Re: Patch "x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations" has been added to the 6.14-stable tree

Re: Patch "x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations" has been added to the 6.14-stable tree

[Nathan Chancellor]

On Thu, May 22, 2025 at 05:30:09PM -0400, Sasha Levin wrote:
> This is a note to let you know that I've just added the patch titled
> 
>     x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations
> 
> to the 6.14-stable tree which can be found at:
>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> 
> The filename of the patch is:
>      x86-relocs-handle-r_x86_64_rex_gotpcrelx-relocations.patch
> and it can be found in the queue-6.14 subdirectory.
> 
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
> 
> 
> 
> commit d8e603969259e50aa632d1a3fde8883f41e26150
> Author: Brian Gerst <brgerst@gmail.com>
> Date:   Thu Jan 23 14:07:37 2025 -0500
> 
>     x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations
>     
>     [ Upstream commit cb7927fda002ca49ae62e2782c1692acc7b80c67 ]
>     
>     Clang may produce R_X86_64_REX_GOTPCRELX relocations when redefining the
>     stack protector location.  Treat them as another type of PC-relative
>     relocation.
>     
>     Signed-off-by: Brian Gerst <brgerst@gmail.com>
>     Signed-off-by: Ingo Molnar <mingo@kernel.org>
>     Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
>     Cc: Linus Torvalds <torvalds@linux-foundation.org>
>     Link: https://lore.kernel.org/r/20250123190747.745588-6-brgerst@gmail.com
>     Signed-off-by: Sasha Levin <sashal@kernel.org>
> 
> diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
> index e937be979ec86..92a1e503305ef 100644
> --- a/arch/x86/tools/relocs.c
> +++ b/arch/x86/tools/relocs.c
> @@ -32,6 +32,11 @@ static struct relocs		relocs32;
>  static struct relocs		relocs32neg;
>  static struct relocs		relocs64;
>  # define FMT PRIu64
> +
> +#ifndef R_X86_64_REX_GOTPCRELX
> +# define R_X86_64_REX_GOTPCRELX 42
> +#endif
> +
>  #else
>  # define FMT PRIu32
>  #endif
> @@ -227,6 +232,7 @@ static const char *rel_type(unsigned type)
>  		REL_TYPE(R_X86_64_PC16),
>  		REL_TYPE(R_X86_64_8),
>  		REL_TYPE(R_X86_64_PC8),
> +		REL_TYPE(R_X86_64_REX_GOTPCRELX),
>  #else
>  		REL_TYPE(R_386_NONE),
>  		REL_TYPE(R_386_32),
> @@ -861,6 +867,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
>  
>  	case R_X86_64_PC32:
>  	case R_X86_64_PLT32:
> +	case R_X86_64_REX_GOTPCRELX:
>  		/*
>  		 * PC relative relocations don't need to be adjusted unless
>  		 * referencing a percpu symbol.

Didn't Ard just say this has no purpose in stable?

https://lore.kernel.org/CAMj1kXGtasdqRPn8koNN095VEEU4K409QvieMdgGXNUK0kPgkw@mail.gmail.com/

Cheers,
Nathan

Re: Patch "x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations" has been added to the 6.14-stable tree

[Sasha Levin]

On Thu, May 22, 2025 at 04:01:01PM -0700, Nathan Chancellor wrote:
>On Thu, May 22, 2025 at 05:30:09PM -0400, Sasha Levin wrote:
>> This is a note to let you know that I've just added the patch titled
>>
>>     x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations
>>
>> to the 6.14-stable tree which can be found at:
>>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>>
>> The filename of the patch is:
>>      x86-relocs-handle-r_x86_64_rex_gotpcrelx-relocations.patch
>> and it can be found in the queue-6.14 subdirectory.
>>
>> If you, or anyone else, feels it should not be added to the stable tree,
>> please let <stable@vger.kernel.org> know about it.
>>
>>
>>
>> commit d8e603969259e50aa632d1a3fde8883f41e26150
>> Author: Brian Gerst <brgerst@gmail.com>
>> Date:   Thu Jan 23 14:07:37 2025 -0500
>>
>>     x86/relocs: Handle R_X86_64_REX_GOTPCRELX relocations
>>
>>     [ Upstream commit cb7927fda002ca49ae62e2782c1692acc7b80c67 ]
>>
>>     Clang may produce R_X86_64_REX_GOTPCRELX relocations when redefining the
>>     stack protector location.  Treat them as another type of PC-relative
>>     relocation.
>>
>>     Signed-off-by: Brian Gerst <brgerst@gmail.com>
>>     Signed-off-by: Ingo Molnar <mingo@kernel.org>
>>     Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
>>     Cc: Linus Torvalds <torvalds@linux-foundation.org>
>>     Link: https://lore.kernel.org/r/20250123190747.745588-6-brgerst@gmail.com
>>     Signed-off-by: Sasha Levin <sashal@kernel.org>
>>
>> diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
>> index e937be979ec86..92a1e503305ef 100644
>> --- a/arch/x86/tools/relocs.c
>> +++ b/arch/x86/tools/relocs.c
>> @@ -32,6 +32,11 @@ static struct relocs		relocs32;
>>  static struct relocs		relocs32neg;
>>  static struct relocs		relocs64;
>>  # define FMT PRIu64
>> +
>> +#ifndef R_X86_64_REX_GOTPCRELX
>> +# define R_X86_64_REX_GOTPCRELX 42
>> +#endif
>> +
>>  #else
>>  # define FMT PRIu32
>>  #endif
>> @@ -227,6 +232,7 @@ static const char *rel_type(unsigned type)
>>  		REL_TYPE(R_X86_64_PC16),
>>  		REL_TYPE(R_X86_64_8),
>>  		REL_TYPE(R_X86_64_PC8),
>> +		REL_TYPE(R_X86_64_REX_GOTPCRELX),
>>  #else
>>  		REL_TYPE(R_386_NONE),
>>  		REL_TYPE(R_386_32),
>> @@ -861,6 +867,7 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
>>
>>  	case R_X86_64_PC32:
>>  	case R_X86_64_PLT32:
>> +	case R_X86_64_REX_GOTPCRELX:
>>  		/*
>>  		 * PC relative relocations don't need to be adjusted unless
>>  		 * referencing a percpu symbol.
>
>Didn't Ard just say this has no purpose in stable?
>
>https://lore.kernel.org/CAMj1kXGtasdqRPn8koNN095VEEU4K409QvieMdgGXNUK0kPgkw@mail.gmail.com/

Indeed! This was an issue with my scripts and happened to ~10 more
commits I was dropping. I've now dropped all of those.

Sorry for the noise and thanks for catching this!

-- 
Thanks,
Sasha