>
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#include <asm/system.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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#include "fault.h"
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#ifdef CONFIG_MMU
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#ifdef CONFIG_KPROBES
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static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
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{
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int ret = 0;
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if (!user_mode(regs)) {
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/* kprobe_running() needs smp_processor_id() */
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, fsr))
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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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#else
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static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
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{
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return 0;
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}
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#endif
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/*
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* This is useful to dump out the page tables associated with
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* 'addr' in mm 'mm'.
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*/
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void show_pte(struct mm_struct *mm, unsigned long addr)
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{
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pgd_t *pgd;
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if (!mm)
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mm = &init_mm;
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printk(KERN_ALERT "pgd = %p\n", mm->pgd);
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pgd = pgd_offset(mm, addr);
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printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
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do {
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pmd_t *pmd;
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pte_t *pte;
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if (pgd_none(*pgd))
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break;
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if (pgd_bad(*pgd)) {
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printk("(bad)");
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break;
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}
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pmd = pmd_offset(pgd, addr);
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if (PTRS_PER_PMD != 1)
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printk(", *pmd=%08lx", pmd_val(*pmd));
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if (pmd_none(*pmd))
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break;
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if (pmd_bad(*pmd)) {
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printk("(bad)");
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break;
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}
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/* We must not map this if we have highmem enabled */
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if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
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break;
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pte = pte_offset_map(pmd, addr);
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printk(", *pte=%08lx", pte_val(*pte));
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printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
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pte_unmap(pte);
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} while(0);
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printk("\n");
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}
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#else /* CONFIG_MMU */
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void show_pte(struct mm_struct *mm, unsigned long addr)
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{ }
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#endif /* CONFIG_MMU */
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/*
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* Oops. The kernel tried to access some page that wasn't present.
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*/
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static void
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__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
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struct pt_regs *regs)
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{
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/*
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* Are we prepared to handle this kernel fault?
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*/
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if (fixup_exception(regs))
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return;
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/*
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* No handler, we'll have to terminate things with extreme prejudice.
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*/
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bust_spinlocks(1);
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printk(KERN_ALERT
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"Unable to handle kernel %s at virtual address %08lx\n",
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(addr < PAGE_SIZE) ? "NULL pointer dereference" :
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"paging request", addr);
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show_pte(mm, addr);
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die("Oops", regs, fsr);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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}
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/*
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* Something tried to access memory that isn't in our memory map..
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* User mode accesses just cause a SIGSEGV
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*/
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static void
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__do_user_fault(struct task_struct *tsk, unsigned long addr,
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unsigned int fsr, unsigned int sig, int code,
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struct pt_regs *regs)
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{
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struct siginfo si;
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#ifdef CONFIG_DEBUG_USER
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if (user_debug & UDBG_SEGV) {
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printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
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tsk->comm, sig, addr, fsr);
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show_pte(tsk->mm, addr);
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show_regs(regs);
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}
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#endif
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tsk->thread.address = addr;
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tsk->thread.error_code = fsr;
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tsk->thread.trap_no = 14;
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si.si_signo = sig;
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si.si_errno = 0;
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si.si_code = code;
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si.si_addr = (void __user *)addr;
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force_sig_info(sig, &si, tsk);
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}
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void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->active_mm;
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/*
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* If we are in kernel mode at this point, we
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* have no context to handle this fault with.
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*/
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if (user_mode(regs))
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__do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
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else
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__do_kernel_fault(mm, addr, fsr, regs);
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}
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#ifdef CONFIG_MMU
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#define VM_FAULT_BADMAP 0x010000
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#define VM_FAULT_BADACCESS 0x020000
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static int
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__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
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struct task_struct *tsk)
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{
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struct vm_area_struct *vma;
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int fault, mask;
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vma = find_vma(mm, addr);
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fault = VM_FAULT_BADMAP;
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if (!vma)
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goto out;
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if (vma->vm_start > addr)
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goto check_stack;
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/*
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* Ok, we have a good vm_area for this
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* memory access, so we can handle it.
