1524 строки
38 KiB
C
1524 строки
38 KiB
C
/*
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* Copyright (C) 1995 Linus Torvalds
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* Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs.
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* Copyright (C) 2008-2009, Red Hat Inc., Ingo Molnar
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*/
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#include <linux/sched.h> /* test_thread_flag(), ... */
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#include <linux/sched/task_stack.h> /* task_stack_*(), ... */
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#include <linux/kdebug.h> /* oops_begin/end, ... */
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#include <linux/extable.h> /* search_exception_tables */
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#include <linux/bootmem.h> /* max_low_pfn */
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#include <linux/kprobes.h> /* NOKPROBE_SYMBOL, ... */
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#include <linux/mmiotrace.h> /* kmmio_handler, ... */
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#include <linux/perf_event.h> /* perf_sw_event */
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#include <linux/hugetlb.h> /* hstate_index_to_shift */
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#include <linux/prefetch.h> /* prefetchw */
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#include <linux/context_tracking.h> /* exception_enter(), ... */
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#include <linux/uaccess.h> /* faulthandler_disabled() */
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#include <asm/cpufeature.h> /* boot_cpu_has, ... */
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#include <asm/traps.h> /* dotraplinkage, ... */
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#include <asm/pgalloc.h> /* pgd_*(), ... */
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#include <asm/kmemcheck.h> /* kmemcheck_*(), ... */
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#include <asm/fixmap.h> /* VSYSCALL_ADDR */
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#include <asm/vsyscall.h> /* emulate_vsyscall */
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#include <asm/vm86.h> /* struct vm86 */
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#include <asm/mmu_context.h> /* vma_pkey() */
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#define CREATE_TRACE_POINTS
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#include <asm/trace/exceptions.h>
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/*
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* Page fault error code bits:
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*
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* bit 0 == 0: no page found 1: protection fault
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* bit 1 == 0: read access 1: write access
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* bit 2 == 0: kernel-mode access 1: user-mode access
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* bit 3 == 1: use of reserved bit detected
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* bit 4 == 1: fault was an instruction fetch
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* bit 5 == 1: protection keys block access
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*/
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enum x86_pf_error_code {
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PF_PROT = 1 << 0,
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PF_WRITE = 1 << 1,
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PF_USER = 1 << 2,
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PF_RSVD = 1 << 3,
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PF_INSTR = 1 << 4,
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PF_PK = 1 << 5,
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};
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/*
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* Returns 0 if mmiotrace is disabled, or if the fault is not
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* handled by mmiotrace:
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*/
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static nokprobe_inline int
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kmmio_fault(struct pt_regs *regs, unsigned long addr)
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{
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if (unlikely(is_kmmio_active()))
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if (kmmio_handler(regs, addr) == 1)
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return -1;
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return 0;
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}
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static nokprobe_inline int kprobes_fault(struct pt_regs *regs)
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{
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int ret = 0;
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/* kprobe_running() needs smp_processor_id() */
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if (kprobes_built_in() && !user_mode(regs)) {
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preempt_disable();
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if (kprobe_running() && kprobe_fault_handler(regs, 14))
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ret = 1;
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preempt_enable();
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}
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return ret;
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}
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/*
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* Prefetch quirks:
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*
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* 32-bit mode:
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*
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* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* 64-bit mode:
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*
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* Sometimes the CPU reports invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* Opcode checker based on code by Richard Brunner.
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*/
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static inline int
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check_prefetch_opcode(struct pt_regs *regs, unsigned char *instr,
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unsigned char opcode, int *prefetch)
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{
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unsigned char instr_hi = opcode & 0xf0;
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unsigned char instr_lo = opcode & 0x0f;
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switch (instr_hi) {
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case 0x20:
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case 0x30:
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/*
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* Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
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* In X86_64 long mode, the CPU will signal invalid
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* opcode if some of these prefixes are present so
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* X86_64 will never get here anyway
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*/
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return ((instr_lo & 7) == 0x6);
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#ifdef CONFIG_X86_64
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case 0x40:
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/*
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* In AMD64 long mode 0x40..0x4F are valid REX prefixes
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* Need to figure out under what instruction mode the
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* instruction was issued. Could check the LDT for lm,
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* but for now it's good enough to assume that long
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* mode only uses well known segments or kernel.
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*/
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return (!user_mode(regs) || user_64bit_mode(regs));
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#endif
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case 0x60:
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/* 0x64 thru 0x67 are valid prefixes in all modes. */
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return (instr_lo & 0xC) == 0x4;
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case 0xF0:
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/* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
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return !instr_lo || (instr_lo>>1) == 1;
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case 0x00:
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/* Prefetch instruction is 0x0F0D or 0x0F18 */
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if (probe_kernel_address(instr, opcode))
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return 0;
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*prefetch = (instr_lo == 0xF) &&
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(opcode == 0x0D || opcode == 0x18);
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return 0;
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default:
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return 0;
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}
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}
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static int
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is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
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{
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unsigned char *max_instr;
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unsigned char *instr;
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int prefetch = 0;
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/*
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* If it was a exec (instruction fetch) fault on NX page, then
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* do not ignore the fault:
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*/
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if (error_code & PF_INSTR)
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return 0;
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instr = (void *)convert_ip_to_linear(current, regs);
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max_instr = instr + 15;
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if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE_MAX)
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return 0;
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while (instr < max_instr) {
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unsigned char opcode;
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if (probe_kernel_address(instr, opcode))
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break;
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instr++;
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if (!check_prefetch_opcode(regs, instr, opcode, &prefetch))
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break;
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}
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return prefetch;
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}
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/*
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* A protection key fault means that the PKRU value did not allow
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* access to some PTE. Userspace can figure out what PKRU was
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* from the XSAVE state, and this function fills out a field in
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* siginfo so userspace can discover which protection key was set
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* on the PTE.
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*
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* If we get here, we know that the hardware signaled a PF_PK
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* fault and that there was a VMA once we got in the fault
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* handler. It does *not* guarantee that the VMA we find here
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* was the one that we faulted on.
