lib/libc/amd64/SYS.h                       | 20 ++++++++++++++-----
 lib/libc/amd64/gen/_setjmp.S               | 16 +++++++++++++++
 lib/libc/amd64/gen/rfork_thread.S          | 13 +++++++++++++
 lib/libc/amd64/gen/setjmp.S                | 31 ++++++++++++++++++++++++++++++
 lib/libc/amd64/gen/sigsetjmp.S             | 28 +++++++++++++++++++++++++++
 lib/libc/amd64/string/bcopy.S              |  7 +++++++
 lib/libc/amd64/string/bzero.S              |  1 +
 lib/libc/amd64/string/memcmp.S             |  2 ++
 lib/libc/amd64/string/memset.S             |  3 +++
 lib/libc/amd64/string/stpcpy.S             |  6 ++++++
 lib/libc/amd64/string/strcat.S             |  4 ++++
 lib/libc/amd64/string/strcmp.S             |  2 ++
 lib/libc/amd64/sys/brk.S                   |  8 ++++++++
 lib/libc/amd64/sys/cerror.S                |  9 +++++++++
 lib/libc/amd64/sys/exect.S                 |  6 ++++++
 lib/libc/amd64/sys/getcontext.S            | 12 ++++++++++++
 lib/libc/amd64/sys/pipe.S                  |  1 +
 lib/libc/amd64/sys/ptrace.S                |  2 ++
 lib/libc/amd64/sys/reboot.S                |  1 +
 lib/libc/amd64/sys/sbrk.S                  |  9 +++++++++
 lib/libc/amd64/sys/setlogin.S              |  2 ++
 lib/libc/amd64/sys/vfork.S                 |  6 ++++++
 lib/libthr/arch/amd64/amd64/_umtx_op_err.S | 16 ++++++++++++---
 sys/amd64/include/asm.h                    | 28 +++++++++++++++++++--------
 24 files changed, 217 insertions(+), 16 deletions(-)

diff --git a/lib/libc/amd64/SYS.h b/lib/libc/amd64/SYS.h
index a232383..3101be5 100644
--- a/lib/libc/amd64/SYS.h
+++ b/lib/libc/amd64/SYS.h
@@ -41,15 +41,25 @@
 			.set CNAME(x),CNAME(__CONCAT(__sys_,x));	\
 			.weak CNAME(__CONCAT(_,x));			\
 			.set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \
-			mov __CONCAT($SYS_,x),%eax; KERNCALL;		\
-			jb HIDENAME(cerror); ret;			\
+			mov __CONCAT($SYS_,x),%eax;			\
+			.cfi_undefined %rax;				\
+			KERNCALL;					\
+			jb HIDENAME(cerror);				\
+			ret;						\
 			END(__CONCAT(__sys_,x))
 
 #define	PSEUDO(x)	ENTRY(__CONCAT(__sys_,x));			\
 			.weak CNAME(__CONCAT(_,x));			\
 			.set CNAME(__CONCAT(_,x)),CNAME(__CONCAT(__sys_,x)); \
-			mov __CONCAT($SYS_,x),%eax; KERNCALL;		\
-			jb HIDENAME(cerror); ret;			\
+			mov __CONCAT($SYS_,x),%eax;			\
+			.cfi_undefined %rax;				\
+			KERNCALL;					\
+			jb HIDENAME(cerror);				\
+			ret;						\
 			END(__CONCAT(__sys_,x))
 
-#define KERNCALL	movq %rcx, %r10; syscall
+#define KERNCALL	movq %rcx,%r10;					\
+			.cfi_undefined %r10;				\
+			.cfi_register %rcx,%r10;			\
+			syscall;					\
+			.cfi_undefined %rax,%rdx
diff --git a/lib/libc/amd64/gen/_setjmp.S b/lib/libc/amd64/gen/_setjmp.S
index 9035632..84cc0c9 100644
--- a/lib/libc/amd64/gen/_setjmp.S
+++ b/lib/libc/amd64/gen/_setjmp.S
@@ -48,7 +48,9 @@ __FBSDID("$FreeBSD$");
 
