[PATCH 00/10] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[PATCH 00/10] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[Nathan Chancellor]

s390 and x86 have required LLVM 15 since

  30d17fac6aae ("scripts/min-tool-version.sh: raise minimum clang version to 15.0.0 for s390")
  7861640aac52 ("x86/build: Raise the minimum LLVM version to 15.0.0")

respectively. This series bumps the rest of the kernel to 15.0.0 to
match, which allows for a decent number of clean ups.

On the distros front, we will only leave behind Debian Bookworm and
Ubuntu Jammy. In both of those cases, builders / developers can either
use the kernel.org toolchains or https://apt.llvm.org to get newer
versions that will run on those distributions, if they cannot upgrade.

  archlinux:latest              clang version 20.1.8
  debian:oldoldstable-slim      Debian clang version 11.0.1-2
  debian:oldstable-slim         Debian clang version 14.0.6
  debian:stable-slim            Debian clang version 19.1.7 (3+b1)
  debian:testing-slim           Debian clang version 19.1.7 (3+b1)
  debian:unstable-slim          Debian clang version 19.1.7 (3+b2)
  fedora:41                     clang version 19.1.7 (Fedora 19.1.7-4.fc41)
  fedora:latest                 clang version 20.1.8 (Fedora 20.1.8-3.fc42)
  fedora:rawhide                clang version 20.1.8 (Fedora 20.1.8-3.fc43)
  opensuse/leap:latest          clang version 17.0.6
  opensuse/tumbleweed:latest    clang version 20.1.8
  ubuntu:focal                  clang version 10.0.0-4ubuntu1
  ubuntu:jammy                  Ubuntu clang version 14.0.0-1ubuntu1.1
  ubuntu:noble                  Ubuntu clang version 18.1.3 (1ubuntu1)
  ubuntu:latest                 Ubuntu clang version 18.1.3 (1ubuntu1)
  ubuntu:rolling                Ubuntu clang version 20.1.2 (0ubuntu1)
  ubuntu:devel                  Ubuntu clang version 20.1.8 (0ubuntu1)

I think it makes sense for either Andrew to carry this via -mm on a
nonmm branch or me to carry this via the Kbuild tree, with the
appropriate acks.

---
Nathan Chancellor (10):
      kbuild: Bump minimum version of LLVM for building the kernel to 15.0.0
      arch/Kconfig: Drop always true condition from RANDOMIZE_KSTACK_OFFSET
      ARM: Clean up definition of ARM_HAS_GROUP_RELOCS
      arm64: Remove tautological LLVM Kconfig conditions
      mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER
      powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()
      riscv: Remove version check for LTO_CLANG selects
      lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
      objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY
      KMSAN: Remove tautological checks

 Documentation/process/changes.rst |  2 +-
 arch/Kconfig                      |  1 -
 arch/arm/Kconfig                  | 11 ++++-------
 arch/arm64/Kconfig                |  5 +----
 arch/mips/Kconfig                 |  2 +-
 arch/powerpc/include/asm/inst.h   |  4 ----
 arch/riscv/Kconfig                |  5 ++---
 lib/Kconfig.debug                 |  2 +-
 lib/Kconfig.kcsan                 |  6 ------
 lib/Kconfig.kmsan                 | 11 +----------
 scripts/min-tool-version.sh       |  6 ++----
 tools/objtool/check.c             | 10 ----------
 12 files changed, 13 insertions(+), 52 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250710-bump-min-llvm-ver-15-95231f1eb655

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

[PATCH 05/10] mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, the selection of
ARCH_HAS_CURRENT_STACK_POINTER can be made unconditional since it is
always true.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
---
 arch/mips/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index caf508f6e9ec..bc7473505f4a 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,7 +6,7 @@ config MIPS
 	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
 	select ARCH_HAS_CPU_CACHE_ALIASING
 	select ARCH_HAS_CPU_FINALIZE_INIT
-	select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 140000
+	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
 	select ARCH_HAS_DMA_OPS if MACH_JAZZ
 	select ARCH_HAS_FORTIFY_SOURCE

-- 
2.50.1

Re: [PATCH 00/10] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[Kees Cook]

On Mon, Aug 18, 2025 at 11:57:16AM -0700, Nathan Chancellor wrote:
> s390 and x86 have required LLVM 15 since
>
>   30d17fac6aae ("scripts/min-tool-version.sh: raise minimum clang version to 15.0.0 for s390")
>   7861640aac52 ("x86/build: Raise the minimum LLVM version to 15.0.0")
>
> respectively. This series bumps the rest of the kernel to 15.0.0 to
> match, which allows for a decent number of clean ups.

Looks good to me!

Reviewed-by: Kees Cook <kees@kernel.org>

> I think it makes sense for either Andrew to carry this via -mm on a
> nonmm branch or me to carry this via the Kbuild tree, with the
> appropriate acks.

I vote you carry it with Kbuild. :)

--
Kees Cook

Re: [PATCH 05/10] mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER

[Thomas Bogendoerfer]

On Mon, Aug 18, 2025 at 11:57:21AM -0700, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, the selection of
> ARCH_HAS_CURRENT_STACK_POINTER can be made unconditional since it is
> always true.
> 
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: linux-mips@vger.kernel.org
> ---
>  arch/mips/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index caf508f6e9ec..bc7473505f4a 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -6,7 +6,7 @@ config MIPS
>  	select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT
>  	select ARCH_HAS_CPU_CACHE_ALIASING
>  	select ARCH_HAS_CPU_FINALIZE_INIT
> -	select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 140000
> +	select ARCH_HAS_CURRENT_STACK_POINTER
>  	select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
>  	select ARCH_HAS_DMA_OPS if MACH_JAZZ
>  	select ARCH_HAS_FORTIFY_SOURCE
> 
> -- 
> 2.50.1

Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]