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Diffstat (limited to 'arch/x86/mm/fault.c')
-rw-r--r--arch/x86/mm/fault.c100
1 files changed, 45 insertions, 55 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index e2baeaa053a5..3109ba6c6ede 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1995 Linus Torvalds
* Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs.
@@ -29,26 +30,6 @@
#include <asm/trace/exceptions.h>
/*
- * Page fault error code bits:
- *
- * bit 0 == 0: no page found 1: protection fault
- * bit 1 == 0: read access 1: write access
- * bit 2 == 0: kernel-mode access 1: user-mode access
- * bit 3 == 1: use of reserved bit detected
- * bit 4 == 1: fault was an instruction fetch
- * bit 5 == 1: protection keys block access
- */
-enum x86_pf_error_code {
-
- PF_PROT = 1 << 0,
- PF_WRITE = 1 << 1,
- PF_USER = 1 << 2,
- PF_RSVD = 1 << 3,
- PF_INSTR = 1 << 4,
- PF_PK = 1 << 5,
-};
-
-/*
* Returns 0 if mmiotrace is disabled, or if the fault is not
* handled by mmiotrace:
*/
@@ -149,7 +130,7 @@ is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
* If it was a exec (instruction fetch) fault on NX page, then
* do not ignore the fault:
*/
- if (error_code & PF_INSTR)
+ if (error_code & X86_PF_INSTR)
return 0;
instr = (void *)convert_ip_to_linear(current, regs);
@@ -179,7 +160,7 @@ is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
* siginfo so userspace can discover which protection key was set
* on the PTE.
*
- * If we get here, we know that the hardware signaled a PF_PK
+ * If we get here, we know that the hardware signaled a X86_PF_PK
* fault and that there was a VMA once we got in the fault
* handler. It does *not* guarantee that the VMA we find here
* was the one that we faulted on.
@@ -204,7 +185,7 @@ static void fill_sig_info_pkey(int si_code, siginfo_t *info, u32 *pkey)
/*
* force_sig_info_fault() is called from a number of
* contexts, some of which have a VMA and some of which
- * do not. The PF_PK handing happens after we have a
+ * do not. The X86_PF_PK handing happens after we have a
* valid VMA, so we should never reach this without a
* valid VMA.
*/
@@ -697,7 +678,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
if (!oops_may_print())
return;
- if (error_code & PF_INSTR) {
+ if (error_code & X86_PF_INSTR) {
unsigned int level;
pgd_t *pgd;
pte_t *pte;
@@ -779,7 +760,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
*/
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.error_code = error_code | X86_PF_USER;
tsk->thread.cr2 = address;
/* XXX: hwpoison faults will set the wrong code. */
@@ -897,7 +878,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
struct task_struct *tsk = current;
/* User mode accesses just cause a SIGSEGV */
- if (error_code & PF_USER) {
+ if (error_code & X86_PF_USER) {
/*
* It's possible to have interrupts off here:
*/
@@ -918,7 +899,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
* Instruction fetch faults in the vsyscall page might need
* emulation.
*/
- if (unlikely((error_code & PF_INSTR) &&
+ if (unlikely((error_code & X86_PF_INSTR) &&
((address & ~0xfff) == VSYSCALL_ADDR))) {
if (emulate_vsyscall(regs, address))
return;
@@ -931,7 +912,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
* are always protection faults.
*/
if (address >= TASK_SIZE_MAX)
- error_code |= PF_PROT;
+ error_code |= X86_PF_PROT;
if (likely(show_unhandled_signals))
show_signal_msg(regs, error_code, address, tsk);
@@ -992,11 +973,11 @@ static inline bool bad_area_access_from_pkeys(unsigned long error_code,
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return false;
- if (error_code & PF_PK)
+ if (error_code & X86_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))
+ if (!arch_vma_access_permitted(vma, (error_code & X86_PF_WRITE),
+ (error_code & X86_PF_INSTR), foreign))
return true;
return false;
}
@@ -1024,7 +1005,7 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
int code = BUS_ADRERR;
/* Kernel mode? Handle exceptions or die: */
- if (!(error_code & PF_USER)) {
+ if (!(error_code & X86_PF_USER)) {
no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
return;
}
@@ -1052,14 +1033,14 @@ static noinline void
mm_fault_error(struct pt_regs *regs, unsigned long error_code,
unsigned long address, u32 *pkey, unsigned int fault)
{
- if (fatal_signal_pending(current) && !(error_code & PF_USER)) {
+ if (fatal_signal_pending(current) && !(error_code & X86_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)) {
+ if (!(error_code & X86_PF_USER)) {
no_context(regs, error_code, address,
SIGSEGV, SEGV_MAPERR);
return;
@@ -1084,16 +1065,16 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code,
static int spurious_fault_check(unsigned long error_code, pte_t *pte)
{
- if ((error_code & PF_WRITE) && !pte_write(*pte))
+ if ((error_code & X86_PF_WRITE) && !pte_write(*pte))
return 0;
- if ((error_code & PF_INSTR) && !pte_exec(*pte))
+ if ((error_code & X86_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.
