Fix some CFI issues in x86_64 assembly

The add/double shortcut in ecp_nistz256-x86_64.pl left one instruction
point that did not unwind, and the "slow" path in AES_cbc_encrypt was
not annotated correctly. For the latter, add
.cfi_{remember,restore}_state support to perlasm.

Next, fill in a bunch of functions that are missing no-op .cfi_startproc
and .cfi_endproc blocks. libunwind cannot unwind those stack frames
otherwise.

Finally, work around a bug in libunwind by not encoding rflags. (rflags
isn't a callee-saved register, so there's not much need to annotate it
anyway.)

These were found as part of ABI testing work in BoringSSL.

Reviewed-by: Richard Levitte <levitte@openssl.org>
GH: #8109

1 files changed, 34 insertions, 0 deletions

diff --git a/crypto/ec/asm/ecp_nistz256-x86_64.pl b/crypto/ec/asm/ecp_nistz256-x86_64.pl
index 0579f45..a28ee8e 100755
--- a/crypto/ec/asm/ecp_nistz256-x86_64.pl
+++ b/crypto/ec/asm/ecp_nistz256-x86_64.pl
@@ -1674,6 +1674,7 @@ $code.=<<___;
 .type	__ecp_nistz256_mul_montq,\@abi-omnipotent
 .align	32
 __ecp_nistz256_mul_montq:
+.cfi_startproc
 	########################################################################
 	# Multiply a by b[0]
 	mov	%rax, $t1
@@ -1885,6 +1886,7 @@ __ecp_nistz256_mul_montq:
 	mov	$acc1, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_mul_montq,.-__ecp_nistz256_mul_montq
 
 ################################################################################
@@ -1968,6 +1970,7 @@ $code.=<<___;
 .type	__ecp_nistz256_sqr_montq,\@abi-omnipotent
 .align	32
 __ecp_nistz256_sqr_montq:
+.cfi_startproc
 	mov	%rax, $acc5
 	mulq	$acc6			# a[1]*a[0]
 	mov	%rax, $acc1
@@ -2125,6 +2128,7 @@ __ecp_nistz256_sqr_montq:
 	mov	$acc7, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_sqr_montq,.-__ecp_nistz256_sqr_montq
 ___
 
@@ -2133,6 +2137,7 @@ $code.=<<___;
 .type	__ecp_nistz256_mul_montx,\@abi-omnipotent
 .align	32
 __ecp_nistz256_mul_montx:
+.cfi_startproc
 	########################################################################
 	# Multiply by b[0]
 	mulx	$acc1, $acc0, $acc1
@@ -2295,11 +2300,13 @@ __ecp_nistz256_mul_montx:
 	mov	$acc1, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_mul_montx,.-__ecp_nistz256_mul_montx
 
 .type	__ecp_nistz256_sqr_montx,\@abi-omnipotent
 .align	32
 __ecp_nistz256_sqr_montx:
+.cfi_startproc
 	mulx	$acc6, $acc1, $acc2	# a[0]*a[1]
 	mulx	$acc7, $t0, $acc3	# a[0]*a[2]
 	xor	%eax, %eax
@@ -2423,6 +2430,7 @@ __ecp_nistz256_sqr_montx:
 	mov	$acc7, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_sqr_montx,.-__ecp_nistz256_sqr_montx
 ___
 }
@@ -2578,6 +2586,7 @@ ecp_nistz256_scatter_w5:
 .type	ecp_nistz256_gather_w5,\@abi-omnipotent
 .align	32
 ecp_nistz256_gather_w5:
+.cfi_startproc
 ___
 $code.=<<___	if ($avx>1);
 	mov	OPENSSL_ia32cap_P+8(%rip), %eax
@@ -2666,6 +2675,7 @@ $code.=<<___	if ($win64);
 ___
 $code.=<<___;
 	ret
+.cfi_endproc
 .LSEH_end_ecp_nistz256_gather_w5:
 .size	ecp_nistz256_gather_w5,.-ecp_nistz256_gather_w5
 
