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authorSven Schnelle <svens@linux.ibm.com>2019-12-09 09:03:12 +0100
committerVasily Gorbik <gor@linux.ibm.com>2019-12-18 23:29:26 +0100
commit6feeee8efc53035c3195b02068b58ae947538aa4 (patch)
tree7d7e00a80b7725e5664d44809f83b5674723528d /arch
parentd1eef1c619749b2a57e514a3fa67d9a516ffa919 (diff)
s390/ftrace: fix endless recursion in function_graph tracer
The following sequence triggers a kernel stack overflow on s390x: mount -t tracefs tracefs /sys/kernel/tracing cd /sys/kernel/tracing echo function_graph > current_tracer [crash] This is because preempt_count_{add,sub} are in the list of traced functions, which can be demonstrated by: echo preempt_count_add >set_ftrace_filter echo function_graph > current_tracer [crash] The stack overflow happens because get_tod_clock_monotonic() gets called by ftrace but itself calls preempt_{disable,enable}(), which leads to a endless recursion. Fix this by using preempt_{disable,enable}_notrace(). Fixes: 011620688a71 ("s390/time: ensure get_clock_monotonic() returns monotonic values") Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/include/asm/timex.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index 6da8885251d6..670f14a228e5 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -194,9 +194,9 @@ static inline unsigned long long get_tod_clock_monotonic(void)
{
unsigned long long tod;
- preempt_disable();
+ preempt_disable_notrace();
tod = get_tod_clock() - *(unsigned long long *) &tod_clock_base[1];
- preempt_enable();
+ preempt_enable_notrace();
return tod;
}