[PATCH v3 13/15] powerpc/64s: machine check do not trace real-mode handler

[Christophe Leroy]

Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
> Rather than notrace annotations throughout a significant part of the
> machine check code across kernel/ pseries/ and powernv/ which can
> easily be broken and is infrequently tested, use paca->ftrace_enabled
> to blanket-disable tracing of the real-mode non-maskable handler.
> 
> Acked-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Reviewed-by: Christophe Leroy <christophe.leroy at c-s.fr>

> ---
>   arch/powerpc/kernel/mce.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
> index be7e3f92a7b5..fd90c0eda229 100644
> --- a/arch/powerpc/kernel/mce.c
> +++ b/arch/powerpc/kernel/mce.c
> @@ -16,6 +16,7 @@
>   #include <linux/export.h>
>   #include <linux/irq_work.h>
>   #include <linux/extable.h>
> +#include <linux/ftrace.h>
>   
>   #include <asm/machdep.h>
>   #include <asm/mce.h>
> @@ -571,10 +572,14 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
>    *
>    * regs->nip and regs->msr contains srr0 and ssr1.
>    */
> -long machine_check_early(struct pt_regs *regs)
> +long notrace machine_check_early(struct pt_regs *regs)
>   {
>   	long handled = 0;
>   	bool nested = in_nmi();
> +	u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
> +
> +	this_cpu_set_ftrace_enabled(0);
> +
>   	if (!nested)
>   		nmi_enter();
>   
> @@ -589,6 +594,8 @@ long machine_check_early(struct pt_regs *regs)
>   	if (!nested)
>   		nmi_exit();
>   
> +	this_cpu_set_ftrace_enabled(ftrace_enabled);
> +
>   	return handled;
>   }
>   
>