Commit 5685e0ff authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
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perf: Add perf_output_skip function to skip bytes in sample 



Introducing perf_output_skip function to be able to skip data within the
perf ring buffer.

When writing data into perf ring buffer we first reserve needed place in
ring buffer and then copy the actual data.

There's a possibility we won't be able to fill all the reserved size
with data, so we need a way to skip the remaining bytes.

This is going to be useful when storing the user stack dump, where we
might end up with less data than we originally requested.

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Ulrich Drepper <drepper@gmail.com>
Link: http://lkml.kernel.org/r/1344345647-11536-5-git-send-email-jolsa@redhat.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 91d7753a

include/linux/perf_event.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -1321,6 +1321,8 @@ extern int perf_output_begin(struct perf_output_handle *handle, 
extern void perf_output_end(struct perf_output_handle *handle);

extern void perf_output_end(struct perf_output_handle *handle);

extern unsigned int perf_output_copy(struct perf_output_handle *handle,

extern unsigned int perf_output_copy(struct perf_output_handle *handle,

			     const void *buf, unsigned int len);

			     const void *buf, unsigned int len);

extern unsigned int perf_output_skip(struct perf_output_handle *handle,

				     unsigned int len);

extern int perf_swevent_get_recursion_context(void);

extern int perf_swevent_get_recursion_context(void);

extern void perf_swevent_put_recursion_context(int rctx);

extern void perf_swevent_put_recursion_context(int rctx);

extern void perf_event_enable(struct perf_event *event);

extern void perf_event_enable(struct perf_event *event);

kernel/events/internal.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -114,6 +114,10 @@ static inline int memcpy_common(void *dst, const void *src, size_t n) 




DEFINE_OUTPUT_COPY(__output_copy, memcpy_common)

DEFINE_OUTPUT_COPY(__output_copy, memcpy_common)





#define MEMCPY_SKIP(dst, src, n) (n)



DEFINE_OUTPUT_COPY(__output_skip, MEMCPY_SKIP)



#ifndef arch_perf_out_copy_user

#ifndef arch_perf_out_copy_user

#define arch_perf_out_copy_user __copy_from_user_inatomic

#define arch_perf_out_copy_user __copy_from_user_inatomic

#endif

#endif

kernel/events/ring_buffer.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -188,6 +188,12 @@ unsigned int perf_output_copy(struct perf_output_handle *handle, 
	return __output_copy(handle, buf, len);

	return __output_copy(handle, buf, len);

}

}





unsigned int perf_output_skip(struct perf_output_handle *handle,

			      unsigned int len)

{

	return __output_skip(handle, NULL, len);

}



void perf_output_end(struct perf_output_handle *handle)

void perf_output_end(struct perf_output_handle *handle)

{

{

	perf_output_put_handle(handle);

	perf_output_put_handle(handle);

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