 ENTRY(_setjmp)
 	movq	%rdi,%rax
+	.cfi_register	%rdi,%rax
 	movq	0(%rsp),%rdx		/* retval */
+	.cfi_undefined	%rdx
 	movq	%rdx, 0(%rax)		/* 0; retval */
 	movq	%rbx, 8(%rax)		/* 1; rbx */
 	movq	%rsp,16(%rax)		/* 2; rsp */
@@ -60,6 +62,7 @@ ENTRY(_setjmp)
 	fnstcw	64(%rax)		/* 8; fpu cw */
 	stmxcsr	68(%rax)		/*    and mxcsr */
 	xorq	%rax,%rax
+	.cfi_undefined	%rax
 	ret
 END(_setjmp)
 
@@ -67,17 +70,30 @@ END(_setjmp)
 	.set	CNAME(_longjmp),CNAME(___longjmp)
 ENTRY(___longjmp)
 	movq	%rdi,%rdx
+	.cfi_undefined	%rdx
+	.cfi_register	%rdi,%rdx
 	/* Restore the mxcsr, but leave exception flags intact. */
 	stmxcsr	-4(%rsp)
 	movl	68(%rdx),%eax
+	.cfi_undefined	%rax
 	andl	$0xffffffc0,%eax
 	movl	-4(%rsp),%edi
+	.cfi_undefined	%rdi
 	andl	$0x3f,%edi
 	xorl	%eax,%edi
 	movl	%edi,-4(%rsp)
 	ldmxcsr -4(%rsp)
 	movq	%rsi,%rax		/* retval */
+	.cfi_def_cfa	%rdx,16
+	.cfi_offset	%rbx,8
+	.cfi_offset	%rbp,24
+	.cfi_offset	%r12,32
+	.cfi_offset	%r13,40
+	.cfi_offset	%r14,48
+	.cfi_offset	%r15,56
 	movq	0(%rdx),%rcx
+	.cfi_undefined	%rcx
+	.cfi_return_column %rcx
 	movq	8(%rdx),%rbx
 	movq	16(%rdx),%rsp
 	movq	24(%rdx),%rbp
diff --git a/lib/libc/amd64/gen/rfork_thread.S b/lib/libc/amd64/gen/rfork_thread.S
index 5e764db..9ce0484 100644
--- a/lib/libc/amd64/gen/rfork_thread.S
+++ b/lib/libc/amd64/gen/rfork_thread.S
@@ -46,7 +46,11 @@ __FBSDID("$FreeBSD$");
 
 ENTRY(rfork_thread)
 	pushq	%rbx
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%rbx,-8
 	pushq	%r12
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%r12,-16
 	movq	%rdx, %rbx
 	movq	%rcx, %r12
 
@@ -63,7 +67,11 @@ ENTRY(rfork_thread)
 	cmpl	$0, %edx
 	jnz	1f
 	popq	%r12
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore %r12
 	popq	%rbx
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore %rbx
 	ret
 
 	/*
@@ -73,6 +81,7 @@ ENTRY(rfork_thread)
 	 */
 1:
 	movq	%rsi, %rsp
+	.cfi_def_cfa_register	%rsi
 	movq	%r12, %rdi 
 	call	*%rbx
 	movl	%eax, %edi
@@ -92,7 +101,11 @@ ENTRY(rfork_thread)
 	 */
 2:
 	popq	%r12
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore %r12
 	popq	%rbx
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore %rbx
 	jmp	HIDENAME(cerror)
 END(rfork_thread)
 
diff --git a/lib/libc/amd64/gen/setjmp.S b/lib/libc/amd64/gen/setjmp.S
index 47772be..356d34c 100644
--- a/lib/libc/amd64/gen/setjmp.S
+++ b/lib/libc/amd64/gen/setjmp.S
@@ -50,13 +50,21 @@ __FBSDID("$FreeBSD$");
 