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*
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* 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4);
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* 2. T1 : set PKRU to deny access to pkey=4, touches page
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* 3. T1 : faults...
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* 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5);
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* 5. T1 : enters fault handler, takes mmap_sem, etc...
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* 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really
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* faulted on a pte with its pkey=4.
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*/
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static void fill_sig_info_pkey(int si_code, siginfo_t *info,
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struct vm_area_struct *vma)
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{
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/* This is effectively an #ifdef */
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if (!boot_cpu_has(X86_FEATURE_OSPKE))
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return;
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/* Fault not from Protection Keys: nothing to do */
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if (si_code != SEGV_PKUERR)
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return;
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/*
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* force_sig_info_fault() is called from a number of
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* contexts, some of which have a VMA and some of which
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* do not. The PF_PK handing happens after we have a
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* valid VMA, so we should never reach this without a
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* valid VMA.
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*/
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if (!vma) {
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WARN_ONCE(1, "PKU fault with no VMA passed in");
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info->si_pkey = 0;
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return;
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}
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/*
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* si_pkey should be thought of as a strong hint, but not
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* absolutely guranteed to be 100% accurate because of
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* the race explained above.
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*/
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info->si_pkey = vma_pkey(vma);
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}
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static void
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force_sig_info_fault(int si_signo, int si_code, unsigned long address,
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struct task_struct *tsk, struct vm_area_struct *vma,
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int fault)
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{
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unsigned lsb = 0;
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siginfo_t info;
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info.si_signo = si_signo;
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info.si_errno = 0;
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info.si_code = si_code;
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info.si_addr = (void __user *)address;
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if (fault & VM_FAULT_HWPOISON_LARGE)
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lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
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if (fault & VM_FAULT_HWPOISON)
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lsb = PAGE_SHIFT;
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info.si_addr_lsb = lsb;
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fill_sig_info_pkey(si_code, &info, vma);
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force_sig_info(si_signo, &info, tsk);
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}
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DEFINE_SPINLOCK(pgd_lock);
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LIST_HEAD(pgd_list);
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#ifdef CONFIG_X86_32
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static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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{
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unsigned index = pgd_index(address);
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pgd_t *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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pgd += index;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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return NULL;
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/*
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* set_pgd(pgd, *pgd_k); here would be useless on PAE
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* and redundant with the set_pmd() on non-PAE. As would
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* set_p4d/set_pud.
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*/
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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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return NULL;
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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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return NULL;
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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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return NULL;
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if (!pmd_present(*pmd))
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set_pmd(pmd, *pmd_k);
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else
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BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
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return pmd_k;
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}
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void vmalloc_sync_all(void)
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{
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unsigned long address;
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if (SHARED_KERNEL_PMD)
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return;
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for (address = VMALLOC_START & PMD_MASK;
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address >= TASK_SIZE_MAX && address < FIXADDR_TOP;
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address += PMD_SIZE) {
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struct page *page;
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spin_lock(&pgd_lock);
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list_for_each_entry(page, &pgd_list, lru) {
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spinlock_t *pgt_lock;
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pmd_t *ret;
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/* the pgt_lock only for Xen */
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pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
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spin_lock(pgt_lock);
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ret = vmalloc_sync_one(page_address(page), address);
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spin_unlock(pgt_lock);
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if (!ret)
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break;
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}
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spin_unlock(&pgd_lock);
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}
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}
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/*
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* 32-bit:
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*
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* Handle a fault on the vmalloc or module mapping area
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*/
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static noinline int vmalloc_fault(unsigned long address)
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{
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unsigned long pgd_paddr;
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pmd_t *pmd_k;
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pte_t *pte_k;
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/* Make sure we are in vmalloc area: */
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if (!(address >= VMALLOC_START && address < VMALLOC_END))
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return -1;
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WARN_ON_ONCE(in_nmi());
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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 "current" 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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pgd_paddr = read_cr3_pa();
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pmd_k = vmalloc_sync_one(__va(pgd_paddr), address);
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if (!pmd_k)
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return -1;
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if (pmd_huge(*pmd_k))
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return 0;
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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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return -1;
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return 0;
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}
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NOKPROBE_SYMBOL(vmalloc_fault);
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/*
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* Did it hit the DOS screen memory VA from vm86 mode?
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*/
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static inline void
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check_v8086_mode(struct pt_regs *regs, unsigned long address,
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struct task_struct *tsk)
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{
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#ifdef CONFIG_VM86
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unsigned long bit;
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if (!v8086_mode(regs) || !tsk->thread.vm86)
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return;
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bit = (address - 0xA0000) >> PAGE_SHIFT;
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if (bit < 32)
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tsk->thread.vm86->screen_bitmap |= 1 << bit;
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#endif
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}
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static bool low_pfn(unsigned long pfn)
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{
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return pfn < max_low_pfn;
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}
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static void dump_pagetable(unsigned long address)
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{
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pgd_t *base = __va(read_cr3_pa());
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pgd_t *pgd = &base[pgd_index(address)];
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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#ifdef CONFIG_X86_PAE
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pr_info("*pdpt = %016Lx ", pgd_val(*pgd));
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if (!low_pfn(pgd_val(*pgd) >> PAGE_SHIFT) || !pgd_present(*pgd))
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goto out;
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#define pr_pde pr_cont
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#else
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#define pr_pde pr_info
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#endif
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p4d = p4d_offset(pgd, address);
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pud = pud_offset(p4d, address);
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pmd = pmd_offset(pud, address);
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pr_pde("*pde = %0*Lx ", sizeof(*pmd) * 2, (u64)pmd_val(*pmd));
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#undef pr_pde
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/*
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* We must not directly access the pte in the highpte
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* case if the page table is located in highmem.
