| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 27/89] x86/retpoline: Swizzle retpoline thunk | Date | Fri, 22 Jul 2022 11:11:01 +0200 |
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From: Peter Zijlstra <peterz@infradead.org>
commit 00e1533325fd1fb5459229fe37f235462649f668 upstream.
Put the actual retpoline thunk as the original code so that it can become more complicated. Specifically, it allows RET to be a JMP, which can't be .altinstr_replacement since that doesn't do relocations (except for the very first instruction).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/lib/retpoline.S | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -32,9 +32,9 @@ SYM_INNER_LABEL(__x86_indirect_thunk_\reg, SYM_L_GLOBAL) UNWIND_HINT_EMPTY - ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \ - __stringify(RETPOLINE \reg), X86_FEATURE_RETPOLINE, \ - __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg; int3), X86_FEATURE_RETPOLINE_LFENCE + ALTERNATIVE_2 __stringify(RETPOLINE \reg), \ + __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg; int3), X86_FEATURE_RETPOLINE_LFENCE, \ + __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), ALT_NOT(X86_FEATURE_RETPOLINE) .endm
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