 ENTRY(setjmp)
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
 	movq	%rdi,%rcx
+	.cfi_undefined	%rcx
+	.cfi_register	%rdi,%rcx
 	movq	$1,%rdi			/* SIG_BLOCK       */
+	.cfi_undefined	%rdi
 	movq	$0,%rsi			/* (sigset_t*)set  */
+	.cfi_undefined	%rsi
 	leaq	72(%rcx),%rdx		/* 9,10; (sigset_t*)oset */
+	.cfi_undefined	%rdx
 	/* stack is 16-byte aligned */
 	call	PIC_PLT(CNAME(_sigprocmask))
 	popq	%rdi
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore	%rdi
 	movq	%rdi,%rcx
 	movq	0(%rsp),%rdx		/* retval */
 	movq	%rdx, 0(%rcx)		/* 0; retval */
@@ -77,28 +85,51 @@ END(setjmp)
 	.set CNAME(longjmp),CNAME(__longjmp)
 ENTRY(__longjmp)
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%rdi,-8
 	pushq	%rsi
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%rsi,-16
 	movq	%rdi,%rdx
+	.cfi_undefined	%rdx
+	.cfi_register	%rdi,%rdx
 	movq	$3,%rdi			/* SIG_SETMASK     */
 	leaq	72(%rdx),%rsi		/* (sigset_t*)set  */
 	movq	$0,%rdx			/* (sigset_t*)oset */
 	subq	$0x8,%rsp		/* make the stack 16-byte aligned */
+	.cfi_adjust_cfa_offset 8
 	call	PIC_PLT(CNAME(_sigprocmask))
 	addq	$0x8,%rsp
+	.cfi_adjust_cfa_offset -8
 	popq	%rsi
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore	%rsi
 	popq	%rdi			/* jmpbuf */
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore	%rdi
 	movq	%rdi,%rdx
+	.cfi_register	%rdi,%rdx
 	/* Restore the mxcsr, but leave exception flags intact. */
 	stmxcsr	-4(%rsp)
 	movl	68(%rdx),%eax
 	andl	$0xffffffc0,%eax
 	movl	-4(%rsp),%edi
+	.cfi_undefined	%rdi
 	andl	$0x3f,%edi
 	xorl	%eax,%edi
 	movl	%edi,-4(%rsp)
 	ldmxcsr -4(%rsp)
 	movq	%rsi,%rax		/* retval */
+	.cfi_def_cfa	%rdx,16
+	.cfi_offset	%rbx,8
+	.cfi_offset	%rbp,24
+	.cfi_offset	%r12,32
+	.cfi_offset	%r13,40
+	.cfi_offset	%r14,48
+	.cfi_offset	%r15,56
 	movq	0(%rdx),%rcx
+	.cfi_undefined	%rcx
+	.cfi_return_column %rcx
 	movq	8(%rdx),%rbx
 	movq	16(%rdx),%rsp
 	movq	24(%rdx),%rbp
diff --git a/lib/libc/amd64/gen/sigsetjmp.S b/lib/libc/amd64/gen/sigsetjmp.S
index ef90bc6..1568584 100644
--- a/lib/libc/amd64/gen/sigsetjmp.S
+++ b/lib/libc/amd64/gen/sigsetjmp.S
@@ -58,14 +58,22 @@ ENTRY(sigsetjmp)
 	testl	%esi,%esi
 	jz	2f
 	pushq	%rdi
+	.cfi_adjust_cfa_offset -8
 	movq	%rdi,%rcx
+	.cfi_undefined	%rcx
+	.cfi_register	%rdi,%rcx
 	movq	$1,%rdi			/* SIG_BLOCK       */
 	movq	$0,%rsi			/* (sigset_t*)set  */
 	leaq	72(%rcx),%rdx		/* 9,10 (sigset_t*)oset */
+	.cfi_undefined	%rdx
 	/* stack is 16-byte aligned */
 	call	PIC_PLT(CNAME(_sigprocmask))
 	popq	%rdi
+	.cfi_adjust_cfa_offset 8
+	.cfi_restore	%rdi
 2:	movq	%rdi,%rcx
+	.cfi_undefined	%rcx
+	.cfi_register	%rdi,%rcx
 	movq	0(%rsp),%rdx		/* retval */
 	movq	%rdx, 0(%rcx)		/* 0; retval */
 	movq	%rbx, 8(%rcx)		/* 1; rbx */
@@ -86,8 +94,14 @@ ENTRY(__siglongjmp)
 	cmpl	$0,88(%rdi)
 	jz	2f
 	movq	%rdi,%rdx
+	.cfi_undefined	%rdx
+	.cfi_register	%rdi,%rdx
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%rdi,-8
 	pushq	%rsi
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset	%rsi,-16
 	movq	$3,%rdi			/* SIG_SETMASK     */
 	leaq	72(%rdx),%rsi		/* (sigset_t*)set  */
 	movq	$0,%rdx			/* (sigset_t*)oset */
@@ -95,10 +109,24 @@ ENTRY(__siglongjmp)
 	call	PIC_PLT(CNAME(_sigprocmask))
 	addq	$0x8,%rsp
 	popq	%rsi
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore	%rsi
 	popq	%rdi			/* jmpbuf */
+	.cfi_adjust_cfa_offset -8
+	.cfi_restore	%rdi
 2:	movq	%rdi,%rdx
 	movq	%rsi,%rax		/* retval */
 	movq	0(%rdx),%rcx
+	.cfi_endproc
+	.cfi_startproc
+	.cfi_return_column %rcx
+	.cfi_def_cfa	%rdx,0
+	.cfi_offset	%rbx,8
+	.cfi_offset	%rbp,24
+	.cfi_offset	%r12,32
+	.cfi_offset	%r13,40
+	.cfi_offset	%r14,48
+	.cfi_offset	%r15,56
 	movq	8(%rdx),%rbx
 	movq	16(%rdx),%rsp
 	movq	24(%rdx),%rbp
diff --git a/lib/libc/amd64/string/bcopy.S b/lib/libc/amd64/string/bcopy.S
index cc38f47..378cb45 100644
--- a/lib/libc/amd64/string/bcopy.S
+++ b/lib/libc/amd64/string/bcopy.S
@@ -54,9 +54,12 @@ ENTRY(bcopy)
 	movq	%rdi,%rax	/* return dst */
 #else
 	xchgq	%rdi,%rsi
+	.cfi_register	%rdi,%rsi
+	.cfi_register	%rsi,%rdi
 #endif
 	movq	%rdx,%rcx
 	movq	%rdi,%r8
+	.cfi_undefined	%r8
 	subq	%rsi,%r8
 	cmpq	%rcx,%r8	/* overlapping? */
 	jb	1f
@@ -64,6 +67,8 @@ ENTRY(bcopy)
 	shrq	$3,%rcx		/* copy by words */
 	rep
 	movsq
+	.cfi_undefined	%rdi
+	.cfi_undefined	%rsi
 	movq	%rdx,%rcx
 	andq	$7,%rcx		/* any bytes left? */
 	rep
@@ -71,7 +76,9 @@ ENTRY(bcopy)
 	ret
 1:
 	addq	%rcx,%rdi	/* copy backwards. */
+	.cfi_undefined	%rdi
 	addq	%rcx,%rsi
+	.cfi_undefined	%rsi
 	std
 	andq	$7,%rcx		/* any fractional bytes? */
 	decq	%rdi
diff --git a/lib/libc/amd64/string/bzero.S b/lib/libc/amd64/string/bzero.S
index cf46a2a..e2acb56 100644
--- a/lib/libc/amd64/string/bzero.S
+++ b/lib/libc/amd64/string/bzero.S
@@ -27,6 +27,7 @@ ENTRY(bzero)
 	negq	%rcx
 	andq	$7,%rcx
 	subq	%rcx,%rsi
+	.cfi_undefined	%rsi
 	rep				/* zero until word aligned */
 	stosb
 
