265 lines
6.7 KiB
C
265 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
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*
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* Derived from MIPS:
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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/entry-common.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/kdebug.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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int show_unhandled_signals = 1;
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static void __kprobes no_context(struct pt_regs *regs, unsigned long address)
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{
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const int field = sizeof(unsigned long) * 2;
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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("CPU %d Unable to handle kernel paging request at "
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"virtual address %0*lx, era == %0*lx, ra == %0*lx\n",
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raw_smp_processor_id(), field, address, field, regs->csr_era,
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field, regs->regs[1]);
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die("Oops", regs);
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}
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static void __kprobes do_out_of_memory(struct pt_regs *regs, unsigned long address)
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{
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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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if (!user_mode(regs)) {
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no_context(regs, address);
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return;
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}
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pagefault_out_of_memory();
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}
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static void __kprobes do_sigbus(struct pt_regs *regs,
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unsigned long write, unsigned long address, int si_code)
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{
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/* Kernel mode? Handle exceptions or die */
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if (!user_mode(regs)) {
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no_context(regs, address);
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return;
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}
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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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current->thread.csr_badvaddr = address;
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current->thread.trap_nr = read_csr_excode();
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force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
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}
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static void __kprobes do_sigsegv(struct pt_regs *regs,
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unsigned long write, unsigned long address, int si_code)
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{
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const int field = sizeof(unsigned long) * 2;
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static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
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/* Kernel mode? Handle exceptions or die */
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if (!user_mode(regs)) {
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no_context(regs, address);
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return;
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}
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/* User mode accesses just cause a SIGSEGV */
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current->thread.csr_badvaddr = address;
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if (!write)
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current->thread.error_code = 1;
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else
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current->thread.error_code = 2;
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current->thread.trap_nr = read_csr_excode();
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if (show_unhandled_signals &&
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unhandled_signal(current, SIGSEGV) && __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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current->comm,
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write ? "write access to" : "read access from",
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field, address);
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pr_info("era = %0*lx in", field,
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(unsigned long) regs->csr_era);
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print_vma_addr(KERN_CONT " ", regs->csr_era);
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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[1]);
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print_vma_addr(KERN_CONT " ", regs->regs[1]);
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pr_cont("\n");
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}
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force_sig_fault(SIGSEGV, si_code, (void __user *)address);
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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 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,
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unsigned long write, unsigned long address)
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{
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int si_code = SEGV_MAPERR;
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unsigned int flags = FAULT_FLAG_DEFAULT;
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struct task_struct *tsk = current;
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struct mm_struct *mm = tsk->mm;
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struct vm_area_struct *vma = NULL;
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vm_fault_t fault;
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if (kprobe_page_fault(regs, current->thread.trap_nr))
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return;
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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 (address & __UA_LIMIT) {
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if (!user_mode(regs))
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no_context(regs, address);
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else
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do_sigsegv(regs, write, address, si_code);
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return;
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}
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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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do_sigsegv(regs, write, address, si_code);
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return;
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}
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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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vma = lock_mm_and_find_vma(mm, address, regs);
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if (unlikely(!vma))
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goto bad_area_nosemaphore;
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goto good_area;
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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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do_sigsegv(regs, write, address, si_code);
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return;
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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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flags |= FAULT_FLAG_WRITE;
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & VM_READ) && address != exception_era(regs))
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goto bad_area;
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if (!(vma->vm_flags & VM_EXEC) && address == exception_era(regs))
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goto bad_area;
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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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if (!user_mode(regs))
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no_context(regs, address);
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return;
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}
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/* The fault is fully completed (including releasing mmap lock) */
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if (fault & VM_FAULT_COMPLETED)
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return;
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if (unlikely(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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if (unlikely(fault & VM_FAULT_ERROR)) {
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mmap_read_unlock(mm);
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if (fault & VM_FAULT_OOM) {
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do_out_of_memory(regs, address);
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return;
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} else if (fault & VM_FAULT_SIGSEGV) {
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do_sigsegv(regs, write, address, si_code);
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return;
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} else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
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do_sigbus(regs, write, address, si_code);
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return;
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}
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BUG();
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}
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mmap_read_unlock(mm);
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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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irqentry_state_t state = irqentry_enter(regs);
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/* Enable interrupt if enabled in parent context */
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if (likely(regs->csr_prmd & CSR_PRMD_PIE))
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local_irq_enable();
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__do_page_fault(regs, write, address);
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local_irq_disable();
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irqentry_exit(regs, state);
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}
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