[PATCH v2 3/4] perf tests: stop reading if objdump output crossed sections

From: Jan Stancek
Date: Wed Sep 02 2015 - 04:21:06 EST


objdump output can span across multiple sections:

Disassembly of section .text:
0000000000000008 <crc32c+0x8>:
8: 48 89 e5 mov %rsp,%rbp
b: 53 push %rbx
c: 8b 01 mov (%rcx),%eax
<snip>
6b: 90 nop

Disassembly of section .init.text:
0000000000000008 <init_module+0x8>:
8: 00 00 add %al,(%rax)
a: 00 00 add %al,(%rax)
c: 48 89 e5

Stop further reading if address starts going backwards,
assuming we crossed sections.

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 | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 375ba30e4ed0..e6bf47ff7e91 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -79,7 +79,7 @@ static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)
size_t line_len, off_last = 0;
ssize_t ret;
int err = 0;
- u64 addr;
+ u64 addr, last_addr = start_addr;

while (off_last < *len) {
size_t off, read_bytes, written_bytes;
@@ -101,6 +101,11 @@ static int read_objdump_output(FILE *f, void *buf, size_t *len, u64 start_addr)

if (sscanf(line, "%"PRIx64, &addr) != 1)
continue;
+ if (addr < last_addr) {
+ pr_debug("addr going backwards, read beyond section?\n");
+ break;
+ }
+ last_addr = addr;

/* copy it from temporary buffer to 'buf' according
* to address on current objdump line */
--
1.8.3.1

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