diff --git a/lib/libc/amd64/string/memcmp.S b/lib/libc/amd64/string/memcmp.S
index 66d64a0..a794238 100644
--- a/lib/libc/amd64/string/memcmp.S
+++ b/lib/libc/amd64/string/memcmp.S
@@ -17,6 +17,8 @@ ENTRY(memcmp)
 	shrq	$3,%rcx
 	repe
 	cmpsq
+	.cfi_undefined	%rsi
+	.cfi_undefined	%rdi
 	jne	L5			/* do we match so far? */
 
 	movq	%rdx,%rcx		/* compare remainder by bytes */
diff --git a/lib/libc/amd64/string/memset.S b/lib/libc/amd64/string/memset.S
index 84d1562..bec8654 100644
--- a/lib/libc/amd64/string/memset.S
+++ b/lib/libc/amd64/string/memset.S
@@ -16,6 +16,7 @@ ENTRY(memset)
 	andq	$0xff,%rax
 	movq	%rdx,%rcx
 	movq	%rdi,%r11
+	.cfi_undefined	%r11
 
 	cld				/* set fill direction forward */
 
@@ -45,6 +46,7 @@ ENTRY(memset)
 	movq	%rdx,%rcx		/* set until word aligned */
 	rep
 	stosb
+	.cfi_undefined	%rdi
 
 	movq	%r8,%rcx
 	shrq	$3,%rcx			/* set by words */
@@ -55,6 +57,7 @@ ENTRY(memset)
 	andq	$7,%rcx
 L1:	rep
 	stosb
+	.cfi_undefined	%rdi
 	movq	%r11,%rax
 
