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perf tools: Make perf able to read files from older ABIs

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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 <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/1328826068-11713-19-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Stephane Eranian 2012-02-09 23:21:08 +01:00 committed by Ingo Molnar
parent 62db90681c
commit 114382a0ae
1 changed files with 95 additions and 29 deletions
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124
tools/perf/util/header.c
View File

@ -1803,35 +1803,101 @@ out_free:
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)
{
uint64_t ref_size, attr_size;
int i;
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;
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;
}
#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));
ret = memcmp(&magic, __perf_magic1, sizeof(magic));
if (ret == 0) {
pr_debug("legacy perf.data format\n");
if (!header)
return -1;
if (is_pipe)
return try_all_pipe_abis(hdr_sz, ph);
if (header->attr_size != sizeof(struct perf_file_attr)) {
u64 attr_size = bswap_64(header->attr_size);
if (attr_size != sizeof(struct perf_file_attr))
return -1;
ph->needs_swap = true;
}
return 0;
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;
@ -1850,8 +1916,11 @@ 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,
@ -1938,21 +2007,17 @@ 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;
}
@ -1992,6 +2057,7 @@ static int read_attr(int fd, struct perf_header *ph,
/* on file perf_event_attr size */
sz = attr->size;
if (ph->needs_swap)
sz = bswap_32(sz);