[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 01/12] kbuild: Bump minimum 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 but most other architectures allow LLVM 13.0.1 or newer. In
accordance with the recent minimum supported version of GCC bump that
happened in

  118c40b7b503 ("kbuild: require gcc-8 and binutils-2.30")

do the same for LLVM to 15.0.0.

Of the supported releases of Arch Linux, Debian, Fedora, and OpenSUSE
surveyed in evaluating this bump, this only leaves behind Debian
Bookworm (14.0.6) and Ubuntu Jammy (14.0.0). Debian Trixie has 19.1.7
and Ubuntu Noble has 18.1.3 (so there are viable upgrade paths) or users
can use apt.llvm.org, which provides even newer packages for those
distributions.

Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Schier <nsc@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: linux-kbuild@vger.kernel.org
---
 Documentation/process/changes.rst | 2 +-
 scripts/min-tool-version.sh       | 6 ++----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index bccfa19b45df..b38622b0d525 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -30,7 +30,7 @@ you probably needn't concern yourself with pcmciautils.
         Program        Minimal version       Command to check the version
 ====================== ===============  ========================================
 GNU C                  8.1              gcc --version
-Clang/LLVM (optional)  13.0.1           clang --version
+Clang/LLVM (optional)  15.0.0           clang --version
 Rust (optional)        1.78.0           rustc --version
 bindgen (optional)     0.65.1           bindgen --version
 GNU make               4.0              make --version
diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
index 0d223b4a9445..99b5575c1ef7 100755
--- a/scripts/min-tool-version.sh
+++ b/scripts/min-tool-version.sh
@@ -24,12 +24,10 @@ gcc)
 	fi
 	;;
 llvm)
-	if [ "$SRCARCH" = s390 -o "$SRCARCH" = x86 ]; then
-		echo 15.0.0
-	elif [ "$SRCARCH" = loongarch ]; then
+	if [ "$SRCARCH" = loongarch ]; then
 		echo 18.0.0
 	else
-		echo 13.0.1
+		echo 15.0.0
 	fi
 	;;
 rustc)

-- 
2.50.1

[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

[PATCH v2 03/12] ARM: Clean up definition of ARM_HAS_GROUP_RELOCS

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, the first depends line of
ARM_HAS_GROUP_RELOCS is always true, so it can be safely removed.
Combine the !COMPILE_TEST dependency into the 'def_bool' line and update
the comment as well.

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
---
 arch/arm/Kconfig | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index b1f3df39ed40..faf83015b961 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -166,15 +166,12 @@ config ARM
 	  <http://www.arm.linux.org.uk/>.
 
 config ARM_HAS_GROUP_RELOCS
-	def_bool y
-	depends on !LD_IS_LLD || LLD_VERSION >= 140000
-	depends on !COMPILE_TEST
+	def_bool !COMPILE_TEST
 	help
 	  Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
-	  relocations, which have been around for a long time, but were not
-	  supported in LLD until version 14. The combined range is -/+ 256 MiB,
-	  which is usually sufficient, but not for allyesconfig, so we disable
-	  this feature when doing compile testing.
+	  relocations. The combined range is -/+ 256 MiB, which is usually
+	  sufficient, but not for allyesconfig, so we disable this feature
+	  when doing compile testing.
 
 config ARM_DMA_USE_IOMMU
 	bool

-- 
2.50.1

Re: [PATCH v2 03/12] ARM: Clean up definition of ARM_HAS_GROUP_RELOCS

[Arnd Bergmann]

On Thu, Aug 21, 2025, at 23:15, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, the first depends line of
> ARM_HAS_GROUP_RELOCS is always true, so it can be safely removed.
> Combine the !COMPILE_TEST dependency into the 'def_bool' line and update
> the comment as well.
>
> Reviewed-by: Kees Cook <kees@kernel.org>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Acked-by: Arnd Bergmann <arnd@arndb.de>

>.
> 
>  config ARM_HAS_GROUP_RELOCS
> -	def_bool y
> -	depends on !LD_IS_LLD || LLD_VERSION >= 140000
> -	depends on !COMPILE_TEST
> +	def_bool !COMPILE_TEST
>  	help
>  	  Whether or not to use R_ARM_ALU_PC_Gn or R_ARM_LDR_PC_Gn group
> -	  relocations, which have been around for a long time, but were not
> -	  supported in LLD until version 14. The combined range is -/+ 256 MiB,
> -	  which is usually sufficient, but not for allyesconfig, so we disable
> -	  this feature when doing compile testing.

