[PATCH v3 1/4] perf tests: take into account address of each objdump line

[Jan Stancek]

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 | 53 +++++++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 13 deletions(-)

Changes in v3:
  align read_objdump_line parameters on 2nd line
  fix multiline comment
  replace MIN with min

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 39c784a100a9..7fd7ebc0b692 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 +93,30 @@ 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 +147,7 @@ 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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