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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a perf.data file which is using a newer version of the ABI than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>
This commit is contained in:
Stephane Eranian 2012-02-09 23:21:06 +01:00 committed by Ingo Molnar
parent cb5d769990
commit 69996df486
2 changed files with 50 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
tools/perf/util/header.c
View File

@ -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)

4
tools/perf/util/session.c
View File

@ -24,7 +24,7 @@ static int perf_session__open(struct perf_session *self, bool force)
self->fd = STDIN_FILENO;
if (perf_session__read_header(self, self->fd) < 0)
pr_err("incompatible file format");
pr_err("incompatible file format (rerun with -v to learn more)");
return 0;
}
@ -56,7 +56,7 @@ static int perf_session__open(struct perf_session *self, bool force)
}
if (perf_session__read_header(self, self->fd) < 0) {
pr_err("incompatible file format");
pr_err("incompatible file format (rerun with -v to learn more)");
goto out_close;
}