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Subject[tip:perf/core] kprobes/x86: Move the get_kprobe_ctlblk() into irq-disabled block
Commit-ID:  cd52edad55fbcd8064877a77d31445b2fb4b85c3
Gitweb: https://git.kernel.org/tip/cd52edad55fbcd8064877a77d31445b2fb4b85c3
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Tue, 19 Sep 2017 18:59:39 +0900
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 28 Sep 2017 09:23:03 +0200

kprobes/x86: Move the get_kprobe_ctlblk() into irq-disabled block

Since get_kprobe_ctlblk() accesses per-cpu variables
which calls smp_processor_id(), it must be called under
preempt-disabled or irq-disabled.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/150581517952.32348.2655896843219158446.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/kprobes/opt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 0cae7c0..f558103 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -154,7 +154,6 @@ STACK_FRAME_NON_STANDARD(optprobe_template_func);
static void
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 */
@@ -165,6 +164,7 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
if (kprobe_running()) {
kprobes_inc_nmissed_count(&op->kp);
} else {
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
/* Save skipped registers */
#ifdef CONFIG_X86_64
regs->cs = __KERNEL_CS;
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