linux-kernel - [PATCH V3 7/9] x86/speculation: Change __FILL_RETURN

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Date:   Tue, 14 Apr 2020 12:36:16 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, jpoimboe@...hat.com,
        peterz@...radead.org, jthierry@...hat.com, tglx@...utronix.de,
        alexandre.chartre@...cle.com
Subject: [PATCH V3 7/9] x86/speculation: Change __FILL_RETURN_BUFFER to work with objtool

Change __FILL_RETURN_BUFFER so that the stack state is deterministically
defined for each iteration and that objtool can have an accurate view
of the stack.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Alexandre Chartre <alexandre.chartre@...cle.com>
---
 arch/x86/include/asm/nospec-branch.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 07e95dcb40ad..b0db793fd083 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -59,8 +59,8 @@
 	jmp	775b;				\
 774:						\
 	dec	reg;				\
-	jnz	771b;				\
-	add	$(BITS_PER_LONG/8) * nr, sp;
+	add	$(BITS_PER_LONG/8) * 2, sp;	\
+	jnz	771b;
 
 #ifdef __ASSEMBLY__
 
-- 
2.18.2