From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm64: Add __exception_irq_entry definition for function graph
Date: Wed, 12 Aug 2015 17:53:24 +0100 [thread overview]
Message-ID: <20150812165324.GK23540@arm.com> (raw)
In-Reply-To: <9C0002C4-EEC5-415F-A0BC-2284E662D308@gmail.com>
On Wed, Aug 12, 2015 at 04:18:49PM +0100, Jungseok Lee wrote:
> On Aug 13, 2015, at 12:02 AM, Will Deacon wrote:
> > On Wed, Aug 12, 2015 at 03:16:19PM +0100, Jungseok Lee wrote:
> >> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
> >> index 232e4ba..0cc2f29 100644
> >> --- a/arch/arm64/include/asm/traps.h
> >> +++ b/arch/arm64/include/asm/traps.h
> >> @@ -34,13 +34,32 @@ struct undef_hook {
> >> void register_undef_hook(struct undef_hook *hook);
> >> void unregister_undef_hook(struct undef_hook *hook);
> >>
> >> +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> >> +static inline int __in_irqentry_text(unsigned long ptr)
> >> +{
> >> + extern char __irqentry_text_start[];
> >> + extern char __irqentry_text_end[];
> >> +
> >> + return ptr >= (unsigned long)&__irqentry_text_start &&
> >> + ptr < (unsigned long)&__irqentry_text_end;
> >> +}
> >> +#else
> >> +static inline int __in_irqentry_text(unsigned long ptr)
> >> +{
> >> + return 0;
> >> +}
> >> +#endif
> >> +
> >> static inline int in_exception_text(unsigned long ptr)
> >> {
> >> extern char __exception_text_start[];
> >> extern char __exception_text_end[];
> >> + int in;
> >> +
> >> + in = ptr >= (unsigned long)&__exception_text_start &&
> >> + ptr < (unsigned long)&__exception_text_end;
> >>
> >> - return ptr >= (unsigned long)&__exception_text_start &&
> >> - ptr < (unsigned long)&__exception_text_end;
> >> + return in ? : __in_irqentry_text(ptr);
> >> }
> >
> > On arm64, this function is only called from dump_backtrace, so I'm
> > struggling to see why this change makes any difference to the ftrace
> > output.
> >
> > What am I missing?
>
> As you mentioned, the above hunk does not change the ftrace behavior.
>
> The first diff directly affects the first condition check in print_graph_irq
> function in kernel/trace/trace_functions_graph.c. The code snippet is as follows.
>
> if (addr < (unsigned long)__irqentry_text_start ||
> addr >= (unsigned long)__irqentry_text_end)
> return;
>
> I hope it would be helpful.
Gotcha, thanks for the explanation.
Will
prev parent reply other threads:[~2015-08-12 16:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 14:16 [PATCH] arm64: Add __exception_irq_entry definition for function graph Jungseok Lee
2015-08-12 15:02 ` Will Deacon
2015-08-12 15:18 ` Jungseok Lee
2015-08-12 16:53 ` Will Deacon [this message]
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