On 24/05/2019 10:10, Julien Thierry wrote:
> With v5.2-rc1, The ftrace functions_graph tracer locks up whenever it is
> enabled on arm64.
>
> Since commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use
> arch_timer_read_counter to access stable counters") a function pointer
> is consistently used to read the counter instead of potentially
> referencing an inlinable function.
>
> The graph tacers relies on accessing the timer counters to compute the
nit: tracers
> time spent in functions which causes the lockup when attempting to trace
> these code paths.
>
> Annontate the arm arch timer counter accessors as notrace.
nit: Annotate
>
> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use
> arch_timer_read_counter to access stable counters")
> Signed-off-by: Julien Thierry <[email protected]>
> Cc: Marc Zyngier <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Daniel Lezcano <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Steven Rostedt <[email protected]>
> ---
> drivers/clocksource/arm_arch_timer.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c
> b/drivers/clocksource/arm_arch_timer.c
> index b2a951a..5c69c9a 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -149,22 +149,22 @@ u32 arch_timer_reg_read(int access, enum arch_timer_reg
> reg,
> return val;
> }
>
> -static u64 arch_counter_get_cntpct_stable(void)
> +static notrace u64 arch_counter_get_cntpct_stable(void)
> {
> return __arch_counter_get_cntpct_stable();
> }
>
> -static u64 arch_counter_get_cntpct(void)
> +static notrace u64 arch_counter_get_cntpct(void)
> {
> return __arch_counter_get_cntpct();
> }
>
> -static u64 arch_counter_get_cntvct_stable(void)
> +static notrace u64 arch_counter_get_cntvct_stable(void)
> {
> return __arch_counter_get_cntvct_stable();
> }
>
> -static u64 arch_counter_get_cntvct(void)
> +static notrace u64 arch_counter_get_cntvct(void)
> {
> return __arch_counter_get_cntvct();
> }
>
Well spotted, thanks Julien.
Acked-by: Marc Zyngier <[email protected]>
Daniel, can you please pick this up for the next batch of clocksource fixes?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
