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Message-ID: <CAA3XUr2sMr1wgPDCqNrQnbUb-zJ67v6M=kFfFRHzLg6YR=ZtZw@mail.gmail.com>
Date: Thu, 22 Jan 2015 08:02:20 -0800
From: Victor Kamensky <victor.kamensky@...aro.org>
To: Russell King - ARM Linux <linux@....linux.org.uk>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
David Ahern <dsahern@...il.com>,
Will Deacon <will.deacon@....com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Ingo Molnar <mingo@...hat.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Jiri Olsa <jolsa@...hat.com>,
Avi Kivity <avi@...udius-systems.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Anton Blanchard <anton@...ba.org>,
Dave Martin <Dave.Martin@....com>,
open list <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2 2/3] perf symbols: improve abi compliance in arm
mapping symbols handling
On 22 January 2015 at 07:29, Russell King - ARM Linux
<linux@....linux.org.uk> wrote:
> On Wed, Jan 21, 2015 at 08:52:57PM -0800, Victor Kamensky wrote:
>> Both Arm and Aarch64 ELF ABI allow mapping symbols be in from
>> either "$d" or "$d.<any>". But current code that handles mapping
>> symbols only deals with the first, dollar character and a single
>> letter, case.
>>
>> The patch adds handling of the second case with period
>> followed by any characters.
>>
>> Suggested-by: Russell King <linux@....linux.org.uk>
>> Suggested-by: Will Deacon <will.deacon@....com>
>> Signed-off-by: Victor Kamensky <victor.kamensky@...aro.org>
>> Acked-by: Will Deacon <will.deacon@....com>
>> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
>> Cc: Paul Mackerras <paulus@...ba.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
>> Cc: Adrian Hunter <adrian.hunter@...el.com>
>> Cc: Jiri Olsa <jolsa@...hat.com>
>> Cc: Namhyung Kim <namhyung@...nel.org>
>> Cc: Avi Kivity <avi@...udius-systems.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
>> Cc: Anton Blanchard <anton@...ba.org>
>> Cc: David Ahern <dsahern@...il.com>
>> Cc: Dave Martin <Dave.Martin@....com>
>> ---
>> tools/perf/util/symbol-elf.c | 9 ++++-----
>> 1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
>> index 1e188dd..7fd35d6 100644
>> --- a/tools/perf/util/symbol-elf.c
>> +++ b/tools/perf/util/symbol-elf.c
>> @@ -857,17 +857,16 @@ int dso__load_sym(struct dso *dso, struct map *map,
>> * don't identify functions, so will confuse the profile
>> * output: */
>> if (ehdr.e_machine == EM_ARM) {
>> - if (!strcmp(elf_name, "$a") ||
>> - !strcmp(elf_name, "$d") ||
>> - !strcmp(elf_name, "$t"))
>> + if (elf_name[0] == '$' && strchr("adt", elf_name[1])
>> + && (elf_name[2] == '\0' || elf_name[2] == '.'))
>> continue;
>> }
>> /* Reject Aarch64 ELF "mapping symbols": these aren't unique and
>> * don't identify functions, so will confuse the profile
>> * output: */
>> if (ehdr.e_machine == EM_AARCH64) {
>> - if (!strcmp(elf_name, "$x") ||
>> - !strcmp(elf_name, "$d"))
>> + if (elf_name[0] == '$' && strchr("dx", elf_name[1])
>> + && (elf_name[2] == '\0' || elf_name[2] == '.'))
>> continue;
>> }
>
> Why not fix this first? Then, all you'd need to do would be to change
> the test for EM_ARM to EM_ARM or EM_AARCH64, and add the 'x' into the
> strchr() string.
In previously discussed [1] I proposed two variants and ask
for people's preferences. Will replied that he did not care and
let me choose that I like.
It seems to me that you more like variant 2 (provided here
for reference again). It would replace patch 1 and patch 2 of
version 2. Please confirm. I don't practically care much and
can use either. I personally preferred variant 1 because in
variant 2 $x will be filtered on ARM V7, but V7 ABI does not
say anything about $x, only Aarch64 does. I.e special symbols
do to match between V7 and V8 exactly. But as it is
already in other places like kallsyms, I agree practically it
may not matter. If you give your node to variant 2 (as below)
I can report this miniseries: Please let me know
Variant 2:
>From c8d08ebddc61203daf21b17c891c26c1d08e14f1 Mon Sep 17 00:00:00 2001
From: Victor Kamensky <victor.kamensky@...aro.org>
Date: Mon, 12 Jan 2015 14:13:36 -0800
Subject: [PATCH 1/2] perf symbols: Ignore mapping symbols on aarch64
Aarch64 ELF files use mapping symbols with special names $x, $d
to identify regions of Aarch64 code (see Aarch64 ELF ABI - "ARM
IHI 0056B", section "4.5.4 Mapping symbols").
The patch filters out these symbols at load time, similar to
"696b97a perf symbols: Ignore mapping symbols on ARM" changes
done for ARM before V8.
Also added handling of mapping symbols that has format
"$d.<any>" and similar for both cases.
Note we are not making difference between EM_ARM and
EM_AARCH64 mapping symbols instead code handles superset
of both.
Signed-off-by: Victor Kamensky <victor.kamensky@...aro.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Avi Kivity <avi@...udius-systems.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Anton Blanchard <anton@...ba.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Will Deacon <will.deacon@....com>
Cc: Russell King <linux@....linux.org.uk>
Cc: Dave Martin <Dave.Martin@....com>
---
tools/perf/util/symbol-elf.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 06fcd1b..b2eb0f9 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -856,10 +856,9 @@ int dso__load_sym(struct dso *dso, struct map *map,
/* Reject ARM ELF "mapping symbols": these aren't unique and
* don't identify functions, so will confuse the profile
* output: */
- if (ehdr.e_machine == EM_ARM) {
- if (!strcmp(elf_name, "$a") ||
- !strcmp(elf_name, "$d") ||
- !strcmp(elf_name, "$t"))
+ if (ehdr.e_machine == EM_ARM || ehdr.e_machine == EM_AARCH64) {
+ if (elf_name[0] == '$' && strchr("adtx", elf_name[1])
+ && (elf_name[2] == '\0' || elf_name[2] == '.'))
continue;
}
--
1.9.3
Thanks,
Victor
[1] https://lkml.org/lkml/2015/1/14/1019
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