[PATCH v2 00/12] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[PATCH v2 00/12] 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 plan to carry this via the Kbuild tree with the appropriate acks.

---
Changes in v2:
- Add two new patches for RISC-V to clean up more LLD_VERSION checks
  (Alex)
- Pick up provided tags (thanks all!)
- Link to v1: https://lore.kernel.org/r/20250818-bump-min-llvm-ver-15-v1-0-c8b1d0f955e0@kernel.org

---
Nathan Chancellor (12):
      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
      riscv: Unconditionally use linker relaxation
      riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
      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                | 21 +++++++--------------
 arch/riscv/Makefile               |  9 +--------
 lib/Kconfig.debug                 |  2 +-
 lib/Kconfig.kcsan                 |  6 ------
 lib/Kconfig.kmsan                 | 11 +----------
 scripts/min-tool-version.sh       |  6 ++----
 tools/objtool/check.c             | 10 ----------
 13 files changed, 19 insertions(+), 71 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20250710-bump-min-llvm-ver-15-95231f1eb655

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

[PATCH v2 06/12] powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, the zero initializations of val and suffix
added by commit 0d76914a4c99 ("powerpc/inst: Optimise
copy_inst_from_kernel_nofault()") to avoid a bogus case of
-Wuninitialized can be dropped because the preprocessor condition is
always false.

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linuxppc-dev@lists.ozlabs.org
---
 arch/powerpc/include/asm/inst.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
index 684d3f453282..ffa82167c860 100644
--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h
@@ -143,10 +143,6 @@ static inline int __copy_inst_from_kernel_nofault(ppc_inst_t *inst, u32 *src)
 {
 	unsigned int val, suffix;
 
-/* See https://github.com/ClangBuiltLinux/linux/issues/1521 */
-#if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 140000
-	val = suffix = 0;
-#endif
 	__get_kernel_nofault(&val, src, u32, Efault);
 	if (IS_ENABLED(CONFIG_PPC64) && get_op(val) == OP_PREFIX) {
 		__get_kernel_nofault(&suffix, src + 1, u32, Efault);

-- 
2.50.1

Re: [PATCH v2 06/12] powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()

[Christophe Leroy]

Le 21/08/2025 à 23:15, Nathan Chancellor a écrit :
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, the zero initializations of val and suffix
> added by commit 0d76914a4c99 ("powerpc/inst: Optimise
> copy_inst_from_kernel_nofault()") to avoid a bogus case of
> -Wuninitialized can be dropped because the preprocessor condition is
> always false.
> 
> Reviewed-by: Kees Cook <kees@kernel.org>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: linuxppc-dev@lists.ozlabs.org
> ---
>   arch/powerpc/include/asm/inst.h | 4 ----
>   1 file changed, 4 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/inst.h b/arch/powerpc/include/asm/inst.h
> index 684d3f453282..ffa82167c860 100644
> --- a/arch/powerpc/include/asm/inst.h
> +++ b/arch/powerpc/include/asm/inst.h
> @@ -143,10 +143,6 @@ static inline int __copy_inst_from_kernel_nofault(ppc_inst_t *inst, u32 *src)
>   {
>   	unsigned int val, suffix;
>   
> -/* See https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FClangBuiltLinux%2Flinux%2Fissues%2F1521&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C23038335822b4dbe2adc08dde0f7f50e%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638914077769007882%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=EfgIB7nIdCB2e3KWeEvsXKG%2B8LrK%2FjpUrA4RIeMcreo%3D&reserved=0 */
> -#if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 140000
> -	val = suffix = 0;
> -#endif
>   	__get_kernel_nofault(&val, src, u32, Efault);
>   	if (IS_ENABLED(CONFIG_PPC64) && get_op(val) == OP_PREFIX) {
>   		__get_kernel_nofault(&suffix, src + 1, u32, Efault);
> 

Re: [PATCH v2 00/12] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[Nathan Chancellor]

On Thu, 21 Aug 2025 14:15:37 -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.
> 
> [...]

Applied, thanks!

[01/12] kbuild: Bump minimum version of LLVM for building the kernel to 15.0.0
        https://git.kernel.org/kbuild/c/20c0989283564
[02/12] arch/Kconfig: Drop always true condition from RANDOMIZE_KSTACK_OFFSET
        https://git.kernel.org/kbuild/c/65aebf6f5880e
[03/12] ARM: Clean up definition of ARM_HAS_GROUP_RELOCS
        https://git.kernel.org/kbuild/c/02aba266e391f
[04/12] arm64: Remove tautological LLVM Kconfig conditions
        https://git.kernel.org/kbuild/c/23cb0514208da
[05/12] mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER
        https://git.kernel.org/kbuild/c/e633c2e78fd1c
[06/12] powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()
        https://git.kernel.org/kbuild/c/488954ca195d0
[07/12] riscv: Remove version check for LTO_CLANG selects
        https://git.kernel.org/kbuild/c/6578a1ff6aa49
[08/12] riscv: Unconditionally use linker relaxation
        https://git.kernel.org/kbuild/c/7ccbe91796d7b
[09/12] riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
        https://git.kernel.org/kbuild/c/87b28d71396bf
[10/12] lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
        https://git.kernel.org/kbuild/c/a817de20091c3
[11/12] objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY
        https://git.kernel.org/kbuild/c/573ad421cc551
[12/12] KMSAN: Remove tautological checks
        https://git.kernel.org/kbuild/c/5ff8c11775c74

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

Re: [PATCH v2 00/12] Bump minimum supported version of LLVM for building the kernel to 15.0.0

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (for-next)
by Nathan Chancellor <nathan@kernel.org>:

On Thu, 21 Aug 2025 14:15:37 -0700 you 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.
> 
> [...]

Here is the summary with links:
  - [v2,07/12] riscv: Remove version check for LTO_CLANG selects
    https://git.kernel.org/riscv/c/6578a1ff6aa4
  - [v2,08/12] riscv: Unconditionally use linker relaxation
    https://git.kernel.org/riscv/c/7ccbe91796d7
  - [v2,09/12] riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
    https://git.kernel.org/riscv/c/87b28d71396b

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
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