The change is obviously correct by itself, but can we revisit the
question of whether the COMPILE_TEST check is still needed?

Trying it out, I single link issue using llvm-21:

ld.lld-21: error: vmlinux.a(arch/arm/kernel/entry-armv.o):(function __bad_stack: .text+0x110): relocation R_ARM_LDR_PC_G2 out of range: 10168 is not in [0, 4095]; references 'overflow_stack_ptr'
>>> defined in vmlinux.a(arch/arm/kernel/traps.o)

which is from this line

arch/arm/kernel/entry-armv.S:   ldr_this_cpu_armv6 ip, overflow_stack_ptr

with the macro expanding to

        .macro          ldr_this_cpu_armv6, rd:req, sym:req
        this_cpu_offset \rd
        .globl          \sym 
        .reloc          .L0_\@, R_ARM_ALU_PC_G0_NC, \sym
        .reloc          .L1_\@, R_ARM_ALU_PC_G1_NC, \sym
        .reloc          .L2_\@, R_ARM_LDR_PC_G2, \sym
        add             \rd, \rd, pc
.L0_\@: sub             \rd, \rd, #4
.L1_\@: sub             \rd, \rd, #0
.L2_\@: ldr             \rd, [\rd, #4]
        .endm

Would it be possible to either change the macro or to move
the overflow_stack_ptr closer in order to completely eliminate
the CONFIG_ARM_HAS_GROUP_RELOCS symbol and have VMAP_STACK
enabled for all CONFIG_MMU builds?

Are there any other build testing issues with ARM_HAS_GROUP_RELOCS
besides the one I saw here?

      Arnd

Re: [PATCH v2 03/12] ARM: Clean up definition of ARM_HAS_GROUP_RELOCS

[Arnd Bergmann]

On Fri, Aug 22, 2025, at 09:05, Arnd Bergmann wrote:
> On Thu, Aug 21, 2025, at 23:15, Nathan Chancellor wrote:
>
> Would it be possible to either change the macro or to move
> the overflow_stack_ptr closer in order to completely eliminate
> the CONFIG_ARM_HAS_GROUP_RELOCS symbol and have VMAP_STACK
> enabled for all CONFIG_MMU builds?
>
> Are there any other build testing issues with ARM_HAS_GROUP_RELOCS
> besides the one I saw here?

With some more randconfig testing, I did come across a few
configurations that each fail with hundreds of errors like

arm-linux-gnueabi-ld: drivers/crypto/hifn_795x.o(.text+0x99c): overflow whilst splitting 0x10a61854 for group relocation R_ARM_LDR_PC_G2

so I guess we'll have to stick with the current dependency,
at least for ARMv6 and below.

    Arnd

Re: [PATCH v2 03/12] ARM: Clean up definition of ARM_HAS_GROUP_RELOCS

[Ard Biesheuvel]

On Fri, 22 Aug 2025 at 22:04, Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Fri, Aug 22, 2025, at 09:05, Arnd Bergmann wrote:
> > On Thu, Aug 21, 2025, at 23:15, Nathan Chancellor wrote:
> >
> > Would it be possible to either change the macro or to move
> > the overflow_stack_ptr closer in order to completely eliminate
> > the CONFIG_ARM_HAS_GROUP_RELOCS symbol and have VMAP_STACK
> > enabled for all CONFIG_MMU builds?
> >
> > Are there any other build testing issues with ARM_HAS_GROUP_RELOCS
> > besides the one I saw here?
>
> With some more randconfig testing, I did come across a few
> configurations that each fail with hundreds of errors like
>
> arm-linux-gnueabi-ld: drivers/crypto/hifn_795x.o(.text+0x99c): overflow whilst splitting 0x10a61854 for group relocation R_ARM_LDR_PC_G2
>
> so I guess we'll have to stick with the current dependency,
> at least for ARMv6 and below.
>

