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Subject[PATCH] kprobes,x86: disable irq durinr optimized callback
Date
hi,

attached patch is disabling irqs during optimized callback,
so we dont miss any in-irq kprobes as missed.

Also I think there's small window where current_kprobe variable
could be touched in non-safe way, but I was not able to hit
any issue.

I'm not sure wether this is a bug or if it was intentional to have
irqs enabled during the pre_handler callback.

wbr,
jirka

---
Disabling irqs during optimized callback, so we dont miss
any in-irq kprobes as missed.
Interrupts are also disabled during non-optimized kprobes callbacks.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
arch/x86/kernel/kprobes.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index c969fd9..917cb31 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -1183,11 +1183,13 @@ static void __kprobes optimized_callback(struct optimized_kprobe *op,
struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long flags;

/* This is possible if op is under delayed unoptimizing */
if (kprobe_disabled(&op->kp))
return;

+ local_irq_save(flags);
preempt_disable();
if (kprobe_running()) {
kprobes_inc_nmissed_count(&op->kp);
@@ -1208,6 +1210,7 @@ static void __kprobes optimized_callback(struct optimized_kprobe *op,
__this_cpu_write(current_kprobe, NULL);
}
preempt_enable_no_resched();
+ local_irq_restore(flags);
}

static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
--
1.7.1


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