 	ret
diff --git a/lib/libc/amd64/string/stpcpy.S b/lib/libc/amd64/string/stpcpy.S
index 52ac69c..95054dc 100644
--- a/lib/libc/amd64/string/stpcpy.S
+++ b/lib/libc/amd64/string/stpcpy.S
@@ -24,7 +24,9 @@ __FBSDID("$FreeBSD$");
 ENTRY(stpcpy)
 __stpcpy:
 	movabsq $0x0101010101010101,%r8
+	.cfi_undefined	%r8
 	movabsq $0x8080808080808080,%r9
+	.cfi_undefined	%r9
 
 	/*
 	 * Align source to a word boundary.
@@ -35,8 +37,10 @@ __stpcpy:
 	je	.Lword_aligned
 	movb	(%rsi),%dl
 	incq	%rsi
+	.cfi_undefined	%rsi
 	movb	%dl,(%rdi)
 	incq	%rdi
+	.cfi_undefined	%rdi
 	testb	%dl,%dl
 	jne	.Lalign
 	movq	%rdi,%rax
@@ -51,6 +55,7 @@ __stpcpy:
 	movq	(%rsi),%rdx
 	movq	%rdx,%rcx
 	addq	$8,%rsi
+	.cfi_undefined	%rsi
 	subq	%r8,%rcx
 	testq	%r9,%rcx
 	je	.Lloop
@@ -64,6 +69,7 @@ __stpcpy:
 	testb	%dl,%dl		/* 1st byte == 0? */
 	je	.Ldone
 	incq	%rdi
+	.cfi_undefined	%rdi
 
 	shrq	$8,%rdx
 	movb	%dl,(%rdi)
diff --git a/lib/libc/amd64/string/strcat.S b/lib/libc/amd64/string/strcat.S
index 7b5a1dd..daaaac1 100644
--- a/lib/libc/amd64/string/strcat.S
+++ b/lib/libc/amd64/string/strcat.S
@@ -33,6 +33,7 @@ ENTRY(strcat)
 .Lscan_loop:
 	movq	(%rdi),%rdx
 	addq	$8,%rdi
+	.cfi_undefined	%rdi
 	subq	%r8,%rdx
 	testq	%r9,%rdx
 	je	.Lscan_loop
@@ -91,6 +92,7 @@ ENTRY(strcat)
 	je	.Lcopy_aligned
 	movb	(%rsi),%dl
 	incq	%rsi
+	.cfi_undefined	%rsi
 	movb	%dl,(%rdi)
 	incq	%rdi
 	testb	%dl,%dl
@@ -101,10 +103,12 @@ ENTRY(strcat)
 .Lcopy_loop:
 	movq	%rdx,(%rdi)
 	addq	$8,%rdi
+	.cfi_undefined	%rdi
 .Lcopy_aligned:
 	movq	(%rsi),%rdx
 	movq	%rdx,%rcx
 	addq	$8,%rsi
+	.cfi_undefined	%rsi
 	subq	%r8,%rcx
 	testq	%r9,%rcx
 	je	.Lcopy_loop
diff --git a/lib/libc/amd64/string/strcmp.S b/lib/libc/amd64/string/strcmp.S
index 07009c1..2132187 100644
--- a/lib/libc/amd64/string/strcmp.S
+++ b/lib/libc/amd64/string/strcmp.S
@@ -20,8 +20,10 @@ ENTRY(strcmp)
 	je	.Ls1aligned
 	movb	(%rdi),%al
 	incq	%rdi
+	.cfi_undefined	%rdi
 	movb	(%rsi),%dl
 	incq	%rsi
+	.cfi_undefined	%rsi
 	testb	%al,%al
 	je	.Ldone
 	cmpb	%al,%dl
diff --git a/lib/libc/amd64/sys/brk.S b/lib/libc/amd64/sys/brk.S
index 4048ae6..76e6280 100644
--- a/lib/libc/amd64/sys/brk.S
+++ b/lib/libc/amd64/sys/brk.S
@@ -42,14 +42,18 @@ __FBSDID("$FreeBSD$");
 	.globl	HIDENAME(minbrk)
 ENTRY(_brk)
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
 	jmp	ok
 END(_brk)
 
