From: Masami Hiramatsu Date: Sun, 30 Jul 2006 10:03:21 +0000 (-0700) Subject: [PATCH] kprobe-booster: disable in preemptible kernel X-Git-Tag: v2.6.18-rc4~136 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c39df470e04822965d945473d831786ab79dd4cd;p=linux-2.6 [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 Cc: Ananth N Mavinakayanahalli Cc: Prasanna S Panchamukhi Cc: Anil S Keshavamurthy Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index de2e16e561..afe6505ca0 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;