[PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Alyssa Ross]

From: Miguel Ojeda <ojeda@kernel.org>

Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
[1][2] as `-Cjump-tables=n` [3].

Without this change, one would eventually see:

      RUSTC L rust/core.o
    error: unknown unstable option: `no-jump-tables`

Thus support the upcoming version.

Link: https://github.com/rust-lang/rust/issues/116592 [1]
Link: https://github.com/rust-lang/rust/pull/105812 [2]
Link: https://github.com/rust-lang/rust/pull/145974 [3]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Acked-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
(cherry picked from commit 789521b4717fd6bd85164ba5c131f621a79c9736)
Signed-off-by: Alyssa Ross <hi@alyssa.is>
---
 arch/x86/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 5b773b34768d1..7c921514c6d0f 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -109,7 +109,7 @@ ifeq ($(CONFIG_X86_KERNEL_IBT),y)
 #   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
 #
 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
-KBUILD_RUSTFLAGS += -Zcf-protection=branch -Zno-jump-tables
+KBUILD_RUSTFLAGS += -Zcf-protection=branch $(if $(call rustc-min-version,109300),-Cjump-tables=n,-Zno-jump-tables)
 else
 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
 endif

base-commit: abf529abd660d8ccad46dd8c8f20e93db6134f5f
-- 
2.52.0

Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Miguel Ojeda]

On Thu, Jan 29, 2026 at 2:37 PM Alyssa Ross <hi@alyssa.is> wrote:
>
> From: Miguel Ojeda <ojeda@kernel.org>
>
> Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
> [1][2] as `-Cjump-tables=n` [3].
>
> Without this change, one would eventually see:
>
>       RUSTC L rust/core.o
>     error: unknown unstable option: `no-jump-tables`
>
> Thus support the upcoming version.
>
> Link: https://github.com/rust-lang/rust/issues/116592 [1]
> Link: https://github.com/rust-lang/rust/pull/105812 [2]
> Link: https://github.com/rust-lang/rust/pull/145974 [3]
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Trevor Gross <tmgross@umich.edu>
> Acked-by: Nicolas Schier <nsc@kernel.org>
> Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> (cherry picked from commit 789521b4717fd6bd85164ba5c131f621a79c9736)
> Signed-off-by: Alyssa Ross <hi@alyssa.is>

Thanks!

Greg, Sasha: yes, please take this one -- this commit should have had:

  Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is
pinned in older LTSs).

which was in the email thread, but I didn't pick it up and neither
`b4` did, my mistake.

Cheers,
Miguel

Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Miguel Ojeda]

On Thu, Jan 29, 2026 at 3:55 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, Jan 29, 2026 at 2:37 PM Alyssa Ross <hi@alyssa.is> wrote:
> >
> > From: Miguel Ojeda <ojeda@kernel.org>
> >
> > Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
> > [1][2] as `-Cjump-tables=n` [3].
> >
> > Without this change, one would eventually see:
> >
> >       RUSTC L rust/core.o
> >     error: unknown unstable option: `no-jump-tables`
> >
> > Thus support the upcoming version.
> >
> > Link: https://github.com/rust-lang/rust/issues/116592 [1]
> > Link: https://github.com/rust-lang/rust/pull/105812 [2]
> > Link: https://github.com/rust-lang/rust/pull/145974 [3]
> > Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> > Reviewed-by: Trevor Gross <tmgross@umich.edu>
> > Acked-by: Nicolas Schier <nsc@kernel.org>
> > Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org
> > Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> > (cherry picked from commit 789521b4717fd6bd85164ba5c131f621a79c9736)
> > Signed-off-by: Alyssa Ross <hi@alyssa.is>
>
> Thanks!
>
> Greg, Sasha: yes, please take this one -- this commit should have had:
>
>   Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is
> pinned in older LTSs).
>
> which was in the email thread, but I didn't pick it up and neither
> `b4` did, my mistake.

By the way, if LoongArch (Cc'd) would like to backport commit

  74f8295c6fb8 ("LoongArch: Handle jump tables options for RUST")

then this would be a good chance to do so, since the one here would go
on top of that one (Alyssa backported the x86 subset of the patch --
for the future, by the way, it would be nice to note it in the commit
message in between [ ... ]).

Thanks!

Cheers,
Miguel

Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Greg KH]

