linux-kernel - [PATCH 07/13] x86/crypto/sha_ni: Standardize stack alignment prologue

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Date:   Wed, 24 Feb 2021 10:29:20 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org, Herbert Xu <herbert@...dor.apana.org.au>
Cc:     linux-kernel@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Eric Biggers <ebiggers@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-crypto@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>
Subject: [PATCH 07/13] x86/crypto/sha_ni: Standardize stack alignment prologue

Use a more standard prologue for saving the stack pointer before
realigning the stack.

This enables ORC unwinding by allowing objtool to understand the stack
realignment.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/crypto/sha1_ni_asm.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/crypto/sha1_ni_asm.S b/arch/x86/crypto/sha1_ni_asm.S
index 11efe3a45a1f..5d8415f482bd 100644
--- a/arch/x86/crypto/sha1_ni_asm.S
+++ b/arch/x86/crypto/sha1_ni_asm.S
@@ -59,8 +59,6 @@
 #define DATA_PTR	%rsi	/* 2nd arg */
 #define NUM_BLKS	%rdx	/* 3rd arg */
 
-#define RSPSAVE		%rax
-
 /* gcc conversion */
 #define FRAME_SIZE	32	/* space for 2x16 bytes */
 
@@ -96,7 +94,8 @@
 .text
 .align 32
 SYM_FUNC_START(sha1_ni_transform)
-	mov		%rsp, RSPSAVE
+	push		%rbp
+	mov		%rsp, %rbp
 	sub		$FRAME_SIZE, %rsp
 	and		$~0xF, %rsp
 
@@ -288,7 +287,8 @@ SYM_FUNC_START(sha1_ni_transform)
 	pextrd		$3, E0, 1*16(DIGEST_PTR)
 
 .Ldone_hash:
-	mov		RSPSAVE, %rsp
+	mov		%rbp, %rsp
+	pop		%rbp
 
 	ret
 SYM_FUNC_END(sha1_ni_transform)
-- 
2.29.2