From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755901Ab2BBM4o (ORCPT ); Thu, 2 Feb 2012 07:56:44 -0500 Received: from mail-ww0-f44.google.com ([74.125.82.44]:37265 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755445Ab2BBM4j (ORCPT ); Thu, 2 Feb 2012 07:56:39 -0500 From: Stephane Eranian To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@elte.hu, acme@redhat.com, robert.richter@amd.com, ming.m.lin@intel.com, andi@firstfloor.org, asharma@fb.com, ravitillo@lbl.gov, vweaver1@eecs.utk.edu, khandual@linux.vnet.ibm.com, dsahern@gmail.com Subject: [PATCH v5 18/18] perf: make perf able to read file from older ABIs Date: Thu, 2 Feb 2012 13:54:48 +0100 Message-Id: <1328187288-24395-19-git-send-email-eranian@google.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1328187288-24395-1-git-send-email-eranian@google.com> References: <1328187288-24395-1-git-send-email-eranian@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patches provides a way to handle legacy perf.data files. Legacy files are those using the older PERFFILE signature. For those, it is still necessary to detect endianness but without comparing their header->attr_size with the tool's own version as it may be different. Instead, we use a reference table for all known sizes from the legacy era. We try all the combinations for sizes and endianness. If we find a match, we proceed, otherwise we return: "incompatible file format". This is also done for the pipe-mode file format. Signed-off-by: Stephane Eranian --- tools/perf/util/header.c | 125 +++++++++++++++++++++++++++++++++++---------- 1 files changed, 97 insertions(+), 28 deletions(-) diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 1fb365d..487605a 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -1630,35 +1630,101 @@ int perf_header__process_sections(struct perf_header *header, int fd, return err; } -static int check_magic_endian(u64 *magic, struct perf_file_header *header, - struct perf_header *ph) +static const int attr_file_abi_sizes[] = { + [0] = PERF_ATTR_SIZE_VER0, + [1] = PERF_ATTR_SIZE_VER1, + 0, +}; + +/* + * In the legacy file format, the magic number is not used to encode endianness. + * hdr_sz was used to encode endianness. But given that hdr_sz can vary based + * on ABI revisions, we need to try all combinations for all endianness to + * detect the endianness. + */ +static int try_all_file_abis(uint64_t hdr_sz, struct perf_header *ph) { - int ret; + uint64_t ref_size, attr_size; + int i; - /* check for legacy format */ - ret = memcmp(magic, __perf_magic1, sizeof(*magic)); - if (ret == 0) { - pr_debug("legacy perf.data format\n"); - if (!header) - return -1; + for (i = 0 ; attr_file_abi_sizes[i]; i++) { + ref_size = attr_file_abi_sizes[i] + + sizeof(struct perf_file_section); + if (hdr_sz != ref_size) { + attr_size = bswap_64(hdr_sz); + if (attr_size != ref_size) + continue; - if (header->attr_size != sizeof(struct perf_file_attr)) { - u64 attr_size = bswap_64(header->attr_size); + ph->needs_swap = true; + } + pr_debug("ABI%d perf.data file detected, need_swap=%d\n", + i, + ph->needs_swap); + return 0; + } + /* could not determine endianness */ + return -1; +} - if (attr_size != sizeof(struct perf_file_attr)) - return -1; +#define PERF_PIPE_HDR_VER0 16 + +static const size_t attr_pipe_abi_sizes[] = { + [0] = PERF_PIPE_HDR_VER0, + 0, +}; + +/* + * In the legacy pipe format, there is an implicit assumption that endiannesss + * between host recording the samples, and host parsing the samples is the + * same. This is not always the case given that the pipe output may always be + * redirected into a file and analyzed on a different machine with possibly a + * different endianness and perf_event ABI revsions in the perf tool itself. + */ +static int try_all_pipe_abis(uint64_t hdr_sz, struct perf_header *ph) +{ + u64 attr_size; + int i; + + for (i = 0 ; attr_pipe_abi_sizes[i]; i++) { + if (hdr_sz != attr_pipe_abi_sizes[i]) { + attr_size = bswap_64(hdr_sz); + if (attr_size != hdr_sz) + continue; ph->needs_swap = true; } + pr_debug("Pipe ABI%d perf.data file detected\n", i); return 0; } + return -1; +} + +static int check_magic_endian(u64 magic, uint64_t hdr_sz, + bool is_pipe, struct perf_header *ph) +{ + int ret; + + /* check for legacy format */ + ret = memcmp(&magic, __perf_magic1, sizeof(magic)); + if (ret == 0) { + pr_debug("legacy perf.data format\n"); + if (is_pipe) + return try_all_pipe_abis(hdr_sz, ph); + + return try_all_file_abis(hdr_sz, ph); + } + /* + * the new magic number serves two purposes: + * - unique number to identify actual perf.data files + * - encode endianness of file + */ - /* check magic number with same endianness */ - if (*magic == __perf_magic2) + /* check magic number with one endianness */ + if (magic == __perf_magic2) return 0; - /* check magic number but opposite endianness */ - if (*magic != __perf_magic2_sw) + /* check magic number with opposite endianness */ + if (magic != __perf_magic2_sw) return -1; ph->needs_swap = true; @@ -1677,8 +1743,11 @@ int perf_file_header__read(struct perf_file_header *header, if (ret <= 0) return -1; - if (check_magic_endian(&header->magic, header, ph) < 0) + if (check_magic_endian(header->magic, + header->attr_size, false, ph) < 0) { + pr_debug("magic/endian check failed\n"); return -1; + } if (ph->needs_swap) { mem_bswap_64(header, offsetof(struct perf_file_header, @@ -1924,21 +1993,17 @@ static int perf_file_header__read_pipe(struct perf_pipe_file_header *header, if (ret <= 0) return -1; - if (check_magic_endian(&header->magic, NULL, ph) < 0) + if (check_magic_endian(header->magic, header->size, true, ph) < 0) { + pr_debug("endian/magic failed\n"); return -1; + } + + if (ph->needs_swap) + header->size = bswap_64(header->size); if (repipe && do_write(STDOUT_FILENO, header, sizeof(*header)) < 0) return -1; - if (header->size != sizeof(*header)) { - u64 size = bswap_64(header->size); - - if (size != sizeof(*header)) - return -1; - - ph->needs_swap = true; - } - return 0; } @@ -1975,6 +2040,10 @@ static int read_attr(int fd, struct perf_header *ph, /* on file perf_event_attr size */ sz = attr->size; + if (sz != our_sz) + pr_debug("on file attr=%zu vs. %zu bytes," + " ignoring extra fields\n", sz, our_sz); + if (ph->needs_swap) sz = bswap_32(sz); -- 1.7.4.1