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SubjectRe: [PATCH] arm64: make secondary_start_kernel() notrace
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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 <zhizhouzhang@asrmicro.com>
> ---
> 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 = &init_mm;
>

Tested-by: Suzuki K Poulose <suzuki.poulose@arm.com>

I think this should go to stable releases as well.

Suzuki

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