From: Alexander Lobakin <alobakin@pm.me>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Alexander Lobakin <alobakin@pm.me>,
Fangrui Song <maskray@google.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
linux-mips@vger.kernel.org,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Ralf Baechle <ralf@linux-mips.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [BUG mips llvm] MIPS: malformed R_MIPS_{HI16,LO16} with LLVM
Date: Wed, 13 Jan 2021 10:16:41 +0000 [thread overview]
Message-ID: <20210113101623.3020-1-alobakin@pm.me> (raw)
In-Reply-To: <CAKwvOdnvd1NaBQEJ0fPsYiGff4=tUdrcuAR0no9FUMqnOZSu6Q@mail.gmail.com>
From: Nick Desaulniers <ndesaulniers@google.com>
Date: Tue, 12 Jan 2021 14:14:58 -0800
> On Mon, Jan 11, 2021 at 12:50 PM Alexander Lobakin <alobakin@pm.me> wrote:
>>
>>> The disassembly for me produces:
>>> 399c: 3c 03 00 00 lui $3, 0 <phy_device_free>
>>> 0000399c: R_MIPS_HI16 .text
>>> ...
>>> 39a8: 24 63 3a 5c addiu $3, $3, 14940 <phy_probe>
>>> 000039a8: R_MIPS_LO16 .text
>>
>> So, in your case the values of the instructions that relocs refer are:
>>
>> 0x3c030000 R_MIPS_HI16
>> 0x24633a5c R_MIPS_LO16
>>
>> Mine were:
>>
>> 0x3c010000
>> 0x24339444
>>
>> Your second one doesn't have bit 15 set, so I think this pair won't
>> break the code.
>> Try to hunt for R_MIPS_LO16 that have this bit set, i.e. they have
>> '8', '9', 'a', 'b', 'c', 'd' or 'e' as their [15:12].
>
> I don't think any of my R_MIPS_LO16 in that file have that bit set.
> See attached.
Well, seems like you got lucky here.
You can try to check for other modules if any of them have
R_MIPS_LO16 with bit 15 set.
Also, you can try to enable:
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y
CONFIG_TRIM_UNUSED_KSYMS=y
to alter the build process. These options didn't change anything
in terms of relocs for me though.
> --
> Thanks,
> ~Nick Desaulniers
Thanks,
Al
next prev parent reply other threads:[~2021-01-13 10:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 17:11 [BUG mips llvm] MIPS: malformed R_MIPS_{HI16,LO16} with LLVM Alexander Lobakin
2021-01-09 17:50 ` Nick Desaulniers
2021-01-09 19:15 ` Alexander Lobakin
2021-01-09 23:29 ` Alexander Lobakin
2021-01-10 1:08 ` Alexander Lobakin
2021-01-11 20:03 ` Nick Desaulniers
2021-01-11 20:50 ` Alexander Lobakin
2021-01-12 22:14 ` Nick Desaulniers
2021-01-13 10:16 ` Alexander Lobakin [this message]
2021-05-07 7:47 ` Nathan Chancellor
2021-05-08 16:29 ` Alexander Lobakin
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