From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Wed, 28 Oct 2015 14:11:26 +0100 Subject: [PATCH 1/8] clocksource/drivers/arm_global_timer: Prevent ftrace recursion In-Reply-To: <5630C947.4020706@linaro.org> References: <5630C947.4020706@linaro.org> Message-ID: <1446037894-22601-1-git-send-email-daniel.lezcano@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Jisheng Zhang Currently arm_global_timer can be used as a scheduler clock. We properly marked gt_sched_clock_read() as notrace but we then call another function gt_counter_read() that _wasn't_ notrace. Having a traceable function in the sched_clock() path leads to a recursion within ftrace and a kernel crash. Fix this by adding an extra notrace function to keep other users of gt_counter_read() traceable. Signed-off-by: Jisheng Zhang Signed-off-by: Daniel Lezcano --- drivers/clocksource/arm_global_timer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c index 29ea50a..a2cb6fa 100644 --- a/drivers/clocksource/arm_global_timer.c +++ b/drivers/clocksource/arm_global_timer.c @@ -60,7 +60,7 @@ static struct clock_event_device __percpu *gt_evt; * different to the 32-bit upper value read previously, go back to step 2. * Otherwise the 64-bit timer counter value is correct. */ -static u64 gt_counter_read(void) +static u64 notrace _gt_counter_read(void) { u64 counter; u32 lower; @@ -79,6 +79,11 @@ static u64 gt_counter_read(void) return counter; } +static u64 gt_counter_read(void) +{ + return _gt_counter_read(); +} + /** * To ensure that updates to comparator value register do not set the * Interrupt Status Register proceed as follows: @@ -201,7 +206,7 @@ static struct clocksource gt_clocksource = { #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK static u64 notrace gt_sched_clock_read(void) { - return gt_counter_read(); + return _gt_counter_read(); } #endif -- 1.9.1