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From: Yonghong Song <yhs@fb.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo <arnaldo.melo@gmail.com>,
	David Blaikie <dblaikie@gmail.com>, <dwarves@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Bill Wendling <morbo@google.com>, bpf <bpf@vger.kernel.org>,
	<kernel-team@fb.com>, Nick Desaulniers <ndesaulniers@google.com>,
	Jiri Olsa <jolsa@kernel.org>
Subject: Re: [PATCH dwarves] dwarf_loader: handle subprogram ret type with abstract_origin properly
Date: Wed, 7 Apr 2021 15:51:43 -0700	[thread overview]
Message-ID: <32069669-c2aa-11ae-e54b-4852af145b10@fb.com> (raw)
In-Reply-To: <YG3RpVgLC9UEUrb8@kernel.org>



On 4/7/21 8:37 AM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Apr 07, 2021 at 07:54:26AM -0700, Yonghong Song escreveu:
>> On 4/2/21 11:08 AM, Arnaldo wrote:
>>> On April 2, 2021 2:42:21 PM GMT-03:00, Yonghong Song <yhs@fb.com> wrote:
>>>> On 4/2/21 10:23 AM, Yonghong Song wrote:
>>> :> Thanks. I checked out the branch and did some testing with latest
>>>> clang
>>>>> trunk (just pulled in).
>>>>>
>>>>> With kernel LTO note support, I tested gcc non-lto, and llvm-lto
>>>> mode,
>>>>> it works fine.
>>>>>
>>>>> Without kernel LTO note support, I tested
>>>>>      gcc non-lto  <=== ok
>>>>>      llvm non-lto  <=== not ok
>>>>>      llvm lto     <=== ok
>>>>>
>>>>> Surprisingly llvm non-lto vmlinux had the same "tcp_slow_start"
>>>> issue.
>>>>> Some previous version of clang does not have this issue.
>>>>> I double checked the dwarfdump and it is indeed has the same reason
>>>>> for lto vmlinux. I checked abbrev section and there is no cross-cu
>>>>> references.
>>>>>
>>>>> That means we need to adapt this patch
>>>>>      dwarf_loader: Handle subprogram ret type with abstract_origin
>>>> properly
>>>>> for non merging case as well.
>>>>> The previous patch fixed lto subprogram abstract_origin issue,
>>>>> I will submit a followup patch for this.
>>>>
>>>> Actually, the change is pretty simple,
>>>>
>>>> diff --git a/dwarf_loader.c b/dwarf_loader.c
>>>> index 5dea837..82d7131 100644
>>>> --- a/dwarf_loader.c
>>>> +++ b/dwarf_loader.c
>>>> @@ -2323,7 +2323,11 @@ static int die__process_and_recode(Dwarf_Die
>>>> *die, struct cu *cu)
>>>>           int ret = die__process(die, cu);
>>>>           if (ret != 0)
>>>>                   return ret;
>>>> -       return cu__recode_dwarf_types(cu);
>>>> +       ret = cu__recode_dwarf_types(cu);
>>>> +       if (ret != 0)
>>>> +               return ret;
>>>> +
>>>> +       return cu__resolve_func_ret_types(cu);
>>>>    }
>>>>
>>>> Arnaldo, do you just want to fold into previous patches, or
>>>> you want me to submit a new one?
>>>
>>> I can take care of that.
>>
>> Arnaldo, just in case that you missed it, please remember
>> to fold the above changes to the patch:
>>     [PATCH dwarves] dwarf_loader: handle subprogram ret type with
>> abstract_origin properly
>> Thanks!
> 
> Its there, I did it Sunday, IIRC:
> 
> https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?h=tmp.master&id=9adb014930f31c66608fa39a35ccea2daa5586ad
> 
> @@ -2295,7 +2323,11 @@ static int die__process_and_recode(Dwarf_Die *die, struct cu *cu)
>   	int ret = die__process(die, cu);
>   	if (ret != 0)
>   		return ret;
> -	return cu__recode_dwarf_types(cu);
> +	ret = cu__recode_dwarf_types(cu);
> +	if (ret != 0)
> +		return ret;
> +
> +	return cu__resolve_func_ret_types(cu);
>   }
> 
>   static int class_member__cache_byte_size(struct tag *tag, struct cu *cu,
> 
> ----

Thanks! I just saw it in the master branch now. Somehow I did not see
it in tmp.master branch yesterday and I don't know why.

> 
> My latest tests were all with it in place.
> 
> - Arnaldo
>   
>>>
>>> And I think it's time for to look at Jiri's test suite... :-)
>>>
>>> It's a holiday here, so I'll take some time to get to this, hopefully I'll tag 1.21 tomorrow tho.
>>>
>>> Cheers,
>>>
>>> - Arnaldo
>>>
> 

      parent reply	other threads:[~2021-04-07 22:52 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 21:36 [PATCH dwarves] dwarf_loader: handle subprogram ret type with abstract_origin properly Yonghong Song
2021-04-01 21:41 ` Yonghong Song
2021-04-01 22:30   ` David Blaikie
     [not found]   ` <CAENS6EsZ5OX9o=Cn5L1jmx8ucR9siEWbGYiYHCUWuZjLyP3E7Q@mail.gmail.com>
2021-04-01 23:40     ` Yonghong Song
2021-04-02  0:00       ` David Blaikie
2021-04-02 14:04         ` Arnaldo Carvalho de Melo
2021-04-02 14:57           ` Arnaldo Carvalho de Melo
2021-04-02 17:23             ` Yonghong Song
2021-04-02 17:42               ` Yonghong Song
2021-04-02 18:08                 ` Arnaldo
2021-04-02 19:01                   ` Jiri Olsa
2021-04-02 19:41                   ` Yonghong Song
2021-04-03 17:08                     ` Arnaldo Carvalho de Melo
2021-04-04 17:22                       ` Jiri Olsa
2021-04-07 14:54                   ` Yonghong Song
2021-04-07 15:37                     ` Arnaldo Carvalho de Melo
2021-04-07 15:40                       ` [RFT] prepping up pahole 1.21, wanna test it? was " Arnaldo Carvalho de Melo
2021-04-07 22:53                         ` Yonghong Song
2021-04-09 13:52                           ` Arnaldo Carvalho de Melo
2021-04-08 21:23                         ` Jiri Olsa
2021-04-09 13:51                           ` Arnaldo Carvalho de Melo
2021-04-07 22:51                       ` Yonghong Song [this message]

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