Counterpart to 09d09531a51a ("x86,nospec: Simplify
{JMP,CALL}_NOSPEC"), x86_64 will rewrite all this anyway, see
apply_retpoline.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/nospec-branch.h | 29 +++++++++++------------------
1 file changed, 11 insertions(+), 18 deletions(-)
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -429,31 +429,24 @@ static inline void call_depth_return_thu
#ifdef CONFIG_X86_64
+#define __CS_PREFIX \
+ ".irp rs,r8,r9,r10,r11,r12,r13,r14,r15\n" \
+ ".ifc %V[thunk_target],\\rs\n" \
+ ".byte 0x2e\n" \
+ ".endif\n" \
+ ".endr\n"
+
/*
* Inline asm uses the %V modifier which is only in newer GCC
* which is ensured when CONFIG_MITIGATION_RETPOLINE is defined.
*/
# define CALL_NOSPEC \
- ALTERNATIVE_2( \
- ANNOTATE_RETPOLINE_SAFE \
- "call *%[thunk_target]\n", \
- "call __x86_indirect_thunk_%V[thunk_target]\n", \
- X86_FEATURE_RETPOLINE, \
- "lfence;\n" \
- ANNOTATE_RETPOLINE_SAFE \
- "call *%[thunk_target]\n", \
- X86_FEATURE_RETPOLINE_LFENCE)
+ __CS_PREFIX \
+ "call __x86_indirect_thunk_%V[thunk_target]\n"
# define JMP_NOSPEC \
- ALTERNATIVE_2( \
- ANNOTATE_RETPOLINE_SAFE \
- "jmp *%[thunk_target]\n", \
- "jmp __x86_indirect_thunk_%V[thunk_target]\n", \
- X86_FEATURE_RETPOLINE, \
- "lfence;\n" \
- ANNOTATE_RETPOLINE_SAFE \
- "jmp *%[thunk_target]\n", \
- X86_FEATURE_RETPOLINE_LFENCE)
+ __CS_PREFIX \
+ "jmp __x86_indirect_thunk_%V[thunk_target]\n"
# define THUNK_TARGET(addr) [thunk_target] "r" (addr)
