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Commit d6df3576 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Daniel Lezcano
Browse files

clocksource/drivers/arm_global_timer: Prevent ftrace recursion 



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: default avatarJisheng Zhang <jszhang@marvell.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent 56fd16ca

drivers/clocksource/arm_global_timer.c

+7 −2
Original line number Diff line number Diff line
@@ -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