[PATCH v4 1/2] perf util: Print al_addr when symbol is not found

Jin Yao
2020-02-25T05:15:15Z

For branch mode, if the symbol is not found, it prints
the address.

For example, 0x0000555eee0365a0 in below output.

Overhead Command Source Shared Object Source Symbol Target Symbol
17.55% div libc-2.27.so [.] __random [.] __random
6.11% div div [.] 0x0000555eee0365a0 [.] rand
6.10% div libc-2.27.so [.] rand [.] 0x0000555eee036769
5.80% div libc-2.27.so [.] __random_r [.] __random
5.72% div libc-2.27.so [.] __random [.] __random_r
5.62% div libc-2.27.so [.] __random_r [.] __random_r
5.38% div libc-2.27.so [.] __random [.] rand
4.56% div libc-2.27.so [.] __random [.] __random
4.49% div div [.] 0x0000555eee036779 [.] 0x0000555eee0365ff
4.25% div div [.] 0x0000555eee0365fa [.] 0x0000555eee036760

But it's not very easy to understand what the instructions
are in the binary. So this patch uses the al_addr instead.

With this patch, the output is

Overhead Command Source Shared Object Source Symbol Target Symbol
17.55% div libc-2.27.so [.] __random [.] __random
6.11% div div [.] 0x00000000000005a0 [.] rand
6.10% div libc-2.27.so [.] rand [.] 0x0000000000000769
5.80% div libc-2.27.so [.] __random_r [.] __random
5.72% div libc-2.27.so [.] __random [.] __random_r
5.62% div libc-2.27.so [.] __random_r [.] __random_r
5.38% div libc-2.27.so [.] __random [.] rand
4.56% div libc-2.27.so [.] __random [.] __random
4.49% div div [.] 0x0000000000000779 [.] 0x00000000000005ff
4.25% div div [.] 0x00000000000005fa [.] 0x0000000000000760

Now we can use objdump to dump the object starting from 0x5a0.

For example,
objdump -d --start-address 0x5a0 div

00000000000005a0 <rand@plt>:
5a0: ff 25 2a 0a 20 00 jmpq *0x200a2a(%rip) # 200fd0 <__cxa_finalize@plt+0x200a20>
5a6: 68 02 00 00 00 pushq $0x2
5ab: e9 c0 ff ff ff jmpq 570 <srand@plt-0x10>
...

v2:
---
No change

Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
tools/perf/util/sort.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index ab0cfd790ad0..e860595576c2 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -869,7 +869,8 @@ static int hist_entry__sym_from_snprintf(struct hist_entry *he, char *bf,
if (he->branch_info) {
struct addr_map_symbol *from = &he->branch_info->from;

- return _hist_entry__sym_snprintf(&from->ms, from->addr, he->level, bf, size, width);
+ return _hist_entry__sym_snprintf(&from->ms, from->al_addr,
+ he->level, bf, size, width);
}

return repsep_snprintf(bf, size, "%-*.*s", width, width, "N/A");
@@ -881,7 +882,8 @@ static int hist_entry__sym_to_snprintf(struct hist_entry *he, char *bf,
if (he->branch_info) {
struct addr_map_symbol *to = &he->branch_info->to;

- return _hist_entry__sym_snprintf(&to->ms, to->addr, he->level, bf, size, width);
+ return _hist_entry__sym_snprintf(&to->ms, to->al_addr,
+ he->level, bf, size, width);
}

return repsep_snprintf(bf, size, "%-*.*s", width, width, "N/A");
--
2.17.1