Reimplement brk() and sbrk() to avoid the use of _end.

Previously, libc.so would initialize its notion of the break address
using _end, a special symbol emitted by the static linker following
the bss section.  Compatibility issues between lld and ld.bfd could
cause the wrong definition of _end (libc.so's definition rather than
that of the executable) to be used, breaking the brk()/sbrk()
interface.

Avoid this problem and future interoperability issues by simply not
relying on _end.  Instead, modify the break() system call to return
the kernel's view of the current break address, and have libc
initialize its state using an extra syscall upon the first use of the
interface.  As a side effect, this appears to fix brk()/sbrk() usage
in executables run with rtld direct exec, since the kernel and libc.so
no longer maintain separate views of the process' break address.

PR:		228574
Reviewed by:	kib (previous version)
MFC after:	2 months
Differential Revision:	https://reviews.freebsd.org/D15663

34 files changed, 277 insertions, 1111 deletions

diff --git a/lib/libc/amd64/Symbol.map b/lib/libc/amd64/Symbol.map
index 7405e4c1dede..7b1f7b7301ca 100644
--- a/lib/libc/amd64/Symbol.map
+++ b/lib/libc/amd64/Symbol.map
@@ -63,7 +63,6 @@ FBSDprivate_1.0 {
 	signalcontext;
 	__siglongjmp;
 	_brk;
-	_end;
 	__sys_vfork;
 	_vfork;
 };
diff --git a/lib/libc/amd64/sys/Makefile.inc b/lib/libc/amd64/sys/Makefile.inc
index 750d5a886be3..8463750692c6 100644
--- a/lib/libc/amd64/sys/Makefile.inc
+++ b/lib/libc/amd64/sys/Makefile.inc
@@ -8,7 +8,7 @@ SRCS+=	\
 	amd64_set_fsbase.c \
 	amd64_set_gsbase.c
 
-MDASM=	vfork.S brk.S cerror.S getcontext.S sbrk.S
+MDASM=	vfork.S cerror.S getcontext.S
 
 # Don't generate default code for these syscalls:
-NOASM+=	vfork.o
+NOASM+=	sbrk.o vfork.o
diff --git a/lib/libc/amd64/sys/brk.S b/lib/libc/amd64/sys/brk.S
deleted file mode 100644
index 60ecd96087e6..000000000000
--- a/lib/libc/amd64/sys/brk.S
+++ /dev/null
@@ -1,82 +0,0 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * William Jolitz.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)brk.s	5.2 (Berkeley) 12/17/90"
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	HIDENAME(curbrk)
-	.globl	HIDENAME(minbrk)
-ENTRY(_brk)
-	pushq	%rdi
-	jmp	ok
-END(_brk)
-
-ENTRY(brk)
-	pushq	%rdi
-	movq	%rdi,%rax
-#ifdef PIC
-	movq	PIC_GOT(HIDENAME(minbrk)),%rdx
-	cmpq	%rax,(%rdx)
-#else
-	cmpq	%rax,HIDENAME(minbrk)(%rip)
-#endif
-	jbe	ok
-#ifdef PIC
-	movq	(%rdx),%rdi
-#else
-	movq	HIDENAME(minbrk)(%rip),%rdi
-#endif
-ok:
-	movq	$SYS_break,%rax
-	KERNCALL
-	jb	err
-	movq	0(%rsp),%rax
-#ifdef PIC
-	movq	PIC_GOT(HIDENAME(curbrk)),%rdx
-	movq	%rax,(%rdx)
-#else
-	movq	%rax,HIDENAME(curbrk)(%rip)
-#endif
-	movq	$0,%rax
-	popq	%rdi
-	ret
-err:
-	addq	$8, %rsp
-	jmp	HIDENAME(cerror)
-END(brk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/amd64/sys/sbrk.S b/lib/libc/amd64/sys/sbrk.S
deleted file mode 100644
index 025282ed226e..000000000000
--- a/lib/libc/amd64/sys/sbrk.S
+++ /dev/null
@@ -1,85 +0,0 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * William Jolitz.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)sbrk.s	5.1 (Berkeley) 4/23/90"
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	CNAME(_end)
-	.globl	HIDENAME(minbrk)
-	.globl	HIDENAME(curbrk)
-
-	.data
-HIDENAME(minbrk):	.quad	CNAME(_end)
-HIDENAME(curbrk):	.quad	CNAME(_end)
-	.text
-
-ENTRY(sbrk)
-	pushq	%rdi
-	movq	%rdi,%rcx
-#ifdef PIC
-	movq	PIC_GOT(HIDENAME(curbrk)),%rdx
-	movq	(%rdx),%rax
-#else
-	movq	HIDENAME(curbrk)(%rip),%rax
-#endif
-	testq	%rcx,%rcx
-	jz	back
-	addq	%rax,%rdi
-	mov	$SYS_break,%eax
-	KERNCALL
-	jb	err
-#ifdef PIC
-	movq	PIC_GOT(HIDENAME(curbrk)),%rdx
-	movq	(%rdx),%rax
-#else
-	movq	HIDENAME(curbrk)(%rip),%rax
-#endif
-	movq	0(%rsp), %rcx
-#ifdef PIC
-	addq	%rcx,(%rdx)
-#else
-	addq	%rcx,HIDENAME(curbrk)(%rip)
-#endif
-back:
-	addq	$8, %rsp
-	ret
-err:
-	addq	$8, %rsp
-	jmp	HIDENAME(cerror)
-END(sbrk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/arm/Symbol.map b/lib/libc/arm/Symbol.map
index ad1b1b01ffec..6c3f2765f8b0 100644
--- a/lib/libc/arm/Symbol.map
+++ b/lib/libc/arm/Symbol.map
@@ -58,7 +58,6 @@ FBSDprivate_1.0 {
 	__sys_vfork;
 	_vfork;
 	_brk;
-	_end;
 	_sbrk;
 
