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author | Stephane Eranian <eranian@google.com> | 2012-02-09 23:21:06 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2012-03-09 08:26:06 +0100 |
commit | 69996df486fc3921bbaaa17fca0d68f537f9eabf (patch) | |
tree | 4d41484700db59dbf769af11b5e3f70ba34e222d /tools/perf/util/header.c | |
parent | cb5d76999029ae7a517cb07dfa732c1b5a934fc2 (diff) | |
download | op-kernel-dev-69996df486fc3921bbaaa17fca0d68f537f9eabf.zip op-kernel-dev-69996df486fc3921bbaaa17fca0d68f537f9eabf.tar.gz |
perf tools: Enable reading of perf.data files from different ABI rev
This patch allows perf to process perf.data files generated
using an ABI that has a different perf_event_attr struct size,
i.e., a different ABI version.
The perf_event_attr can be extended, yet perf needs to cope with
older perf.data files. Similarly, perf must be able to cope with
a perf.data file which is using a newer version of the ABI than
what it knows about.
This patch adds read_attr(), a routine that reads a
perf_event_attr struct from a file incrementally based on its
advertised size. If the on-file struct is smaller than what perf
knows, then the extra fields are zeroed. If the on-file struct
is bigger, then perf only uses what it knows about, the rest is
skipped.
Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: acme@redhat.com
Cc: robert.richter@amd.com
Cc: ming.m.lin@intel.com
Cc: andi@firstfloor.org
Cc: asharma@fb.com
Cc: ravitillo@lbl.gov
Cc: vweaver1@eecs.utk.edu
Cc: khandual@linux.vnet.ibm.com
Cc: dsahern@gmail.com
Link: http://lkml.kernel.org/r/1328826068-11713-17-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'tools/perf/util/header.c')
-rw-r--r-- | tools/perf/util/header.c | 53 |
1 files changed, 48 insertions, 5 deletions
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 9f867d9..666f189 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1973,6 +1973,51 @@ static int perf_header__read_pipe(struct perf_session *session, int fd) return 0; } +static int read_attr(int fd, struct perf_header *ph, + struct perf_file_attr *f_attr) +{ + struct perf_event_attr *attr = &f_attr->attr; + size_t sz, left; + size_t our_sz = sizeof(f_attr->attr); + int ret; + + memset(f_attr, 0, sizeof(*f_attr)); + + /* read minimal guaranteed structure */ + ret = readn(fd, attr, PERF_ATTR_SIZE_VER0); + if (ret <= 0) { + pr_debug("cannot read %d bytes of header attr\n", + PERF_ATTR_SIZE_VER0); + return -1; + } + + /* on file perf_event_attr size */ + sz = attr->size; + if (ph->needs_swap) + sz = bswap_32(sz); + + if (sz == 0) { + /* assume ABI0 */ + sz = PERF_ATTR_SIZE_VER0; + } else if (sz > our_sz) { + pr_debug("file uses a more recent and unsupported ABI" + " (%zu bytes extra)\n", sz - our_sz); + return -1; + } + /* what we have not yet read and that we know about */ + left = sz - PERF_ATTR_SIZE_VER0; + if (left) { + void *ptr = attr; + ptr += PERF_ATTR_SIZE_VER0; + + ret = readn(fd, ptr, left); + } + /* read perf_file_section, ids are read in caller */ + ret = readn(fd, &f_attr->ids, sizeof(f_attr->ids)); + + return ret <= 0 ? -1 : 0; +} + int perf_session__read_header(struct perf_session *session, int fd) { struct perf_header *header = &session->header; @@ -1988,19 +2033,17 @@ int perf_session__read_header(struct perf_session *session, int fd) if (session->fd_pipe) return perf_header__read_pipe(session, fd); - if (perf_file_header__read(&f_header, header, fd) < 0) { - pr_debug("incompatible file format\n"); + if (perf_file_header__read(&f_header, header, fd) < 0) return -EINVAL; - } - nr_attrs = f_header.attrs.size / sizeof(f_attr); + nr_attrs = f_header.attrs.size / f_header.attr_size; lseek(fd, f_header.attrs.offset, SEEK_SET); for (i = 0; i < nr_attrs; i++) { struct perf_evsel *evsel; off_t tmp; - if (readn(fd, &f_attr, sizeof(f_attr)) <= 0) + if (read_attr(fd, header, &f_attr) < 0) goto out_errno; if (header->needs_swap) |