linux-kernel - Re: [PATCH] riscv module: remove (NOLOAD)

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Message-ID: <mhng-7fe2c5d9-a8e6-4123-ac5c-0c9190792520@palmer-ri-x1c9>
Date:   Fri, 18 Mar 2022 16:18:14 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     maskray@...gle.com, nathan@...nel.org
CC:     Paul Walmsley <paul.walmsley@...ive.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject:     Re: [PATCH] riscv module: remove (NOLOAD)

On Sat, 19 Feb 2022 08:45:10 PST (-0800), nathan@...nel.org wrote:
> On Fri, Feb 18, 2022 at 12:26:11AM -0800, Fangrui Song wrote:
>> On ELF, (NOLOAD) sets the section type to SHT_NOBITS[1]. It is conceptually
>> inappropriate for .plt, .got, and .got.plt sections which are always
>> SHT_PROGBITS.
>>
>> In GNU ld, if PLT entries are needed, .plt will be SHT_PROGBITS anyway
>> and (NOLOAD) will be essentially ignored. In ld.lld, since
>> https://reviews.llvm.org/D118840 ("[ELF] Support (TYPE=<value>) to
>> customize the output section type"), ld.lld will report a `section type
>> mismatch` error. Just remove (NOLOAD) to fix the error.
>>
>> [1] https://lld.llvm.org/ELF/linker_script.html As of today, "The
>> section should be marked as not loadable" on
>> https://sourceware.org/binutils/docs/ld/Output-Section-Type.html is
>> outdated for ELF.
>
> Thank you for the patch! As mentioned on the arm64 patch, this needs
> your Signed-off-by tag. With that provided:
>
> Cc: stable@...r.kernel.org
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> Tested-by: Nathan Chancellor <nathan@...nel.org>
>
> This needs to go to stable so that older trees with a newer toolchain do
> not warn.

Yep, just checking on that SOB line.  A 

Fixes: 596b0474d3d9 ("kbuild: preprocess module linker script")

seems appropriate as well.

Thanks!

>
>> ---
>>  arch/riscv/include/asm/module.lds.h | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/riscv/include/asm/module.lds.h b/arch/riscv/include/asm/module.lds.h
>> index 4254ff2ff049..1075beae1ac6 100644
>> --- a/arch/riscv/include/asm/module.lds.h
>> +++ b/arch/riscv/include/asm/module.lds.h
>> @@ -2,8 +2,8 @@
>>  /* Copyright (C) 2017 Andes Technology Corporation */
>>  #ifdef CONFIG_MODULE_SECTIONS
>>  SECTIONS {
>> -	.plt (NOLOAD) : { BYTE(0) }
>> -	.got (NOLOAD) : { BYTE(0) }
>> -	.got.plt (NOLOAD) : { BYTE(0) }
>> +	.plt : { BYTE(0) }
>> +	.got : { BYTE(0) }
>> +	.got.plt : { BYTE(0) }
>>  }
>>  #endif
>> --
>> 2.35.1.265.g69c8d7142f-goog
>>
>>