 	_libc_arm_fpu_present;
diff --git a/lib/libc/arm/sys/Makefile.inc b/lib/libc/arm/sys/Makefile.inc
index 42afe22a5e99..be6a58f8aaf5 100644
--- a/lib/libc/arm/sys/Makefile.inc
+++ b/lib/libc/arm/sys/Makefile.inc
@@ -2,7 +2,7 @@
 
 SRCS+=	__vdso_gettc.c
 
-MDASM= Ovfork.S brk.S cerror.S sbrk.S syscall.S
+MDASM= Ovfork.S cerror.S syscall.S
 
 # Don't generate default code for these syscalls:
-NOASM+=	vfork.o
+NOASM+=	sbrk.o vfork.o
diff --git a/lib/libc/arm/sys/brk.S b/lib/libc/arm/sys/brk.S
deleted file mode 100644
index bf1b4fb61d7b..000000000000
--- a/lib/libc/arm/sys/brk.S
+++ /dev/null
@@ -1,95 +0,0 @@
-/*	$NetBSD: brk.S,v 1.6 2003/08/07 16:42:04 agc Exp $	*/
-
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- *	from: @(#)brk.s	5.2 (Berkeley) 12/17/90
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-#include "SYS.h"
-
-	.globl	_C_LABEL(_end)
-	.globl	CURBRK
-
-#ifdef WEAK_ALIAS
-WEAK_ALIAS(brk, _brk)
-#endif
-
-	.data
-	.align	0
-	.globl	_C_LABEL(minbrk)
-	.type	_C_LABEL(minbrk),#object
-_C_LABEL(minbrk):
-	.word	_C_LABEL(_end)
-
-/*
- * Change the data segment size
- */
-ENTRY(_brk)
-	/* Setup the GOT */
-	GOT_INIT(r3, .Lgot, .L1)
-	GOT_GET(r1, r3, .Lminbrk)
-
-	/* Get the minimum allowable brk address */
-	ldr	r1, [r1]
-
-	/*
-	 * Valid the address specified and set to the minimum
-	 * if the address is below minbrk.
-	 */
-	cmp	r0, r1
-	it	lt
-	movlt	r0, r1
-	mov	r2, r0
-	SYSTRAP(break)
-	bcs	PIC_SYM(CERROR, PLT)
-
-#ifdef PIC
-	ldr	r1, .Lcurbrk
-	ldr	r1, [r3, r1]
-#else
-	ldr	r1, .Lcurbrk
-#endif
-	/* Store the new address in curbrk */
-	str	r2, [r1]
-
-	/* Return 0 for success */
-	mov	r0, #0x00000000
-	RET
-
-	.align	2
-	GOT_INITSYM(.Lgot, .L1)
-.Lminbrk:
-	.word	PIC_SYM(_C_LABEL(minbrk), GOT)
-.Lcurbrk:
-	.word	PIC_SYM(CURBRK, GOT)
-END(_brk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/arm/sys/sbrk.S b/lib/libc/arm/sys/sbrk.S
deleted file mode 100644
index 25622c4a809b..000000000000
--- a/lib/libc/arm/sys/sbrk.S
+++ /dev/null
@@ -1,82 +0,0 @@
-/*	$NetBSD: sbrk.S,v 1.7 2003/08/07 16:42:05 agc Exp $	*/
-
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- *	from: @(#)sbrk.s	5.1 (Berkeley) 4/23/90
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-#include "SYS.h"
-
-	.globl	_C_LABEL(_end)
-
-#ifdef WEAK_ALIAS
-WEAK_ALIAS(sbrk, _sbrk)
-#endif
-
-	.data
-	.align	0
-	.globl	CURBRK
-	.type	CURBRK,#object
-CURBRK:
-	.word	_C_LABEL(_end)
-
-/*
- * Change the data segment size
- */
-ENTRY(_sbrk)
-	/* Setup the GOT */
-	GOT_INIT(r3, .Lgot, .L1)
-	GOT_GET(r2, r3, .Lcurbrk)
-
-	/* Get the current brk address */
-	ldr	r1, [r2]
-
-	/* Calculate new value */
-	mov	r3, r0
-	add	r0, r0, r1
-	SYSTRAP(break)
-	bcs	PIC_SYM(CERROR, PLT)
-
-	/* Store new curbrk value */
-	ldr	r0, [r2]
-	add	r1, r0, r3
-	str	r1, [r2]
-
-	/* Return old curbrk value */
-	RET
-
-	.align	0
-	GOT_INITSYM(.Lgot, .L1)
-.Lcurbrk:
-	.word	PIC_SYM(CURBRK, GOT)
-END(_sbrk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/i386/Symbol.map b/lib/libc/i386/Symbol.map
index ca0296b9bc26..cdc2db6bb01a 100644
--- a/lib/libc/i386/Symbol.map
+++ b/lib/libc/i386/Symbol.map
@@ -61,6 +61,5 @@ FBSDprivate_1.0 {
 	__siglongjmp;
 	__sys_vfork;
 	_vfork;
-	_end;
 	_brk;
 };
diff --git a/lib/libc/i386/sys/Makefile.inc b/lib/libc/i386/sys/Makefile.inc
index 6c6bebdbdfaa..cf5d390ca094 100644
--- a/lib/libc/i386/sys/Makefile.inc
+++ b/lib/libc/i386/sys/Makefile.inc
@@ -7,9 +7,9 @@ SRCS+=	i386_clr_watch.c i386_set_watch.c i386_vm86.c
 SRCS+=	i386_get_fsbase.c i386_get_gsbase.c i386_get_ioperm.c i386_get_ldt.c \
 	i386_set_fsbase.c i386_set_gsbase.c i386_set_ioperm.c i386_set_ldt.c
 
