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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2006-07-30 03:03:21 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-31 13:28:38 -0700
commitc39df470e04822965d945473d831786ab79dd4cd (patch)
tree5a16bc4b29c71d9ae3cd234995c66daedc85e6bf
parent2a8a3d5b65e86ec1dfef7d268c64a909eab94af7 (diff)
downloadlinux-2.6.34-ux500-c39df470e04822965d945473d831786ab79dd4cd.tar.gz
[PATCH] kprobe-booster: disable in preemptible kernel
The kprobe-booster's safety check against preemption does not work well now, because the preemption count has been modified by read_rcu_lock() in atomic_notifier_call_chain() before we check it. So, I'd like to prevent boosting kprobe temporarily if the kernel is preemptable. Now we are searching for the good solution. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/kprobes.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index de2e16e561c..afe6505ca0b 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -256,11 +256,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
int ret = 0;
kprobe_opcode_t *addr;
struct kprobe_ctlblk *kcb;
-#ifdef CONFIG_PREEMPT
- unsigned pre_preempt_count = preempt_count();
-#else
- unsigned pre_preempt_count = 1;
-#endif
addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
@@ -338,13 +333,15 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
return 1;
ss_probe:
- if (pre_preempt_count && p->ainsn.boostable == 1 && !p->post_handler){
+#ifndef CONFIG_PREEMPT
+ if (p->ainsn.boostable == 1 && !p->post_handler){
/* Boost up -- we can execute copied instructions directly */
reset_current_kprobe();
regs->eip = (unsigned long)p->ainsn.insn;
preempt_enable_no_resched();
return 1;
}
+#endif
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;