perf session: Fix loading of compressed data split across adjacent records

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>

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index d0fd6c6..37efa1f 100644 (file)
--- 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 dd8920b..863dbad 100644 (file)
--- 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 23bdb98..d220239 100644 (file)
--- 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;