[PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Yao Zi]

R_MIPS_PC32 is a GNU extension, its definition is available in glibc
only since 2.39 (released in 2024), and not available in musl libc yet.
Provide our own definition for R_MIPS_PC32 and use it if necessary to
fix relocs tool building on musl and older glibc systems.

Fixes: ff79d31eb536 ("mips: Add support for PC32 relocations in vmlinux")
Signed-off-by: Yao Zi <me@ziyao.cc>
---
 arch/mips/boot/tools/relocs.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/mips/boot/tools/relocs.h b/arch/mips/boot/tools/relocs.h
index 607ff0103064..942981d9ce73 100644
--- a/arch/mips/boot/tools/relocs.h
+++ b/arch/mips/boot/tools/relocs.h
@@ -29,6 +29,13 @@ void die(char *fmt, ...);
 #define R_MIPS_PC26_S2		61
 #endif
 
+/*
+ * GNU extension that available in glibc only since 2023, not available on musl.
+ */
+#ifndef R_MIPS_PC32
+#define R_MIPS_PC32		248
+#endif
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 enum symtype {
-- 
2.52.0

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Ard Biesheuvel]

On Mon, 2 Feb 2026, at 05:16, Yao Zi wrote:
> R_MIPS_PC32 is a GNU extension, its definition is available in glibc
> only since 2.39 (released in 2024), and not available in musl libc yet.
> Provide our own definition for R_MIPS_PC32 and use it if necessary to
> fix relocs tool building on musl and older glibc systems.
>
> Fixes: ff79d31eb536 ("mips: Add support for PC32 relocations in vmlinux")
> Signed-off-by: Yao Zi <me@ziyao.cc>

Thanks for fixing this.

It does imply that the subsequent kallsyms patch will result in 32-bit MIPS no longer being buildable with older toolchains if CONFIG_RELOCATABLE=y.

Not sure if that is an issue, but it needs calling out. Nathan, any thoughts?

> ---
>  arch/mips/boot/tools/relocs.h | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/mips/boot/tools/relocs.h b/arch/mips/boot/tools/relocs.h
> index 607ff0103064..942981d9ce73 100644
> --- a/arch/mips/boot/tools/relocs.h
> +++ b/arch/mips/boot/tools/relocs.h
> @@ -29,6 +29,13 @@ void die(char *fmt, ...);
>  #define R_MIPS_PC26_S2		61
>  #endif
> 
> +/*
> + * GNU extension that available in glibc only since 2023, not 
> available on musl.
> + */
> +#ifndef R_MIPS_PC32
> +#define R_MIPS_PC32		248
> +#endif
> +
>  #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> 
>  enum symtype {
> -- 
> 2.52.0

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Nathan Chancellor]

On Mon, Feb 02, 2026 at 10:17:53AM +0100, Ard Biesheuvel wrote:
> 
> On Mon, 2 Feb 2026, at 05:16, Yao Zi wrote:
> > R_MIPS_PC32 is a GNU extension, its definition is available in glibc
> > only since 2.39 (released in 2024), and not available in musl libc yet.
> > Provide our own definition for R_MIPS_PC32 and use it if necessary to
> > fix relocs tool building on musl and older glibc systems.
> >
> > Fixes: ff79d31eb536 ("mips: Add support for PC32 relocations in vmlinux")
> > Signed-off-by: Yao Zi <me@ziyao.cc>
> 
> Thanks for fixing this.
> 
> It does imply that the subsequent kallsyms patch will result in 32-bit MIPS no longer being buildable with older toolchains if CONFIG_RELOCATABLE=y.

Doing a little research, it seems like R_MIPS_PC32 has been recognized
by the toolchains for a long time, as I found these commits in binutils:

  https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=092dcd755dcdcf664b25a7011fd15957f124c29f
  https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=b47468a6dbd1b54c44c2edc0f7db64a073d894ea

It seems like this relocation was not documented in glibc until
recently, along with many other relocation types:

  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a6e8ceb3bb532236e1eecd0bb0ee8e4b7fd5ff7c

I interpret that to mean that the kallsyms patch should work fine since
the toolchain can handle these relocations? It is just building the
relocs tool against an older glibc or musl that does not have the
R_MIPS_PC32 definition that is broken? Or am I misunderstanding
something?

If we get an obvious build breakage report down the road, we can always
add another forward fix or back out of the changes altogether.

