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Subject[PATCH 28/37] perf session: Fix loading of compressed data split across adjacent records
Date
From: Alexey Budankov <alexey.budankov@linux.intel.com>

Fix decompression failure found during the loading of compressed trace
collected on larger scale systems (>48 cores).

The error happened due to lack of decompression space for a mmaped
buffer data chunk split across adjacent PERF_RECORD_COMPRESSED records.

$ perf report -i bt.16384.data --stats
failed to decompress (B): 63869 -> 0 : Destination buffer is too small
user stack dump failure
Can't parse sample, err = -14
0x2637e436 [0x4080]: failed to process type: 9
Error:
failed to process sample

$ perf test 71
71: Zstd perf.data compression/decompression : Ok

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/4d839e1b-9c48-89c4-9702-a12217420611@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/session.c | 22 ++++++++++++++--------
tools/perf/util/session.h | 1 +
tools/perf/util/zstd.c | 4 ++--
3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index d0fd6c614e68..37efa1f43d8b 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -36,10 +36,16 @@ static int perf_session__process_compressed_event(struct perf_session *session,
void *src;
size_t decomp_size, src_size;
u64 decomp_last_rem = 0;
- size_t decomp_len = session->header.env.comp_mmap_len;
+ size_t mmap_len, decomp_len = session->header.env.comp_mmap_len;
struct decomp *decomp, *decomp_last = session->decomp_last;

- decomp = mmap(NULL, sizeof(struct decomp) + decomp_len, PROT_READ|PROT_WRITE,
+ if (decomp_last) {
+ decomp_last_rem = decomp_last->size - decomp_last->head;
+ decomp_len += decomp_last_rem;
+ }
+
+ mmap_len = sizeof(struct decomp) + decomp_len;
+ decomp = mmap(NULL, mmap_len, PROT_READ|PROT_WRITE,
MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
if (decomp == MAP_FAILED) {
pr_err("Couldn't allocate memory for decompression\n");
@@ -47,10 +53,10 @@ static int perf_session__process_compressed_event(struct perf_session *session,
}

decomp->file_pos = file_offset;
+ decomp->mmap_len = mmap_len;
decomp->head = 0;

- if (decomp_last) {
- decomp_last_rem = decomp_last->size - decomp_last->head;
+ if (decomp_last_rem) {
memcpy(decomp->data, &(decomp_last->data[decomp_last->head]), decomp_last_rem);
decomp->size = decomp_last_rem;
}
@@ -61,7 +67,7 @@ static int perf_session__process_compressed_event(struct perf_session *session,
decomp_size = zstd_decompress_stream(&(session->zstd_data), src, src_size,
&(decomp->data[decomp_last_rem]), decomp_len - decomp_last_rem);
if (!decomp_size) {
- munmap(decomp, sizeof(struct decomp) + decomp_len);
+ munmap(decomp, mmap_len);
pr_err("Couldn't decompress data\n");
return -1;
}
@@ -255,15 +261,15 @@ static void perf_session__delete_threads(struct perf_session *session)
static void perf_session__release_decomp_events(struct perf_session *session)
{
struct decomp *next, *decomp;
- size_t decomp_len;
+ size_t mmap_len;
next = session->decomp;
- decomp_len = session->header.env.comp_mmap_len;
do {
decomp = next;
if (decomp == NULL)
break;
next = decomp->next;
- munmap(decomp, decomp_len + sizeof(struct decomp));
+ mmap_len = decomp->mmap_len;
+ munmap(decomp, mmap_len);
} while (1);
}

diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index dd8920b745bc..863dbad87849 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -46,6 +46,7 @@ struct perf_session {
struct decomp {
struct decomp *next;
u64 file_pos;
+ size_t mmap_len;
u64 head;
size_t size;
char data[];
diff --git a/tools/perf/util/zstd.c b/tools/perf/util/zstd.c
index 23bdb9884576..d2202392ffdb 100644
--- a/tools/perf/util/zstd.c
+++ b/tools/perf/util/zstd.c
@@ -99,8 +99,8 @@ size_t zstd_decompress_stream(struct zstd_data *data, void *src, size_t src_size
while (input.pos < input.size) {
ret = ZSTD_decompressStream(data->dstream, &output, &input);
if (ZSTD_isError(ret)) {
- pr_err("failed to decompress (B): %ld -> %ld : %s\n",
- src_size, output.size, ZSTD_getErrorName(ret));
+ pr_err("failed to decompress (B): %ld -> %ld, dst_size %ld : %s\n",
+ src_size, output.size, dst_size, ZSTD_getErrorName(ret));
break;
}
output.dst = dst + output.pos;
--
2.21.0
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