This is due to LOAD_SYM_ARMV6() (rather than the ldr_this_cpu_armv6
asm macro), which is used to implement get_current() on configs that
use a global variable to store the current task pointer (i.e., non-k
v6 and older). It eliminates the first of two LDRs, which would
pollute the D-cache otherwise, as every occurrence of get_current()
emits a literal into .text carrying the address of the __current
global variable. The D-cache footprint of each such literal is a
cacheline, which never contains other useful data.
(The second LDR is needed and always refers to the same address so it
does not impact D-cache efficiency)

The LOAD_SYM_ARMV6() sequence has a range of 256 MiB, which is
sufficient for any ARM kernel that can be meaningfully used in
production. However, randconfigs may produce kernels that are larger
than this, and so we need the COMPILE_TEST check if we are going to
keep the optimization, and I think it is meaningful enough to do so.

[PATCH v2 04/12] arm64: Remove tautological LLVM Kconfig conditions

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, two sets of always true conditions can be
safely removed in the arm64 Kconfig file.

Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/Kconfig | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e9bbfacc35a6..41c05562e9af 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1492,8 +1492,6 @@ choice
 
 config CPU_BIG_ENDIAN
 	bool "Build big-endian kernel"
-	# https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
-	depends on AS_IS_GNU || AS_VERSION >= 150000
 	help
 	  Say Y if you plan on running a kernel with a big-endian userspace.
 
@@ -2363,8 +2361,7 @@ config STACKPROTECTOR_PER_TASK
 
 config UNWIND_PATCH_PAC_INTO_SCS
 	bool "Enable shadow call stack dynamically using code patching"
-	# needs Clang with https://github.com/llvm/llvm-project/commit/de07cde67b5d205d58690be012106022aea6d2b3 incorporated
-	depends on CC_IS_CLANG && CLANG_VERSION >= 150000
+	depends on CC_IS_CLANG
 	depends on ARM64_PTR_AUTH_KERNEL && CC_HAS_BRANCH_PROT_PAC_RET
 	depends on SHADOW_CALL_STACK
 	select UNWIND_TABLES

-- 
2.50.1

[PATCH v2 05/12] 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.

Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
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

[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);
> 

[PATCH v2 07/12] riscv: Remove version check for LTO_CLANG selects

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, there is no need to check the LLD version
before selecting ARCH_SUPPORTS_LTO_CLANG{,_THIN} because it will always
be true.

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: linux-riscv@lists.infradead.org

Small note, this will conflict with
https://lore.kernel.org/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/
but I think it is simple enough to deal with.
---
 arch/riscv/Kconfig | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a4b233a0659e..1d53bf02d0fa 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -64,9 +64,8 @@ config RISCV
 	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
 	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
 	select ARCH_SUPPORTS_HUGETLBFS if MMU
-	# LLD >= 14: https://github.com/llvm/llvm-project/issues/50505
-	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000
-	select ARCH_SUPPORTS_LTO_CLANG_THIN if LLD_VERSION >= 140000
+	select ARCH_SUPPORTS_LTO_CLANG
+	select ARCH_SUPPORTS_LTO_CLANG_THIN
 	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU
 	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
 	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU

-- 
2.50.1

Re: [PATCH v2 07/12] riscv: Remove version check for LTO_CLANG selects

[Alexandre Ghiti]

