linux-kernel - Re: [PATCH] perf env: Normalize aarch64.* to arm64 in normalize

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Date:   Mon, 26 Jul 2021 21:04:28 +0800
From:   Li Huafei <lihuafei1@...wei.com>
To:     James Clark <james.clark@....com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     <jolsa@...nel.org>, <peterz@...radead.org>, <mark.rutland@....com>,
        <mingo@...hat.com>, <alexander.shishkin@...ux.intel.com>,
        <namhyung@...nel.org>, <mliska@...e.cz>, <irogers@...gle.com>,
        <dzhu@...ecomp.com>, <rickyman7@...il.com>,
        <yao.jin@...ux.intel.com>, <linux-perf-users@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <zhangjinhao2@...wei.com>
Subject: Re: [PATCH] perf env: Normalize aarch64.* to arm64 in
 normalize_arch()



On 2021/7/26 18:04, James Clark wrote:
> 
> 
> On 23/07/2021 20:23, Arnaldo Carvalho de Melo wrote:
>> Em Fri, Jul 23, 2021 at 09:49:44AM +0800, Li Huafei escreveu:
>>> On my aarch64 big endian machine, the perf annotate does not work.
>>>
>>>   # perf annotate
>>>    Percent |      Source code & Disassembly of [kernel.kallsyms] for cycles (253 samples, percent: local period)
>>>   --------------------------------------------------------------------------------------------------------------
>>>    Percent |      Source code & Disassembly of [kernel.kallsyms] for cycles (1 samples, percent: local period)
>>>   ------------------------------------------------------------------------------------------------------------
>>>    Percent |      Source code & Disassembly of [kernel.kallsyms] for cycles (47 samples, percent: local period)
>>>   -------------------------------------------------------------------------------------------------------------
>>>   ...
>>>
>>> This is because the arch_find() function uses the normalized architecture
>>> name provided by normalize_arch(), and my machine's architecture name
>>> aarch64_be is not normalized to arm64.  Like other architectures such as
>>> arm and powerpc, we can fuzzy match the architecture names associated with
>>> aarch64.* and normalize them.
>>
>> This looks ok modulo fixing the problem and adding that extra pr_err()
>> in a single patch, please split this into two.

OK, I've sent the patch set for v2, which puts pr_err() in a single patch:
https://lore.kernel.org/patchwork/patch/1467154/

>>
>> Also I fail to see why c34df25b40c2 introduced this problem :-\
> 
> I checked the parent commit of c34df25b40c2 and set the architecture to "aarch64_be"
> but it doesn't work either, so I also don't see any regressions.
> 

Sorry, this may be my mistake. It should be that perf annotate adds 
support for aarch64_be, not that there is a bug in the existing code. In 
v2, I've removed the "Fixes" tag.

>>
>> Can some ARM person ack/review this, please?
>>
>> - Arnaldo
>>   
>>> Fixes: c34df25b40c2 ("perf annotate: Add symbol__annotate function")
>>> Signed-off-by: Li Huafei <lihuafei1@...wei.com>
>>> ---
>>>   tools/perf/util/annotate.c | 4 +++-
>>>   tools/perf/util/env.c      | 2 +-
>>>   2 files changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
>>> index aa04a3655236..cb280de3369f 100644
>>> --- a/tools/perf/util/annotate.c
>>> +++ b/tools/perf/util/annotate.c
>>> @@ -2192,8 +2192,10 @@ int symbol__annotate(struct map_symbol *ms, struct evsel *evsel,
>>>   		return errno;
>>>   
>>>   	args.arch = arch = arch__find(arch_name);
>>> -	if (arch == NULL)
>>> +	if (arch == NULL) {
>>> +		pr_err("%s: unsupported arch %s\n", __func__, arch_name);
>>>   		return ENOTSUP;
>>> +	}
>>>   
>>>   	if (parch)
>>>   		*parch = arch;
>>> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
>>> index cec2e6cad8aa..a91da1e9b201 100644
>>> --- a/tools/perf/util/env.c
>>> +++ b/tools/perf/util/env.c
>>> @@ -349,7 +349,7 @@ static const char *normalize_arch(char *arch)
>>>   		return "x86";
>>>   	if (!strcmp(arch, "sun4u") || !strncmp(arch, "sparc", 5))
>>>   		return "sparc";
>>> -	if (!strcmp(arch, "aarch64") || !strcmp(arch, "arm64"))
>>> +	if (!strncmp(arch, "aarch64", 7) || !strcmp(arch, "arm64"))
> 
> This seems ok to me, but a quick google shows some references to "arm64_be".
> I don't know if this could ever get into perf, but most of the other ones
> search for prefixes, so it probably doesn't hurt to do strcmp(arch, "arm64", 5)
> as well.

In v2, I also added a normalization of "arm64_be". After this patch, 
perf annotate seems to work fine on my aarch64_be machine. And I checked 
other source files using perf_env__arch():

  - arch/common.c
  - builtin-trace.c
  - util/sample-raw.c
  - util/thread-stack.c
  - util/unwind-libunwind.c

Looks like it's OK.

Thank you Arnaldo and James for the review.

Huafei
> 
> Thanks
> James
> 
>>>   		return "arm64";
>>>   	if (!strncmp(arch, "arm", 3) || !strcmp(arch, "sa110"))
>>>   		return "arm";
>>> -- 
>>> 2.17.1
>>>
>>
> .
>