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* And let's rather not kmap-atomic the pte, just in case
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* it's allocated already:
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*/
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if (!low_pfn(pmd_pfn(*pmd)) || !pmd_present(*pmd) || pmd_large(*pmd))
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goto out;
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pte = pte_offset_kernel(pmd, address);
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pr_cont("*pte = %0*Lx ", sizeof(*pte) * 2, (u64)pte_val(*pte));
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out:
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pr_cont("\n");
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}
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#else /* CONFIG_X86_64: */
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void vmalloc_sync_all(void)
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{
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sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END);
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}
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/*
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* 64-bit:
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*
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* Handle a fault on the vmalloc area
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*/
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static noinline int vmalloc_fault(unsigned long address)
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{
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pgd_t *pgd, *pgd_ref;
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p4d_t *p4d, *p4d_ref;
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pud_t *pud, *pud_ref;
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pmd_t *pmd, *pmd_ref;
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pte_t *pte, *pte_ref;
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/* Make sure we are in vmalloc area: */
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if (!(address >= VMALLOC_START && address < VMALLOC_END))
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return -1;
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WARN_ON_ONCE(in_nmi());
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/*
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* Copy kernel mappings over when needed. This can also
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* happen within a race in page table update. In the later
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* case just flush:
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*/
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pgd = (pgd_t *)__va(read_cr3_pa()) + pgd_index(address);
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pgd_ref = pgd_offset_k(address);
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if (pgd_none(*pgd_ref))
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return -1;
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if (pgd_none(*pgd)) {
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set_pgd(pgd, *pgd_ref);
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arch_flush_lazy_mmu_mode();
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} else if (CONFIG_PGTABLE_LEVELS > 4) {
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/*
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* With folded p4d, pgd_none() is always false, so the pgd may
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* point to an empty page table entry and pgd_page_vaddr()
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* will return garbage.
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*
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* We will do the correct sanity check on the p4d level.
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*/
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BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
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}
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/* With 4-level paging, copying happens on the p4d level. */
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p4d = p4d_offset(pgd, address);
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p4d_ref = p4d_offset(pgd_ref, address);
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if (p4d_none(*p4d_ref))
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return -1;
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if (p4d_none(*p4d)) {
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set_p4d(p4d, *p4d_ref);
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arch_flush_lazy_mmu_mode();
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} else {
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BUG_ON(p4d_pfn(*p4d) != p4d_pfn(*p4d_ref));
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}
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/*
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* Below here mismatches are bugs because these lower tables
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* are shared:
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*/
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pud = pud_offset(p4d, address);
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pud_ref = pud_offset(p4d_ref, address);
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if (pud_none(*pud_ref))
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return -1;
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if (pud_none(*pud) || pud_pfn(*pud) != pud_pfn(*pud_ref))
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BUG();
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if (pud_huge(*pud))
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return 0;
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|
pmd = pmd_offset(pud, address);
|
|
pmd_ref = pmd_offset(pud_ref, address);
|
|
if (pmd_none(*pmd_ref))
|
|
return -1;
|
|
|
|
if (pmd_none(*pmd) || pmd_pfn(*pmd) != pmd_pfn(*pmd_ref))
|
|
BUG();
|
|
|
|
if (pmd_huge(*pmd))
|
|
return 0;
|
|
|
|
pte_ref = pte_offset_kernel(pmd_ref, address);
|
|
if (!pte_present(*pte_ref))
|
|
return -1;
|
|
|
|
pte = pte_offset_kernel(pmd, address);
|
|
|
|
/*
|
|
* Don't use pte_page here, because the mappings can point
|
|
* outside mem_map, and the NUMA hash lookup cannot handle
|
|
* that:
|
|
*/
|
|
if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref))
|
|
BUG();
|
|
|
|
return 0;
|
|
}
|
|
NOKPROBE_SYMBOL(vmalloc_fault);
|
|
|
|
#ifdef CONFIG_CPU_SUP_AMD
|
|
static const char errata93_warning[] =
|
|
KERN_ERR
|
|
"******* Your BIOS seems to not contain a fix for K8 errata #93\n"
|
|
"******* Working around it, but it may cause SEGVs or burn power.\n"
|
|
"******* Please consider a BIOS update.\n"
|
|
"******* Disabling USB legacy in the BIOS may also help.\n";
|
|
#endif
|
|
|
|
/*
|
|
* No vm86 mode in 64-bit mode:
|
|
*/
|
|
static inline void
|
|
check_v8086_mode(struct pt_regs *regs, unsigned long address,
|
|
struct task_struct *tsk)
|
|
{
|
|
}
|
|
|
|
static int bad_address(void *p)
|
|
{
|
|
unsigned long dummy;
|
|
|
|
return probe_kernel_address((unsigned long *)p, dummy);
|
|
}
|
|
|
|
static void dump_pagetable(unsigned long address)
|
|
{
|
|
pgd_t *base = __va(read_cr3_pa());
|
|
pgd_t *pgd = base + pgd_index(address);
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *pte;
|
|
|
|
if (bad_address(pgd))
|
|
goto bad;
|
|
|
|
pr_info("PGD %lx ", pgd_val(*pgd));
|
|
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
p4d = p4d_offset(pgd, address);
|
|
if (bad_address(p4d))
|
|
goto bad;
|
|
|
|
pr_cont("P4D %lx ", p4d_val(*p4d));
|
|
if (!p4d_present(*p4d) || p4d_large(*p4d))
|
|
goto out;
|
|
|
|
pud = pud_offset(p4d, address);
|
|
if (bad_address(pud))
|
|
goto bad;
|
|
|
|
pr_cont("PUD %lx ", pud_val(*pud));
|
|
if (!pud_present(*pud) || pud_large(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
if (bad_address(pmd))
|
|
goto bad;
|
|
|
|
pr_cont("PMD %lx ", pmd_val(*pmd));
|
|
if (!pmd_present(*pmd) || pmd_large(*pmd))
|
|
goto out;
|
|
|
|
pte = pte_offset_kernel(pmd, address);
|
|
if (bad_address(pte))
|
|
goto bad;
|
|
|
|
pr_cont("PTE %lx", pte_val(*pte));
|
|
out:
|
|
pr_cont("\n");
|
|
return;
|
|
bad:
|
|
pr_info("BAD\n");
|
|
}
|
|
|
|
#endif /* CONFIG_X86_64 */
|
|
|
|
/*
|
|
* Workaround for K8 erratum #93 & buggy BIOS.
