Re: [PATCH v2] x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.text

From	Alexander Potapenko <glider@google.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.text
Date	2016-08-05 18:40 +0200
Message-ID	<s2Qk9-1va-1@gated-at.bofh.it> (permalink)
References	<rV7UR-5ff-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Fri, Jul 15, 2016 at 11:42 AM, Alexander Potapenko <glider@google.com> wrote:
> When building with CONFIG_FUNCTION_GRAPH_TRACER or CONFIG_KASAN, put the
> APIC interrupt handlers into the .irqentry.text section. This is needed
> because both KASAN and function graph tracer use __irqentry_text_start and
> __irqentry_text_end to determine whether a function is an IRQ entry point.
>
> Dmitry Vyukov has reported unexpected KASAN stackdepot growth
> (https://github.com/google/kasan/issues/36), which had been caused by
> the APIC handlers not being present in .irqentry.text.
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> ---
> v2: - fixed kbuild warning (incorrect #if directive)
> ---
>  arch/x86/entry/entry_64.S | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
> index 9ee0da1..2ef4f0b 100644
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -601,9 +601,20 @@ apicinterrupt3 \num trace(\sym) smp_trace(\sym)
>  .endm
>  #endif
>
> +/* Make sure APIC interrupt handlers end up in the irqentry section. */
> +#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
> +#define PUSH_SECTION_IRQENTRY  .pushsection .irqentry.text, "ax"
> +#define POP_SECTION_IRQENTRY   .popsection
> +#else
> +#define PUSH_SECTION_IRQENTRY
> +#define POP_SECTION_IRQENTRY
> +#endif
> +
>  .macro apicinterrupt num sym do_sym
> +PUSH_SECTION_IRQENTRY
>  apicinterrupt3 \num \sym \do_sym
>  trace_apicinterrupt \num \sym
> +POP_SECTION_IRQENTRY
>  .endm
>
>  #ifdef CONFIG_SMP
> --
> 2.8.0.rc3.226.g39d4020
>
A friendly ping.


-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
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Re: [PATCH v2] x86, kasan, ftrace: Put APIC interrupt handlers into .irqentry.text Alexander Potapenko <glider@google.com> - 2016-08-05 18:40 +0200

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