linux-kernel - [PATCH -tip v3 2/7] kprobes/x86: Move get_kprobe

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Date:   Tue, 19 Sep 2017 18:59:39 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>, mingo@...hat.com
Cc:     x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Alexei Starovoitov <ast@...com>
Subject: [PATCH -tip v3 2/7] kprobes/x86: Move get_kprobe_ctlblk in irq-disabled block

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

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.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 4f98aad38237..259b7e828b02 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;