|
|
*
|
|
* BIOS SMM functions are required to use a specific workaround
|
|
* to avoid corruption of the 64bit RIP register on C stepping K8.
|
|
*
|
|
* A lot of BIOS that didn't get tested properly miss this.
|
|
*
|
|
* The OS sees this as a page fault with the upper 32bits of RIP cleared.
|
|
* Try to work around it here.
|
|
*
|
|
* Note we only handle faults in kernel here.
|
|
* Does nothing on 32-bit.
|
|
*/
|
|
static int is_errata93(struct pt_regs *regs, unsigned long address)
|
|
{
|
|
#if defined(CONFIG_X86_64) && defined(CONFIG_CPU_SUP_AMD)
|
|
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD
|
|
|| boot_cpu_data.x86 != 0xf)
|
|
return 0;
|
|
|
|
if (address != regs->ip)
|
|
return 0;
|
|
|
|
if ((address >> 32) != 0)
|
|
return 0;
|
|
|
|
address |= 0xffffffffUL << 32;
|
|
if ((address >= (u64)_stext && address <= (u64)_etext) ||
|
|
(address >= MODULES_VADDR && address <= MODULES_END)) {
|
|
printk_once(errata93_warning);
|
|
regs->ip = address;
|
|
return 1;
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Work around K8 erratum #100 K8 in compat mode occasionally jumps
|
|
* to illegal addresses >4GB.
|
|
*
|
|
* We catch this in the page fault handler because these addresses
|
|
* are not reachable. Just detect this case and return. Any code
|
|
* segment in LDT is compatibility mode.
|
|
*/
|
|
static int is_errata100(struct pt_regs *regs, unsigned long address)
|
|
{
|
|
#ifdef CONFIG_X86_64
|
|
if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32))
|
|
return 1;
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
|
|
{
|
|
#ifdef CONFIG_X86_F00F_BUG
|
|
unsigned long nr;
|
|
|
|
/*
|
|
* Pentium F0 0F C7 C8 bug workaround:
|
|
*/
|
|
if (boot_cpu_has_bug(X86_BUG_F00F)) {
|
|
nr = (address - idt_descr.address) >> 3;
|
|
|
|
if (nr == 6) {
|
|
do_invalid_op(regs, 0);
|
|
return 1;
|
|
}
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static const char nx_warning[] = KERN_CRIT
|
|
"kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n";
|
|
static const char smep_warning[] = KERN_CRIT
|
|
"unable to execute userspace code (SMEP?) (uid: %d)\n";
|
|
|
|
static void
|
|
show_fault_oops(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address)
|
|
{
|
|
if (!oops_may_print())
|
|
return;
|
|
|
|
if (error_code & PF_INSTR) {
|
|
unsigned int level;
|
|
pgd_t *pgd;
|
|
pte_t *pte;
|
|
|
|
pgd = __va(read_cr3_pa());
|
|
pgd += pgd_index(address);
|
|
|
|
pte = lookup_address_in_pgd(pgd, address, &level);
|
|
|
|
if (pte && pte_present(*pte) && !pte_exec(*pte))
|
|
printk(nx_warning, from_kuid(&init_user_ns, current_uid()));
|
|
if (pte && pte_present(*pte) && pte_exec(*pte) &&
|
|
(pgd_flags(*pgd) & _PAGE_USER) &&
|
|
(__read_cr4() & X86_CR4_SMEP))
|
|
printk(smep_warning, from_kuid(&init_user_ns, current_uid()));
|
|
}
|
|
|
|
printk(KERN_ALERT "BUG: unable to handle kernel ");
|
|
if (address < PAGE_SIZE)
|
|
printk(KERN_CONT "NULL pointer dereference");
|
|
else
|
|
printk(KERN_CONT "paging request");
|
|
|
|
printk(KERN_CONT " at %p\n", (void *) address);
|
|
printk(KERN_ALERT "IP: %pS\n", (void *)regs->ip);
|
|
|
|
dump_pagetable(address);
|
|
}
|
|
|
|
static noinline void
|
|
pgtable_bad(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address)
|
|
{
|
|
struct task_struct *tsk;
|
|
unsigned long flags;
|
|
int sig;
|
|
|
|
flags = oops_begin();
|
|
tsk = current;
|
|
sig = SIGKILL;
|
|
|
|
printk(KERN_ALERT "%s: Corrupted page table at address %lx\n",
|
|
tsk->comm, address);
|
|
dump_pagetable(address);
|
|
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.trap_nr = X86_TRAP_PF;
|
|
tsk->thread.error_code = error_code;
|
|
|
|
if (__die("Bad pagetable", regs, error_code))
|
|
sig = 0;
|
|
|
|
oops_end(flags, regs, sig);
|
|
}
|
|
|
|
static noinline void
|
|
no_context(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, int signal, int si_code)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
unsigned long flags;
|
|
int sig;
|
|
/* No context means no VMA to pass down */
|
|
struct vm_area_struct *vma = NULL;
|
|
|
|
/* Are we prepared to handle this kernel fault? */
|
|
if (fixup_exception(regs, X86_TRAP_PF)) {
|
|
/*
|
|
* Any interrupt that takes a fault gets the fixup. This makes
|
|
* the below recursive fault logic only apply to a faults from
|
|
* task context.
|
|
*/
|
|
if (in_interrupt())
|
|
return;
|
|
|
|
/*
|
|
* Per the above we're !in_interrupt(), aka. task context.
|
|
*
|
|
* In this case we need to make sure we're not recursively
|
|
* faulting through the emulate_vsyscall() logic.
|
|
*/
|
|
if (current->thread.sig_on_uaccess_err && signal) {
|
|
tsk->thread.trap_nr = X86_TRAP_PF;
|
|
tsk->thread.error_code = error_code | PF_USER;
|
|
tsk->thread.cr2 = address;
|
|
|
|
/* XXX: hwpoison faults will set the wrong code. */
|
|
force_sig_info_fault(signal, si_code, address,
|
|
tsk, vma, 0);
|
|
}
|
|
|
|
/*
|
|
* Barring that, we can do the fixup and be happy.