Hi Nathan,

On 8/21/25 23:15, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, there is no need to check the LLD version
> before selecting ARCH_SUPPORTS_LTO_CLANG{,_THIN} because it will always
> be true.
>
> Reviewed-by: Kees Cook <kees@kernel.org>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Alexandre Ghiti <alex@ghiti.fr>
> Cc: linux-riscv@lists.infradead.org
>
> Small note, this will conflict with
> https://lore.kernel.org/20250710-riscv-restrict-lto-to-medany-v1-1-b1dac9871ecf@kernel.org/
> but I think it is simple enough to deal with.
> ---
>   arch/riscv/Kconfig | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index a4b233a0659e..1d53bf02d0fa 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -64,9 +64,8 @@ config RISCV
>   	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
>   	select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
>   	select ARCH_SUPPORTS_HUGETLBFS if MMU
> -	# LLD >= 14: https://github.com/llvm/llvm-project/issues/50505
> -	select ARCH_SUPPORTS_LTO_CLANG if LLD_VERSION >= 140000
> -	select ARCH_SUPPORTS_LTO_CLANG_THIN if LLD_VERSION >= 140000
> +	select ARCH_SUPPORTS_LTO_CLANG
> +	select ARCH_SUPPORTS_LTO_CLANG_THIN
>   	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS if 64BIT && MMU
>   	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
>   	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU
>

Acked-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex

Re: [PATCH v2 07/12] riscv: Remove version check for LTO_CLANG selects

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 463 bytes --]

On Thu, Aug 21, 2025 at 02:15:44PM -0700, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, there is no need to check the LLD version
> before selecting ARCH_SUPPORTS_LTO_CLANG{,_THIN} because it will always
> be true.
> 
> Reviewed-by: Kees Cook <kees@kernel.org>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

[-- Attachment #2: signature.asc --]
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[PATCH v2 08/12] riscv: Unconditionally use linker relaxation

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, CONFIG_RISCV_USE_LINKER_RELAXATION will
always be enabled, so it can be removed.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: linux-riscv@lists.infradead.org
---
 arch/riscv/Kconfig  | 6 ------
 arch/riscv/Makefile | 9 +--------
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 1d53bf02d0fa..d482236e93f4 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -246,15 +246,9 @@ config HAVE_SHADOW_CALL_STACK
 	# https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769
 	depends on $(ld-option,--no-relax-gp)
 
-config RISCV_USE_LINKER_RELAXATION
-	def_bool y
-	# https://github.com/llvm/llvm-project/commit/6611d58f5bbcbec77262d392e2923e1d680f6985
-	depends on !LD_IS_LLD || LLD_VERSION >= 150000
-
 # https://github.com/llvm/llvm-project/commit/bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6
 config ARCH_HAS_BROKEN_DWARF5
 	def_bool y
-	depends on RISCV_USE_LINKER_RELAXATION
 	# https://github.com/llvm/llvm-project/commit/1df5ea29b43690b6622db2cad7b745607ca4de6a
 	depends on AS_IS_LLVM && AS_VERSION < 180000
 	# https://github.com/llvm/llvm-project/commit/7ffabb61a5569444b5ac9322e22e5471cc5e4a77
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index df57654a615e..ecf2fcce2d92 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -46,17 +46,10 @@ else
 	KBUILD_LDFLAGS += -melf32lriscv
 endif
 
-ifndef CONFIG_RISCV_USE_LINKER_RELAXATION
-	KBUILD_CFLAGS += -mno-relax
-	KBUILD_AFLAGS += -mno-relax
-ifndef CONFIG_AS_IS_LLVM
-	KBUILD_CFLAGS += -Wa,-mno-relax
-	KBUILD_AFLAGS += -Wa,-mno-relax
-endif
 # LLVM has an issue with target-features and LTO: https://github.com/llvm/llvm-project/issues/59350
 # Ensure it is aware of linker relaxation with LTO, otherwise relocations may
 # be incorrect: https://github.com/llvm/llvm-project/issues/65090
-else ifeq ($(CONFIG_LTO_CLANG),y)
+ifeq ($(CONFIG_LTO_CLANG),y)
 	KBUILD_LDFLAGS += -mllvm -mattr=+c -mllvm -mattr=+relax
 endif
 

