[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 02/12] arch/Kconfig: Drop always true condition from RANDOMIZE_KSTACK_OFFSET

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, the second depends line in
RANDOMIZE_KSTACK_OFFSET is always true, so it can be removed.

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: linux-hardening@vger.kernel.org
---
 arch/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index d1b4ffd6e085..4935c4c26f09 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1475,7 +1475,6 @@ config RANDOMIZE_KSTACK_OFFSET
 	bool "Support for randomizing kernel stack offset on syscall entry" if EXPERT
 	default y
 	depends on HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
-	depends on INIT_STACK_NONE || !CC_IS_CLANG || CLANG_VERSION >= 140000
 	help
 	  The kernel stack offset can be randomized (after pt_regs) by
 	  roughly 5 bits of entropy, frustrating memory corruption

-- 
2.50.1

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>