|
|
*/
|
|
return;
|
|
}
|
|
|
|
#ifdef CONFIG_VMAP_STACK
|
|
/*
|
|
* Stack overflow? During boot, we can fault near the initial
|
|
* stack in the direct map, but that's not an overflow -- check
|
|
* that we're in vmalloc space to avoid this.
|
|
*/
|
|
if (is_vmalloc_addr((void *)address) &&
|
|
(((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
|
|
address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
|
|
register void *__sp asm("rsp");
|
|
unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_STACK]) - sizeof(void *);
|
|
/*
|
|
* We're likely to be running with very little stack space
|
|
* left. It's plausible that we'd hit this condition but
|
|
* double-fault even before we get this far, in which case
|
|
* we're fine: the double-fault handler will deal with it.
|
|
*
|
|
* We don't want to make it all the way into the oops code
|
|
* and then double-fault, though, because we're likely to
|
|
* break the console driver and lose most of the stack dump.
|
|
*/
|
|
asm volatile ("movq %[stack], %%rsp\n\t"
|
|
"call handle_stack_overflow\n\t"
|
|
"1: jmp 1b"
|
|
: "+r" (__sp)
|
|
: "D" ("kernel stack overflow (page fault)"),
|
|
"S" (regs), "d" (address),
|
|
[stack] "rm" (stack));
|
|
unreachable();
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 32-bit:
|
|
*
|
|
* Valid to do another page fault here, because if this fault
|
|
* had been triggered by is_prefetch fixup_exception would have
|
|
* handled it.
|
|
*
|
|
* 64-bit:
|
|
*
|
|
* Hall of shame of CPU/BIOS bugs.
|
|
*/
|
|
if (is_prefetch(regs, error_code, address))
|
|
return;
|
|
|
|
if (is_errata93(regs, address))
|
|
return;
|
|
|
|
/*
|
|
* Oops. The kernel tried to access some bad page. We'll have to
|
|
* terminate things with extreme prejudice:
|
|
*/
|
|
flags = oops_begin();
|
|
|
|
show_fault_oops(regs, error_code, address);
|
|
|
|
if (task_stack_end_corrupted(tsk))
|
|
printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
|
|
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.trap_nr = X86_TRAP_PF;
|
|
tsk->thread.error_code = error_code;
|
|
|
|
sig = SIGKILL;
|
|
if (__die("Oops", regs, error_code))
|
|
sig = 0;
|
|
|
|
/* Executive summary in case the body of the oops scrolled away */
|
|
printk(KERN_DEFAULT "CR2: %016lx\n", address);
|
|
|
|
oops_end(flags, regs, sig);
|
|
}
|
|
|
|
/*
|
|
* Print out info about fatal segfaults, if the show_unhandled_signals
|
|
* sysctl is set:
|
|
*/
|
|
static inline void
|
|
show_signal_msg(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct task_struct *tsk)
|
|
{
|
|
if (!unhandled_signal(tsk, SIGSEGV))
|
|
return;
|
|
|
|
if (!printk_ratelimit())
|
|
return;
|
|
|
|
printk("%s%s[%d]: segfault at %lx ip %p sp %p error %lx",
|
|
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
|
|
tsk->comm, task_pid_nr(tsk), address,
|
|
(void *)regs->ip, (void *)regs->sp, error_code);
|
|
|
|
print_vma_addr(KERN_CONT " in ", regs->ip);
|
|
|
|
printk(KERN_CONT "\n");
|
|
}
|
|
|
|
static void
|
|
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct vm_area_struct *vma,
|
|
int si_code)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
|
|
/* User mode accesses just cause a SIGSEGV */
|
|
if (error_code & PF_USER) {
|
|
/*
|
|
* It's possible to have interrupts off here:
|
|
*/
|
|
local_irq_enable();
|
|
|
|
/*
|
|
* Valid to do another page fault here because this one came
|
|
* from user space:
|
|
*/
|
|
if (is_prefetch(regs, error_code, address))
|
|
return;
|
|
|
|
if (is_errata100(regs, address))
|
|
return;
|
|
|
|
#ifdef CONFIG_X86_64
|
|
/*
|
|
* Instruction fetch faults in the vsyscall page might need
|
|
* emulation.
|
|
*/
|
|
if (unlikely((error_code & PF_INSTR) &&
|
|
((address & ~0xfff) == VSYSCALL_ADDR))) {
|
|
if (emulate_vsyscall(regs, address))
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* To avoid leaking information about the kernel page table
|
|
* layout, pretend that user-mode accesses to kernel addresses
|
|
* are always protection faults.
|
|
*/
|
|
if (address >= TASK_SIZE_MAX)
|
|
error_code |= PF_PROT;
|
|
|
|
if (likely(show_unhandled_signals))
|
|
show_signal_msg(regs, error_code, address, tsk);
|
|
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.error_code = error_code;
|
|
tsk->thread.trap_nr = X86_TRAP_PF;
|
|
|
|
force_sig_info_fault(SIGSEGV, si_code, address, tsk, vma, 0);
|
|
|
|
return;
|
|
}
|
|
|
|
if (is_f00f_bug(regs, address))
|
|
return;
|
|
|
|
no_context(regs, error_code, address, SIGSEGV, si_code);
|
|
}
|
|
|
|
static noinline void
|
|
bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct vm_area_struct *vma)
|
|
{
|
|
__bad_area_nosemaphore(regs, error_code, address, vma, SEGV_MAPERR);
|
|
}
|
|
|
|
static void
|
|
__bad_area(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct vm_area_struct *vma, int si_code)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
|
|
/*
|
|
* Something tried to access memory that isn't in our memory map..
|
|
* Fix it, but check if it's kernel or user first..
