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

Arnaldo Carvalho de Melo
2016-08-02T19:07:16Z

Em Wed, Jan 13, 2016 at 10:22:04AM +0200, Adrian Hunter escreveu:
> 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>

Oops, this one got lost, finally applying...

- Arnaldo

> >
> > 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
> >