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*/
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good_area:
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if (fsr & (1 << 11)) /* write? */
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mask = VM_WRITE;
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else
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mask = VM_READ|VM_EXEC|VM_WRITE;
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fault = VM_FAULT_BADACCESS;
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if (!(vma->vm_flags & mask))
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goto out;
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/*
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* If for any reason at all we couldn't handle
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* the fault, make sure we exit gracefully rather
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* than endlessly redo the fault.
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*/
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survive:
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fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & (1 << 11)) ? 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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return fault;
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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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else
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tsk->min_flt++;
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return fault;
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out_of_memory:
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if (!is_global_init(tsk))
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goto out;
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/*
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* If we are out of memory for pid1, sleep for a while and retry
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*/
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up_read(&mm->mmap_sem);
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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check_stack:
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if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
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goto good_area;
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out:
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return fault;
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}
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static int __kprobes
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do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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int fault, sig, code;
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if (notify_page_fault(regs, fsr))
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return 0;
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tsk = current;
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mm = tsk->mm;
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/*
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* If we're in an interrupt or have no user
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* context, 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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/*
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* As per x86, we may deadlock here. However, since the kernel only
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* validly references user space from well defined areas of the code,
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* we can bug out early if this is from code which shouldn't.
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*/
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if (!down_read_trylock(&mm->mmap_sem)) {
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if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
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goto no_context;
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down_read(&mm->mmap_sem);
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}
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fault = __do_page_fault(mm, addr, fsr, tsk);
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up_read(&mm->mmap_sem);
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/*
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* Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
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*/
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if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
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return 0;
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/*
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* If we are in kernel mode at this point, we
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* have no context to handle this fault with.
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*/
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if (!user_mode(regs))
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goto no_context;
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if (fault & VM_FAULT_OOM) {
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/*
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* We ran out of memory, or some other thing
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* happened to us that made us unable to handle
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* the page fault gracefully.
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*/
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printk("VM: killing process %s\n", tsk->comm);
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do_group_exit(SIGKILL);
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return 0;
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}
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if (fault & VM_FAULT_SIGBUS) {
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/*
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* We had some memory, but were unable to
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* successfully fix up this page fault.
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*/
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sig = SIGBUS;
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code = BUS_ADRERR;
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} else {
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/*
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* Something tried to access memory that
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* isn't in our memory map..
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*/
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sig = SIGSEGV;
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code = fault == VM_FAULT_BADACCESS ?
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SEGV_ACCERR : SEGV_MAPERR;
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}
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__do_user_fault(tsk, addr, fsr, sig, code, regs);
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return 0;
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no_context:
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__do_kernel_fault(mm, addr, fsr, regs);
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return 0;
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}
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#else /* CONFIG_MMU */
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static int
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do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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return 0;
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}
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#endif /* CONFIG_MMU */
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/*
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* First Level Translation Fault Handler
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*
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* We enter here because the first level page table doesn't contain
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* a valid entry for the address.
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*
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* If the address is in kernel space (>= TASK_SIZE), then we are
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* probably faulting in the vmalloc() area.
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*
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* If the init_task's first level page tables contains the relevant
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* entry, we copy the it to this task. If not, we send the process
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* a signal, fixup the exception, or oops the kernel.
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*
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* NOTE! We MUST NOT take any locks for this case. We may be in an
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* interrupt or a critical region, and should only copy the information
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* from the master page table, nothing more.
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*/
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#ifdef CONFIG_MMU
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static int __kprobes
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do_translation_fault(unsigned long addr, unsigned int fsr,
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struct pt_regs *regs)
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{
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unsigned int index;
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pgd_t *pgd, *pgd_k;
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pmd_t *pmd, *pmd_k;
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if (addr < TASK_SIZE)
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return do_page_fault(addr, fsr, regs);
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index = pgd_index(addr);
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/*
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* FIXME: CP15 C1 is write only on ARMv3 architectures.
