248 lines
5.6 KiB
C
Executable File
248 lines
5.6 KiB
C
Executable File
// SPDX-License-Identifier: GPL-2.0
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/*
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* Meta page fault handling.
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*
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* Copyright (C) 2005-2012 Imagination Technologies Ltd.
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*/
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/kernel.h>
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#include <linux/ptrace.h>
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#include <linux/sched/debug.h>
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#include <linux/interrupt.h>
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#include <linux/uaccess.h>
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#include <asm/tlbflush.h>
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#include <asm/mmu.h>
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#include <asm/traps.h>
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/* Clear any pending catch buffer state. */
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static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr,
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unsigned int trapno)
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{
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PTBICTXEXTCB0 cbuf = regs->extcb0;
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switch (trapno) {
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/* Instruction fetch faults leave no catch buffer state. */
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case TBIXXF_SIGNUM_IGF:
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case TBIXXF_SIGNUM_IPF:
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return;
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default:
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if (cbuf[0].CBAddr == addr) {
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cbuf[0].CBAddr = 0;
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cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS;
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/* And, as this is the ONLY catch entry, we
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* need to clear the cbuf bit from the context!
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*/
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regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT |
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TBICTX_XCBF_BIT);
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return;
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}
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pr_err("Failed to clear cbuf entry!\n");
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}
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}
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int show_unhandled_signals = 1;
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int do_page_fault(struct pt_regs *regs, unsigned long address,
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unsigned int write_access, unsigned int trapno)
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{
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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, *prev_vma;
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siginfo_t info;
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int fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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tsk = current;
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if ((address >= VMALLOC_START) && (address < VMALLOC_END)) {
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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 "tsk" 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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int offset = pgd_index(address);
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pgd_t *pgd, *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pte_t *pte_k;
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pgd = ((pgd_t *)mmu_get_base()) + offset;
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pgd_k = swapper_pg_dir + offset;
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/* This will never happen with the folded page table. */
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if (!pgd_present(*pgd)) {
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if (!pgd_present(*pgd_k))
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goto bad_area_nosemaphore;
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set_pgd(pgd, *pgd_k);
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return 0;
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}
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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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goto bad_area_nosemaphore;
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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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goto bad_area_nosemaphore;
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set_pmd(pmd, *pmd_k);
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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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goto bad_area_nosemaphore;
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/* May only be needed on Chorus2 */
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flush_tlb_all();
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return 0;
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}
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mm = tsk->mm;
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if (faulthandler_disabled() || !mm)
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goto no_context;
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma_prev(mm, address, &prev_vma);
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if (!vma || address < vma->vm_start)
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goto check_expansion;
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good_area:
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if (write_access) {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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flags |= FAULT_FLAG_WRITE;
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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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fault = handle_mm_fault(vma, address, flags);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return 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_SIGSEGV)
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goto bad_area;
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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 (flags & FAULT_FLAG_ALLOW_RETRY) {
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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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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* in mm/filemap.c.
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*/
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goto retry;
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}
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}
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up_read(&mm->mmap_sem);
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return 0;
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check_expansion:
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vma = prev_vma;
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if (vma && (expand_stack(vma, address) == 0))
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goto good_area;
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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 = SEGV_MAPERR;
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info.si_addr = (__force void __user *)address;
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info.si_trapno = trapno;
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if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
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printk_ratelimit()) {
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printk("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
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task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
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tsk->comm, task_pid_nr(tsk), address,
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regs->ctx.CurrPC, regs->ctx.AX[0].U0,
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write_access, trapno, trap_name(trapno));
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print_vma_addr(" in ", regs->ctx.CurrPC);
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print_vma_addr(" rtp in ", regs->ctx.DX[4].U1);
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printk("\n");
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show_regs(regs);
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}
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force_sig_info(SIGSEGV, &info, tsk);
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return 1;
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}
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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 = (__force void __user *)address;
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info.si_trapno = trapno;
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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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return 1;
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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 (user_mode(regs)) {
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pagefault_out_of_memory();
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return 1;
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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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clear_cbuf_entry(regs, address, trapno);
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return 1;
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}
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die("Oops", regs, (write_access << 15) | trapno, address);
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do_exit(SIGKILL);
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}
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