lkml.org 
[lkml]   [2020]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 2/2] Support interactive annotation of code without symbols
On Mon, Feb 24, 2020 at 10:22:25AM +0800, Jin Yao wrote:
> 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.
>
> Percent│
> │
> │
> │ Disassembly of section .text:
> │
> │ 0000000000000628 <.text+0x68>:
> │ divsd %xmm4,%xmm0
> │ divsd %xmm3,%xmm1
> │ movsd (%rsp),%xmm2
> │ addsd %xmm1,%xmm0
> │ addsd %xmm2,%xmm0
> │ movsd %xmm0,(%rsp)
>
> Now we can see the dump of object starting from 0x628.
>
> 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@linux.intel.com>
> ---
> 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;
> + }

hi,
I like the patchset:

Acked-by: Jiri Olsa <jolsa@redhat.com>

could you please also check if we can do this earlier,
so the dummy symbol is actualy collecting all the hits?

like within the symbol__inc_addr_samples function,
but I mght be missing something..

thanks,
jirka

\
 
 \ /
  Last update: 2020-02-24 13:36    [W:0.118 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site