Commit c39df470 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Linus Torvalds

[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: default avatarMasami 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2a8a3d5b
......@@ -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;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment