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Date: Thu, 3 Sep 2015 12:08:10 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Jan Stancek <jstancek@...hat.com>
Cc: linux-kernel@...r.kernel.org, acme@...nel.org, jolsa@...nel.org,
dsahern@...il.com, cjashfor@...ux.vnet.ibm.com, fweisbec@...il.com,
mingo@...nel.org, namhyung@...nel.org, paulus@...ba.org,
a.p.zijlstra@...llo.nl
Subject: Re: [PATCH v2 1/4] perf tests: take into account address of each
objdump line
On 02/09/15 11:19, Jan Stancek wrote:
> objdump output can contain repeated bytes. At the moment test reads
> all output sequentially, assuming each address is represented in
> output only once:
>
> ffffffff8164efb3 <retint_swapgs+0x9>:
> ffffffff8164efb3: c1 5d 00 eb rcrl $0xeb,0x0(%rbp)
> ffffffff8164efb7: 00 4c 8b 5c add %cl,0x5c(%rbx,%rcx,4)
>
> ffffffff8164efb8 <restore_c_regs_and_iret>:
> ffffffff8164efb8: 4c 8b 5c 24 30 mov 0x30(%rsp),%r11
> ffffffff8164efbd: 4c 8b 54 24 38 mov 0x38(%rsp),%r10
>
> Store objdump output to buffer according to offset calculated
> from address on each line.
>
> Signed-off-by: Jan Stancek <jstancek@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Cc: David Ahern <dsahern@...il.com>
> Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
> Cc: Frederic Weisbecker <fweisbec@...il.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Apart from a couple of nitpicks below:
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
> tools/perf/tests/code-reading.c | 51 ++++++++++++++++++++++++++++++-----------
> 1 file changed, 38 insertions(+), 13 deletions(-)
>
> Changes in v2:
> patch split into series
>
> diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
> index 39c784a100a9..38ee90bc2228 100644
> --- a/tools/perf/tests/code-reading.c
> +++ b/tools/perf/tests/code-reading.c
> @@ -33,20 +33,20 @@ static unsigned int hex(char c)
> return c - 'A' + 10;
> }
>
> -static void read_objdump_line(const char *line, size_t line_len, void **buf,
> - size_t *len)
> +static size_t read_objdump_line(const char *line, size_t line_len, void *buf,
> + size_t len)
Some (e.g. checkpatch) suggest that alignment should match open parenthesis
> {
> const char *p;
> - size_t i;
> + size_t i, j = 0;
>
> /* Skip to a colon */
> p = strchr(line, ':');
> if (!p)
> - return;
> + return 0;
> i = p + 1 - line;
>
> /* Read bytes */
> - while (*len) {
> + while (j < len) {
> char c1, c2;
>
> /* Skip spaces */
> @@ -65,20 +65,26 @@ static void read_objdump_line(const char *line, size_t line_len, void **buf,
> if (i < line_len && line[i] && !isspace(line[i]))
> break;
> /* Store byte */
> - *(unsigned char *)*buf = (hex(c1) << 4) | hex(c2);
> - *buf += 1;
> - *len -= 1;
> + *(unsigned char *)buf = (hex(c1) << 4) | hex(c2);
> + buf += 1;
> + j++;
> }
> + /* return number of successfully read bytes */
> + return j;
> }
>
> -static int read_objdump_output(FILE *f, void **buf, size_t *len)
> +static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
> {
> char *line = NULL;
> - size_t line_len;
> + size_t line_len, off_last = 0;
> ssize_t ret;
> int err = 0;
> + u64 addr;
> +
> + while (off_last < *len) {
> + size_t off, read_bytes, written_bytes;
> + unsigned char tmp[BUFSZ];
>
> - while (1) {
> ret = getline(&line, &line_len, f);
> if (feof(f))
> break;
> @@ -87,9 +93,28 @@ static int read_objdump_output(FILE *f, void **buf, size_t *len)
> err = -1;
> break;
> }
> - read_objdump_line(line, ret, buf, len);
> +
> + /* read objdump data into temporary buffer */
> + read_bytes = read_objdump_line(line, ret, tmp, sizeof(tmp));
> + if (!read_bytes)
> + continue;
> +
> + if (sscanf(line, "%"PRIx64, &addr) != 1)
> + continue;
> +
> + /* copy it from temporary buffer to 'buf' according
> + * to address on current objdump line */
The preferred style for long (multi-line) comments is:
/*
* Copy it from temporary buffer to 'buf' according
* to address on current objdump line.
*/
> + off = addr - start_addr;
> + if (off >= *len)
> + break;
> + written_bytes = MIN(read_bytes, *len - off);
We don't use MIN. Use min() instead.
> + memcpy(buf + off, tmp, written_bytes);
> + off_last = off + written_bytes;
> }
>
> + /* len returns number of bytes that could not be read */
> + *len -= off_last;
> +
> free(line);
>
> return err;
> @@ -120,7 +145,7 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
> return -1;
> }
>
> - ret = read_objdump_output(f, &buf, &len);
> + ret = read_objdump_output(f, buf, &len, addr);
> if (len) {
> pr_debug("objdump read too few bytes\n");
> if (!ret)
>
--
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