> Not sure if that is an issue, but it needs calling out. Nathan, any thoughts?
> 
> > ---
> >  arch/mips/boot/tools/relocs.h | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/arch/mips/boot/tools/relocs.h b/arch/mips/boot/tools/relocs.h
> > index 607ff0103064..942981d9ce73 100644
> > --- a/arch/mips/boot/tools/relocs.h
> > +++ b/arch/mips/boot/tools/relocs.h
> > @@ -29,6 +29,13 @@ void die(char *fmt, ...);
> >  #define R_MIPS_PC26_S2		61
> >  #endif
> > 
> > +/*
> > + * GNU extension that available in glibc only since 2023, not 
> > available on musl.
> > + */
> > +#ifndef R_MIPS_PC32
> > +#define R_MIPS_PC32		248
> > +#endif
> > +
> >  #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> > 
> >  enum symtype {
> > -- 
> > 2.52.0

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Yao Zi]

On Mon, Feb 02, 2026 at 04:07:29PM -0700, Nathan Chancellor wrote:
> On Mon, Feb 02, 2026 at 10:17:53AM +0100, Ard Biesheuvel wrote:
> > 
> > On Mon, 2 Feb 2026, at 05:16, Yao Zi wrote:
> > > R_MIPS_PC32 is a GNU extension, its definition is available in glibc
> > > only since 2.39 (released in 2024), and not available in musl libc yet.
> > > Provide our own definition for R_MIPS_PC32 and use it if necessary to
> > > fix relocs tool building on musl and older glibc systems.
> > >
> > > Fixes: ff79d31eb536 ("mips: Add support for PC32 relocations in vmlinux")
> > > Signed-off-by: Yao Zi <me@ziyao.cc>
> > 
> > Thanks for fixing this.
> > 
> > It does imply that the subsequent kallsyms patch will result in 32-bit MIPS no longer being buildable with older toolchains if CONFIG_RELOCATABLE=y.
> 
> Doing a little research, it seems like R_MIPS_PC32 has been recognized
> by the toolchains for a long time, as I found these commits in binutils:
> 
>   https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=092dcd755dcdcf664b25a7011fd15957f124c29f
>   https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=b47468a6dbd1b54c44c2edc0f7db64a073d894ea
> 
> It seems like this relocation was not documented in glibc until
> recently, along with many other relocation types:
> 
>   https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a6e8ceb3bb532236e1eecd0bb0ee8e4b7fd5ff7c
> 
> I interpret that to mean that the kallsyms patch should work fine since
> the toolchain can handle these relocations? It is just building the
> relocs tool against an older glibc or musl that does not have the
> R_MIPS_PC32 definition that is broken? Or am I misunderstanding
> something?

Yes, this patch is only meant to fix building of relocs tool. I don't
think there are problems about toolchain supporting since R_MIPS_PC32
has been in binutils for a long time, as Nathan found, since 2004. The
situation is that it's likely to have a toolchain supporting
R_MIPS_PC32, while elf.h on the build machine doesn't have its
definition. And after ff79d31eb536 ("mips: Add support for PC32
relocations in vmlinux"), the relocs tool started to require a
definition of R_MIPS_PC32 to build.

> If we get an obvious build breakage report down the road, we can always
> add another forward fix or back out of the changes altogether.
> 
> > Not sure if that is an issue, but it needs calling out. Nathan, any thoughts?
> > 

Best regards,
Yao Zi

> > > ---
> > >  arch/mips/boot/tools/relocs.h | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > >
> > > diff --git a/arch/mips/boot/tools/relocs.h b/arch/mips/boot/tools/relocs.h
> > > index 607ff0103064..942981d9ce73 100644
> > > --- a/arch/mips/boot/tools/relocs.h
> > > +++ b/arch/mips/boot/tools/relocs.h
> > > @@ -29,6 +29,13 @@ void die(char *fmt, ...);
> > >  #define R_MIPS_PC26_S2		61
> > >  #endif
> > > 
> > > +/*
> > > + * GNU extension that available in glibc only since 2023, not 
> > > available on musl.
> > > + */
> > > +#ifndef R_MIPS_PC32
> > > +#define R_MIPS_PC32		248
> > > +#endif
> > > +
> > >  #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> > > 
> > >  enum symtype {
> > > -- 
> > > 2.52.0

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Ard Biesheuvel]