-- 
2.50.1

Re: [PATCH v2 08/12] riscv: Unconditionally use linker relaxation

[Alexandre Ghiti]

On 8/21/25 23:15, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, CONFIG_RISCV_USE_LINKER_RELAXATION will
> always be enabled, so it can be removed.
>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Alexandre Ghiti <alex@ghiti.fr>
> Cc: linux-riscv@lists.infradead.org
> ---
>   arch/riscv/Kconfig  | 6 ------
>   arch/riscv/Makefile | 9 +--------
>   2 files changed, 1 insertion(+), 14 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 1d53bf02d0fa..d482236e93f4 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -246,15 +246,9 @@ config HAVE_SHADOW_CALL_STACK
>   	# https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769
>   	depends on $(ld-option,--no-relax-gp)
>   
> -config RISCV_USE_LINKER_RELAXATION
> -	def_bool y
> -	# https://github.com/llvm/llvm-project/commit/6611d58f5bbcbec77262d392e2923e1d680f6985
> -	depends on !LD_IS_LLD || LLD_VERSION >= 150000
> -
>   # https://github.com/llvm/llvm-project/commit/bbc0f99f3bc96f1db16f649fc21dd18e5b0918f6
>   config ARCH_HAS_BROKEN_DWARF5
>   	def_bool y
> -	depends on RISCV_USE_LINKER_RELAXATION
>   	# https://github.com/llvm/llvm-project/commit/1df5ea29b43690b6622db2cad7b745607ca4de6a
>   	depends on AS_IS_LLVM && AS_VERSION < 180000
>   	# https://github.com/llvm/llvm-project/commit/7ffabb61a5569444b5ac9322e22e5471cc5e4a77
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index df57654a615e..ecf2fcce2d92 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -46,17 +46,10 @@ else
>   	KBUILD_LDFLAGS += -melf32lriscv
>   endif
>   
> -ifndef CONFIG_RISCV_USE_LINKER_RELAXATION
> -	KBUILD_CFLAGS += -mno-relax
> -	KBUILD_AFLAGS += -mno-relax
> -ifndef CONFIG_AS_IS_LLVM
> -	KBUILD_CFLAGS += -Wa,-mno-relax
> -	KBUILD_AFLAGS += -Wa,-mno-relax
> -endif
>   # LLVM has an issue with target-features and LTO: https://github.com/llvm/llvm-project/issues/59350
>   # Ensure it is aware of linker relaxation with LTO, otherwise relocations may
>   # be incorrect: https://github.com/llvm/llvm-project/issues/65090
> -else ifeq ($(CONFIG_LTO_CLANG),y)
> +ifeq ($(CONFIG_LTO_CLANG),y)
>   	KBUILD_LDFLAGS += -mllvm -mattr=+c -mllvm -mattr=+relax
>   endif
>   
>

Acked-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex

[PATCH v2 09/12] riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, several ld.lld version checks become
tautological, as they are always true. Replace them with a simple
CONFIG_LD_IS_LLD check.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: linux-riscv@lists.infradead.org
---
 arch/riscv/Kconfig | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d482236e93f4..850ba4b4b534 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -620,7 +620,7 @@ config TOOLCHAIN_HAS_V
 	default y
 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64imv)
 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv)
-	depends on LLD_VERSION >= 140000 || LD_VERSION >= 23800
+	depends on LD_IS_LLD || LD_VERSION >= 23800
 	depends on AS_HAS_OPTION_ARCH
 
 config RISCV_ISA_V
@@ -721,7 +721,7 @@ config TOOLCHAIN_HAS_ZBB
 	default y
 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb)
 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
-	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on LD_IS_LLD || LD_VERSION >= 23900
 	depends on AS_HAS_OPTION_ARCH
 