On Thu, Jan 29, 2026 at 04:03:06PM +0100, Miguel Ojeda wrote:
> On Thu, Jan 29, 2026 at 3:55 PM Miguel Ojeda
> <miguel.ojeda.sandonis@gmail.com> wrote:
> >
> > On Thu, Jan 29, 2026 at 2:37 PM Alyssa Ross <hi@alyssa.is> wrote:
> > >
> > > From: Miguel Ojeda <ojeda@kernel.org>
> > >
> > > Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
> > > [1][2] as `-Cjump-tables=n` [3].
> > >
> > > Without this change, one would eventually see:
> > >
> > >       RUSTC L rust/core.o
> > >     error: unknown unstable option: `no-jump-tables`
> > >
> > > Thus support the upcoming version.
> > >
> > > Link: https://github.com/rust-lang/rust/issues/116592 [1]
> > > Link: https://github.com/rust-lang/rust/pull/105812 [2]
> > > Link: https://github.com/rust-lang/rust/pull/145974 [3]
> > > Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> > > Reviewed-by: Trevor Gross <tmgross@umich.edu>
> > > Acked-by: Nicolas Schier <nsc@kernel.org>
> > > Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org
> > > Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
> > > (cherry picked from commit 789521b4717fd6bd85164ba5c131f621a79c9736)
> > > Signed-off-by: Alyssa Ross <hi@alyssa.is>
> >
> > Thanks!
> >
> > Greg, Sasha: yes, please take this one -- this commit should have had:
> >
> >   Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is
> > pinned in older LTSs).
> >
> > which was in the email thread, but I didn't pick it up and neither
> > `b4` did, my mistake.
> 
> By the way, if LoongArch (Cc'd) would like to backport commit
> 
>   74f8295c6fb8 ("LoongArch: Handle jump tables options for RUST")
> 
> then this would be a good chance to do so, since the one here would go
> on top of that one (Alyssa backported the x86 subset of the patch --
> for the future, by the way, it would be nice to note it in the commit
> message in between [ ... ]).

It doesn't apply to the 6.12.y tree cleanly :(

thanks,

greg k-h

Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Alyssa Ross]

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Greg KH <gregkh@linuxfoundation.org> writes:

> On Thu, Jan 29, 2026 at 04:03:06PM +0100, Miguel Ojeda wrote:
>> On Thu, Jan 29, 2026 at 3:55 PM Miguel Ojeda
>> <miguel.ojeda.sandonis@gmail.com> wrote:
>> >
>> > On Thu, Jan 29, 2026 at 2:37 PM Alyssa Ross <hi@alyssa.is> wrote:
>> > >
>> > > From: Miguel Ojeda <ojeda@kernel.org>
>> > >
>> > > Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
>> > > [1][2] as `-Cjump-tables=n` [3].
>> > >
>> > > Without this change, one would eventually see:
>> > >
>> > >       RUSTC L rust/core.o
>> > >     error: unknown unstable option: `no-jump-tables`
>> > >
>> > > Thus support the upcoming version.
>> > >
>> > > Link: https://github.com/rust-lang/rust/issues/116592 [1]
>> > > Link: https://github.com/rust-lang/rust/pull/105812 [2]
>> > > Link: https://github.com/rust-lang/rust/pull/145974 [3]
>> > > Reviewed-by: Alice Ryhl <aliceryhl@google.com>
>> > > Reviewed-by: Trevor Gross <tmgross@umich.edu>
>> > > Acked-by: Nicolas Schier <nsc@kernel.org>
>> > > Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org
>> > > Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
>> > > (cherry picked from commit 789521b4717fd6bd85164ba5c131f621a79c9736)
>> > > Signed-off-by: Alyssa Ross <hi@alyssa.is>
>> >
>> > Thanks!
>> >
>> > Greg, Sasha: yes, please take this one -- this commit should have had:
>> >
>> >   Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is
>> > pinned in older LTSs).
>> >
>> > which was in the email thread, but I didn't pick it up and neither
>> > `b4` did, my mistake.
>> 
>> By the way, if LoongArch (Cc'd) would like to backport commit
>> 
>>   74f8295c6fb8 ("LoongArch: Handle jump tables options for RUST")
>> 
>> then this would be a good chance to do so, since the one here would go
>> on top of that one (Alyssa backported the x86 subset of the patch --
>> for the future, by the way, it would be nice to note it in the commit
>> message in between [ ... ]).
>
> It doesn't apply to the 6.12.y tree cleanly :(

Doesn't need to be AFAICT, because -Zno-jump-tables isn't used on 6.12.

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Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Miguel Ojeda]

On Tue, Feb 3, 2026 at 6:18 PM Alyssa Ross <hi@alyssa.is> wrote:
>
> Doesn't need to be AFAICT, because -Zno-jump-tables isn't used on 6.12.

I am not sure what you mean -- the commit I referenced is the one that
introduces `-Zno-jump-tables`.

Cheers,
Miguel

Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Alyssa Ross]

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Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> writes:

> On Tue, Feb 3, 2026 at 6:18 PM Alyssa Ross <hi@alyssa.is> wrote:
>>
>> Doesn't need to be AFAICT, because -Zno-jump-tables isn't used on 6.12.
>
> I am not sure what you mean -- the commit I referenced is the one that
> introduces `-Zno-jump-tables`.

Sorry, I got mixed up.

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Re: [PATCH 6.12.y] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Miguel Ojeda]

On Tue, Feb 3, 2026 at 3:42 PM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> It doesn't apply to the 6.12.y tree cleanly :(

Yeah, that is why it wasn't applied in the past -- I was just bringing
it up again to keep the "chain of dependencies" we would need going in
case LoongArch decides to apply it. This is the past thread:

  https://lore.kernel.org/stable/CANiq72kEzOa60EhLQ2YnBOD6bsAHc7qA9v9-MP2FtxMa04Q5PQ@mail.gmail.com/

Cheers,
Miguel