Re: [PATCH] perf tests: objdump output can contain multi byte chunks

Adrian Hunter
2016-01-13T08:25:31Z

On 12/01/16 17:30, Arnaldo Carvalho de Melo wrote:
> Em Tue, Jan 12, 2016 at 11:07:44AM +0100, Jan Stancek escreveu:
>> objdump's raw insn output can vary across architectures on number of
>> bytes per chunk (bpc) displayed and their endian.
>>
>> code-reading test relied on reading objdump output as 1 bpc. Kaixu Xia
>> reported test failure on ARM64, where objdump displays 4 bpc:
>> 70c48: f90027bf str xzr, [x29,#72]
>> 70c4c: 91224000 add x0, x0, #0x890
>> 70c50: f90023a0 str x0, [x29,#64]
>>
>> This patch adds support to read raw insn output for any bpc length.
>> In case of 2+ bpc it also guesses objdump's display endian.
>
> Adrian, from a quick read of the patch and problem/solution description,
> I think this is ok and Kaixu reports it solves the problem on ARM64, can
> I have your reviewed-by/Acked-by?

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

>
> Thanks,
>
> - Arnaldo
>
>> Signed-off-by: Jan Stancek <jstancek@redhat.com>
>> Reported-and-tested-by: Kaixu Xia <xiakaixu@huawei.com>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Adrian Hunter <adrian.hunter@intel.com>
>> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
>> Cc: David Ahern <dsahern@gmail.com>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Jiri Olsa <jolsa@kernel.org>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> ---
>> tools/perf/tests/code-reading.c | 100 ++++++++++++++++++++++++++++------------
>> 1 file changed, 71 insertions(+), 29 deletions(-)
>>
>> diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
>> index a767a6400c5c..0108cb22d1a2 100644
>> --- a/tools/perf/tests/code-reading.c
>> +++ b/tools/perf/tests/code-reading.c
>> @@ -33,44 +33,86 @@ static unsigned int hex(char c)
>> return c - 'A' + 10;
>> }
>>
>> -static size_t read_objdump_line(const char *line, size_t line_len, void *buf,
>> - size_t len)
>> +static size_t read_objdump_chunk(const char **line, unsigned char **buf,
>> + size_t *buf_len)
>> +{
>> + size_t bytes_read = 0;
>> + unsigned char *chunk_start = *buf;
>> +
>> + /* Read bytes */
>> + while (*buf_len > 0) {
>> + char c1, c2;
>> +
>> + /* Get 2 hex digits */
>> + c1 = *(*line)++;
>> + if (!isxdigit(c1))
>> + break;
>> + c2 = *(*line)++;
>> + if (!isxdigit(c2))
>> + break;
>> +
>> + /* Store byte and advance buf */
>> + **buf = (hex(c1) << 4) | hex(c2);
>> + (*buf)++;
>> + (*buf_len)--;
>> + bytes_read++;
>> +
>> + /* End of chunk? */
>> + if (isspace(**line))
>> + break;
>> + }
>> +
>> + /*
>> + * objdump will display raw insn as LE if code endian
>> + * is LE and bytes_per_chunk > 1. In that case reverse
>> + * the chunk we just read.
>> + *
>> + * see disassemble_bytes() at binutils/objdump.c for details
>> + * how objdump chooses display endian)
>> + */
>> + if (bytes_read > 1 && !bigendian()) {
>> + unsigned char *chunk_end = chunk_start + bytes_read - 1;
>> + unsigned char tmp;
>> +
>> + while (chunk_start < chunk_end) {
>> + tmp = *chunk_start;
>> + *chunk_start = *chunk_end;
>> + *chunk_end = tmp;
>> + chunk_start++;
>> + chunk_end--;
>> + }
>> + }
>> +
>> + return bytes_read;
>> +}
>> +
>> +static size_t read_objdump_line(const char *line, unsigned char *buf,
>> + size_t buf_len)
>> {
>> const char *p;
>> - size_t i, j = 0;
>> + size_t ret, bytes_read = 0;
>>
>> /* Skip to a colon */
>> p = strchr(line, ':');
>> if (!p)
>> return 0;
>> - i = p + 1 - line;
>> + p++;
>>
>> - /* Read bytes */
>> - while (j < len) {
>> - char c1, c2;
>> -
>> - /* Skip spaces */
>> - for (; i < line_len; i++) {
>> - if (!isspace(line[i]))
>> - break;
>> - }
>> - /* Get 2 hex digits */
>> - if (i >= line_len || !isxdigit(line[i]))
>> - break;
>> - c1 = line[i++];
>> - if (i >= line_len || !isxdigit(line[i]))
>> - break;
>> - c2 = line[i++];
>> - /* Followed by a space */
>> - if (i < line_len && line[i] && !isspace(line[i]))
>> + /* Skip initial spaces */
>> + while (*p) {
>> + if (!isspace(*p))
>> break;
>> - /* Store byte */
>> - *(unsigned char *)buf = (hex(c1) << 4) | hex(c2);
>> - buf += 1;
>> - j++;
>> + p++;
>> }
>> +
>> + do {
>> + ret = read_objdump_chunk(&p, &buf, &buf_len);
>> + bytes_read += ret;
>> + p++;
>> + } while (ret > 0);
>> +
>> /* return number of successfully read bytes */
>> - return j;
>> + return bytes_read;
>> }
>>
>> static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
>> @@ -95,7 +137,7 @@ static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
>> }
>>
>> /* read objdump data into temporary buffer */
>> - read_bytes = read_objdump_line(line, ret, tmp, sizeof(tmp));
>> + read_bytes = read_objdump_line(line, tmp, sizeof(tmp));
>> if (!read_bytes)
>> continue;
>>
>> @@ -152,7 +194,7 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
>>
>> ret = read_objdump_output(f, buf, &len, addr);
>> if (len) {
>> - pr_debug("objdump read too few bytes\n");
>> + pr_debug("objdump read too few bytes: %lu\n", len);
>> if (!ret)
>> ret = len;
>> }
>> --
>> 1.8.3.1
>