linux-kernel - [PATCH 2/6] x86/build: Remove cc-option from stack alignment flags

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Message-Id: <20250814-x86-min-ver-cleanups-v1-2-ff7f19457523@kernel.org>
Date: Thu, 14 Aug 2025 18:31:38 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
 x86@...nel.org
Cc: linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
 patches@...ts.linux.dev, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH 2/6] x86/build: Remove cc-option from stack alignment flags

'-mpreferred-stack-boundary' (the GCC option) and '-mstack-alignment'
(the clang option) have been supported in their respective compilers for
some time, so it is unnecessary to check for support for them via
cc-option. '-mpreferred-stack-boundary=3' had a restriction on
'-mno-sse' until GCC 7.1 but that is irrelevant for most of the kernel,
which includes '-mno-sse'.

Move to simple Kconfig checks to avoid querying the compiler for the
flags that it supports.

Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 arch/x86/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index ed5657395d6a..f0aa58d2ec17 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -37,10 +37,11 @@ export RETPOLINE_VDSO_CFLAGS
 
 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
 # clang has the option -mstack-alignment for that purpose.
-ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
+ifdef CONFIG_CC_IS_GCC
       cc_stack_align4 := -mpreferred-stack-boundary=2
       cc_stack_align8 := -mpreferred-stack-boundary=3
-else ifneq ($(call cc-option, -mstack-alignment=16),)
+endif
+ifdef CONFIG_CC_IS_CLANG
       cc_stack_align4 := -mstack-alignment=4
       cc_stack_align8 := -mstack-alignment=8
 endif

-- 
2.50.1