linux-kernel - [PATCH 1/3] x86: Move RETPOLINE*

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Message-ID: <20211119165630.219152765@infradead.org>
Date:   Fri, 19 Nov 2021 17:50:24 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        keescook@...omium.org, hjl.tools@...il.com,
        andrew.cooper3@...rix.com, mark.rutland@....com, will@...nel.org,
        ndesaulniers@...gle.com
Subject: [PATCH 1/3] x86: Move RETPOLINE*_CFLAGS to arch Makefile

Currently RETPOLINE*_CFLAGS are defined in the top-level Makefile but
only x86 makes use of them, move them there. If ever another
architecture finds the need, we can reconsider.

Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 Makefile          |   11 -----------
 arch/x86/Makefile |   11 +++++++++++
 2 files changed, 11 insertions(+), 11 deletions(-)

--- a/Makefile
+++ b/Makefile
@@ -688,17 +688,6 @@ ifdef CONFIG_FUNCTION_TRACER
   CC_FLAGS_FTRACE := -pg
 endif
 
-ifdef CONFIG_CC_IS_GCC
-RETPOLINE_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
-RETPOLINE_VDSO_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)
-endif
-ifdef CONFIG_CC_IS_CLANG
-RETPOLINE_CFLAGS	:= -mretpoline-external-thunk
-RETPOLINE_VDSO_CFLAGS	:= -mretpoline
-endif
-export RETPOLINE_CFLAGS
-export RETPOLINE_VDSO_CFLAGS
-
 include $(srctree)/arch/$(SRCARCH)/Makefile
 
 ifdef need-config
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -12,6 +12,17 @@ else
         KBUILD_DEFCONFIG := $(ARCH)_defconfig
 endif
 
+ifdef CONFIG_CC_IS_GCC
+RETPOLINE_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register)
+RETPOLINE_VDSO_CFLAGS	:= $(call cc-option,-mindirect-branch=thunk-inline -mindirect-branch-register)
+endif
+ifdef CONFIG_CC_IS_CLANG
+RETPOLINE_CFLAGS	:= -mretpoline-external-thunk
+RETPOLINE_VDSO_CFLAGS	:= -mretpoline
+endif
+export RETPOLINE_CFLAGS
+export RETPOLINE_VDSO_CFLAGS
+
 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
 # clang has the option -mstack-alignment for that purpose.
 ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)