 ENTRY(brk)
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
 	movq	%rdi,%rax
+	.cfi_undefined	%rax
 #ifdef PIC
 	movq	PIC_GOT(HIDENAME(minbrk)),%rdx
+	.cfi_undefined	%rdx
 	cmpq	%rax,(%rdx)
 #else
 	cmpq	%rax,HIDENAME(minbrk)(%rip)
@@ -60,8 +64,10 @@ ENTRY(brk)
 #else
 	movq	HIDENAME(minbrk)(%rip),%rdi
 #endif
+	.cfi_undefined	%rdi
 ok:
 	movq	$SYS_break,%rax
+	.cfi_undefined	%rax
 	KERNCALL
 	jb	err
 	movq	0(%rsp),%rax
@@ -73,9 +79,11 @@ ok:
 #endif
 	movq	$0,%rax
 	popq	%rdi
+	.cfi_adjust_cfa_offset -8
 	ret
 err:
 	addq	$8, %rsp
+	.cfi_adjust_cfa_offset -8
 	jmp	HIDENAME(cerror)
 END(brk)
 
diff --git a/lib/libc/amd64/sys/cerror.S b/lib/libc/amd64/sys/cerror.S
index d01cf4a..43032e4 100644
--- a/lib/libc/amd64/sys/cerror.S
+++ b/lib/libc/amd64/sys/cerror.S
@@ -48,12 +48,21 @@ __FBSDID("$FreeBSD$");
 	.globl	CNAME(__error)
 	.type	CNAME(__error),@function
 HIDENAME(cerror):
+	.cfi_startproc
 	pushq	%rax
+	.cfi_adjust_cfa_offset 8
+	.cfi_offset %rax,0
 	call	PIC_PLT(CNAME(__error))
 	popq	%rcx
+	.cfi_adjust_cfa_offset -8
+	.cfi_undefined %rcx
+	.cfi_register %rax,%rcx
 	movl	%ecx,(%rax)
 	movq	$-1,%rax
+	.cfi_undefined %rax
 	movq	$-1,%rdx
+	.cfi_undefined %rdx
 	ret
+	.cfi_endproc
 
 	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/amd64/sys/exect.S b/lib/libc/amd64/sys/exect.S
index 04a97ed..ce5e717 100644
--- a/lib/libc/amd64/sys/exect.S
+++ b/lib/libc/amd64/sys/exect.S
@@ -41,11 +41,17 @@ __FBSDID("$FreeBSD$");
 
 ENTRY(exect)
 	movq	$SYS_execve,%rax
+	.cfi_undefined	%rax
 	pushfq
+	.cfi_adjust_cfa_offset 8
 	popq	%r8
+	.cfi_adjust_cfa_offset -8
+	.cfi_undefined	%r8
 	orq	$PSL_T,%r8
 	pushq	%r8
+	.cfi_adjust_cfa_offset 8
 	popfq
+	.cfi_adjust_cfa_offset -8
 	KERNCALL
 	jmp	HIDENAME(cerror)
 END(exect)
diff --git a/lib/libc/amd64/sys/getcontext.S b/lib/libc/amd64/sys/getcontext.S
index 1128796..94c894c 100644
--- a/lib/libc/amd64/sys/getcontext.S
+++ b/lib/libc/amd64/sys/getcontext.S
@@ -40,10 +40,22 @@ __FBSDID("$FreeBSD$");
 	.set	getcontext,__sys_getcontext
 ENTRY(__sys_getcontext)
 	movq	(%rsp),%rsi	/* save getcontext return address */
+	.cfi_undefined	%rsi
 	mov	$SYS_getcontext,%rax
+	.cfi_undefined	%rax
 	KERNCALL
 	jb	HIDENAME(cerror)
 	addq	$8,%rsp		/* remove stale (setcontext) return address */
+	/*
+	 * The instruction above adjusted top of the stack so that the stack
+	 * does not contain a return address anymore.  But, due to the red
+	 * zone existence, return address value right below the top of stack
+	 * is non-volatile. Try to describe the trick to unwinder by claiming
+	 * that the standard call frame is one long word below top of the
+	 * stack.
+	 */
+	.cfi_adjust_cfa_offset 8
+	.cfi_return_column	%rsi
 	jmp	*%rsi		/* restore return address */
 END(__sys_getcontext)
 