|
|
*/
|
|
up_read(&mm->mmap_sem);
|
|
|
|
__bad_area_nosemaphore(regs, error_code, address, vma, si_code);
|
|
}
|
|
|
|
static noinline void
|
|
bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
|
|
{
|
|
__bad_area(regs, error_code, address, NULL, SEGV_MAPERR);
|
|
}
|
|
|
|
static inline bool bad_area_access_from_pkeys(unsigned long error_code,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
/* This code is always called on the current mm */
|
|
bool foreign = false;
|
|
|
|
if (!boot_cpu_has(X86_FEATURE_OSPKE))
|
|
return false;
|
|
if (error_code & PF_PK)
|
|
return true;
|
|
/* this checks permission keys on the VMA: */
|
|
if (!arch_vma_access_permitted(vma, (error_code & PF_WRITE),
|
|
(error_code & PF_INSTR), foreign))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
static noinline void
|
|
bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* This OSPKE check is not strictly necessary at runtime.
|
|
* But, doing it this way allows compiler optimizations
|
|
* if pkeys are compiled out.
|
|
*/
|
|
if (bad_area_access_from_pkeys(error_code, vma))
|
|
__bad_area(regs, error_code, address, vma, SEGV_PKUERR);
|
|
else
|
|
__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
|
|
}
|
|
|
|
static void
|
|
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
|
|
struct vm_area_struct *vma, unsigned int fault)
|
|
{
|
|
struct task_struct *tsk = current;
|
|
int code = BUS_ADRERR;
|
|
|
|
/* Kernel mode? Handle exceptions or die: */
|
|
if (!(error_code & PF_USER)) {
|
|
no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
|
|
return;
|
|
}
|
|
|
|
/* User-space => ok to do another page fault: */
|
|
if (is_prefetch(regs, error_code, address))
|
|
return;
|
|
|
|
tsk->thread.cr2 = address;
|
|
tsk->thread.error_code = error_code;
|
|
tsk->thread.trap_nr = X86_TRAP_PF;
|
|
|
|
#ifdef CONFIG_MEMORY_FAILURE
|
|
if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
|
|
printk(KERN_ERR
|
|
"MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
|
|
tsk->comm, tsk->pid, address);
|
|
code = BUS_MCEERR_AR;
|
|
}
|
|
#endif
|
|
force_sig_info_fault(SIGBUS, code, address, tsk, vma, fault);
|
|
}
|
|
|
|
static noinline void
|
|
mm_fault_error(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, struct vm_area_struct *vma,
|
|
unsigned int fault)
|
|
{
|
|
if (fatal_signal_pending(current) && !(error_code & PF_USER)) {
|
|
no_context(regs, error_code, address, 0, 0);
|
|
return;
|
|
}
|
|
|
|
if (fault & VM_FAULT_OOM) {
|
|
/* Kernel mode? Handle exceptions or die: */
|
|
if (!(error_code & PF_USER)) {
|
|
no_context(regs, error_code, address,
|
|
SIGSEGV, SEGV_MAPERR);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We ran out of memory, call the OOM killer, and return the
|
|
* userspace (which will retry the fault, or kill us if we got
|
|
* oom-killed):
|
|
*/
|
|
pagefault_out_of_memory();
|
|
} else {
|
|
if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
|
|
VM_FAULT_HWPOISON_LARGE))
|
|
do_sigbus(regs, error_code, address, vma, fault);
|
|
else if (fault & VM_FAULT_SIGSEGV)
|
|
bad_area_nosemaphore(regs, error_code, address, vma);
|
|
else
|
|
BUG();
|
|
}
|
|
}
|
|
|
|
static int spurious_fault_check(unsigned long error_code, pte_t *pte)
|
|
{
|
|
if ((error_code & PF_WRITE) && !pte_write(*pte))
|
|
return 0;
|
|
|
|
if ((error_code & PF_INSTR) && !pte_exec(*pte))
|
|
return 0;
|
|
/*
|
|
* Note: We do not do lazy flushing on protection key
|
|
* changes, so no spurious fault will ever set PF_PK.
|
|
*/
|
|
if ((error_code & PF_PK))
|
|
return 1;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Handle a spurious fault caused by a stale TLB entry.
|
|
*
|
|
* This allows us to lazily refresh the TLB when increasing the
|
|
* permissions of a kernel page (RO -> RW or NX -> X). Doing it
|
|
* eagerly is very expensive since that implies doing a full
|
|
* cross-processor TLB flush, even if no stale TLB entries exist
|
|
* on other processors.
|
|
*
|
|
* Spurious faults may only occur if the TLB contains an entry with
|
|
* fewer permission than the page table entry. Non-present (P = 0)
|
|
* and reserved bit (R = 1) faults are never spurious.
|
|
*
|
|
* There are no security implications to leaving a stale TLB when
|
|
* increasing the permissions on a page.
|
|
*
|
|
* Returns non-zero if a spurious fault was handled, zero otherwise.
|
|
*
|
|
* See Intel Developer's Manual Vol 3 Section 4.10.4.3, bullet 3
|
|
* (Optional Invalidation).
|
|
*/
|
|
static noinline int
|
|
spurious_fault(unsigned long error_code, unsigned long address)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *pte;
|
|
int ret;
|
|
|
|
/*
|
|
* Only writes to RO or instruction fetches from NX may cause
|
|
* spurious faults.
|
|
*
|
|
* These could be from user or supervisor accesses but the TLB
|
|
* is only lazily flushed after a kernel mapping protection
|
|
* change, so user accesses are not expected to cause spurious
|
|
* faults.
|
|
*/
|
|
if (error_code != (PF_WRITE | PF_PROT)
|
|
&& error_code != (PF_INSTR | PF_PROT))
|
|
return 0;
|
|
|
|
pgd = init_mm.pgd + pgd_index(address);
|
|
if (!pgd_present(*pgd))
|
|
return 0;
|
|
|
|
p4d = p4d_offset(pgd, address);
|
|
if (!p4d_present(*p4d))
|
|
return 0;
|
|
|
|
if (p4d_large(*p4d))
|
|
return spurious_fault_check(error_code, (pte_t *) p4d);
|
|
|
|
pud = pud_offset(p4d, address);
|
|
if (!pud_present(*pud))
|
|
return 0;
|
|
|
|
if (pud_large(*pud))
|
|
return spurious_fault_check(error_code, (pte_t *) pud);
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
if (!pmd_present(*pmd))
|
|
return 0;
|
|
|
|
if (pmd_large(*pmd))
|
|
return spurious_fault_check(error_code, (pte_t *) pmd);
|
|
|
|
pte = pte_offset_kernel(pmd, address);
|
|
if (!pte_present(*pte))
|
|
return 0;
|
|
|
|
ret = spurious_fault_check(error_code, pte);
|
|
if (!ret)
|
|
return 0;
|
|
|
|
/*
|
|
* Make sure we have permissions in PMD.
