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| author | Peter Zijlstra <peterz@infradead.org> | 2022-06-14 23:15:36 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-06-27 10:33:58 +0200 |
| commit | 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae (patch) | |
| tree | 6c68189d053efd4ff530c6ba2b0bb86c7298d6f0 /arch/x86/Makefile | |
| parent | 00e1533325fd1fb5459229fe37f235462649f668 (diff) | |
| download | lwn-0b53c374b9eff2255a386f1f1cfb9a928e52a5ae.tar.gz lwn-0b53c374b9eff2255a386f1f1cfb9a928e52a5ae.zip | |
x86/retpoline: Use -mfunction-return
Utilize -mfunction-return=thunk-extern when available to have the
compiler replace RET instructions with direct JMPs to the symbol
__x86_return_thunk. This does not affect assembler (.S) sources, only C
sources.
-mfunction-return=thunk-extern has been available since gcc 7.3 and
clang 15.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'arch/x86/Makefile')
| -rw-r--r-- | arch/x86/Makefile | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index a74886aed349..6e16057737e5 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -15,11 +15,13 @@ endif ifdef CONFIG_CC_IS_GCC RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch-cs-prefix) +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) 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 +RETPOLINE_CFLAGS += $(call cc-option,-mfunction-return=thunk-extern) endif export RETPOLINE_CFLAGS export RETPOLINE_VDSO_CFLAGS |