On Tue, 3 Feb 2026, at 04:56, Yao Zi wrote:
> On Mon, Feb 02, 2026 at 04:07:29PM -0700, Nathan Chancellor wrote:
>> On Mon, Feb 02, 2026 at 10:17:53AM +0100, Ard Biesheuvel wrote:
>> > 
>> > On Mon, 2 Feb 2026, at 05:16, Yao Zi wrote:
>> > > R_MIPS_PC32 is a GNU extension, its definition is available in glibc
>> > > only since 2.39 (released in 2024), and not available in musl libc yet.
>> > > Provide our own definition for R_MIPS_PC32 and use it if necessary to
>> > > fix relocs tool building on musl and older glibc systems.
>> > >
>> > > Fixes: ff79d31eb536 ("mips: Add support for PC32 relocations in vmlinux")
>> > > Signed-off-by: Yao Zi <me@ziyao.cc>
>> > 
>> > Thanks for fixing this.
>> > 
>> > It does imply that the subsequent kallsyms patch will result in 32-bit MIPS no longer being buildable with older toolchains if CONFIG_RELOCATABLE=y.
>> 
>> Doing a little research, it seems like R_MIPS_PC32 has been recognized
>> by the toolchains for a long time, as I found these commits in binutils:
>> 
>>   https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=092dcd755dcdcf664b25a7011fd15957f124c29f
>>   https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=b47468a6dbd1b54c44c2edc0f7db64a073d894ea
>> 
>> It seems like this relocation was not documented in glibc until
>> recently, along with many other relocation types:
>> 
>>   https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a6e8ceb3bb532236e1eecd0bb0ee8e4b7fd5ff7c
>> 
>> I interpret that to mean that the kallsyms patch should work fine since
>> the toolchain can handle these relocations? It is just building the
>> relocs tool against an older glibc or musl that does not have the
>> R_MIPS_PC32 definition that is broken? Or am I misunderstanding
>> something?
>
> Yes, this patch is only meant to fix building of relocs tool. I don't
> think there are problems about toolchain supporting since R_MIPS_PC32
> has been in binutils for a long time, as Nathan found, since 2004. The
> situation is that it's likely to have a toolchain supporting
> R_MIPS_PC32, while elf.h on the build machine doesn't have its
> definition. And after ff79d31eb536 ("mips: Add support for PC32
> relocations in vmlinux"), the relocs tool started to require a
> definition of R_MIPS_PC32 to build.
>

OK, thanks for the clarification.

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Maciej W. Rozycki]

On Tue, 3 Feb 2026, Yao Zi wrote:

> > I interpret that to mean that the kallsyms patch should work fine since
> > the toolchain can handle these relocations? It is just building the
> > relocs tool against an older glibc or musl that does not have the
> > R_MIPS_PC32 definition that is broken? Or am I misunderstanding
> > something?
> 
> Yes, this patch is only meant to fix building of relocs tool. I don't
> think there are problems about toolchain supporting since R_MIPS_PC32
> has been in binutils for a long time, as Nathan found, since 2004. The

 Since Y2K to be exact:

commit bb2d6cd7b19cd82313963d2d878a94e6e85a38b6
Author: Geoffrey Keating <geoffk@geoffk.org>
Date:   Sat Mar 11 02:16:25 2000 +0000

[...]
    In include/elf:
    	* mips.h: Add R_MIPS_GNU_REL_HI16, R_MIPS_GNU_REL_LO16,
     	R_MIPS_GNU_REL16_S2, R_MIPS_PC64 and R_MIPS_PC32 relocation
     	numbers.

> situation is that it's likely to have a toolchain supporting
> R_MIPS_PC32, while elf.h on the build machine doesn't have its
> definition. And after ff79d31eb536 ("mips: Add support for PC32
> relocations in vmlinux"), the relocs tool started to require a
> definition of R_MIPS_PC32 to build.

 But where does ff79d31eb536 come from?  I can't see it on Linus's master 
and you can't refer an SHA-1 ID from another repo in a 'Fixes:' tag AFAIK, 
as it's going to change as a commit is merged.  Also can't you get the fix 
folded into the offending commit since it hasn't been merged yet?