diff --git a/lib/libc/amd64/sys/pipe.S b/lib/libc/amd64/sys/pipe.S
index 8d089db..6eee962 100644
--- a/lib/libc/amd64/sys/pipe.S
+++ b/lib/libc/amd64/sys/pipe.S
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 	.set	pipe,__sys_pipe
 ENTRY(__sys_pipe)
 	mov	$SYS_pipe,%rax
+	.cfi_undefined %rax
 	KERNCALL
 	jb	HIDENAME(cerror)
 	movl	%eax,(%rdi)	/* %rdi is preserved by syscall */
diff --git a/lib/libc/amd64/sys/ptrace.S b/lib/libc/amd64/sys/ptrace.S
index 9c4628d..5dbde65 100644
--- a/lib/libc/amd64/sys/ptrace.S
+++ b/lib/libc/amd64/sys/ptrace.S
@@ -40,8 +40,10 @@ __FBSDID("$FreeBSD$");
 
 ENTRY(ptrace)
 	xorl	%eax,%eax
+	.cfi_undefined	%rax
 #ifdef PIC
 	movq	PIC_GOT(CNAME(errno)),%r8
+	.cfi_undefined	%r8
 	movl	%eax,(%r8)
 #else
 	movl	%eax,CNAME(errno)(%rip)
diff --git a/lib/libc/amd64/sys/reboot.S b/lib/libc/amd64/sys/reboot.S
index fd04ef4..57fa2df 100644
--- a/lib/libc/amd64/sys/reboot.S
+++ b/lib/libc/amd64/sys/reboot.S
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 	.set	reboot,__sys_reboot
 ENTRY(__sys_reboot)
 	mov	$SYS_reboot,%rax
+	.cfi_undefined %rax
 	KERNCALL
 	jb	HIDENAME(cerror)
 	iretq
diff --git a/lib/libc/amd64/sys/sbrk.S b/lib/libc/amd64/sys/sbrk.S
index 0332aae..f0e3c6b 100644
--- a/lib/libc/amd64/sys/sbrk.S
+++ b/lib/libc/amd64/sys/sbrk.S
@@ -49,16 +49,22 @@ HIDENAME(curbrk):	.quad	CNAME(_end)
 
 ENTRY(sbrk)
 	pushq	%rdi
+	.cfi_adjust_cfa_offset 8
 	movq	%rdi,%rcx
+	.cfi_register %rdi,%rcx
 #ifdef PIC
 	movq	PIC_GOT(HIDENAME(curbrk)),%rdx
+	.cfi_undefined	%rdx
 	movq	(%rdx),%rax
+	.cfi_undefined	%rax
 #else
 	movq	HIDENAME(curbrk)(%rip),%rax
+	.cfi_undefined	%rax
 #endif
 	testq	%rcx,%rcx
 	jz	back
 	addq	%rax,%rdi
+	.cfi_undefined	%rdi
 	mov	$SYS_break,%eax
 	KERNCALL
 	jb	err
@@ -69,6 +75,7 @@ ENTRY(sbrk)
 	movq	HIDENAME(curbrk)(%rip),%rax
 #endif
 	movq	0(%rsp), %rcx
+	.cfi_undefined	%rcx
 #ifdef PIC
 	addq	%rcx,(%rdx)
 #else
@@ -76,9 +83,11 @@ ENTRY(sbrk)
 #endif
 back:
 	addq	$8, %rsp
+	.cfi_adjust_cfa_offset -8
 	ret
 err:
 	addq	$8, %rsp
+	.cfi_adjust_cfa_offset -8
 	jmp	HIDENAME(cerror)
 END(sbrk)
 
diff --git a/lib/libc/amd64/sys/setlogin.S b/lib/libc/amd64/sys/setlogin.S
index a451491..86b220c 100644
--- a/lib/libc/amd64/sys/setlogin.S
+++ b/lib/libc/amd64/sys/setlogin.S
@@ -46,10 +46,12 @@ __FBSDID("$FreeBSD$");
 	.set	setlogin,__sys_setlogin
 ENTRY(__sys_setlogin)
 	mov	$SYS_setlogin,%rax
+	.cfi_undefined	%rax
 	KERNCALL
 	jb	HIDENAME(cerror)
 #ifdef PIC
 	movq	PIC_GOT(CNAME(_logname_valid)),%rdx
+	.cfi_undefined %rdx
 	movl	$0,(%rdx)
 #else
 	movl	$0,CNAME(_logname_valid)(%rip)
diff --git a/lib/libc/amd64/sys/vfork.S b/lib/libc/amd64/sys/vfork.S
index 2afba58..c2673da 100644
--- a/lib/libc/amd64/sys/vfork.S
+++ b/lib/libc/amd64/sys/vfork.S
@@ -44,12 +44,18 @@ __FBSDID("$FreeBSD$");
 	.set	vfork,__sys_vfork
 ENTRY(__sys_vfork)
 	popq	%rsi		/* fetch return address (%rsi preserved) */
+	/* See a comment in getcontext.S */
+	.cfi_adjust_cfa_offset -8
+	.cfi_undefined	%rsi
+	.cfi_return_column %rsi
 	mov	$SYS_vfork,%rax
+	.cfi_undefined	%rax
 	KERNCALL
 	jb	1f
 	jmp	*%rsi
 1:
 	pushq	%rsi
+	.cfi_adjust_cfa_offset 8
 	jmp	HIDENAME(cerror)
 END(__sys_vfork)
 
