x86/crypto/sha512-ssse3: 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/6ecaaac9f3828fbb903513bf90c34a08380a8e35.1614182415.git.jpoimboe@redhat.com

arch/x86/crypto/sha512-ssse3-asm.S

@@ -74,14 +74,10 @@ tmp0 =		%rax
 
 W_SIZE = 80*8
 WK_SIZE = 2*8
-RSPSAVE_SIZE = 1*8
-GPRSAVE_SIZE = 5*8
 
 frame_W = 0
 frame_WK = frame_W + W_SIZE
-frame_RSPSAVE = frame_WK + WK_SIZE
-frame_GPRSAVE = frame_RSPSAVE + RSPSAVE_SIZE
-frame_size = frame_GPRSAVE + GPRSAVE_SIZE
+frame_size = frame_WK + WK_SIZE
 
 # Useful QWORD "arrays" for simpler memory references
 # MSG, DIGEST, K_t, W_t are arrays
@@ -283,18 +279,18 @@ SYM_FUNC_START(sha512_transform_ssse3)
 	test msglen, msglen
 	je nowork
 
+	# 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, frame_GPRSAVE(%rsp)
-	mov	%r12, frame_GPRSAVE +8*1(%rsp)
-	mov	%r13, frame_GPRSAVE +8*2(%rsp)
-	mov	%r14, frame_GPRSAVE +8*3(%rsp)
-	mov	%r15, frame_GPRSAVE +8*4(%rsp)
 
 updateblock:
 
@@ -355,15 +351,16 @@ updateblock:
 	dec	msglen
 	jnz	updateblock
 
-	# Restore GPRs
-	mov	frame_GPRSAVE(%rsp),      %rbx
-	mov	frame_GPRSAVE +8*1(%rsp), %r12
-	mov	frame_GPRSAVE +8*2(%rsp), %r13
-	mov	frame_GPRSAVE +8*3(%rsp), %r14
-	mov	frame_GPRSAVE +8*4(%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
 
 nowork:
 	ret