Messages in this thread | | | Date | Sat, 15 Mar 2014 01:13:52 +0900 | From | AKASHI Takahiro <> | Subject | Re: [PATCH v6 4/7] arm64: Add ftrace support |
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On 03/14/2014 07:07 PM, Will Deacon wrote: > On Fri, Mar 14, 2014 at 04:45:13AM +0000, AKASHI Takahiro wrote: >> On 03/14/2014 02:08 AM, Will Deacon wrote: >>> On Thu, Mar 13, 2014 at 10:13:47AM +0000, AKASHI Takahiro wrote: >>>> This patch implements arm64 specific part to support function tracers, >>>> such as function (CONFIG_FUNCTION_TRACER), function_graph >>>> (CONFIG_FUNCTION_GRAPH_TRACER) and function profiler >>>> (CONFIG_FUNCTION_PROFILER). >>>> >>>> With 'function' tracer, all the functions in the kernel are traced with >>>> timestamps in ${sysfs}/tracing/trace. If function_graph tracer is >>>> specified, call graph is generated. >>>> >>>> The kernel must be compiled with -pg option so that _mcount() is inserted >>>> at the beginning of functions. This function is called on every function's >>>> entry as long as tracing is enabled. >>>> In addition, function_graph tracer also needs to be able to probe function's >>>> exit. ftrace_graph_caller() & return_to_handler do this by faking link >>>> register's value to intercept function's return path. >>>> >>>> More details on architecture specific requirements are described in >>>> Documentation/trace/ftrace-design.txt. >>> >>> [...] >> >> You seem not to like this statement :-) > > Huh? I was just using '[...]' to signify that I'd removed a lot of context > (since the code all looked fine there). Otherwise, review emails can get > really long.
Please ignore my comment.
>>>> + str x0, [sp, #-16]! >>>> + mov x0, x29 // parent's fp >>>> + bl ftrace_return_to_handler// addr = ftrace_return_to_hander(fp); >>>> + mov x30, x0 // restore the original return address >>>> + ldr x0, [sp], #16 >>>> + ret >>> >>> and an ENDPROC here. >> >> Fix it. >> But please note that this (return_to_handler) is not a real function. >> Declaring it as ENDPROC is not very useful. > > Then use END(...). The opening macro was the main point, since that avoid > the need for an explicit .globl.
Fix it.
-Takahiro AKASHI
> Will >
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