diff options
| author | Nathan Chancellor <nathan@kernel.org> | 2025-03-24 20:23:00 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-03-25 08:24:06 +0100 |
| commit | ad9b861824ac55d81431815fffaaff5e981badc1 (patch) | |
| tree | 07be43213b58c2aab2b9d040df879a88435de357 | |
| parent | 01412081863aa81db47423d5719f2726d2a00a32 (diff) | |
x86/kbuild/64: Restrict clang versions that can use '-march=native'
There are two issues that can appear when building with clang and
'-march=native'.
The first issue is a compiler crash in the ipv6 stack with clang-18,
such as when building allmodconfig. This was frequently reported on the
LLVM issue tracker:
# Link: https://github.com/llvm/llvm-project/issues?q=is%3Aissue%20ip6_rcv_core
Stack dump:
0. Program arguments: clang ... -march=native ... net/ipv6/ip6_input.c
1. <eof> parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module 'net/ipv6/ip6_input.c'.
4. Running pass 'X86 DAG->DAG Instruction Selection' on function '@ip6_rcv_core'
The second issue is certain -Wframe-larger-than warnings that appear
with clang versions prior to 19, which introduced an optimization that
produces much better code:
# Link: https://github.com/llvm/llvm-project/commit/90ba33099cbb17e7c159e9ebc5a512037db99d6d [2]
clang-18:
drivers/media/pci/saa7164/saa7164-core.c:605:20: error: stack frame size (2392) exceeds limit (2048) in 'saa7164_irq' [-Werror,-Wframe-larger-than]
605 | static irqreturn_t saa7164_irq(int irq, void *dev_id)
| ^
clang-19:
drivers/media/pci/saa7164/saa7164-core.c:605:20: error: stack frame size (216) exceeds limit (128) in 'saa7164_irq' [-Werror,-Wframe-larger-than]
605 | static irqreturn_t saa7164_irq(int irq, void *dev_id)
| ^
Restrict the testing of the availability of '-march=native' to all
supported GCC versions and clang-19 and newer to avoid these known
resolved issues.
Fixes: 0480bc7e65dc ("x86/kbuild/64: Add the CONFIG_X86_NATIVE_CPU option to locally optimize the kernel with '-march=native'")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tor Vic <torvic9@mailbox.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250324-x86-march-native-clang-19-and-newer-v1-1-3a05ed32a89e@kernel.org
| -rw-r--r-- | arch/x86/Kconfig.cpu | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu index 87bede96e800..f928cf6e3252 100644 --- a/arch/x86/Kconfig.cpu +++ b/arch/x86/Kconfig.cpu @@ -248,6 +248,12 @@ endchoice config CC_HAS_MARCH_NATIVE # This flag might not be available in cross-compilers: def_bool $(cc-option, -march=native) + # LLVM 18 has an easily triggered internal compiler error in core + # networking code with '-march=native' on certain systems: + # https://github.com/llvm/llvm-project/issues/72026 + # LLVM 19 introduces an optimization that resolves some high stack + # usage warnings that only appear wth '-march=native'. + depends on CC_IS_GCC || CLANG_VERSION >= 190100 config X86_NATIVE_CPU bool "Build and optimize for local/native CPU" |