diff options
Diffstat (limited to 'arch/i386/mm/fault.c')
| -rw-r--r-- | arch/i386/mm/fault.c | 61 |
1 files changed, 49 insertions, 12 deletions
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c index 7f0fcf219a26..f7279468323a 100644 --- a/arch/i386/mm/fault.c +++ b/arch/i386/mm/fault.c @@ -30,6 +30,40 @@ extern void die(const char *,struct pt_regs *,long); +#ifdef CONFIG_KPROBES +ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); +int register_page_fault_notifier(struct notifier_block *nb) +{ + vmalloc_sync_all(); + return atomic_notifier_chain_register(¬ify_page_fault_chain, nb); +} + +int unregister_page_fault_notifier(struct notifier_block *nb) +{ + return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); +} + +static inline int notify_page_fault(enum die_val val, const char *str, + struct pt_regs *regs, long err, int trap, int sig) +{ + struct die_args args = { + .regs = regs, + .str = str, + .err = err, + .trapnr = trap, + .signr = sig + }; + return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args); +} +#else +static inline int notify_page_fault(enum die_val val, const char *str, + struct pt_regs *regs, long err, int trap, int sig) +{ + return NOTIFY_DONE; +} +#endif + + /* * Unlock any spinlocks which will prevent us from getting the * message out @@ -77,12 +111,15 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, unsigned seg = regs->xcs & 0xffff; u32 seg_ar, seg_limit, base, *desc; + /* Unlikely, but must come before segment checks. */ + if (unlikely(regs->eflags & VM_MASK)) { + base = seg << 4; + *eip_limit = base + 0xffff; + return base + (eip & 0xffff); + } + /* The standard kernel/user address space limit. */ *eip_limit = (seg & 3) ? USER_DS.seg : KERNEL_DS.seg; - - /* Unlikely, but must come before segment checks. */ - if (unlikely((regs->eflags & VM_MASK) != 0)) - return eip + (seg << 4); /* By far the most common cases. */ if (likely(seg == __USER_CS || seg == __KERNEL_CS)) @@ -321,7 +358,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, if (unlikely(address >= TASK_SIZE)) { if (!(error_code & 0x0000000d) && vmalloc_fault(address) >= 0) return; - if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, + if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, SIGSEGV) == NOTIFY_STOP) return; /* @@ -331,7 +368,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, goto bad_area_nosemaphore; } - if (notify_die(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, + if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, SIGSEGV) == NOTIFY_STOP) return; @@ -352,7 +389,7 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, /* 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. Unfortunatly, in the case of an - * erroneous fault occuring in a code path which already holds mmap_sem + * 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 @@ -380,12 +417,12 @@ fastcall void __kprobes do_page_fault(struct pt_regs *regs, goto bad_area; if (error_code & 4) { /* - * accessing the stack below %esp is always a bug. - * The "+ 32" is there due to some instructions (like - * pusha) doing post-decrement on the stack and that - * doesn't show up until later.. + * Accessing the stack below %esp is always a bug. + * The large cushion allows instructions like enter + * and pusha to work. ("enter $65535,$31" pushes + * 32 pointers and then decrements %esp by 65535.) */ - if (address + 32 < regs->esp) + if (address + 65536 + 32 * sizeof(unsigned long) < regs->esp) goto bad_area; } if (expand_stack(vma, address)) |