Re: [PATCH v5 2/3] perf report: Support interactive annotation of code without symbols
From: Jin, Yao
Date: Wed Mar 18 2020 - 20:49:46 EST
On 3/18/2020 11:42 PM, Arnaldo Carvalho de Melo wrote:
Em Thu, Feb 27, 2020 at 12:39:38PM +0800, Jin Yao escreveu:
For perf report on stripped binaries it is currently impossible to do
annotation. The annotation state is all tied to symbols, but there are
either no symbols, or symbols are not covering all the code.
We should support the annotation functionality even without symbols.
This patch fakes a symbol and the symbol name is the string of address.
After that, we just follow current annotation working flow.
For example,
1. perf report
Overhead Command Shared Object Symbol
20.67% div libc-2.27.so [.] __random_r
17.29% div libc-2.27.so [.] __random
10.59% div div [.] 0x0000000000000628
9.25% div div [.] 0x0000000000000612
6.11% div div [.] 0x0000000000000645
2. Select the line of "10.59% div div [.] 0x0000000000000628" and ENTER.
Annotate 0x0000000000000628
Zoom into div thread
Zoom into div DSO (use the 'k' hotkey to zoom directly into the kernel)
Browse map details
Run scripts for samples of symbol [0x0000000000000628]
Run scripts for all samples
Switch to another data file in PWD
Exit
3. Select the "Annotate 0x0000000000000628" and ENTER.
Percentâ
â
â
â Disassembly of section .text:
â
â 0000000000000628 <.text+0x68>:
â divsd %xmm4,%xmm0
â divsd %xmm3,%xmm1
â movsd (%rsp),%xmm2
â addsd %xmm1,%xmm0
â addsd %xmm2,%xmm0
â movsd %xmm0,(%rsp)
Now we can see the dump of object starting from 0x628.
Testing this I noticed this discrepancy when using 'o' in the annotate
view to see the address columns:
Samples: 10K of event 'cycles', 4000 Hz, Event count (approx.): 7738221585
0x0000000000ea8b97 /usr/libexec/gcc/x86_64-redhat-linux/9/cc1 [Percent: local period]
Percentâ â
â â
â â
â Disassembly of section .text: â
â â
â 00000000012a8b97 <linemap_get_expansion_line@@Base+0x227>: â
â12a8b97: cmp %rax,(%rdi) â
â12a8b9a: â je 12a8ba0 <linemap_get_expansion_line@@Base+0x230> â
â12a8b9c: xor %eax,%eax â
â12a8b9e: â retq â
â12a8b9f: nop â
â12a8ba0: mov 0x8(%rsi),%edx
See that 0x0000000000ea8b97 != 12a8b97
How can we explain that?
- Arnaldo
Not very clear about the reason. Actually the patch doesn't change the
annotate view, it only fakes a dummy symbol.
I want to debug it but I'm failed to reproduce this issue on my machine. :(
Thanks
Jin Yao
v5:
---
Remove the hotkey 'a' implementation from this patch. It
will be moved to a separate patch.
v4:
---
1. Support the hotkey 'a'. When we press 'a' on address,
now it supports the annotation.
2. Change the patch title from
"Support interactive annotation of code without symbols" to
"perf report: Support interactive annotation of code without symbols"
v3:
---
Keep just the ANNOTATION_DUMMY_LEN, and remove the
opts->annotate_dummy_len since it's the "maybe in future
we will provide" feature.
v2:
---
Fix a crash issue when annotating an address in "unknown" object.
The steps to reproduce this issue:
perf record -e cycles:u ls
perf report
75.29% ls ld-2.27.so [.] do_lookup_x
23.64% ls ld-2.27.so [.] __GI___tunables_init
1.04% ls [unknown] [k] 0xffffffff85c01210
0.03% ls ld-2.27.so [.] _start
When annotating 0xffffffff85c01210, the crash happens.
v2 adds checking for ms->map in add_annotate_opt(). If the object is
"unknown", ms->map is NULL.
Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
tools/perf/ui/browsers/hists.c | 43 +++++++++++++++++++++++++++++-----
tools/perf/util/annotate.h | 1 +
2 files changed, 38 insertions(+), 6 deletions(-)
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index f36dee499320..2f07680559c4 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -2465,13 +2465,41 @@ do_annotate(struct hist_browser *browser, struct popup_action *act)
return 0;
}
+static struct symbol *new_annotate_sym(u64 addr, struct map *map)
+{
+ struct symbol *sym;
+ struct annotated_source *src;
+ char name[64];
+
+ snprintf(name, sizeof(name), "%-#.*lx", BITS_PER_LONG / 4, addr);
+
+ sym = symbol__new(addr, ANNOTATION_DUMMY_LEN, 0, 0, name);
+ if (sym) {
+ src = symbol__hists(sym, 1);
+ if (!src) {
+ symbol__delete(sym);
+ return NULL;
+ }
+
+ dso__insert_symbol(map->dso, sym);
+ }
+
+ return sym;
+}
+
static int
add_annotate_opt(struct hist_browser *browser __maybe_unused,
struct popup_action *act, char **optstr,
- struct map_symbol *ms)
+ struct map_symbol *ms,
+ u64 addr)
{
- if (ms->sym == NULL || ms->map->dso->annotate_warned ||
- symbol__annotation(ms->sym)->src == NULL)
+ if (!ms->map || !ms->map->dso || ms->map->dso->annotate_warned)
+ return 0;
+
+ if (!ms->sym)
+ ms->sym = new_annotate_sym(addr, ms->map);
+
+ if (ms->sym == NULL || symbol__annotation(ms->sym)->src == NULL)
return 0;
if (asprintf(optstr, "Annotate %s", ms->sym->name) < 0)
@@ -3219,17 +3247,20 @@ static int perf_evsel__hists_browse(struct evsel *evsel, int nr_events,
nr_options += add_annotate_opt(browser,
&actions[nr_options],
&options[nr_options],
- &bi->from.ms);
+ &bi->from.ms,
+ bi->from.al_addr);
if (bi->to.ms.sym != bi->from.ms.sym)
nr_options += add_annotate_opt(browser,
&actions[nr_options],
&options[nr_options],
- &bi->to.ms);
+ &bi->to.ms,
+ bi->to.al_addr);
} else {
nr_options += add_annotate_opt(browser,
&actions[nr_options],
&options[nr_options],
- browser->selection);
+ browser->selection,
+ browser->he_selection->ip);
}
skip_annotation:
nr_options += add_thread_opt(browser, &actions[nr_options],
diff --git a/tools/perf/util/annotate.h b/tools/perf/util/annotate.h
index 455403e8fede..c8463c48adf2 100644
--- a/tools/perf/util/annotate.h
+++ b/tools/perf/util/annotate.h
@@ -74,6 +74,7 @@ bool ins__is_fused(struct arch *arch, const char *ins1, const char *ins2);
#define ANNOTATION__CYCLES_WIDTH 6
#define ANNOTATION__MINMAX_CYCLES_WIDTH 19
#define ANNOTATION__AVG_IPC_WIDTH 36
+#define ANNOTATION_DUMMY_LEN 256
struct annotation_options {
bool hide_src_code,
--
2.17.1