diff options
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 32 |
1 files changed, 24 insertions, 8 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 1dbade870f90..d973e61e450d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -3,7 +3,6 @@ * Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs. * Copyright (C) 2008-2009, Red Hat Inc., Ingo Molnar */ -#include <linux/magic.h> /* STACK_END_MAGIC */ #include <linux/sched.h> /* test_thread_flag(), ... */ #include <linux/kdebug.h> /* oops_begin/end, ... */ #include <linux/module.h> /* search_exception_table */ @@ -350,7 +349,7 @@ out: void vmalloc_sync_all(void) { - sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END); + sync_global_pgds(VMALLOC_START & PGDIR_MASK, VMALLOC_END, 0); } /* @@ -649,7 +648,6 @@ 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 *stackend; unsigned long flags; int sig; @@ -709,8 +707,7 @@ no_context(struct pt_regs *regs, unsigned long error_code, show_fault_oops(regs, error_code, address); - stackend = end_of_stack(tsk); - if (tsk != &init_task && *stackend != STACK_END_MAGIC) + if (task_stack_end_corrupted(tsk)) printk(KERN_EMERG "Thread overran stack, or stack corrupted\n"); tsk->thread.cr2 = address; @@ -933,8 +930,17 @@ static int spurious_fault_check(unsigned long error_code, pte_t *pte) * 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) @@ -945,8 +951,17 @@ spurious_fault(unsigned long error_code, unsigned long address) pte_t *pte; int ret; - /* Reserved-bit violation or user access to kernel space? */ - if (error_code & (PF_USER | PF_RSVD)) + /* + * 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); @@ -1218,7 +1233,8 @@ good_area: /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo - * the fault: + * 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(mm, vma, address, flags); |
