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250 lines
6.0 KiB
250 lines
6.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/arch/alpha/mm/fault.c |
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* |
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* Copyright (C) 1995 Linus Torvalds |
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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 <asm/io.h> |
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#define __EXTERN_INLINE inline |
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#include <asm/mmu_context.h> |
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#include <asm/tlbflush.h> |
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#undef __EXTERN_INLINE |
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#include <linux/signal.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/smp.h> |
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#include <linux/interrupt.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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extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *); |
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/* |
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* Force a new ASN for a task. |
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*/ |
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#ifndef CONFIG_SMP |
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unsigned long last_asn = ASN_FIRST_VERSION; |
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#endif |
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void |
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__load_new_mm_context(struct mm_struct *next_mm) |
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{ |
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unsigned long mmc; |
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struct pcb_struct *pcb; |
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mmc = __get_new_mm_context(next_mm, smp_processor_id()); |
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next_mm->context[smp_processor_id()] = mmc; |
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pcb = ¤t_thread_info()->pcb; |
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pcb->asn = mmc & HARDWARE_ASN_MASK; |
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pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; |
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__reload_thread(pcb); |
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} |
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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 handle_mm_fault(). |
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* |
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* mmcsr: |
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* 0 = translation not valid |
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* 1 = access violation |
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* 2 = fault-on-read |
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* 3 = fault-on-execute |
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* 4 = fault-on-write |
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* |
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* cause: |
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* -1 = instruction fetch |
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* 0 = load |
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* 1 = store |
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* |
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* Registers $9 through $15 are saved in a block just prior to `regs' and |
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* are saved and restored around the call to allow exception code to |
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* modify them. |
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*/ |
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/* Macro for exception fixup code to access integer registers. */ |
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#define dpf_reg(r) \ |
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(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \ |
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(r) <= 18 ? (r)+10 : (r)-10]) |
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asmlinkage void |
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do_page_fault(unsigned long address, unsigned long mmcsr, |
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long cause, 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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const struct exception_table_entry *fixup; |
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int si_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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/* As of EV6, a load into $31/$f31 is a prefetch, and never faults |
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(or is suppressed by the PALcode). Support that for older CPUs |
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by ignoring such an instruction. */ |
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if (cause == 0) { |
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unsigned int insn; |
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__get_user(insn, (unsigned int __user *)regs->pc); |
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if ((insn >> 21 & 0x1f) == 0x1f && |
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/* ldq ldl ldt lds ldg ldf ldwu ldbu */ |
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(1ul << (insn >> 26) & 0x30f00001400ul)) { |
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regs->pc += 4; |
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return; |
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} |
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} |
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/* If we're in an interrupt context, or have no user context, |
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we must not take the fault. */ |
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if (!mm || faulthandler_disabled()) |
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goto no_context; |
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#ifdef CONFIG_ALPHA_LARGE_VMALLOC |
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if (address >= TASK_SIZE) |
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goto vmalloc_fault; |
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#endif |
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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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good_area: |
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si_code = SEGV_ACCERR; |
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if (cause < 0) { |
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if (!(vma->vm_flags & VM_EXEC)) |
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goto bad_area; |
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} else if (!cause) { |
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/* Allow reads even for write-only mappings */ |
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if (!(vma->vm_flags & (VM_READ | VM_WRITE))) |
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goto bad_area; |
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} else { |
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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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} |
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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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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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/* 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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bad_area: |
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mmap_read_unlock(mm); |
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if (user_mode(regs)) |
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goto do_sigsegv; |
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no_context: |
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/* Are we prepared to handle this fault as an exception? */ |
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if ((fixup = search_exception_tables(regs->pc)) != 0) { |
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unsigned long newpc; |
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newpc = fixup_exception(dpf_reg, fixup, regs->pc); |
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regs->pc = newpc; |
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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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printk(KERN_ALERT "Unable to handle kernel paging request at " |
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"virtual address %016lx\n", address); |
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die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16); |
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do_exit(SIGKILL); |
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/* We ran out of memory, or some other thing happened to us that |
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made us unable to handle the page fault gracefully. */ |
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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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/* Send a sigbus, regardless of whether we were in kernel |
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or user mode. */ |
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force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *) address, 0); |
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if (!user_mode(regs)) |
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goto no_context; |
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return; |
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do_sigsegv: |
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force_sig_fault(SIGSEGV, si_code, (void __user *) address, 0); |
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return; |
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#ifdef CONFIG_ALPHA_LARGE_VMALLOC |
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vmalloc_fault: |
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if (user_mode(regs)) |
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goto do_sigsegv; |
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else { |
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/* Synchronize this task's top level page-table |
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with the "reference" page table from init. */ |
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long index = pgd_index(address); |
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pgd_t *pgd, *pgd_k; |
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pgd = current->active_mm->pgd + index; |
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pgd_k = swapper_pg_dir + index; |
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if (!pgd_present(*pgd) && pgd_present(*pgd_k)) { |
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pgd_val(*pgd) = pgd_val(*pgd_k); |
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return; |
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} |
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goto no_context; |
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} |
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#endif |
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}
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