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| author | Peter Zijlstra <peterz@infradead.org> | 2022-06-15 00:15:36 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-07-25 12:26:36 +0300 |
| commit | 270de63cf4a380fe9942d3e0da599c0e966fad78 (patch) | |
| tree | 0dff5c88749f9d5c6fbc0e40b078a55c8c105131 /Makefile | |
| parent | 37b9bb094123a14a986137d693b5aa18a240128b (diff) | |
| download | linux-270de63cf4a380fe9942d3e0da599c0e966fad78.tar.xz | |
x86/retpoline: Use -mfunction-return
commit 0b53c374b9eff2255a386f1f1cfb9a928e52a5ae upstream.
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>
[cascardo: RETPOLINE_CFLAGS is at Makefile]
[cascardo: remove ANNOTATE_NOENDBR from __x86_return_thunk]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Makefile')
| -rw-r--r-- | Makefile | 2 |
1 files changed, 2 insertions, 0 deletions
@@ -672,11 +672,13 @@ endif ifdef CONFIG_CC_IS_GCC RETPOLINE_CFLAGS := $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) +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 |