[PATCH -tip v3 07/10] kprobes: Prohibit probing on preempt_check debug functions

Masami Hiramatsu
2019-02-12T16:14:35Z

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);