Re: [PATCH v2 1/4] perf tests: take into account address of each objdump line

[Adrian Hunter]

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@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Cc: David Ahern <dsahern@xxxxxxxxx>
> Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

Apart from a couple of nitpicks below:

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

> ---
>  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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