x86/crypto/sha512-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@redhat.com>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/b1a7b29fcfc65d60a3b6e77ef75f4762a5b8488d.1614182415.git.jpoimboe@redhat.com

arch/x86/crypto/sha512-avx2-asm.S

@@ -102,17 +102,13 @@ SRND_SIZE = 1*8
 INP_SIZE = 1*8
 INPEND_SIZE = 1*8
 CTX_SIZE = 1*8
-RSPSAVE_SIZE = 1*8
-GPRSAVE_SIZE = 5*8
 
 frame_XFER = 0
 frame_SRND = frame_XFER + XFER_SIZE
 frame_INP = frame_SRND + SRND_SIZE
 frame_INPEND = frame_INP + INP_SIZE
 frame_CTX = frame_INPEND + INPEND_SIZE
-frame_RSPSAVE = frame_CTX + CTX_SIZE
-frame_GPRSAVE = frame_RSPSAVE + RSPSAVE_SIZE
-frame_size = frame_GPRSAVE + GPRSAVE_SIZE
+frame_size = frame_CTX + CTX_SIZE
 
 ## assume buffers not aligned
 #define	VMOVDQ vmovdqu
@@ -570,18 +566,18 @@ frame_size = frame_GPRSAVE + GPRSAVE_SIZE
 # "blocks" is the message length in SHA512 blocks
 ########################################################################
 SYM_FUNC_START(sha512_transform_rorx)
+	# Save GPRs
+	push	%rbx
+	push	%r12
+	push	%r13
+	push	%r14
+	push	%r15
+
 	# Allocate Stack Space
-	mov	%rsp, %rax
+	push	%rbp
+	mov	%rsp, %rbp
 	sub	$frame_size, %rsp
 	and	$~(0x20 - 1), %rsp
-	mov	%rax, frame_RSPSAVE(%rsp)
-
-	# Save GPRs
-	mov	%rbx, 8*0+frame_GPRSAVE(%rsp)
-	mov	%r12, 8*1+frame_GPRSAVE(%rsp)
-	mov	%r13, 8*2+frame_GPRSAVE(%rsp)
-	mov	%r14, 8*3+frame_GPRSAVE(%rsp)
-	mov	%r15, 8*4+frame_GPRSAVE(%rsp)
 
 	shl	$7, NUM_BLKS	# convert to bytes
 	jz	done_hash
@@ -672,15 +668,17 @@ loop2:
 
 done_hash:
 
-# Restore GPRs
-	mov	8*0+frame_GPRSAVE(%rsp), %rbx
-	mov	8*1+frame_GPRSAVE(%rsp), %r12
-	mov	8*2+frame_GPRSAVE(%rsp), %r13
-	mov	8*3+frame_GPRSAVE(%rsp), %r14
-	mov	8*4+frame_GPRSAVE(%rsp), %r15
-
 	# Restore Stack Pointer
-	mov	frame_RSPSAVE(%rsp), %rsp
+	mov	%rbp, %rsp
+	pop	%rbp
+
+	# Restore GPRs
+	pop	%r15
+	pop	%r14
+	pop	%r13
+	pop	%r12
+	pop	%rbx
+
 	ret
 SYM_FUNC_END(sha512_transform_rorx)