|
|
* If not, then there's a bug in the page tables:
|
|
*/
|
|
ret = spurious_fault_check(error_code, (pte_t *) pmd);
|
|
WARN_ONCE(!ret, "PMD has incorrect permission bits\n");
|
|
|
|
return ret;
|
|
}
|
|
NOKPROBE_SYMBOL(spurious_fault);
|
|
|
|
int show_unhandled_signals = 1;
|
|
|
|
static inline int
|
|
access_error(unsigned long error_code, struct vm_area_struct *vma)
|
|
{
|
|
/* This is only called for the current mm, so: */
|
|
bool foreign = false;
|
|
|
|
/*
|
|
* Read or write was blocked by protection keys. This is
|
|
* always an unconditional error and can never result in
|
|
* a follow-up action to resolve the fault, like a COW.
|
|
*/
|
|
if (error_code & PF_PK)
|
|
return 1;
|
|
|
|
/*
|
|
* Make sure to check the VMA so that we do not perform
|
|
* faults just to hit a PF_PK as soon as we fill in a
|
|
* page.
|
|
*/
|
|
if (!arch_vma_access_permitted(vma, (error_code & PF_WRITE),
|
|
(error_code & PF_INSTR), foreign))
|
|
return 1;
|
|
|
|
if (error_code & PF_WRITE) {
|
|
/* write, present and write, not present: */
|
|
if (unlikely(!(vma->vm_flags & VM_WRITE)))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/* read, present: */
|
|
if (unlikely(error_code & PF_PROT))
|
|
return 1;
|
|
|
|
/* read, not present: */
|
|
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int fault_in_kernel_space(unsigned long address)
|
|
{
|
|
return address >= TASK_SIZE_MAX;
|
|
}
|
|
|
|
static inline bool smap_violation(int error_code, struct pt_regs *regs)
|
|
{
|
|
if (!IS_ENABLED(CONFIG_X86_SMAP))
|
|
return false;
|
|
|
|
if (!static_cpu_has(X86_FEATURE_SMAP))
|
|
return false;
|
|
|
|
if (error_code & PF_USER)
|
|
return false;
|
|
|
|
if (!user_mode(regs) && (regs->flags & X86_EFLAGS_AC))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* This routine handles page faults. It determines the address,
|
|
* and the problem, and then passes it off to one of the appropriate
|
|
* routines.
|
|
*/
|
|
static noinline void
|
|
__do_page_fault(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
struct task_struct *tsk;
|
|
struct mm_struct *mm;
|
|
int fault, major = 0;
|
|
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
|
|
|
|
tsk = current;
|
|
mm = tsk->mm;
|
|
|
|
/*
|
|
* Detect and handle instructions that would cause a page fault for
|
|
* both a tracked kernel page and a userspace page.
|
|
*/
|
|
if (kmemcheck_active(regs))
|
|
kmemcheck_hide(regs);
|
|
prefetchw(&mm->mmap_sem);
|
|
|
|
if (unlikely(kmmio_fault(regs, address)))
|
|
return;
|
|
|
|
/*
|
|
* We fault-in kernel-space virtual memory on-demand. The
|
|
* 'reference' page table is init_mm.pgd.
|
|
*
|
|
* NOTE! We MUST NOT take any locks for this case. We may
|
|
* be in an interrupt or a critical region, and should
|
|
* only copy the information from the master page table,
|
|
* nothing more.
|
|
*
|
|
* This verifies that the fault happens in kernel space
|
|
* (error_code & 4) == 0, and that the fault was not a
|
|
* protection error (error_code & 9) == 0.
|
|
*/
|
|
if (unlikely(fault_in_kernel_space(address))) {
|
|
if (!(error_code & (PF_RSVD | PF_USER | PF_PROT))) {
|
|
if (vmalloc_fault(address) >= 0)
|
|
return;
|
|
|
|
if (kmemcheck_fault(regs, address, error_code))
|
|
return;
|
|
}
|
|
|
|
/* Can handle a stale RO->RW TLB: */
|
|
if (spurious_fault(error_code, address))
|
|
return;
|
|
|
|
/* kprobes don't want to hook the spurious faults: */
|
|
if (kprobes_fault(regs))
|
|
return;
|
|
/*
|
|
* Don't take the mm semaphore here. If we fixup a prefetch
|
|
* fault we could otherwise deadlock:
|
|
*/
|
|
bad_area_nosemaphore(regs, error_code, address, NULL);
|
|
|
|
return;
|
|
}
|
|
|
|
/* kprobes don't want to hook the spurious faults: */
|
|
if (unlikely(kprobes_fault(regs)))
|
|
return;
|
|
|
|
if (unlikely(error_code & PF_RSVD))
|
|
pgtable_bad(regs, error_code, address);
|
|
|
|
if (unlikely(smap_violation(error_code, regs))) {
|
|
bad_area_nosemaphore(regs, error_code, address, NULL);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running
|
|
* in a region with pagefaults disabled then we must not take the fault
|
|
*/
|
|
if (unlikely(faulthandler_disabled() || !mm)) {
|
|
bad_area_nosemaphore(regs, error_code, address, NULL);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* It's safe to allow irq's after cr2 has been saved and the
|
|
* vmalloc fault has been handled.
