Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Ingo Molnar <mingo@redhat.com>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>, peterz@infradead.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Andrea Righi <righi.andrea@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH v2 7/9] kprobes: Prohibit probing on preempt_check debug functions
Date:   Sat, 12 Jan 2019 11:28:59 +0900
Message-Id: <154726013890.18060.11204538289611057483.stgit@devbox>
In-Reply-To: <154725993986.18060.2759150647140353514.stgit@devbox>
References: <154725993986.18060.2759150647140353514.stgit@devbox>
User-Agent: StGit/0.17.1-dirty
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Since kprobes depends on preempt disable/enable, probing
on the preempt debug routine can cause recursive breakpoint
problem.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 lib/smp_processor_id.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 85925aaa4fff..157d9e31f6c2 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -5,10 +5,11 @@
  * DEBUG_PREEMPT variant of smp_processor_id().
  */
 #include <linux/export.h>
+#include <linux/kprobes.h>
 #include <linux/sched.h>
 
-notrace static unsigned int check_preemption_disabled(const char *what1,
-							const char *what2)
+notrace static nokprobe_inline
+unsigned int check_preemption_disabled(const char *what1, const char *what2)
 {
 	int this_cpu = raw_smp_processor_id();
 
@@ -56,9 +57,11 @@ notrace unsigned int debug_smp_processor_id(void)
 	return check_preemption_disabled("smp_processor_id", "");
 }
 EXPORT_SYMBOL(debug_smp_processor_id);
+NOKPROBE_SYMBOL(debug_smp_processor_id);
 
 notrace void __this_cpu_preempt_check(const char *op)
 {
 	check_preemption_disabled("__this_cpu_", op);
 }
 EXPORT_SYMBOL(__this_cpu_preempt_check);
+NOKPROBE_SYMBOL(__this_cpu_preempt_check);