[PATCH 3/3] lib/crypto: x86/sha512: Follow the normal %rbp convention

[Eric Biggers <ebiggers@kernel.org>]

The SHA-512 assembly functions push callee-save GPRs to the stack
*before* they set up the frame pointer (%rbp).  (They are leaf
functions, but they need to set up a frame pointer anyway because they
allocate a 32-byte-aligned buffer on the stack.)

As a result, during these functions, 8(%rbp) doesn't contain a return
address like it is supposed to.

This differs from the convention used by C code, and it interferes with
the frame pointer unwinder (CONFIG_UNWINDER_FRAME_POINTER=y).
Specifically, if a call trace is dumped in these functions, then all
entries are populated purely from the fallback scan of the entire stack:

    RIP: 0010:sha512_transform_rorx+0x673/0xdf0
    [...]
    Call Trace:
     <TASK>
     ? sha512_blocks_avx2+0x37/0x60
     ? __sha512_update+0x80/0x230
     ? sha512+0x31/0x190
     ? sha512+0x114/0x190
     [...]
     ? do_syscall_64+0x6f/0x3e0

With this fix to follow the normal %rbp convention, the call trace is
generated reliably:

    RIP: 0010:sha512_transform_rorx+0x90c/0xdf0
    [...]
    Call Trace:
     <TASK>
     sha512_blocks_avx2+0x37/0x60
     __sha512_update+0x80/0x230
     sha512+0x114/0x190
     [...]
     do_syscall_64+0x6f/0x3e0

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 lib/crypto/x86/sha512-avx-asm.S   | 11 ++++++-----
 lib/crypto/x86/sha512-avx2-asm.S  | 11 ++++++-----
 lib/crypto/x86/sha512-ssse3-asm.S | 11 ++++++-----
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/lib/crypto/x86/sha512-avx-asm.S b/lib/crypto/x86/sha512-avx-asm.S
index 7732aa8fd850..a17dfedc1c51 100644
--- a/lib/crypto/x86/sha512-avx-asm.S
+++ b/lib/crypto/x86/sha512-avx-asm.S
@@ -276,6 +276,9 @@ frame_size = frame_WK + WK_SIZE
 ########################################################################
 SYM_FUNC_START(sha512_transform_avx)
 
+	push	%rbp
+	mov	%rsp, %rbp
+
 	# Save GPRs
 	push	%rbx
 	push	%r12
@@ -284,8 +287,6 @@ SYM_FUNC_START(sha512_transform_avx)
 	push	%r15
 
 	# Allocate Stack Space
-	push	%rbp
-	mov	%rsp, %rbp
 	sub     $frame_size, %rsp
 	and	$~(0x20 - 1), %rsp
 
@@ -348,9 +349,8 @@ SYM_FUNC_START(sha512_transform_avx)
 	dec     msglen
 	jnz     .Lupdateblock
 
-	# Restore Stack Pointer
-	mov	%rbp, %rsp
-	pop	%rbp
+	# Deallocate Stack Space
+	lea	-40(%rbp), %rsp
 
 	# Restore GPRs
 	pop	%r15
@@ -358,6 +358,7 @@ SYM_FUNC_START(sha512_transform_avx)
 	pop	%r13
 	pop	%r12
 	pop	%rbx
+	pop	%rbp
 
 	RET
 SYM_FUNC_END(sha512_transform_avx)
diff --git a/lib/crypto/x86/sha512-avx2-asm.S b/lib/crypto/x86/sha512-avx2-asm.S
index 22bdbfd899d0..2256d51297e1 100644
--- a/lib/crypto/x86/sha512-avx2-asm.S
+++ b/lib/crypto/x86/sha512-avx2-asm.S
@@ -568,6 +568,9 @@ frame_size = frame_CTX + CTX_SIZE
 ########################################################################
 SYM_FUNC_START(sha512_transform_rorx)
 
+	push	%rbp
+	mov	%rsp, %rbp
+
 	# Save GPRs
 	push	%rbx
 	push	%r12
@@ -576,8 +579,6 @@ SYM_FUNC_START(sha512_transform_rorx)
 	push	%r15
 
 	# Allocate Stack Space
-	push	%rbp
-	mov	%rsp, %rbp
 	sub	$frame_size, %rsp
 	and	$~(0x20 - 1), %rsp
 
@@ -667,9 +668,8 @@ SYM_FUNC_START(sha512_transform_rorx)
 	cmp	frame_INPEND(%rsp), INP
 	jne	.Lloop0
 
-	# Restore Stack Pointer
-	mov	%rbp, %rsp
-	pop	%rbp
+	# Deallocate Stack Space
+	lea	-40(%rbp), %rsp
 
 	# Restore GPRs
 	pop	%r15
@@ -677,6 +677,7 @@ SYM_FUNC_START(sha512_transform_rorx)
 	pop	%r13
 	pop	%r12
 	pop	%rbx
+	pop	%rbp
 
 	vzeroupper
 	RET
diff --git a/lib/crypto/x86/sha512-ssse3-asm.S b/lib/crypto/x86/sha512-ssse3-asm.S
index 4cae7445b2a8..1a37b7a735cf 100644
--- a/lib/crypto/x86/sha512-ssse3-asm.S
+++ b/lib/crypto/x86/sha512-ssse3-asm.S
@@ -275,6 +275,9 @@ frame_size = frame_WK + WK_SIZE
 ########################################################################
 SYM_FUNC_START(sha512_transform_ssse3)
 
+	push	%rbp
+	mov	%rsp, %rbp
+
 	# Save GPRs
 	push	%rbx
 	push	%r12
@@ -283,8 +286,6 @@ SYM_FUNC_START(sha512_transform_ssse3)
 	push	%r15
 
 	# Allocate Stack Space
-	push	%rbp
-	mov	%rsp, %rbp
 	sub	$frame_size, %rsp
 	and	$~(0x20 - 1), %rsp
 
@@ -347,9 +348,8 @@ SYM_FUNC_START(sha512_transform_ssse3)
 	dec	msglen
 	jnz	.Lupdateblock
 
-	# Restore Stack Pointer
-	mov	%rbp, %rsp
-	pop	%rbp
+	# Deallocate Stack Space
+	lea	-40(%rbp), %rsp
 
 	# Restore GPRs
 	pop	%r15
@@ -357,6 +357,7 @@ SYM_FUNC_START(sha512_transform_ssse3)
 	pop	%r13
 	pop	%r12
 	pop	%rbx
+	pop	%rbp
 
 	RET
 SYM_FUNC_END(sha512_transform_ssse3)
-- 
2.56.0