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

From: Jan Stancek
Date: Wed Sep 02 2015 - 04:19:32 EST


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>
---
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)
{
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 */
+ off = addr - start_addr;
+ if (off >= *len)
+ break;
+ written_bytes = MIN(read_bytes, *len - off);
+ 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)
--
1.8.3.1

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