[PATCH] powerpc/pseries: Mark accumulate_stolen_time() as notrace

[PATCH] powerpc/pseries: Mark accumulate_stolen_time() as notrace

[Michael Ellerman]

accumulate_stolen_time() is called prior to interrupt state being
reconciled, which can trip the warning in arch_local_irq_restore():

  WARNING: CPU: 5 PID: 1017 at arch/powerpc/kernel/irq.c:258 .arch_local_irq_restore+0x9c/0x130
  ...
  NIP .arch_local_irq_restore+0x9c/0x130
  LR  .rb_start_commit+0x38/0x80
  Call Trace:
    .ring_buffer_lock_reserve+0xe4/0x620
    .trace_function+0x44/0x210
    .function_trace_call+0x148/0x170
    .ftrace_ops_no_ops+0x180/0x1d0
    ftrace_call+0x4/0x8
    .accumulate_stolen_time+0x1c/0xb0
    decrementer_common+0x124/0x160

For now just mark it as notrace. We may change the ordering to call it
after interrupt state has been reconciled, but that is a larger
change.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/kernel/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 694522308cd5..968ae97382b4 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -232,7 +232,7 @@ static u64 scan_dispatch_log(u64 stop_tb)
  * Accumulate stolen time by scanning the dispatch trace log.
  * Called on entry from user mode.
  */
-void accumulate_stolen_time(void)
+void notrace accumulate_stolen_time(void)
 {
 	u64 sst, ust;
 	unsigned long save_irq_soft_mask = irq_soft_mask_return();
-- 
2.21.0

Re: [PATCH] powerpc/pseries: Mark accumulate_stolen_time() as notrace

[Michael Ellerman]

On Thu, 2019-10-24 at 05:59:32 UTC, Michael Ellerman wrote:
> accumulate_stolen_time() is called prior to interrupt state being
> reconciled, which can trip the warning in arch_local_irq_restore():
> 
>   WARNING: CPU: 5 PID: 1017 at arch/powerpc/kernel/irq.c:258 .arch_local_irq_restore+0x9c/0x130
>   ...
>   NIP .arch_local_irq_restore+0x9c/0x130
>   LR  .rb_start_commit+0x38/0x80
>   Call Trace:
>     .ring_buffer_lock_reserve+0xe4/0x620
>     .trace_function+0x44/0x210
>     .function_trace_call+0x148/0x170
>     .ftrace_ops_no_ops+0x180/0x1d0
>     ftrace_call+0x4/0x8
>     .accumulate_stolen_time+0x1c/0xb0
>     decrementer_common+0x124/0x160
> 
> For now just mark it as notrace. We may change the ordering to call it
> after interrupt state has been reconciled, but that is a larger
> change.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Applied to powerpc next.

https://git.kernel.org/powerpc/c/eb8e20f89093b64f48975c74ccb114e6775cee22

cheers