 # This symbol indicates that the toolchain supports all v1.0 vector crypto
@@ -736,7 +736,7 @@ config TOOLCHAIN_HAS_ZBA
 	default y
 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zba)
 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zba)
-	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on LD_IS_LLD || LD_VERSION >= 23900
 	depends on AS_HAS_OPTION_ARCH
 
 config RISCV_ISA_ZBA
@@ -771,7 +771,7 @@ config TOOLCHAIN_HAS_ZBC
 	default y
 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbc)
 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
-	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on LD_IS_LLD || LD_VERSION >= 23900
 	depends on AS_HAS_OPTION_ARCH
 
 config RISCV_ISA_ZBC
@@ -794,7 +794,7 @@ config TOOLCHAIN_HAS_ZBKB
 	default y
 	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbkb)
 	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbkb)
-	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
+	depends on LD_IS_LLD || LD_VERSION >= 23900
 	depends on AS_HAS_OPTION_ARCH
 
 config RISCV_ISA_ZBKB

-- 
2.50.1

Re: [PATCH v2 09/12] riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs

[Alexandre Ghiti]

On 8/21/25 23:15, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, several ld.lld version checks become
> tautological, as they are always true. Replace them with a simple
> CONFIG_LD_IS_LLD check.
>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Alexandre Ghiti <alex@ghiti.fr>
> Cc: linux-riscv@lists.infradead.org
> ---
>   arch/riscv/Kconfig | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index d482236e93f4..850ba4b4b534 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -620,7 +620,7 @@ config TOOLCHAIN_HAS_V
>   	default y
>   	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64imv)
>   	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32imv)
> -	depends on LLD_VERSION >= 140000 || LD_VERSION >= 23800
> +	depends on LD_IS_LLD || LD_VERSION >= 23800
>   	depends on AS_HAS_OPTION_ARCH
>   
>   config RISCV_ISA_V
> @@ -721,7 +721,7 @@ config TOOLCHAIN_HAS_ZBB
>   	default y
>   	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb)
>   	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
> -	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
> +	depends on LD_IS_LLD || LD_VERSION >= 23900
>   	depends on AS_HAS_OPTION_ARCH
>   
>   # This symbol indicates that the toolchain supports all v1.0 vector crypto
> @@ -736,7 +736,7 @@ config TOOLCHAIN_HAS_ZBA
>   	default y
>   	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zba)
>   	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zba)
> -	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
> +	depends on LD_IS_LLD || LD_VERSION >= 23900
>   	depends on AS_HAS_OPTION_ARCH
>   
>   config RISCV_ISA_ZBA
> @@ -771,7 +771,7 @@ config TOOLCHAIN_HAS_ZBC
>   	default y
>   	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbc)
>   	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbc)
> -	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
> +	depends on LD_IS_LLD || LD_VERSION >= 23900
>   	depends on AS_HAS_OPTION_ARCH
>   
>   config RISCV_ISA_ZBC
> @@ -794,7 +794,7 @@ config TOOLCHAIN_HAS_ZBKB
>   	default y
>   	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbkb)
>   	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbkb)
> -	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
> +	depends on LD_IS_LLD || LD_VERSION >= 23900
>   	depends on AS_HAS_OPTION_ARCH
>   
>   config RISCV_ISA_ZBKB
>

Acked-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks for the v2!

Alex

Re: [PATCH v2 09/12] riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 423 bytes --]

On Thu, Aug 21, 2025 at 02:15:46PM -0700, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 15.0.0, several ld.lld version checks become
> tautological, as they are always true. Replace them with a simple
> CONFIG_LD_IS_LLD check.
> 
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

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[PATCH v2 10/12] lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, the CLANG_VERSION check for older than 14.0.0
is always false, so remove it.

Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 lib/Kconfig.debug | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index dc0e0c6ed075..6c12852e77c8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -259,7 +259,7 @@ config DEBUG_INFO_NONE
 config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
 	bool "Rely on the toolchain's implicit default DWARF version"
 	select DEBUG_INFO
-	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
+	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
 	help
 	  The implicit default version of DWARF debug info produced by a
 	  toolchain changes over time.