|
|
*
|
|
* User-mode registers count as a user access even for any
|
|
* potential system fault or CPU buglet:
|
|
*/
|
|
if (user_mode(regs)) {
|
|
local_irq_enable();
|
|
error_code |= PF_USER;
|
|
flags |= FAULT_FLAG_USER;
|
|
} else {
|
|
if (regs->flags & X86_EFLAGS_IF)
|
|
local_irq_enable();
|
|
}
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
|
|
if (error_code & PF_WRITE)
|
|
flags |= FAULT_FLAG_WRITE;
|
|
if (error_code & PF_INSTR)
|
|
flags |= FAULT_FLAG_INSTRUCTION;
|
|
|
|
/*
|
|
* When running in the kernel we expect faults to occur only to
|
|
* addresses in user space. All other faults represent errors in
|
|
* the kernel and should generate an OOPS. Unfortunately, in the
|
|
* case of an erroneous fault occurring in a code path which already
|
|
* holds mmap_sem we will deadlock attempting to validate the fault
|
|
* against the address space. Luckily the kernel only validly
|
|
* references user space from well defined areas of code, which are
|
|
* listed in the exceptions table.
|
|
*
|
|
* As the vast majority of faults will be valid we will only perform
|
|
* the source reference check when there is a possibility of a
|
|
* deadlock. Attempt to lock the address space, if we cannot we then
|
|
* validate the source. If this is invalid we can skip the address
|
|
* space check, thus avoiding the deadlock:
|
|
*/
|
|
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
|
|
if ((error_code & PF_USER) == 0 &&
|
|
!search_exception_tables(regs->ip)) {
|
|
bad_area_nosemaphore(regs, error_code, address, NULL);
|
|
return;
|
|
}
|
|
retry:
|
|
down_read(&mm->mmap_sem);
|
|
} else {
|
|
/*
|
|
* The above down_read_trylock() might have succeeded in
|
|
* which case we'll have missed the might_sleep() from
|
|
* down_read():
|
|
*/
|
|
might_sleep();
|
|
}
|
|
|
|
vma = find_vma(mm, address);
|
|
if (unlikely(!vma)) {
|
|
bad_area(regs, error_code, address);
|
|
return;
|
|
}
|
|
if (likely(vma->vm_start <= address))
|
|
goto good_area;
|
|
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
|
|
bad_area(regs, error_code, address);
|
|
return;
|
|
}
|
|
if (error_code & PF_USER) {
|
|
/*
|
|
* Accessing the stack below %sp is always a bug.
|
|
* The large cushion allows instructions like enter
|
|
* and pusha to work. ("enter $65535, $31" pushes
|
|
* 32 pointers and then decrements %sp by 65535.)
|
|
*/
|
|
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
|
|
bad_area(regs, error_code, address);
|
|
return;
|
|
}
|
|
}
|
|
if (unlikely(expand_stack(vma, address))) {
|
|
bad_area(regs, error_code, address);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Ok, we have a good vm_area for this memory access, so
|
|
* we can handle it..
|
|
*/
|
|
good_area:
|
|
if (unlikely(access_error(error_code, vma))) {
|
|
bad_area_access_error(regs, error_code, address, vma);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If for any reason at all we couldn't handle the fault,
|
|
* make sure we exit gracefully rather than endlessly redo
|
|
* the fault. Since we never set FAULT_FLAG_RETRY_NOWAIT, if
|
|
* we get VM_FAULT_RETRY back, the mmap_sem has been unlocked.
|
|
*/
|
|
fault = handle_mm_fault(vma, address, flags);
|
|
major |= fault & VM_FAULT_MAJOR;
|
|
|
|
/*
|
|
* If we need to retry the mmap_sem has already been released,
|
|
* and if there is a fatal signal pending there is no guarantee
|
|
* that we made any progress. Handle this case first.
|
|
*/
|
|
if (unlikely(fault & VM_FAULT_RETRY)) {
|
|
/* Retry at most once */
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
flags &= ~FAULT_FLAG_ALLOW_RETRY;
|
|
flags |= FAULT_FLAG_TRIED;
|
|
if (!fatal_signal_pending(tsk))
|
|
goto retry;
|
|
}
|
|
|
|
/* User mode? Just return to handle the fatal exception */
|
|
if (flags & FAULT_FLAG_USER)
|
|
return;
|
|
|
|
/* Not returning to user mode? Handle exceptions or die: */
|
|
no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
|
|
return;
|
|
}
|
|
|
|
up_read(&mm->mmap_sem);
|
|
if (unlikely(fault & VM_FAULT_ERROR)) {
|
|
mm_fault_error(regs, error_code, address, vma, fault);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Major/minor page fault accounting. If any of the events
|
|
* returned VM_FAULT_MAJOR, we account it as a major fault.
|
|
*/
|
|
if (major) {
|
|
tsk->maj_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
|
|
} else {
|
|
tsk->min_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
|
|
}
|
|
|
|
check_v8086_mode(regs, address, tsk);
|
|
}
|
|
NOKPROBE_SYMBOL(__do_page_fault);
|
|
|
|
static nokprobe_inline void
|
|
trace_page_fault_entries(unsigned long address, struct pt_regs *regs,
|
|
unsigned long error_code)
|
|
{
|
|
if (user_mode(regs))
|
|
trace_page_fault_user(address, regs, error_code);
|
|
else
|
|
trace_page_fault_kernel(address, regs, error_code);
|
|
}
|
|
|
|
/*
|
|
* We must have this function blacklisted from kprobes, tagged with notrace
|
|
* and call read_cr2() before calling anything else. To avoid calling any
|
|
* kind of tracing machinery before we've observed the CR2 value.
|
|
*
|
|
* exception_{enter,exit}() contains all sorts of tracepoints.
|
|
*/
|
|
dotraplinkage void notrace
|
|
do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
|
{
|
|
unsigned long address = read_cr2(); /* Get the faulting address */
|
|
enum ctx_state prev_state;
|
|
|
|
prev_state = exception_enter();
|
|
if (trace_pagefault_enabled())
|
|
trace_page_fault_entries(address, regs, error_code);
|
|
|
|
__do_page_fault(regs, error_code, address);
|
|
exception_exit(prev_state);
|
|
}
|
|
NOKPROBE_SYMBOL(do_page_fault);
|