@@ -2694,6 +2704,7 @@ ecp_nistz256_scatter_w7:
 .type	ecp_nistz256_gather_w7,\@abi-omnipotent
 .align	32
 ecp_nistz256_gather_w7:
+.cfi_startproc
 ___
 $code.=<<___	if ($avx>1);
 	mov	OPENSSL_ia32cap_P+8(%rip), %eax
@@ -2771,6 +2782,7 @@ $code.=<<___	if ($win64);
 ___
 $code.=<<___;
 	ret
+.cfi_endproc
 .LSEH_end_ecp_nistz256_gather_w7:
 .size	ecp_nistz256_gather_w7,.-ecp_nistz256_gather_w7
 ___
@@ -2787,6 +2799,7 @@ $code.=<<___;
 .type	ecp_nistz256_avx2_gather_w5,\@abi-omnipotent
 .align	32
 ecp_nistz256_avx2_gather_w5:
+.cfi_startproc
 .Lavx2_gather_w5:
 	vzeroupper
 ___
@@ -2874,6 +2887,7 @@ $code.=<<___	if ($win64);
 ___
 $code.=<<___;
 	ret
+.cfi_endproc
 .LSEH_end_ecp_nistz256_avx2_gather_w5:
 .size	ecp_nistz256_avx2_gather_w5,.-ecp_nistz256_avx2_gather_w5
 ___
@@ -2893,6 +2907,7 @@ $code.=<<___;
 .type	ecp_nistz256_avx2_gather_w7,\@abi-omnipotent
 .align	32
 ecp_nistz256_avx2_gather_w7:
+.cfi_startproc
 .Lavx2_gather_w7:
 	vzeroupper
 ___
@@ -2995,6 +3010,7 @@ $code.=<<___	if ($win64);
 ___
 $code.=<<___;
 	ret
+.cfi_endproc
 .LSEH_end_ecp_nistz256_avx2_gather_w7:
 .size	ecp_nistz256_avx2_gather_w7,.-ecp_nistz256_avx2_gather_w7
 ___
@@ -3064,6 +3080,7 @@ $code.=<<___;
 .type	__ecp_nistz256_add_toq,\@abi-omnipotent
 .align	32
 __ecp_nistz256_add_toq:
+.cfi_startproc
 	xor	$t4,$t4
 	add	8*0($b_ptr), $a0
 	adc	8*1($b_ptr), $a1
@@ -3091,11 +3108,13 @@ __ecp_nistz256_add_toq:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_add_toq,.-__ecp_nistz256_add_toq
 
 .type	__ecp_nistz256_sub_fromq,\@abi-omnipotent
 .align	32
 __ecp_nistz256_sub_fromq:
+.cfi_startproc
 	sub	8*0($b_ptr), $a0
 	sbb	8*1($b_ptr), $a1
 	 mov	$a0, $t0
@@ -3122,11 +3141,13 @@ __ecp_nistz256_sub_fromq:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_sub_fromq,.-__ecp_nistz256_sub_fromq
 
 .type	__ecp_nistz256_subq,\@abi-omnipotent
 .align	32
 __ecp_nistz256_subq:
+.cfi_startproc
 	sub	$a0, $t0
 	sbb	$a1, $t1
 	 mov	$t0, $a0
@@ -3149,11 +3170,13 @@ __ecp_nistz256_subq:
 	cmovnz	$t3, $a3
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_subq,.-__ecp_nistz256_subq
 
 .type	__ecp_nistz256_mul_by_2q,\@abi-omnipotent
 .align	32
 __ecp_nistz256_mul_by_2q:
+.cfi_startproc
 	xor	$t4, $t4
 	add	$a0, $a0		# a0:a3+a0:a3
 	adc	$a1, $a1
@@ -3181,6 +3204,7 @@ __ecp_nistz256_mul_by_2q:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_mul_by_2q,.-__ecp_nistz256_mul_by_2q
 ___
 									}
@@ -3620,7 +3644,9 @@ $code.=<<___;
 	movq	%xmm1, $a_ptr			# restore $a_ptr
 	movq	%xmm0, $r_ptr			# restore $r_ptr
 	add	\$`32*(18-5)`, %rsp		# difference in frame sizes
+.cfi_adjust_cfa_offset	`-32*(18-5)`
 	jmp	.Lpoint_double_shortcut$x
+.cfi_adjust_cfa_offset	`32*(18-5)`
 
 .align	32
 .Ladd_proceed$x:
@@ -4156,6 +4182,7 @@ $code.=<<___;
 .type	__ecp_nistz256_add_tox,\@abi-omnipotent
 .align	32
 __ecp_nistz256_add_tox:
+.cfi_startproc
 	xor	$t4, $t4
 	adc	8*0($b_ptr), $a0
 	adc	8*1($b_ptr), $a1
@@ -4184,11 +4211,13 @@ __ecp_nistz256_add_tox:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_add_tox,.-__ecp_nistz256_add_tox
 
 .type	__ecp_nistz256_sub_fromx,\@abi-omnipotent
 .align	32
 __ecp_nistz256_sub_fromx:
+.cfi_startproc
 	xor	$t4, $t4
 	sbb	8*0($b_ptr), $a0
 	sbb	8*1($b_ptr), $a1
@@ -4217,11 +4246,13 @@ __ecp_nistz256_sub_fromx:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_sub_fromx,.-__ecp_nistz256_sub_fromx
 
 .type	__ecp_nistz256_subx,\@abi-omnipotent
 .align	32
 __ecp_nistz256_subx:
+.cfi_startproc
 	xor	$t4, $t4
 	sbb	$a0, $t0
 	sbb	$a1, $t1
@@ -4246,11 +4277,13 @@ __ecp_nistz256_subx:
 	cmovc	$t3, $a3
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_subx,.-__ecp_nistz256_subx
 
 .type	__ecp_nistz256_mul_by_2x,\@abi-omnipotent
 .align	32
 __ecp_nistz256_mul_by_2x:
+.cfi_startproc
 	xor	$t4, $t4
 	adc	$a0, $a0		# a0:a3+a0:a3
 	adc	$a1, $a1
@@ -4279,6 +4312,7 @@ __ecp_nistz256_mul_by_2x:
 	mov	$a3, 8*3($r_ptr)
 
 	ret
+.cfi_endproc
 .size	__ecp_nistz256_mul_by_2x,.-__ecp_nistz256_mul_by_2x
 ___
 									}