linux-kernel - [PATCH 09/13] x86/crypto/sha256-avx2: Standardize stack alignment prologue

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Date:   Wed, 24 Feb 2021 10:29:22 -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 09/13] x86/crypto/sha256-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/sha256-avx2-asm.S | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/crypto/sha256-avx2-asm.S b/arch/x86/crypto/sha256-avx2-asm.S
index 11ff60c29c8b..4087f7432a7e 100644
--- a/arch/x86/crypto/sha256-avx2-asm.S
+++ b/arch/x86/crypto/sha256-avx2-asm.S
@@ -117,15 +117,13 @@ _XMM_SAVE_SIZE	= 0
 _INP_END_SIZE	= 8
 _INP_SIZE	= 8
 _CTX_SIZE	= 8
-_RSP_SIZE	= 8
 
 _XFER		= 0
 _XMM_SAVE	= _XFER     + _XFER_SIZE
 _INP_END	= _XMM_SAVE + _XMM_SAVE_SIZE
 _INP		= _INP_END  + _INP_END_SIZE
 _CTX		= _INP      + _INP_SIZE
-_RSP		= _CTX      + _CTX_SIZE
-STACK_SIZE	= _RSP      + _RSP_SIZE
+STACK_SIZE	= _CTX      + _CTX_SIZE
 
 # rotate_Xs
 # Rotate values of symbols X0...X3
@@ -533,11 +531,11 @@ SYM_FUNC_START(sha256_transform_rorx)
 	pushq	%r14
 	pushq	%r15
 
-	mov	%rsp, %rax
+	push	%rbp
+	mov	%rsp, %rbp
+
 	subq	$STACK_SIZE, %rsp
 	and	$-32, %rsp	# align rsp to 32 byte boundary
-	mov	%rax, _RSP(%rsp)
-
 
 	shl	$6, NUM_BLKS	# convert to bytes
 	jz	done_hash
@@ -704,7 +702,8 @@ only_one_block:
 
 done_hash:
 
-	mov	_RSP(%rsp), %rsp
+	mov	%rbp, %rsp
+	pop	%rbp
 
 	popq	%r15
 	popq	%r14
-- 
2.29.2