From 69996df486fc3921bbaaa17fca0d68f537f9eabf Mon Sep 17 00:00:00 2001 From: Stephane Eranian Date: Thu, 9 Feb 2012 23:21:06 +0100 Subject: [PATCH] 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 Similarly, perf must be able to cope with a perf.data file which is using a newer version of the ABI than what it knows about.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 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 --- tools/perf/util/header.c | 53 ++++++++++++++++++++++++++++++++++++++++++----- tools/perf/util/session.c | 4 ++-- 2 files changed, 50 insertions(+), 7 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) diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index bec8a32..e650de8 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -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; } -- 2.7.4