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*/
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pgd = cpu_get_pgd() + index;
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pgd_k = init_mm.pgd + index;
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if (pgd_none(*pgd_k))
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goto bad_area;
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if (!pgd_present(*pgd))
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set_pgd(pgd, *pgd_k);
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pmd_k = pmd_offset(pgd_k, addr);
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pmd = pmd_offset(pgd, addr);
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if (pmd_none(*pmd_k))
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goto bad_area;
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copy_pmd(pmd, pmd_k);
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return 0;
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bad_area:
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do_bad_area(addr, fsr, regs);
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return 0;
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}
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#else /* CONFIG_MMU */
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static int
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do_translation_fault(unsigned long addr, unsigned int fsr,
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struct pt_regs *regs)
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{
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return 0;
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}
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#endif /* CONFIG_MMU */
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/*
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* Some section permission faults need to be handled gracefully.
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* They can happen due to a __{get,put}_user during an oops.
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*/
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static int
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do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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do_bad_area(addr, fsr, regs);
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return 0;
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}
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/*
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* This abort handler always returns "fault".
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*/
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static int
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do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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return 1;
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}
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static struct fsr_info {
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int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
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int sig;
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int code;
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const char *name;
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} fsr_info[] = {
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/*
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* The following are the standard ARMv3 and ARMv4 aborts. ARMv5
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* defines these to be "precise" aborts.
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*/
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{ do_bad, SIGSEGV, 0, "vector exception" },
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{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
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{ do_bad, SIGKILL, 0, "terminal exception" },
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{ do_bad, SIGILL, BUS_ADRALN, "alignment exception" },
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{ do_bad, SIGBUS, 0, "external abort on linefetch" },
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{ do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" },
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{ do_bad, SIGBUS, 0, "external abort on linefetch" },
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{ do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" },
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{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
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{ do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" },
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{ do_bad, SIGBUS, 0, "external abort on non-linefetch" },
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{ do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" },
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{ do_bad, SIGBUS, 0, "external abort on translation" },
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{ do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" },
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{ do_bad, SIGBUS, 0, "external abort on translation" },
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{ do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" },
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/*
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* The following are "imprecise" aborts, which are signalled by bit
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* 10 of the FSR, and may not be recoverable. These are only
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* supported if the CPU abort handler supports bit 10.
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*/
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{ do_bad, SIGBUS, 0, "unknown 16" },
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{ do_bad, SIGBUS, 0, "unknown 17" },
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{ do_bad, SIGBUS, 0, "unknown 18" },
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{ do_bad, SIGBUS, 0, "unknown 19" },
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{ do_bad, SIGBUS, 0, "lock abort" }, /* xscale */
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{ do_bad, SIGBUS, 0, "unknown 21" },
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{ do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */
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{ do_bad, SIGBUS, 0, "unknown 23" },
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{ do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */
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{ do_bad, SIGBUS, 0, "unknown 25" },
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{ do_bad, SIGBUS, 0, "unknown 26" },
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{ do_bad, SIGBUS, 0, "unknown 27" },
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{ do_bad, SIGBUS, 0, "unknown 28" },
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{ do_bad, SIGBUS, 0, "unknown 29" },
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{ do_bad, SIGBUS, 0, "unknown 30" },
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{ do_bad, SIGBUS, 0, "unknown 31" }
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};
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void __init
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hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
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int sig, const char *name)
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{
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if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
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fsr_info[nr].fn = fn;
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fsr_info[nr].sig = sig;
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fsr_info[nr].name = name;
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}
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}
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/*
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* Dispatch a data abort to the relevant handler.
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*/
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asmlinkage void __exception
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do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
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struct siginfo info;
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if (!inf->fn(addr, fsr, regs))
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return;
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printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
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inf->name, fsr, addr);
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info.si_signo = inf->sig;
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info.si_errno = 0;
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info.si_code = inf->code;
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info.si_addr = (void __user *)addr;
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arm_notify_die("", regs, &info, fsr, 0);
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}
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asmlinkage void __exception
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do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
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{
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do_translation_fault(addr, 0, regs);
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}
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