[1/2] kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc as notrace

Message ID 20181128081239.18317-1-anders.roxell@linaro.org
State Accepted
Commit 903e8ff86753e6f327bb92166a0665e4ecb8e2e7
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  • [1/2] kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc as notrace
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Commit Message

Anders Roxell Nov. 28, 2018, 8:12 a.m.
Since __sanitizer_cov_trace_pc is marked as notrace, function calls in
__sanitizer_cov_trace_pc shouldn't be traced either. The function
ftrace_graph_caller() gets called for each function that isn't marked
'notrace', like canonicalize_ip(). This is the call trace from a run:

[  139.644550]  ftrace_graph_caller+0x1c/0x24
[  139.648352]  canonicalize_ip+0x18/0x28
[  139.652313]  __sanitizer_cov_trace_pc+0x14/0x58
[  139.656184]  sched_clock+0x34/0x1e8
[  139.659759]  trace_clock_local+0x40/0x88
[  139.663722]  ftrace_push_return_trace+0x8c/0x1f0
[  139.667767]  prepare_ftrace_return+0xa8/0x100
[  139.671709]  ftrace_graph_caller+0x1c/0x24

Rework so that the functions check_kcov_mode and canonicalize_ip that is
callef from __sanitizer_cov_trace_pc also is marked as notrace.

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

Signen-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 kernel/kcov.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.19.2

Comments

Steven Rostedt Nov. 28, 2018, 2:05 p.m. | #1
On Wed, 28 Nov 2018 09:12:39 +0100
Anders Roxell <anders.roxell@linaro.org> wrote:

> Since __sanitizer_cov_trace_pc is marked as notrace, function calls in

> __sanitizer_cov_trace_pc shouldn't be traced either. The function

> ftrace_graph_caller() gets called for each function that isn't marked

> 'notrace', like canonicalize_ip(). This is the call trace from a run:

> 

> [  139.644550]  ftrace_graph_caller+0x1c/0x24

> [  139.648352]  canonicalize_ip+0x18/0x28

> [  139.652313]  __sanitizer_cov_trace_pc+0x14/0x58

> [  139.656184]  sched_clock+0x34/0x1e8

> [  139.659759]  trace_clock_local+0x40/0x88

> [  139.663722]  ftrace_push_return_trace+0x8c/0x1f0

> [  139.667767]  prepare_ftrace_return+0xa8/0x100

> [  139.671709]  ftrace_graph_caller+0x1c/0x24

> 

> Rework so that the functions check_kcov_mode and canonicalize_ip that is

> callef from __sanitizer_cov_trace_pc also is marked as notrace.

> 

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

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

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

> ---


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


-- Steve

Patch

diff --git a/kernel/kcov.c b/kernel/kcov.c
index 3ebd09efe72a..97959d7b77e2 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -56,7 +56,7 @@  struct kcov {
 	struct task_struct	*t;
 };
 
-static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
+static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 {
 	unsigned int mode;
 
@@ -78,7 +78,7 @@  static bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)
 	return mode == needed_mode;
 }
 
-static unsigned long canonicalize_ip(unsigned long ip)
+static notrace unsigned long canonicalize_ip(unsigned long ip)
 {
 #ifdef CONFIG_RANDOMIZE_BASE
 	ip -= kaslr_offset();