* [PATCH] ARM: make cpu_init() notrace
@ 2013-04-18 16:20 Jon Medhurst (Tixy)
2013-04-19 21:37 ` Nicolas Pitre
2013-04-22 14:07 ` Russell King - ARM Linux
0 siblings, 2 replies; 6+ messages in thread
From: Jon Medhurst (Tixy) @ 2013-04-18 16:20 UTC (permalink / raw)
To: linux-arm-kernel
On resume from CPU power down any trace hooks enabled in cpu_init()
will get called before that function has done set_my_cpu_offset(),
so any use of per-cpu variables by trace hook code will cause bad
things to happen. Prevent this by marking the function notrace.
This fixes lockups/crashes seen when enabling function tracer on TC2
with the not yet mainlined cpuidle driver.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
---
arch/arm/kernel/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d343a6c..943cbf0 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -390,7 +390,7 @@ static void __init feat_v6_fixup(void)
*
* cpu_init sets up the per-CPU stacks.
*/
-void cpu_init(void)
+void notrace cpu_init(void)
{
unsigned int cpu = smp_processor_id();
struct stack *stk = &stacks[cpu];
--
1.7.10.4
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH] ARM: make cpu_init() notrace
2013-04-18 16:20 [PATCH] ARM: make cpu_init() notrace Jon Medhurst (Tixy)
@ 2013-04-19 21:37 ` Nicolas Pitre
2013-04-22 14:07 ` Russell King - ARM Linux
1 sibling, 0 replies; 6+ messages in thread
From: Nicolas Pitre @ 2013-04-19 21:37 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, 18 Apr 2013, Jon Medhurst (Tixy) wrote:
> On resume from CPU power down any trace hooks enabled in cpu_init()
> will get called before that function has done set_my_cpu_offset(),
> so any use of per-cpu variables by trace hook code will cause bad
> things to happen. Prevent this by marking the function notrace.
>
> This fixes lockups/crashes seen when enabling function tracer on TC2
> with the not yet mainlined cpuidle driver.
This has potential to fix things on other platforms too.
>
> Signed-off-by: Jon Medhurst <tixy@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
I think you may send it to RMK's patch system.
> ---
> arch/arm/kernel/setup.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index d343a6c..943cbf0 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -390,7 +390,7 @@ static void __init feat_v6_fixup(void)
> *
> * cpu_init sets up the per-CPU stacks.
> */
> -void cpu_init(void)
> +void notrace cpu_init(void)
> {
> unsigned int cpu = smp_processor_id();
> struct stack *stk = &stacks[cpu];
> --
> 1.7.10.4
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: make cpu_init() notrace
2013-04-18 16:20 [PATCH] ARM: make cpu_init() notrace Jon Medhurst (Tixy)
2013-04-19 21:37 ` Nicolas Pitre
@ 2013-04-22 14:07 ` Russell King - ARM Linux
2013-04-22 18:08 ` Jon Medhurst (Tixy)
1 sibling, 1 reply; 6+ messages in thread
From: Russell King - ARM Linux @ 2013-04-22 14:07 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, Apr 18, 2013 at 05:20:46PM +0100, Jon Medhurst (Tixy) wrote:
> On resume from CPU power down any trace hooks enabled in cpu_init()
> will get called before that function has done set_my_cpu_offset(),
> so any use of per-cpu variables by trace hook code will cause bad
> things to happen. Prevent this by marking the function notrace.
>
> This fixes lockups/crashes seen when enabling function tracer on TC2
> with the not yet mainlined cpuidle driver.
Looks sane. Needs to go to the patch system though. Not sure if it'll
make 3.9 given its proximity (we're on -rc8).
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: make cpu_init() notrace
2013-04-22 14:07 ` Russell King - ARM Linux
@ 2013-04-22 18:08 ` Jon Medhurst (Tixy)
2013-04-25 12:15 ` Russell King - ARM Linux
0 siblings, 1 reply; 6+ messages in thread
From: Jon Medhurst (Tixy) @ 2013-04-22 18:08 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, 2013-04-22 at 15:07 +0100, Russell King - ARM Linux wrote:
> On Thu, Apr 18, 2013 at 05:20:46PM +0100, Jon Medhurst (Tixy) wrote:
> > On resume from CPU power down any trace hooks enabled in cpu_init()
> > will get called before that function has done set_my_cpu_offset(),
> > so any use of per-cpu variables by trace hook code will cause bad
> > things to happen. Prevent this by marking the function notrace.
> >
> > This fixes lockups/crashes seen when enabling function tracer on TC2
> > with the not yet mainlined cpuidle driver.
