linux-kernel - [PATCH 08/13] x86/crypto/sha1_avx2: Standardize stack alignment prologue

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Date:   Wed, 24 Feb 2021 10:29:21 -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 08/13] x86/crypto/sha1_avx2: 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_avx2_x86_64_asm.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/crypto/sha1_avx2_x86_64_asm.S b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
index 1e594d60afa5..5eed620f4676 100644
--- a/arch/x86/crypto/sha1_avx2_x86_64_asm.S
+++ b/arch/x86/crypto/sha1_avx2_x86_64_asm.S
@@ -645,9 +645,9 @@ _loop3:
 	RESERVE_STACK  = (W_SIZE*4 + 8+24)
 
 	/* Align stack */
-	mov	%rsp, %rbx
+	push	%rbp
+	mov	%rsp, %rbp
 	and	$~(0x20-1), %rsp
-	push	%rbx
 	sub	$RESERVE_STACK, %rsp
 
 	avx2_zeroupper
@@ -665,8 +665,8 @@ _loop3:
 
 	avx2_zeroupper
 
-	add	$RESERVE_STACK, %rsp
-	pop	%rsp
+	mov	%rbp, %rsp
+	pop	%rbp
 
 	pop	%r15
 	pop	%r14
-- 
2.29.2