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[PATCH] kprobe-booster: disable in preemptible kernel

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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>
This commit is contained in:
Masami Hiramatsu
2006-07-30 03:03:21 -07:00
committed by Linus Torvalds
parent 2a8a3d5b65
commit c39df470e0
1 changed files with 3 additions and 6 deletions
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9
arch/i386/kernel/kprobes.c
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@@ -256,11 +256,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
int ret = 0; int ret = 0;
kprobe_opcode_t *addr; kprobe_opcode_t *addr;
struct kprobe_ctlblk *kcb; 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)); 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; return 1;
ss_probe: 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 */ /* Boost up -- we can execute copied instructions directly */
reset_current_kprobe(); reset_current_kprobe();
regs->eip = (unsigned long)p->ainsn.insn; regs->eip = (unsigned long)p->ainsn.insn;
preempt_enable_no_resched(); preempt_enable_no_resched();
return 1; return 1;
} }
#endif
prepare_singlestep(p, regs); prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS; kcb->kprobe_status = KPROBE_HIT_SS;
return 1; return 1;