__bad_area(regs, error_code, address, vma, SEGV_ACCERR);
}
+/* Handle faults in the kernel portion of the address space */
static void
do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
u32 *pkey, unsigned int fault)
}
}
-static int spurious_fault_check(unsigned long error_code, pte_t *pte)
+static int spurious_kernel_fault_check(unsigned long error_code, pte_t *pte)
{
if ((error_code & X86_PF_WRITE) && !pte_write(*pte))
return 0;
* (Optional Invalidation).
*/
static noinline int
-spurious_fault(unsigned long error_code, unsigned long address)
+spurious_kernel_fault(unsigned long error_code, unsigned long address)
{
pgd_t *pgd;
p4d_t *p4d;
return 0;
if (p4d_large(*p4d))
- return spurious_fault_check(error_code, (pte_t *) p4d);
+ return spurious_kernel_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);
+ return spurious_kernel_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);
+ return spurious_kernel_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);
+ ret = spurious_kernel_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);
+ ret = spurious_kernel_fault_check(error_code, (pte_t *) pmd);
WARN_ONCE(!ret, "PMD has incorrect permission bits\n");
return ret;
}
-NOKPROBE_SYMBOL(spurious_fault);
+NOKPROBE_SYMBOL(spurious_kernel_fault);
int show_unhandled_signals = 1;
}
/*
- * This routine handles page faults. It determines the address,
- * and the problem, and then passes it off to one of the appropriate
- * routines.
+ * Called for all faults where 'address' is part of the kernel address
+ * space. Might get called for faults that originate from *code* that
+ * ran in userspace or the kernel.
*/
-static noinline void
-__do_page_fault(struct pt_regs *regs, unsigned long error_code,
- unsigned long address)
+static void
+do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
+ unsigned long address)
{
- struct vm_area_struct *vma;
- struct task_struct *tsk;
- struct mm_struct *mm;
- vm_fault_t fault, major = 0;
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
- u32 pkey;
-
- tsk = current;
- mm = tsk->mm;
-
- prefetchw(&mm->mmap_sem);
-
- if (unlikely(kmmio_fault(regs, address)))
- return;
-
/*
- * We fault-in kernel-space virtual memory on-demand. The
+ * We can 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
* 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.
+ * Before doing this on-demand faulting, ensure that the
+ * fault is not any of the following:
+ * 1. A fault on a PTE with a reserved bit set.
+ * 2. A fault caused by a user-mode access. (Do not demand-
+ * fault kernel memory due to user-mode accesses).
+ * 3. A fault caused by a page-level protection violation.
+ * (A demand fault would be on a non-present page which
+ * would have X86_PF_PROT==0).
*/
- if (unlikely(fault_in_kernel_space(address))) {
- if (!(error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) {
- if (vmalloc_fault(address) >= 0)
- return;
- }
-
- /* Can handle a stale RO->RW TLB: */
- if (spurious_fault(error_code, address))
+ if (!(hw_error_code & (X86_PF_RSVD | X86_PF_USER | X86_PF_PROT))) {
+ if (vmalloc_fault(address) >= 0)
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);
+ /* Was the fault spurious, caused by lazy TLB invalidation? */
+ if (spurious_kernel_fault(hw_error_code, address))
+ return;
+ /* kprobes don't want to hook the spurious faults: */
+ if (kprobes_fault(regs))
return;
- }
+
+ /*
+ * Note, despite being a "bad area", there are quite a few
+ * acceptable reasons to get here, such as erratum fixups
+ * and handling kernel code that can fault, like get_user().
+ *
+ * Don't take the mm semaphore here. If we fixup a prefetch
+ * fault we could otherwise deadlock:
+ */
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
+}
+NOKPROBE_SYMBOL(do_kern_addr_fault);
+
+/* Handle faults in the user portion of the address space */
+static inline
+void do_user_addr_fault(struct pt_regs *regs,
+ unsigned long hw_error_code,
+ unsigned long address)
+{
+ unsigned long sw_error_code;
+ struct vm_area_struct *vma;
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ vm_fault_t fault, major = 0;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ u32 pkey;
+
+ tsk = current;
+ mm = tsk->mm;
/* kprobes don't want to hook the spurious faults: */
if (unlikely(kprobes_fault(regs)))
return;
- if (unlikely(error_code & X86_PF_RSVD))
- pgtable_bad(regs, error_code, address);
+ if (unlikely(hw_error_code & X86_PF_RSVD))
+ pgtable_bad(regs, hw_error_code, address);
- if (unlikely(smap_violation(error_code, regs))) {
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ if (unlikely(smap_violation(hw_error_code, regs))) {
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
return;
}
* 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);
+ bad_area_nosemaphore(regs, hw_error_code, address, NULL);
return;
}
+ /*
+ * hw_error_code is literally the "page fault error code" passed to
+ * the kernel directly from the hardware. But, we will shortly be
+ * modifying it in software, so give it a new name.
+ */
+ sw_error_code = hw_error_code;
+
/*
* It's safe to allow irq's after cr2 has been saved and the
* vmalloc fault has been handled.
*/
if (user_mode(regs)) {
local_irq_enable();
- error_code |= X86_PF_USER;
+ /*
+ * Up to this point, X86_PF_USER set in hw_error_code
+ * indicated a user-mode access. But, after this,
+ * X86_PF_USER in sw_error_code will indicate either
+ * that, *or* an implicit kernel(supervisor)-mode access
+ * which originated from user mode.
+ */
+ if (!(hw_error_code & X86_PF_USER)) {
+ /*
+ * The CPU was in user mode, but the CPU says
+ * the fault was not a user-mode access.
+ * Must be an implicit kernel-mode access,
+ * which we do not expect to happen in the
+ * user address space.
+ */
+ pr_warn_once("kernel-mode error from user-mode: %lx\n",
+ hw_error_code);
+
+ sw_error_code |= X86_PF_USER;
+ }
flags |= FAULT_FLAG_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
- if (error_code & X86_PF_WRITE)
+ if (sw_error_code & X86_PF_WRITE)
flags |= FAULT_FLAG_WRITE;
- if (error_code & X86_PF_INSTR)
+ if (sw_error_code & X86_PF_INSTR)
flags |= FAULT_FLAG_INSTRUCTION;
/*
* space check, thus avoiding the deadlock:
*/
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
- if (!(error_code & X86_PF_USER) &&
+ if (!(sw_error_code & X86_PF_USER) &&
!search_exception_tables(regs->ip)) {
- bad_area_nosemaphore(regs, error_code, address, NULL);
+ bad_area_nosemaphore(regs, sw_error_code, address, NULL);
return;
}
retry:
vma = find_vma(mm, address);
if (unlikely(!vma)) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_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);
+ bad_area(regs, sw_error_code, address);
return;
}
- if (error_code & X86_PF_USER) {
+ if (sw_error_code & X86_PF_USER) {
/*
* Accessing the stack below %sp is always a bug.
* The large cushion allows instructions like enter
* 32 pointers and then decrements %sp by 65535.)
*/
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
}
if (unlikely(expand_stack(vma, address))) {
- bad_area(regs, error_code, address);
+ bad_area(regs, sw_error_code, address);
return;
}
* we can handle it..
*/
good_area:
- if (unlikely(access_error(error_code, vma))) {
- bad_area_access_error(regs, error_code, address, vma);
+ if (unlikely(access_error(sw_error_code, vma))) {
+ bad_area_access_error(regs, sw_error_code, address, vma);
return;
}
return;
/* Not returning to user mode? Handle exceptions or die: */
- no_context(regs, error_code, address, SIGBUS, BUS_ADRERR);
+ no_context(regs, sw_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, &pkey, fault);
+ mm_fault_error(regs, sw_error_code, address, &pkey, fault);
return;
}
check_v8086_mode(regs, address, tsk);
}
+NOKPROBE_SYMBOL(do_user_addr_fault);
+
+/*
+ * 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 hw_error_code,
+ unsigned long address)
+{
+ prefetchw(¤t->mm->mmap_sem);
+
+ if (unlikely(kmmio_fault(regs, address)))
+ return;
+
+ /* Was the fault on kernel-controlled part of the address space? */
+ if (unlikely(fault_in_kernel_space(address)))
+ do_kern_addr_fault(regs, hw_error_code, address);
+ else
+ do_user_addr_fault(regs, hw_error_code, address);
+}
NOKPROBE_SYMBOL(__do_page_fault);
static nokprobe_inline void
projects / linux-2.6-microblaze.git / blobdiff