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Subject[PATCH 4/3] perf_counter: Correct PERF_SAMPLE_RAW output
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Date
Subject: perf_counter: Correct PERF_SAMPLE_RAW output
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon Aug 10 11:16:52 CEST 2009

PERF_SAMPLE_* output switches should unconditionally output the
correct format, as they are the only way to unambiguously parse the
PERF_EVENT_SAMPLE data.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/perf_counter.h | 2 ++
include/trace/ftrace.h | 3 ++-
kernel/perf_counter.c | 30 ++++++++++++++++++++++++------
3 files changed, 28 insertions(+), 7 deletions(-)
Index: linux-2.6/include/linux/perf_counter.h
===================================================================
--- linux-2.6.orig/include/linux/perf_counter.h
+++ linux-2.6/include/linux/perf_counter.h
@@ -369,6 +369,8 @@ enum perf_event_type {
*
* { u64 nr,
* u64 ips[nr]; } && PERF_SAMPLE_CALLCHAIN
+ * { u32 size;
+ * char data[size];}&& PERF_SAMPLE_RAW
* };
*/
PERF_EVENT_SAMPLE = 9,
Index: linux-2.6/include/trace/ftrace.h
===================================================================
--- linux-2.6.orig/include/trace/ftrace.h
+++ linux-2.6/include/trace/ftrace.h
@@ -687,7 +687,8 @@ static void ftrace_profile_##call(proto)
pc = preempt_count(); \
\
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
- __entry_size = ALIGN(__data_size + sizeof(*entry), sizeof(u64));\
+ __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
+ sizeof(u64)); \
\
do { \
char raw_data[__entry_size]; \
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -2647,7 +2647,6 @@ void perf_counter_output(struct perf_cou
u64 counter;
} group_entry;
struct perf_callchain_entry *callchain = NULL;
- struct perf_raw_record *raw = NULL;
int callchain_size = 0;
u64 time;
struct {
@@ -2717,9 +2716,15 @@ void perf_counter_output(struct perf_cou
}

if (sample_type & PERF_SAMPLE_RAW) {
- raw = data->raw;
- if (raw)
- header.size += raw->size;
+ int size = sizeof(u32);
+
+ if (data->raw)
+ size += data->raw->size;
+ else
+ size += sizeof(u32);
+
+ WARN_ON_ONCE(size & (sizeof(u64)-1));
+ header.size += size;
}

ret = perf_output_begin(&handle, counter, header.size, nmi, 1);
@@ -2785,8 +2790,21 @@ void perf_counter_output(struct perf_cou
}
}

- if ((sample_type & PERF_SAMPLE_RAW) && raw)
- perf_output_copy(&handle, raw->data, raw->size);
+ if (sample_type & PERF_SAMPLE_RAW) {
+ if (data->raw) {
+ perf_output_put(&handle, data->raw->size);
+ perf_output_copy(&handle, data->raw->data, data->raw->size);
+ } else {
+ struct {
+ u32 size;
+ u32 data;
+ } raw = {
+ .size = sizeof(u32),
+ .data = 0,
+ };
+ perf_output_put(&handle, raw);
+ }
+ }

perf_output_end(&handle);
}


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