-- 
2.50.1

[PATCH v2 11/12] objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, __no_kcsan will always ensure that the thread
sanitizer functions are not generated, so remove the check for tsan
functions in is_profiling_func() and the always true depends and
unnecessary select lines in KCSAN_WEAK_MEMORY.

Acked-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infraded.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: kasan-dev@googlegroups.com
---
 lib/Kconfig.kcsan     |  6 ------
 tools/objtool/check.c | 10 ----------
 2 files changed, 16 deletions(-)

diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan
index 609ddfc73de5..4ce4b0c0109c 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -185,12 +185,6 @@ config KCSAN_WEAK_MEMORY
 	bool "Enable weak memory modeling to detect missing memory barriers"
 	default y
 	depends on KCSAN_STRICT
-	# We can either let objtool nop __tsan_func_{entry,exit}() and builtin
-	# atomics instrumentation in .noinstr.text, or use a compiler that can
-	# implement __no_kcsan to really remove all instrumentation.
-	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
-		   CC_IS_GCC || CLANG_VERSION >= 140000
-	select OBJTOOL if HAVE_NOINSTR_HACK
 	help
 	  Enable support for modeling a subset of weak memory, which allows
 	  detecting a subset of data races due to missing memory barriers.
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index d14f20ef1db1..efa4c060ff4e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2453,16 +2453,6 @@ static bool is_profiling_func(const char *name)
 	if (!strncmp(name, "__sanitizer_cov_", 16))
 		return true;
 
-	/*
-	 * Some compilers currently do not remove __tsan_func_entry/exit nor
-	 * __tsan_atomic_signal_fence (used for barrier instrumentation) with
-	 * the __no_sanitize_thread attribute, remove them. Once the kernel's
-	 * minimum Clang version is 14.0, this can be removed.
-	 */
-	if (!strncmp(name, "__tsan_func_", 12) ||
-	    !strcmp(name, "__tsan_atomic_signal_fence"))
-		return true;
-
 	return false;
 }
 

-- 
2.50.1

[PATCH v2 12/12] KMSAN: Remove tautological checks

[Nathan Chancellor]

Now that the minimum supported version of LLVM for building the kernel
has been bumped to 15.0.0, two KMSAN checks can be cleaned up.

CONFIG_HAVE_KMSAN_COMPILER will always be true when using clang so
remove the cc-option test and use a simple check for CONFIG_CC_IS_CLANG.

CONFIG_HAVE_KMSAN_PARAM_RETVAL will always be true so it can be removed
outright.

Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: kasan-dev@googlegroups.com
---
 lib/Kconfig.kmsan | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan
index 0541d7b079cc..7251b6b59e69 100644
--- a/lib/Kconfig.kmsan
+++ b/lib/Kconfig.kmsan
@@ -3,10 +3,7 @@ config HAVE_ARCH_KMSAN
 	bool
 
 config HAVE_KMSAN_COMPILER
-	# Clang versions <14.0.0 also support -fsanitize=kernel-memory, but not
-	# all the features necessary to build the kernel with KMSAN.
-	depends on CC_IS_CLANG && CLANG_VERSION >= 140000
-	def_bool $(cc-option,-fsanitize=kernel-memory -mllvm -msan-disable-checks=1)
+	def_bool CC_IS_CLANG
 
 config KMSAN
 	bool "KMSAN: detector of uninitialized values use"
@@ -28,15 +25,9 @@ config KMSAN
 
 if KMSAN
 
-config HAVE_KMSAN_PARAM_RETVAL
-	# -fsanitize-memory-param-retval is supported only by Clang >= 14.
-	depends on HAVE_KMSAN_COMPILER
-	def_bool $(cc-option,-fsanitize=kernel-memory -fsanitize-memory-param-retval)
-
 config KMSAN_CHECK_PARAM_RETVAL
 	bool "Check for uninitialized values passed to and returned from functions"
 	default y
-	depends on HAVE_KMSAN_PARAM_RETVAL
 	help
 	  If the compiler supports -fsanitize-memory-param-retval, KMSAN will
 	  eagerly check every function parameter passed by value and every

-- 
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>