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

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Message-ID: <175538155305.1420.8670527495780945494.tip-bot2@tip-bot2>
Date: Sat, 16 Aug 2025 21:59:05 -0000
From: "tip-bot2 for Nathan Chancellor" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Nathan Chancellor <nathan@...nel.org>,
 "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject:
 [tip: x86/build] x86/build: Remove cc-option from stack alignment flags

The following commit has been merged into the x86/build branch of tip:

Commit-ID:     d87208128a3330c0eab18301ab39bdb419647730
Gitweb:        https://git.kernel.org/tip/d87208128a3330c0eab18301ab39bdb419647730
Author:        Nathan Chancellor <nathan@...nel.org>
AuthorDate:    Thu, 14 Aug 2025 18:31:38 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Fri, 15 Aug 2025 22:59:19 +02:00

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>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/20250814-x86-min-ver-cleanups-v1-2-ff7f19457523@kernel.org
---
 arch/x86/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index ed56573..f0aa58d 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