linux-kernel - [tip:perf/core] kprobes/x86: Move the get_kprobe

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Message-ID: <tip-cd52edad55fbcd8064877a77d31445b2fb4b85c3@git.kernel.org>
Date:   Thu, 28 Sep 2017 03:52:58 -0700
From:   tip-bot for Masami Hiramatsu <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
        ananth@...ux.vnet.ibm.com, ast@...nel.org, ast@...com,
        mingo@...nel.org, rostedt@...dmis.org, hpa@...or.com,
        mhiramat@...nel.org, tglx@...utronix.de
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@...nel.org>
AuthorDate: Tue, 19 Sep 2017 18:59:39 +0900
Committer:  Ingo Molnar <mingo@...nel.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@...nel.org>
Cc: Alexei Starovoitov <ast@...com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E . McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/150581517952.32348.2655896843219158446.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@...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 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;