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Commit b2511481 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf build-id: Add quirk to deal with perf.data file format breakage 



The a1645ce1 changeset:

"perf: 'perf kvm' tool for monitoring guest performance from host"

Added a field to struct build_id_event that broke the file format.

Since the kernel build-id is the first entry, process the table using
the old format if the well known '[kernel.kallsyms]' string for the
kernel build-id has the first 4 characters chopped off (where the pid_t
sits).

Reported-by: default avatarHan Pingtian <phan@redhat.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Cc: stable@kernel.org
LKML-Reference: <new-submission>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 9e69c210

tools/perf/util/header.c

+56 −1
Original line number Diff line number Diff line
@@ -695,13 +695,50 @@ static int __event_process_build_id(struct build_id_event *bev, 
	return err;

}



static int perf_header__read_build_ids(struct perf_header *header,

static int perf_header__read_build_ids_abi_quirk(struct perf_header *header,

						 int input, u64 offset, u64 size)

{

	struct perf_session *session = container_of(header, struct perf_session, header);

	struct {

		struct perf_event_header   header;

		u8			   build_id[ALIGN(BUILD_ID_SIZE, sizeof(u64))];

		char			   filename[0];

	} old_bev;

	struct build_id_event bev;

	char filename[PATH_MAX];

	u64 limit = offset + size;



	while (offset < limit) {

		ssize_t len;



		if (read(input, &old_bev, sizeof(old_bev)) != sizeof(old_bev))

			return -1;



		if (header->needs_swap)

			perf_event_header__bswap(&old_bev.header);



		len = old_bev.header.size - sizeof(old_bev);

		if (read(input, filename, len) != len)

			return -1;



		bev.header = old_bev.header;

		bev.pid	   = 0;

		memcpy(bev.build_id, old_bev.build_id, sizeof(bev.build_id));

		__event_process_build_id(&bev, filename, session);



		offset += bev.header.size;

	}



	return 0;

}



static int perf_header__read_build_ids(struct perf_header *header,

				       int input, u64 offset, u64 size)

{

	struct perf_session *session = container_of(header, struct perf_session, header);

	struct build_id_event bev;

	char filename[PATH_MAX];

	u64 limit = offset + size, orig_offset = offset;

	int err = -1;



	while (offset < limit) {
@@ -716,6 +753,24 @@ static int perf_header__read_build_ids(struct perf_header *header, 
		len = bev.header.size - sizeof(bev);

		if (read(input, filename, len) != len)

			goto out;

		/*

		 * The a1645ce1 changeset:

		 *

		 * "perf: 'perf kvm' tool for monitoring guest performance from host"

		 *

		 * Added a field to struct build_id_event that broke the file

		 * format.

		 *

		 * Since the kernel build-id is the first entry, process the

		 * table using the old format if the well known

		 * '[kernel.kallsyms]' string for the kernel build-id has the

		 * first 4 characters chopped off (where the pid_t sits).

		 */

		if (memcmp(filename, "nel.kallsyms]", 13) == 0) {

			if (lseek(input, orig_offset, SEEK_SET) == (off_t)-1)

				return -1;

			return perf_header__read_build_ids_abi_quirk(header, input, offset, size);

		}



		__event_process_build_id(&bev, filename, session);