diff --git a/lib/libthr/arch/amd64/amd64/_umtx_op_err.S b/lib/libthr/arch/amd64/amd64/_umtx_op_err.S
index b54fe64..36d6cf4 100644
--- a/lib/libthr/arch/amd64/amd64/_umtx_op_err.S
+++ b/lib/libthr/arch/amd64/amd64/_umtx_op_err.S
@@ -29,10 +29,20 @@
 #include <sys/syscall.h>
 #include <machine/asm.h>
 
-#define	RSYSCALL_ERR(x)	ENTRY(__CONCAT(x, _err));		\
-			mov __CONCAT($SYS_,x),%rax; KERNCALL; ret; 
+#define	RSYSCALL_ERR(x)						\
+	ENTRY(__CONCAT(x, _err));				\
+	mov __CONCAT($SYS_,x),%rax;				\
+	.cfi_undefined	%rax;					\
+	KERNCALL;						\
+	ret;							\
+	END(__CONCAT(x, _err))
 
-#define KERNCALL	movq %rcx, %r10; syscall
+#define KERNCALL						\
+	movq %rcx,%r10;						\
+	.cfi_undefined %r10;					\
+	.cfi_register %rcx,%r10;				\
+	syscall;						\
+	.cfi_undefined %rax,%rdx
 
 RSYSCALL_ERR(_umtx_op)
 
diff --git a/sys/amd64/include/asm.h b/sys/amd64/include/asm.h
index 7efd642..75603ec 100644
--- a/sys/amd64/include/asm.h
+++ b/sys/amd64/include/asm.h
@@ -59,25 +59,37 @@
 #define _START_ENTRY	.text; .p2align 4,0x90
 
 #define _ENTRY(x)	_START_ENTRY; \
-			.globl CNAME(x); .type CNAME(x),@function; CNAME(x):
+			.globl CNAME(x); .type CNAME(x),@function; \
+			CNAME(x): .cfi_startproc
 
 #ifdef PROF
-#define	ALTENTRY(x)	_ENTRY(x); \
-			pushq %rbp; movq %rsp,%rbp; \
+#define	ALTENTRY(x)	_ENTRY(x);			\
+			pushq %rbp;			\
+			.cfi_adjust_cfa_offset 8;	\
+			.cfi_offset %rbp,0		\
+			movq %rsp,%rbp;			\
 			call PIC_PLT(HIDENAME(mcount)); \
-			popq %rbp; \
+			popq %rbp;			\
+			.cfi_adjust_cfa_offset -8;	\
+			.cfi_restore %rbp;		\
 			jmp 9f
-#define	ENTRY(x)	_ENTRY(x); \
-			pushq %rbp; movq %rsp,%rbp; \
+#define	ENTRY(x)	_ENTRY(x);			\
+			pushq %rbp;			\
+			.cfi_adjust_cfa_offset 8;	\
+			.cfi_offset %rbp,0		\
+			movq %rsp,%rbp;			\
 			call PIC_PLT(HIDENAME(mcount)); \
-			popq %rbp; \
+			popq %rbp;			\
+			.cfi_adjust_cfa_offset -8;	\
+			.cfi_restore %rbp;		\
 			9:
 #else
 #define	ALTENTRY(x)	_ENTRY(x)
 #define	ENTRY(x)	_ENTRY(x)
 #endif
 
-#define	END(x)		.size x, . - x
+#define	END(x)		.cfi_endproc;			\
+			.size x, . - x
 
 #define RCSID(x)	.text; .asciz x