kernel/kcov.c: mark func write_comp_data() as notrace

Message ID 20181206143011.23719-1-anders.roxell@linaro.org
State Accepted
Commit 634724431607f6f46c495dfef801a1c8b44a96d9
Headers show
Series
  • kernel/kcov.c: mark func write_comp_data() as notrace
Related show

Commit Message

Anders Roxell Dec. 6, 2018, 2:30 p.m.
Since __sanitizer_cov_trace_const_cmp4 is marked as notrace, the
function called from __sanitizer_cov_trace_const_cmp4 shouldn't be
traceable either.  ftrace_graph_caller() gets called every time func
write_comp_data() gets called if it isn't marked 'notrace'. This is the
backtrace from gdb:

 #0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179
 #1  0xffffff8010201920 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:151
 #2  0xffffff8010439714 in write_comp_data (type=5, arg1=0, arg2=0, ip=18446743524224276596) at ../kernel/kcov.c:116
 #3  0xffffff8010439894 in __sanitizer_cov_trace_const_cmp4 (arg1=<optimized out>, arg2=<optimized out>) at ../kernel/kcov.c:188
 #4  0xffffff8010201874 in prepare_ftrace_return (self_addr=18446743524226602768, parent=0xffffff801014b918, frame_pointer=18446743524223531344) at ./include/generated/atomic-instrumented.h:27
 #5  0xffffff801020194c in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:182

Rework so that write_comp_data() that are called from
__sanitizer_cov_trace_*_cmp*() are marked as 'notrace'.

Commit 903e8ff86753 ("kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace")
missed to mark write_comp_data() as 'notrace'. When that patch was
created gcc-7 was used. In lib/Kconfig.debug
config KCOV_ENABLE_COMPARISONS
	depends on $(cc-option,-fsanitize-coverage=trace-cmp)

That code path isn't hit with gcc-7. However, it were that with gcc-8.

Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

---
 kernel/kcov.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.19.2

Comments

Steven Rostedt Dec. 6, 2018, 6:14 p.m. | #1
On Thu,  6 Dec 2018 15:30:11 +0100
Anders Roxell <anders.roxell@linaro.org> wrote:

> Since __sanitizer_cov_trace_const_cmp4 is marked as notrace, the

> function called from __sanitizer_cov_trace_const_cmp4 shouldn't be

> traceable either.  ftrace_graph_caller() gets called every time func

> write_comp_data() gets called if it isn't marked 'notrace'. This is the

> backtrace from gdb:

> 

>  #0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179

>  #1  0xffffff8010201920 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:151

>  #2  0xffffff8010439714 in write_comp_data (type=5, arg1=0, arg2=0, ip=18446743524224276596) at ../kernel/kcov.c:116

>  #3  0xffffff8010439894 in __sanitizer_cov_trace_const_cmp4 (arg1=<optimized out>, arg2=<optimized out>) at ../kernel/kcov.c:188

>  #4  0xffffff8010201874 in prepare_ftrace_return (self_addr=18446743524226602768, parent=0xffffff801014b918, frame_pointer=18446743524223531344) at ./include/generated/atomic-instrumented.h:27

>  #5  0xffffff801020194c in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:182

> 

> Rework so that write_comp_data() that are called from

> __sanitizer_cov_trace_*_cmp*() are marked as 'notrace'.

> 

> Commit 903e8ff86753 ("kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace")

> missed to mark write_comp_data() as 'notrace'. When that patch was

> created gcc-7 was used. In lib/Kconfig.debug

> config KCOV_ENABLE_COMPARISONS

> 	depends on $(cc-option,-fsanitize-coverage=trace-cmp)

> 

> That code path isn't hit with gcc-7. However, it were that with gcc-8.

> 

> Co-developed-by: Arnd Bergmann <arnd@arndb.de>

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>


Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>


-- Steve

> ---

>  kernel/kcov.c | 2 +-

>  1 file changed, 1 insertion(+), 1 deletion(-)

> 

> diff --git a/kernel/kcov.c b/kernel/kcov.c

> index 97959d7b77e2..c2277dbdbfb1 100644

> --- a/kernel/kcov.c

> +++ b/kernel/kcov.c

> @@ -112,7 +112,7 @@ void notrace __sanitizer_cov_trace_pc(void)

>  EXPORT_SYMBOL(__sanitizer_cov_trace_pc);

>  

>  #ifdef CONFIG_KCOV_ENABLE_COMPARISONS

> -static void write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)

> +static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)

>  {

>  	struct task_struct *t;

>  	u64 *area;

Patch

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 97959d7b77e2..c2277dbdbfb1 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -112,7 +112,7 @@  void notrace __sanitizer_cov_trace_pc(void)
 EXPORT_SYMBOL(__sanitizer_cov_trace_pc);
 
 #ifdef CONFIG_KCOV_ENABLE_COMPARISONS
-static void write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
+static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
 {
 	struct task_struct *t;
 	u64 *area;