[PATCH V2 8/9] x86/speculation: Add unwind hint to trampoline return

[Alexandre Chartre]

With retpoline, the address to branch to is pushed on the stack and
the return instruction (ret) is used to jump to that address. Use the
UNWIND_HINT_RET_OFFSET directive to inform objtool that the stack
should be adjusted.

Signed-off-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>

replace RETPOLINE_RET with UNWIND_HINT_RET_OFFSET
---
 arch/x86/include/asm/nospec-branch.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index a345c6fa0541..5ce2a40a26da 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -10,6 +10,7 @@
 #include <asm/alternative-asm.h>
 #include <asm/cpufeatures.h>
 #include <asm/msr-index.h>
+#include <asm/unwind_hints.h>
 
 /*
  * This should be used immediately before a retpoline alternative. It tells
@@ -100,6 +101,7 @@
 	jmp	.Lspec_trap_\@
 .Ldo_rop_\@:
 	mov	\reg, (%_ASM_SP)
+	UNWIND_HINT_RET_OFFSET
 	ret
 .endm
 
-- 
2.18.2