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261 lines
6.3 KiB
261 lines
6.3 KiB
// TODO VM_EXEC flag work-around, cache aliasing |
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/* |
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* arch/xtensa/mm/fault.c |
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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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* Copyright (C) 2001 - 2010 Tensilica Inc. |
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* |
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* Chris Zankel <[email protected]> |
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* Joe Taylor <[email protected], [email protected]> |
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*/ |
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#include <linux/mm.h> |
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#include <linux/extable.h> |
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#include <linux/hardirq.h> |
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#include <linux/perf_event.h> |
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#include <linux/uaccess.h> |
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#include <asm/mmu_context.h> |
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#include <asm/cacheflush.h> |
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#include <asm/hardirq.h> |
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DEFINE_PER_CPU(unsigned long, asid_cache) = ASID_USER_FIRST; |
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void bad_page_fault(struct pt_regs*, unsigned long, int); |
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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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* Note: does not handle Miss and MultiHit. |
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*/ |
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void do_page_fault(struct pt_regs *regs) |
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{ |
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struct vm_area_struct * vma; |
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struct mm_struct *mm = current->mm; |
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unsigned int exccause = regs->exccause; |
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unsigned int address = regs->excvaddr; |
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int code; |
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int is_write, is_exec; |
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vm_fault_t fault; |
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unsigned int flags = FAULT_FLAG_DEFAULT; |
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code = SEGV_MAPERR; |
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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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if (address >= TASK_SIZE && !user_mode(regs)) |
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goto vmalloc_fault; |
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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 (faulthandler_disabled() || !mm) { |
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bad_page_fault(regs, address, SIGSEGV); |
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return; |
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} |
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is_write = (exccause == EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0; |
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is_exec = (exccause == EXCCAUSE_ITLB_PRIVILEGE || |
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exccause == EXCCAUSE_ITLB_MISS || |
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exccause == EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0; |
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pr_debug("[%s:%d:%08x:%d:%08lx:%s%s]\n", |
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current->comm, current->pid, |
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address, exccause, regs->pc, |
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is_write ? "w" : "", is_exec ? "x" : ""); |
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if (user_mode(regs)) |
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flags |= FAULT_FLAG_USER; |
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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(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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/* 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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code = SEGV_ACCERR; |
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if (is_write) { |
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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 if (is_exec) { |
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if (!(vma->vm_flags & VM_EXEC)) |
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goto bad_area; |
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} else /* Allow read even from write-only pages. */ |
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if (!(vma->vm_flags & (VM_READ | VM_WRITE))) |
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goto bad_area; |
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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, regs); |
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if (fault_signal_pending(fault, regs)) { |
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if (!user_mode(regs)) |
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goto bad_page_fault; |
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return; |
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} |
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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_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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} |
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mmap_read_unlock(mm); |
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return; |
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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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mmap_read_unlock(mm); |
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if (user_mode(regs)) { |
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current->thread.bad_vaddr = address; |
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current->thread.error_code = is_write; |
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force_sig_fault(SIGSEGV, code, (void *) address); |
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return; |
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} |
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bad_page_fault(regs, address, SIGSEGV); |
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return; |
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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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mmap_read_unlock(mm); |
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if (!user_mode(regs)) |
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bad_page_fault(regs, address, SIGKILL); |
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else |
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pagefault_out_of_memory(); |
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return; |
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do_sigbus: |
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mmap_read_unlock(mm); |
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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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current->thread.bad_vaddr = address; |
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force_sig_fault(SIGBUS, BUS_ADRERR, (void *) address); |
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/* Kernel mode? Handle exceptions or die */ |
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if (!user_mode(regs)) |
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bad_page_fault(regs, address, SIGBUS); |
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return; |
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vmalloc_fault: |
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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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struct mm_struct *act_mm = current->active_mm; |
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int index = pgd_index(address); |
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pgd_t *pgd, *pgd_k; |
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p4d_t *p4d, *p4d_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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if (act_mm == NULL) |
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goto bad_page_fault; |
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pgd = act_mm->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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goto bad_page_fault; |
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pgd_val(*pgd) = pgd_val(*pgd_k); |
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p4d = p4d_offset(pgd, address); |
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p4d_k = p4d_offset(pgd_k, address); |
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if (!p4d_present(*p4d) || !p4d_present(*p4d_k)) |
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goto bad_page_fault; |
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pud = pud_offset(p4d, address); |
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pud_k = pud_offset(p4d_k, address); |
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if (!pud_present(*pud) || !pud_present(*pud_k)) |
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goto bad_page_fault; |
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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) || !pmd_present(*pmd_k)) |
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goto bad_page_fault; |
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pmd_val(*pmd) = pmd_val(*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_page_fault; |
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return; |
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} |
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bad_page_fault: |
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bad_page_fault(regs, address, SIGKILL); |
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return; |
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} |
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void |
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bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) |
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{ |
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extern void die(const char*, struct pt_regs*, long); |
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const struct exception_table_entry *entry; |
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/* Are we prepared to handle this kernel fault? */ |
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if ((entry = search_exception_tables(regs->pc)) != NULL) { |
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pr_debug("%s: Exception at pc=%#010lx (%lx)\n", |
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current->comm, regs->pc, entry->fixup); |
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current->thread.bad_uaddr = address; |
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regs->pc = entry->fixup; |
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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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pr_alert("Unable to handle kernel paging request at virtual " |
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"address %08lx\n pc = %08lx, ra = %08lx\n", |
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address, regs->pc, regs->areg[0]); |
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die("Oops", regs, sig); |
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do_exit(sig); |
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}
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