249 lines
6.2 KiB
C
249 lines
6.2 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* MMU fault handling support.
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*
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* Copyright (C) 1998-2002 Hewlett-Packard Co
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* David Mosberger-Tang <davidm@hpl.hp.com>
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*/
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#include <linux/sched/signal.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/extable.h>
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#include <linux/interrupt.h>
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#include <linux/kprobes.h>
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#include <linux/kdebug.h>
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#include <linux/prefetch.h>
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#include <linux/uaccess.h>
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#include <linux/perf_event.h>
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#include <asm/processor.h>
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#include <asm/exception.h>
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extern int die(char *, struct pt_regs *, long);
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/*
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* Return TRUE if ADDRESS points at a page in the kernel's mapped segment
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* (inside region 5, on ia64) and that page is present.
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*/
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static int
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mapped_kernel_page_is_present (unsigned long address)
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{
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *ptep, pte;
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pgd = pgd_offset_k(address);
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if (pgd_none(*pgd) || pgd_bad(*pgd))
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return 0;
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p4d = p4d_offset(pgd, address);
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if (p4d_none(*p4d) || p4d_bad(*p4d))
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return 0;
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pud = pud_offset(p4d, address);
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if (pud_none(*pud) || pud_bad(*pud))
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return 0;
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pmd = pmd_offset(pud, address);
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if (pmd_none(*pmd) || pmd_bad(*pmd))
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return 0;
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ptep = pte_offset_kernel(pmd, address);
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if (!ptep)
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return 0;
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pte = *ptep;
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return pte_present(pte);
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}
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# define VM_READ_BIT 0
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# define VM_WRITE_BIT 1
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# define VM_EXEC_BIT 2
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void __kprobes
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ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *regs)
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{
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int signal = SIGSEGV, code = SEGV_MAPERR;
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struct vm_area_struct *vma, *prev_vma;
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struct mm_struct *mm = current->mm;
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unsigned long mask;
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vm_fault_t fault;
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unsigned int flags = FAULT_FLAG_DEFAULT;
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mask = ((((isr >> IA64_ISR_X_BIT) & 1UL) << VM_EXEC_BIT)
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| (((isr >> IA64_ISR_W_BIT) & 1UL) << VM_WRITE_BIT));
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/* mmap_lock is performance critical.... */
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prefetchw(&mm->mmap_lock);
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/*
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* If we're in an interrupt or have no user context, we must not take the fault..
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*/
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if (faulthandler_disabled() || !mm)
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goto no_context;
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/*
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* This is to handle the kprobes on user space access instructions
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*/
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if (kprobe_page_fault(regs, TRAP_BRKPT))
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return;
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if (user_mode(regs))
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flags |= FAULT_FLAG_USER;
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if (mask & VM_WRITE)
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flags |= FAULT_FLAG_WRITE;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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retry:
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mmap_read_lock(mm);
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vma = find_vma_prev(mm, address, &prev_vma);
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if (!vma && !prev_vma )
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goto bad_area;
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/*
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* find_vma_prev() returns vma such that address < vma->vm_end or NULL
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*
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* May find no vma, but could be that the last vm area is the
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* register backing store that needs to expand upwards, in
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* this case vma will be null, but prev_vma will ne non-null
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*/
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if (( !vma && prev_vma ) || (address < vma->vm_start) ) {
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vma = expand_stack(mm, address);
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if (!vma)
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goto bad_area_nosemaphore;
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}
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code = SEGV_ACCERR;
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/* OK, we've got a good vm_area for this memory area. Check the access permissions: */
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# if (((1 << VM_READ_BIT) != VM_READ || (1 << VM_WRITE_BIT) != VM_WRITE) \
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|| (1 << VM_EXEC_BIT) != VM_EXEC)
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# error File is out of sync with <linux/mm.h>. Please update.
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# endif
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if (((isr >> IA64_ISR_R_BIT) & 1UL) && (!(vma->vm_flags & (VM_READ | VM_WRITE))))
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goto bad_area;
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if ((vma->vm_flags & mask) != mask)
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goto bad_area;
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/*
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* If for any reason at all we couldn't handle the fault, make
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* sure we exit gracefully rather than endlessly redo the
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* fault.
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*/
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fault = handle_mm_fault(vma, address, flags, regs);
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if (fault_signal_pending(fault, regs))
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return;
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/* The fault is fully completed (including releasing mmap lock) */
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if (fault & VM_FAULT_COMPLETED)
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return;
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if (unlikely(fault & VM_FAULT_ERROR)) {
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/*
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* We ran out of memory, or some other thing happened
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* to us that made us unable to handle the page fault
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* gracefully.
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*/
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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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signal = SIGBUS;
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goto bad_area;
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}
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BUG();
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}
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if (fault & VM_FAULT_RETRY) {
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flags |= FAULT_FLAG_TRIED;
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/* No need to mmap_read_unlock(mm) 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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mmap_read_unlock(mm);
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return;
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bad_area:
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mmap_read_unlock(mm);
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bad_area_nosemaphore:
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if ((isr & IA64_ISR_SP)
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|| ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
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{
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/*
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* This fault was due to a speculative load or lfetch.fault, set the "ed"
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* bit in the psr to ensure forward progress. (Target register will get a
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* NaT for ld.s, lfetch will be canceled.)
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*/
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ia64_psr(regs)->ed = 1;
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return;
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}
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if (user_mode(regs)) {
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force_sig_fault(signal, code, (void __user *) address,
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0, __ISR_VALID, isr);
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return;
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}
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no_context:
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if ((isr & IA64_ISR_SP)
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|| ((isr & IA64_ISR_NA) && (isr & IA64_ISR_CODE_MASK) == IA64_ISR_CODE_LFETCH))
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{
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/*
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* This fault was due to a speculative load or lfetch.fault, set the "ed"
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* bit in the psr to ensure forward progress. (Target register will get a
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* NaT for ld.s, lfetch will be canceled.)
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*/
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ia64_psr(regs)->ed = 1;
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return;
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}
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/*
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* Since we have no vma's for region 5, we might get here even if the address is
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* valid, due to the VHPT walker inserting a non present translation that becomes
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* stale. If that happens, the non present fault handler already purged the stale
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* translation, which fixed the problem. So, we check to see if the translation is
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* valid, and return if it is.
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*/
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if (REGION_NUMBER(address) == 5 && mapped_kernel_page_is_present(address))
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return;
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if (ia64_done_with_exception(regs))
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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 terminate things
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* with extreme prejudice.
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*/
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bust_spinlocks(1);
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if (address < PAGE_SIZE)
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printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference (address %016lx)\n", address);
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else
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printk(KERN_ALERT "Unable to handle kernel paging request at "
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"virtual address %016lx\n", address);
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if (die("Oops", regs, isr))
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regs = NULL;
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bust_spinlocks(0);
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if (regs)
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make_task_dead(SIGKILL);
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return;
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out_of_memory:
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mmap_read_unlock(mm);
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if (!user_mode(regs))
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goto no_context;
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pagefault_out_of_memory();
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}
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