From: Borislav Petkov (AMD) bp@alien8.de
commit 9a48d604672220545d209e9996c2a1edbb5637f6 upstream.
SYM_FUNC_START_LOCAL_NOALIGN() adds an endbr leading to this layout (leaving only the last 2 bytes of the address):
3bff <zen_untrain_ret>: 3bff: f3 0f 1e fa endbr64 3c03: f6 test $0xcc,%bl
3c04 <__x86_return_thunk>: 3c04: c3 ret 3c05: cc int3 3c06: 0f ae e8 lfence
However, "the RET at __x86_return_thunk must be on a 64 byte boundary, for alignment within the BTB."
Use SYM_START instead.
Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: stable@kernel.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/lib/retpoline.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -144,8 +144,8 @@ SYM_CODE_END(__x86_indirect_jump_thunk_a */ .align 64 .skip 63, 0xcc -SYM_FUNC_START_NOALIGN(zen_untrain_ret); - +SYM_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) + ANNOTATE_NOENDBR /* * As executed from zen_untrain_ret, this is: *