  Maciej

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Yao Zi]

On Thu, Feb 05, 2026 at 01:26:39AM +0000, Maciej W. Rozycki wrote:
> On Tue, 3 Feb 2026, Yao Zi wrote:
> 
> > > I interpret that to mean that the kallsyms patch should work fine since
> > > the toolchain can handle these relocations? It is just building the
> > > relocs tool against an older glibc or musl that does not have the
> > > R_MIPS_PC32 definition that is broken? Or am I misunderstanding
> > > something?
> > 
> > Yes, this patch is only meant to fix building of relocs tool. I don't
> > think there are problems about toolchain supporting since R_MIPS_PC32
> > has been in binutils for a long time, as Nathan found, since 2004. The
> 
>  Since Y2K to be exact:
> 
> commit bb2d6cd7b19cd82313963d2d878a94e6e85a38b6
> Author: Geoffrey Keating <geoffk@geoffk.org>
> Date:   Sat Mar 11 02:16:25 2000 +0000
> 
> [...]
>     In include/elf:
>     	* mips.h: Add R_MIPS_GNU_REL_HI16, R_MIPS_GNU_REL_LO16,
>      	R_MIPS_GNU_REL16_S2, R_MIPS_PC64 and R_MIPS_PC32 relocation
>      	numbers.
> 
> > situation is that it's likely to have a toolchain supporting
> > R_MIPS_PC32, while elf.h on the build machine doesn't have its
> > definition. And after ff79d31eb536 ("mips: Add support for PC32
> > relocations in vmlinux"), the relocs tool started to require a
> > definition of R_MIPS_PC32 to build.
> 
>  But where does ff79d31eb536 come from?  I can't see it on Linus's master 
> and you can't refer an SHA-1 ID from another repo in a 'Fixes:' tag AFAIK, 
> as it's going to change as a commit is merged.

This commit has been in kbuild/kbuild-next for some time[1], and has
broken linux-next MIPS builds on my machine.

> Also can't you get the fix folded into the offending commit since it
> hasn't been merged yet?

I'm not the author of ff79d31eb536 ("mips: Add support for PC32
relocations in vmlinux"), and though it hasn't reached Linus' master,
it has been merged into kbuild-next.

I'm fine with it if the maintainer considers it necessary to squash
them together.

>   Maciej

Thanks,
Yao Zi

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux.git/commit/?id=ff79d31eb536f6d87bcbc09287d54d5606bf6dbe

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Ard Biesheuvel]

On Thu, 5 Feb 2026, at 02:26, Maciej W. Rozycki wrote:
> On Tue, 3 Feb 2026, Yao Zi wrote:
>
>> > I interpret that to mean that the kallsyms patch should work fine since
>> > the toolchain can handle these relocations? It is just building the
>> > relocs tool against an older glibc or musl that does not have the
>> > R_MIPS_PC32 definition that is broken? Or am I misunderstanding
>> > something?
>> 
>> Yes, this patch is only meant to fix building of relocs tool. I don't
>> think there are problems about toolchain supporting since R_MIPS_PC32
>> has been in binutils for a long time, as Nathan found, since 2004. The
>
>  Since Y2K to be exact:
>
> commit bb2d6cd7b19cd82313963d2d878a94e6e85a38b6
> Author: Geoffrey Keating <geoffk@geoffk.org>
> Date:   Sat Mar 11 02:16:25 2000 +0000
>
> [...]
>     In include/elf:
>     	* mips.h: Add R_MIPS_GNU_REL_HI16, R_MIPS_GNU_REL_LO16,
>      	R_MIPS_GNU_REL16_S2, R_MIPS_PC64 and R_MIPS_PC32 relocation
>      	numbers.
>
>> situation is that it's likely to have a toolchain supporting
>> R_MIPS_PC32, while elf.h on the build machine doesn't have its
>> definition. And after ff79d31eb536 ("mips: Add support for PC32
>> relocations in vmlinux"), the relocs tool started to require a
>> definition of R_MIPS_PC32 to build.
>
>  But where does ff79d31eb536 come from?  I can't see it on Linus's master 
> and you can't refer an SHA-1 ID from another repo in a 'Fixes:' tag AFAIK, 

Yes, you can, as long as the owner of the tree does not rebase.

Re: [PATCH] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32

[Nathan Chancellor]

On Mon, 02 Feb 2026 04:16:10 +0000, Yao Zi wrote:
> R_MIPS_PC32 is a GNU extension, its definition is available in glibc
> only since 2.39 (released in 2024), and not available in musl libc yet.
> Provide our own definition for R_MIPS_PC32 and use it if necessary to
> fix relocs tool building on musl and older glibc systems.
> 
> 

Applied to

  https://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux.git kbuild-next

Thanks!

[1/1] MIPS: tools: relocs: Ship a definition of R_MIPS_PC32
      https://git.kernel.org/kbuild/c/87abe931fbc34

Please look out for regression or issue reports or other follow up
comments, as they may result in the patch/series getting dropped or
reverted. Patches applied to an "unstable" branch are accepted pending
wider testing in -next and any post-commit review; they will generally
be moved to the main branch in a week if no issues are found.

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>