+ * changes, so no spurious fault will ever set X86_PF_PK.
*/
- if ((error_code & PF_PK))
+ if ((error_code & X86_PF_PK))
return 1;
return 1;
@@ -1139,8 +1120,8 @@ spurious_fault(unsigned long error_code, unsigned long address)
* change, so user accesses are not expected to cause spurious
* faults.
*/
- if (error_code != (PF_WRITE | PF_PROT)
- && error_code != (PF_INSTR | PF_PROT))
+ if (error_code != (X86_PF_WRITE | X86_PF_PROT) &&
+ error_code != (X86_PF_INSTR | X86_PF_PROT))
return 0;
pgd = init_mm.pgd + pgd_index(address);
@@ -1200,19 +1181,19 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
* 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)
+ if (error_code & X86_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
+ * faults just to hit a X86_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))
+ if (!arch_vma_access_permitted(vma, (error_code & X86_PF_WRITE),
+ (error_code & X86_PF_INSTR), foreign))
return 1;
- if (error_code & PF_WRITE) {
+ if (error_code & X86_PF_WRITE) {
/* write, present and write, not present: */
if (unlikely(!(vma->vm_flags & VM_WRITE)))
return 1;
@@ -1220,7 +1201,7 @@ access_error(unsigned long error_code, struct vm_area_struct *vma)
}
/* read, present: */
- if (unlikely(error_code & PF_PROT))
+ if (unlikely(error_code & X86_PF_PROT))
return 1;
/* read, not present: */
@@ -1243,7 +1224,7 @@ static inline bool smap_violation(int error_code, struct pt_regs *regs)
if (!static_cpu_has(X86_FEATURE_SMAP))
return false;
- if (error_code & PF_USER)
+ if (error_code & X86_PF_USER)
return false;
if (!user_mode(regs) && (regs->flags & X86_EFLAGS_AC))
@@ -1296,7 +1277,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
* protection error (error_code & 9) == 0.
*/
if (unlikely(fault_in_kernel_space(address))) {
- if (!(error_code & (PF_RSVD | PF_USER | PF_PROT))) {
+ if (!(error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) {
if (vmalloc_fault(address) >= 0)
return;
@@ -1324,7 +1305,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
if (unlikely(kprobes_fault(regs)))
return;
- if (unlikely(error_code & PF_RSVD))
+ if (unlikely(error_code & X86_PF_RSVD))
pgtable_bad(regs, error_code, address);
if (unlikely(smap_violation(error_code, regs))) {
@@ -1350,7 +1331,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
*/
if (user_mode(regs)) {
local_irq_enable();
- error_code |= PF_USER;
+ error_code |= X86_PF_USER;
flags |= FAULT_FLAG_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
@@ -1359,9 +1340,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
- if (error_code & PF_WRITE)
+ if (error_code & X86_PF_WRITE)
flags |= FAULT_FLAG_WRITE;
- if (error_code & PF_INSTR)
+ if (error_code & X86_PF_INSTR)
flags |= FAULT_FLAG_INSTRUCTION;
/*
@@ -1381,7 +1362,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
* space check, thus avoiding the deadlock:
*/
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
- if ((error_code & PF_USER) == 0 &&
+ if (!(error_code & X86_PF_USER) &&
!search_exception_tables(regs->ip)) {
bad_area_nosemaphore(regs, error_code, address, NULL);
return;
@@ -1408,7 +1389,7 @@ retry:
bad_area(regs, error_code, address);
return;
}
- if (error_code & PF_USER) {
+ if (error_code & X86_PF_USER) {
/*
* Accessing the stack below %sp is always a bug.
* The large cushion allows instructions like enter
@@ -1440,7 +1421,17 @@ good_area:
* 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.
+ *
+ * Note that handle_userfault() may also release and reacquire mmap_sem
+ * (and not return with VM_FAULT_RETRY), when returning to userland to
+ * repeat the page fault later with a VM_FAULT_NOPAGE retval
+ * (potentially after handling any pending signal during the return to
+ * userland). The return to userland is identified whenever
+ * FAULT_FLAG_USER|FAULT_FLAG_KILLABLE are both set in flags.
+ * Thus we have to be careful about not touching vma after handling the
+ * fault, so we read the pkey beforehand.
*/
+ pkey = vma_pkey(vma);
fault = handle_mm_fault(vma, address, flags);
major |= fault & VM_FAULT_MAJOR;
@@ -1467,7 +1458,6 @@ good_area:
return;
}
- pkey = vma_pkey(vma);
up_read(&mm->mmap_sem);
if (unlikely(fault & VM_FAULT_ERROR)) {
mm_fault_error(regs, error_code, address, &pkey, fault);