336 lines
8.5 KiB
C
336 lines
8.5 KiB
C
/*
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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) 1995 - 2000 by Ralf Baechle
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*/
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#include <linux/context_tracking.h>
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#include <linux/signal.h>
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#include <linux/sched.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/ratelimit.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kprobes.h>
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#include <linux/perf_event.h>
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#include <linux/uaccess.h>
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#include <asm/branch.h>
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#include <asm/mmu_context.h>
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#include <asm/ptrace.h>
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#include <asm/highmem.h> /* For VMALLOC_END */
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#include <linux/kdebug.h>
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int show_unhandled_signals = 1;
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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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static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
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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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const int field = sizeof(unsigned long) * 2;
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int si_code;
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int fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
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#if 0
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printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
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current->comm, current->pid, field, address, write,
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field, regs->cp0_epc);
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#endif
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#ifdef CONFIG_KPROBES
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/*
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* This is to notify the fault handler of the kprobes.
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*/
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if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
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current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
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return;
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#endif
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si_code = SEGV_MAPERR;
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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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#ifdef CONFIG_64BIT
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# define VMALLOC_FAULT_TARGET no_context
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#else
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# define VMALLOC_FAULT_TARGET vmalloc_fault
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#endif
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if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
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goto VMALLOC_FAULT_TARGET;
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#ifdef MODULE_START
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if (unlikely(address >= MODULE_START && address < MODULE_END))
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goto VMALLOC_FAULT_TARGET;
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#endif
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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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retry:
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down_read(&mm->mmap_sem);
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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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si_code = SEGV_ACCERR;
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if (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 {
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if (cpu_has_rixi) {
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if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
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#if 0
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pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
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raw_smp_processor_id(),
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current->comm, current->pid,
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field, address, write,
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field, regs->cp0_epc);
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#endif
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goto bad_area;
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}
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if (!(vma->vm_flags & VM_READ) &&
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exception_epc(regs) != address) {
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#if 0
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pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
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raw_smp_processor_id(),
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current->comm, current->pid,
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field, address, write,
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field, regs->cp0_epc);
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#endif
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goto bad_area;
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}
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} else {
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if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
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goto bad_area;
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}
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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);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return;
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
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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_MAJOR) {
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
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regs, address);
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tsk->maj_flt++;
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} else {
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perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
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regs, address);
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tsk->min_flt++;
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}
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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flags |= FAULT_FLAG_TRIED;
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/*
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* No need to up_read(&mm->mmap_sem) 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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up_read(&mm->mmap_sem);
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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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up_read(&mm->mmap_sem);
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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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tsk->thread.cp0_badvaddr = address;
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tsk->thread.error_code = write;
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if (show_unhandled_signals &&
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unhandled_signal(tsk, SIGSEGV) &&
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__ratelimit(&ratelimit_state)) {
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pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
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tsk->comm,
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write ? "write access to" : "read access from",
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field, address);
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pr_info("epc = %0*lx in", field,
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(unsigned long) regs->cp0_epc);
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print_vma_addr(KERN_CONT " ", regs->cp0_epc);
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pr_cont("\n");
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pr_info("ra = %0*lx in", field,
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(unsigned long) regs->regs[31]);
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print_vma_addr(KERN_CONT " ", regs->regs[31]);
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pr_cont("\n");
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}
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current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
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force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk);
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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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current->thread.cp0_baduaddr = address;
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return;
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}
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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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printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
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"virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
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raw_smp_processor_id(), field, address, field, regs->cp0_epc,
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field, regs->regs[31]);
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die("Oops", regs);
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out_of_memory:
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/*
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* We ran out of memory, call the OOM killer, and return the userspace
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* (which will retry the fault, or kill us if we got oom-killed).
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*/
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up_read(&mm->mmap_sem);
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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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up_read(&mm->mmap_sem);
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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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/*
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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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#if 0
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printk("do_page_fault() #3: sending SIGBUS to %s for "
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"invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
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tsk->comm,
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write ? "write access to" : "read access from",
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field, address,
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field, (unsigned long) regs->cp0_epc,
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field, (unsigned long) regs->regs[31]);
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#endif
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current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
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tsk->thread.cp0_badvaddr = address;
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force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk);
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return;
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#ifndef CONFIG_64BIT
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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_offset(address);
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pgd_t *pgd, *pgd_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_t *) pgd_current[raw_smp_processor_id()] + 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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pud = pud_offset(pgd, address);
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pud_k = pud_offset(pgd_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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return;
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}
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#endif
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}
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asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
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unsigned long write, unsigned long address)
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{
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enum ctx_state prev_state;
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prev_state = exception_enter();
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__do_page_fault(regs, write, address);
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exception_exit(prev_state);
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}
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