Re: [PATCH] arm64: make secondary_start_kernel() notrace

2018-06-18 Thread Catalin Marinas
On Tue, Jun 12, 2018 at 05:07:37PM +0800, Zhizhou Zhang wrote:
> We can't call function trace hook before setup percpu offset.
> When entering secondary_start_kernel(), percpu offset has not
> been initialized.  So this lead hotplug malfunction.
> Here is the flow to reproduce this bug:
> 
> echo 0 > /sys/devices/system/cpu/cpu1/online
> echo function > /sys/kernel/debug/tracing/current_tracer
> echo 1 > /sys/kernel/debug/tracing/tracing_on
> echo 1 > /sys/devices/system/cpu/cpu1/online
> 
> Signed-off-by: Zhizhou Zhang 

Queued for 4.18. Thanks.

-- 
Catalin


Re: [PATCH] arm64: make secondary_start_kernel() notrace

2018-06-12 Thread Suzuki K Poulose

On 12/06/18 10:07, Zhizhou Zhang wrote:

We can't call function trace hook before setup percpu offset.
When entering secondary_start_kernel(), percpu offset has not
been initialized.  So this lead hotplug malfunction.
Here is the flow to reproduce this bug:

echo 0 > /sys/devices/system/cpu/cpu1/online
echo function > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on
echo 1 > /sys/devices/system/cpu/cpu1/online

Signed-off-by: Zhizhou Zhang 
---
  arch/arm64/kernel/smp.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index f3e2e3ae..11b0f30 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -179,7 +179,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
   * This is the secondary CPU boot entry.  We're using this CPUs
   * idle thread stack, but a set of temporary page tables.
   */
-asmlinkage void secondary_start_kernel(void)
+notrace asmlinkage void secondary_start_kernel(void)
  {
u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
struct mm_struct *mm = _mm;



Tested-by: Suzuki K Poulose 

I think this should go to stable releases as well.

Suzuki


[PATCH] arm64: make secondary_start_kernel() notrace

2018-06-12 Thread Zhizhou Zhang
We can't call function trace hook before setup percpu offset.
When entering secondary_start_kernel(), percpu offset has not
been initialized.  So this lead hotplug malfunction.
Here is the flow to reproduce this bug:

echo 0 > /sys/devices/system/cpu/cpu1/online
echo function > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on
echo 1 > /sys/devices/system/cpu/cpu1/online

Signed-off-by: Zhizhou Zhang 
---
 arch/arm64/kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index f3e2e3ae..11b0f30 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -179,7 +179,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
  */
-asmlinkage void secondary_start_kernel(void)
+notrace asmlinkage void secondary_start_kernel(void)
 {
u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
struct mm_struct *mm = _mm;
-- 
1.9.1



Re: [PATCH] arm64: make secondary_start_kernel() notrace

2018-06-12 Thread Mark Rutland
On Tue, Jun 12, 2018 at 05:07:37PM +0800, Zhizhou Zhang wrote:
> We can't call function trace hook before setup percpu offset.
> When entering secondary_start_kernel(), percpu offset has not
> been initialized.  So this lead hotplug malfunction.
> Here is the flow to reproduce this bug:
> 
> echo 0 > /sys/devices/system/cpu/cpu1/online
> echo function > /sys/kernel/debug/tracing/current_tracer
> echo 1 > /sys/kernel/debug/tracing/tracing_on
> echo 1 > /sys/devices/system/cpu/cpu1/online
> 
> Signed-off-by: Zhizhou Zhang 
> ---
>  arch/arm64/kernel/smp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index f3e2e3ae..11b0f30 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -179,7 +179,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
>   * This is the secondary CPU boot entry.  We're using this CPUs
>   * idle thread stack, but a set of temporary page tables.
>   */
> -asmlinkage void secondary_start_kernel(void)
> +notrace asmlinkage void secondary_start_kernel(void)

Minor nit: can we please keep asmlinkage first, e.g.

asmlinkage notrace void secondary_start_kernel(void)

Either way:

Acked-by: Mark Rutland 

Thanks,
Mark.

>  {
>   u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
>   struct mm_struct *mm = _mm;
> -- 
> 1.9.1
>