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) <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
Reviewed-by: Josh Poimboeuf <[email protected]>
Tested-by: Nick Desaulniers <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
[cascardo: RETPOLINE_CFLAGS is at Makefile]
[cascardo: remove ANNOTATE_NOENDBR from __x86_return_thunk]
Signed-off-by: Thadeu Lima de Souza Cascardo <[email protected]>
Signed-off-by: Ben Hutchings <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
3 files changed
