mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 08:28:13 +00:00
35ce8ae9ae
Pull signal/exit/ptrace updates from Eric Biederman: "This set of changes deletes some dead code, makes a lot of cleanups which hopefully make the code easier to follow, and fixes bugs found along the way. The end-game which I have not yet reached yet is for fatal signals that generate coredumps to be short-circuit deliverable from complete_signal, for force_siginfo_to_task not to require changing userspace configured signal delivery state, and for the ptrace stops to always happen in locations where we can guarantee on all architectures that the all of the registers are saved and available on the stack. Removal of profile_task_ext, profile_munmap, and profile_handoff_task are the big successes for dead code removal this round. A bunch of small bug fixes are included, as most of the issues reported were small enough that they would not affect bisection so I simply added the fixes and did not fold the fixes into the changes they were fixing. There was a bug that broke coredumps piped to systemd-coredump. I dropped the change that caused that bug and replaced it entirely with something much more restrained. Unfortunately that required some rebasing. Some successes after this set of changes: There are few enough calls to do_exit to audit in a reasonable amount of time. The lifetime of struct kthread now matches the lifetime of struct task, and the pointer to struct kthread is no longer stored in set_child_tid. The flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is removed. Issues where task->exit_code was examined with signal->group_exit_code should been examined were fixed. There are several loosely related changes included because I am cleaning up and if I don't include them they will probably get lost. The original postings of these changes can be found at: https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.org https://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org I trimmed back the last set of changes to only the obviously correct once. Simply because there was less time for review than I had hoped" * 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits) ptrace/m68k: Stop open coding ptrace_report_syscall ptrace: Remove unused regs argument from ptrace_report_syscall ptrace: Remove second setting of PT_SEIZED in ptrace_attach taskstats: Cleanup the use of task->exit_code exit: Use the correct exit_code in /proc/<pid>/stat exit: Fix the exit_code for wait_task_zombie exit: Coredumps reach do_group_exit exit: Remove profile_handoff_task exit: Remove profile_task_exit & profile_munmap signal: clean up kernel-doc comments signal: Remove the helper signal_group_exit signal: Rename group_exit_task group_exec_task coredump: Stop setting signal->group_exit_task signal: Remove SIGNAL_GROUP_COREDUMP signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process signal: Make coredump handling explicit in complete_signal signal: Have prepare_signal detect coredumps using signal->core_state signal: Have the oom killer detect coredumps using signal->core_state exit: Move force_uaccess back into do_exit exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit ...
248 lines
6 KiB
C
248 lines
6 KiB
C
// 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 (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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/* 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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make_task_dead(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);
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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);
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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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