[PATCH] Kprobes: rearrange preempt_disable/enable() calls

[safe/jmp/linux-2.6] / arch / x86_64 / kernel / kprobes.c

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 76a28b0..ebfa2c9 100644 (file)
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -302,9 +302,6 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
        int ret = 0;
        kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t));
 
-       /* We're in an interrupt, but this is clear and BUG()-safe. */
-       preempt_disable();
-
        /* Check we're not actually recursing */
        if (kprobe_running()) {
                /* We *are* holding lock here, so this is safe.
@@ -372,6 +369,11 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
                goto no_kprobe;
        }
 
+       /*
+        * This preempt_disable() matches the preempt_enable_no_resched()
+        * in post_kprobe_handler()
+        */
+       preempt_disable();
        kprobe_status = KPROBE_HIT_ACTIVE;
        set_current_kprobe(p, regs);
 
@@ -385,7 +387,6 @@ ss_probe:
        return 1;
 
 no_kprobe:
-       preempt_enable_no_resched();
        return ret;
 }
 
@@ -456,7 +457,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         /*
          * By returning a non-zero value, we are telling
          * kprobe_handler() that we have handled unlocking
-         * and re-enabling preemption.
+        * and re-enabling preemption
          */
         return 1;
 }
@@ -599,29 +600,29 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
                                       unsigned long val, void *data)
 {
        struct die_args *args = (struct die_args *)data;
+       int ret = NOTIFY_DONE;
+
+       preempt_disable();
        switch (val) {
        case DIE_INT3:
                if (kprobe_handler(args->regs))
-                       return NOTIFY_STOP;
+                       ret = NOTIFY_STOP;
                break;
        case DIE_DEBUG:
                if (post_kprobe_handler(args->regs))
-                       return NOTIFY_STOP;
+                       ret = NOTIFY_STOP;
                break;
        case DIE_GPF:
-               if (kprobe_running() &&
-                   kprobe_fault_handler(args->regs, args->trapnr))
-                       return NOTIFY_STOP;
-               break;
        case DIE_PAGE_FAULT:
                if (kprobe_running() &&
                    kprobe_fault_handler(args->regs, args->trapnr))
-                       return NOTIFY_STOP;
+                       ret = NOTIFY_STOP;
                break;
        default:
                break;
        }
-       return NOTIFY_DONE;
+       preempt_enable();
+       return ret;
 }
 
 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
@@ -647,7 +648,6 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 
 void __kprobes jprobe_return(void)
 {
-       preempt_enable_no_resched();
        asm volatile ("       xchg   %%rbx,%%rsp     \n"
                      "       int3                      \n"
                      "       .globl jprobe_return_end  \n"