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272 lines
6.5 KiB
272 lines
6.5 KiB
/* |
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* Copyright (C) 2009 Wind River Systems Inc |
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* Implemented by [email protected] and [email protected] |
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* |
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* based on arch/mips/mm/fault.c which is: |
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* |
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* Copyright (C) 1995-2000 Ralf Baechle |
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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/signal.h> |
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#include <linux/sched.h> |
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#include <linux/sched/debug.h> |
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#include <linux/interrupt.h> |
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#include <linux/kernel.h> |
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#include <linux/errno.h> |
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#include <linux/string.h> |
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#include <linux/types.h> |
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#include <linux/ptrace.h> |
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#include <linux/mman.h> |
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#include <linux/mm.h> |
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#include <linux/extable.h> |
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#include <linux/uaccess.h> |
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#include <linux/perf_event.h> |
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#include <asm/mmu_context.h> |
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#include <asm/traps.h> |
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#define EXC_SUPERV_INSN_ACCESS 9 /* Supervisor only instruction address */ |
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#define EXC_SUPERV_DATA_ACCESS 11 /* Supervisor only data address */ |
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#define EXC_X_PROTECTION_FAULT 13 /* TLB permission violation (x) */ |
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#define EXC_R_PROTECTION_FAULT 14 /* TLB permission violation (r) */ |
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#define EXC_W_PROTECTION_FAULT 15 /* TLB permission violation (w) */ |
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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 do_page_fault(struct pt_regs *regs, unsigned long cause, |
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unsigned long address) |
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{ |
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struct vm_area_struct *vma = NULL; |
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struct task_struct *tsk = current; |
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struct mm_struct *mm = tsk->mm; |
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int code = SEGV_MAPERR; |
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vm_fault_t fault; |
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unsigned int flags = FAULT_FLAG_DEFAULT; |
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cause >>= 2; |
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/* Restart the instruction */ |
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regs->ea -= 4; |
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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(address >= VMALLOC_START && address <= VMALLOC_END)) { |
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if (user_mode(regs)) |
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goto bad_area_nosemaphore; |
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else |
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goto vmalloc_fault; |
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} |
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if (unlikely(address >= TASK_SIZE)) |
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goto bad_area_nosemaphore; |
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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 (faulthandler_disabled() || !mm) |
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goto bad_area_nosemaphore; |
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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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if (!mmap_read_trylock(mm)) { |
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if (!user_mode(regs) && !search_exception_tables(regs->ea)) |
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goto bad_area_nosemaphore; |
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retry: |
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mmap_read_lock(mm); |
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} |
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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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code = SEGV_ACCERR; |
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switch (cause) { |
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case EXC_SUPERV_INSN_ACCESS: |
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goto bad_area; |
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case EXC_SUPERV_DATA_ACCESS: |
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goto bad_area; |
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case EXC_X_PROTECTION_FAULT: |
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if (!(vma->vm_flags & VM_EXEC)) |
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goto bad_area; |
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break; |
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case EXC_R_PROTECTION_FAULT: |
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if (!(vma->vm_flags & VM_READ)) |
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goto bad_area; |
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break; |
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case EXC_W_PROTECTION_FAULT: |
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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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break; |
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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, regs); |
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if (fault_signal_pending(fault, regs)) |
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return; |
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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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/* |
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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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/* |
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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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bad_area_nosemaphore: |
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/* User mode accesses just cause a SIGSEGV */ |
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if (user_mode(regs)) { |
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if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) { |
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pr_info("%s: unhandled page fault (%d) at 0x%08lx, " |
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"cause %ld\n", current->comm, SIGSEGV, address, cause); |
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show_regs(regs); |
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} |
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_exception(SIGSEGV, regs, code, address); |
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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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/* |
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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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bust_spinlocks(1); |
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pr_alert("Unable to handle kernel %s at virtual address %08lx", |
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address < PAGE_SIZE ? "NULL pointer dereference" : |
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"paging request", address); |
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pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra, |
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cause); |
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panic("Oops"); |
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return; |
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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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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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return; |
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do_sigbus: |
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mmap_read_unlock(mm); |
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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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_exception(SIGBUS, regs, BUS_ADRERR, address); |
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return; |
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vmalloc_fault: |
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{ |
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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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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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pgd = pgd_current + offset; |
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pgd_k = init_mm.pgd + offset; |
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if (!pgd_present(*pgd_k)) |
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goto no_context; |
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set_pgd(pgd, *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_k)) |
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goto no_context; |
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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_k)) |
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goto no_context; |
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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 no_context; |
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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 no_context; |
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flush_tlb_kernel_page(address); |
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return; |
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} |
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}
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