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

[Arnaldo Carvalho de Melo]

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@xxxxxxxxx>

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

- Arnaldo
 
> > 
> > Thanks,
> > 
> > - Arnaldo
> >  
> >> Signed-off-by: Jan Stancek <jstancek@xxxxxxxxxx>
> >> Reported-and-tested-by: Kaixu Xia <xiakaixu@xxxxxxxxxx>
> >> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> >> Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> >> Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
> >> Cc: David Ahern <dsahern@xxxxxxxxx>
> >> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> >> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> >> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> >> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> >> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> >> ---
> >>  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
> >