On Aug 13, 2015, at 12:02 AM, Will Deacon wrote:
Hi Will,
> On Wed, Aug 12, 2015 at 03:16:19PM +0100, Jungseok Lee wrote:
>> The gic_handle_irq() is defined with __exception_irq_entry attribute.
>> A single remaining work is to add its definition as ARM did. Below
>> shows how function graph data is changed with these hunks.
>
> [...]
>
>> 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.
Best Regards
Jungseok Lee--
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