On Fri, Mar 14, 2014 at 04:45:13AM +0000, AKASHI Takahiro wrote:

On 03/14/2014 02:08 AM, Will Deacon wrote:

quoted

On Thu, Mar 13, 2014 at 10:13:47AM +0000, AKASHI Takahiro wrote:

quoted

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.

quoted

quoted

+       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.

Will