>
> Looks sane. Needs to go to the patch system though. Not sure if it'll
> make 3.9 given its proximity (we're on -rc8).
Added as patch 7700/1. Don't think there is a big rush as the problem
has probably been there since 3.8 when commit 14318efb (implement
optimized percpu variable access) started using TPIDRPRW; which is
presumably lost over CPU power down.
--
Tixy
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: make cpu_init() notrace
2013-04-22 18:08 ` Jon Medhurst (Tixy)
@ 2013-04-25 12:15 ` Russell King - ARM Linux
2013-04-25 13:50 ` Jon Medhurst (Tixy)
0 siblings, 1 reply; 6+ messages in thread
From: Russell King - ARM Linux @ 2013-04-25 12:15 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Apr 22, 2013 at 07:08:36PM +0100, Jon Medhurst (Tixy) wrote:
> On Mon, 2013-04-22 at 15:07 +0100, Russell King - ARM Linux wrote:
> > On Thu, Apr 18, 2013 at 05:20:46PM +0100, Jon Medhurst (Tixy) wrote:
> > > On resume from CPU power down any trace hooks enabled in cpu_init()
> > > will get called before that function has done set_my_cpu_offset(),
> > > so any use of per-cpu variables by trace hook code will cause bad
> > > things to happen. Prevent this by marking the function notrace.
> > >
> > > This fixes lockups/crashes seen when enabling function tracer on TC2
> > > with the not yet mainlined cpuidle driver.
> >
> > Looks sane. Needs to go to the patch system though. Not sure if it'll
> > make 3.9 given its proximity (we're on -rc8).
>
> Added as patch 7700/1. Don't think there is a big rush as the problem
> has probably been there since 3.8 when commit 14318efb (implement
> optimized percpu variable access) started using TPIDRPRW; which is
> presumably lost over CPU power down.
$ pdb getpatch 7700/1 |tr ' ' '_' |less
diff_--git_a/arch/arm/kernel/setup.c_b/arch/arm/kernel/setup.c
index_d343a6c..943cbf0_100644
---_a/arch/arm/kernel/setup.c
+++_b/arch/arm/kernel/setup.c
@@_-390,7_+390,7_@@_static_void___init_feat_v6_fixup(void)
__*
__*_cpu_init_sets_up_the_per-CPU_stacks.
__*/
-void_cpu_init(void)
+void_notrace_cpu_init(void)
_{
________unsigned_int_cpu_=_smp_processor_id();
________struct_stack_*stk_=_&stacks[cpu];
Can you guess why git has a problem appying the above... you seem to
have sent the patch from your mailer, I guess your mailer thinks it
knows better when it comes to what characters should be in your
message... or maybe its a cut'n'paste issue?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] ARM: make cpu_init() notrace
2013-04-25 12:15 ` Russell King - ARM Linux
@ 2013-04-25 13:50 ` Jon Medhurst (Tixy)
0 siblings, 0 replies; 6+ messages in thread
From: Jon Medhurst (Tixy) @ 2013-04-25 13:50 UTC (permalink / raw)
To: linux-arm-kernel
On Thu, 2013-04-25 at 13:15 +0100, Russell King - ARM Linux wrote:
> $ pdb getpatch 7700/1 |tr ' ' '_' |less
> diff_--git_a/arch/arm/kernel/setup.c_b/arch/arm/kernel/setup.c
> index_d343a6c..943cbf0_100644
> ---_a/arch/arm/kernel/setup.c
> +++_b/arch/arm/kernel/setup.c
> @@_-390,7_+390,7_@@_static_void___init_feat_v6_fixup(void)
> __*
> __*_cpu_init_sets_up_the_per-CPU_stacks.
> __*/
> -void_cpu_init(void)
> +void_notrace_cpu_init(void)
> _{
> ________unsigned_int_cpu_=_smp_processor_id();
> ________struct_stack_*stk_=_&stacks[cpu];
>
> Can you guess why git has a problem appying the above...
Sorry about that, the user forgot to tell their mailer it was
pre-formatted text. I've sent a fixed version.
Note to self: bcc self on patch submissions and then run them though
'git am' to catch problems before others hit them.
--
Tixy
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-04-25 13:50 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2013-04-18 16:20 [PATCH] ARM: make cpu_init() notrace Jon Medhurst (Tixy)
2013-04-19 21:37 ` Nicolas Pitre
2013-04-22 14:07 ` Russell King - ARM Linux
2013-04-22 18:08 ` Jon Medhurst (Tixy)
2013-04-25 12:15 ` Russell King - ARM Linux
2013-04-25 13:50 ` Jon Medhurst (Tixy)
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