-MDASM=	Ovfork.S brk.S cerror.S getcontext.S sbrk.S syscall.S
+MDASM=	Ovfork.S cerror.S getcontext.S syscall.S
 
-NOASM+=	vfork.o
+NOASM+=	sbrk.o vfork.o
 
 MAN+=	i386_get_ioperm.2 i386_get_ldt.2 i386_vm86.2
 MAN+=	i386_set_watch.3
diff --git a/lib/libc/i386/sys/brk.S b/lib/libc/i386/sys/brk.S
deleted file mode 100644
index 227c819316ba..000000000000
--- a/lib/libc/i386/sys/brk.S
+++ /dev/null
@@ -1,85 +0,0 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * William Jolitz.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)brk.s	5.2 (Berkeley) 12/17/90"
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	HIDENAME(curbrk)
-	.globl	HIDENAME(minbrk)
-ENTRY(_brk)
-	jmp	ok
-END(_brk)
-
-ENTRY(brk)
-#ifdef PIC
-	movl	4(%esp),%eax
-	PIC_PROLOGUE
-	movl	PIC_GOT(HIDENAME(curbrk)),%edx	# set up GOT addressing
-	movl	PIC_GOT(HIDENAME(minbrk)),%ecx	#
-	PIC_EPILOGUE
-	cmpl	%eax,(%ecx)
-	jbe	ok
-	movl	(%ecx),%eax
-	movl	%eax,4(%esp)
-ok:
-	mov	$SYS_break,%eax
-	KERNCALL
-	jb	HIDENAME(cerror)
-	movl	4(%esp),%eax
-	movl	%eax,(%edx)
-	movl	$0,%eax
-	ret
-
-#else
-
-	movl	4(%esp),%eax
-	cmpl	%eax,HIDENAME(minbrk)
-	jbe	ok
-	movl	HIDENAME(minbrk),%eax
-	movl	%eax,4(%esp)
-ok:
-	mov	$SYS_break,%eax
-	KERNCALL
-	jb	HIDENAME(cerror)
-	movl	4(%esp),%eax
-	movl	%eax,HIDENAME(curbrk)
-	movl	$0,%eax
-	ret
-#endif
-END(brk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/i386/sys/sbrk.S b/lib/libc/i386/sys/sbrk.S
deleted file mode 100644
index 56e504fd39cd..000000000000
--- a/lib/libc/i386/sys/sbrk.S
+++ /dev/null
@@ -1,88 +0,0 @@
-/*-
- * Copyright (c) 1990 The Regents of the University of California.
- * All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * William Jolitz.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)sbrk.s	5.1 (Berkeley) 4/23/90"
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	CNAME(_end)
-	.globl	HIDENAME(minbrk)
-	.globl	HIDENAME(curbrk)
-
-	.data
-HIDENAME(minbrk):	.long	CNAME(_end)
-HIDENAME(curbrk):	.long	CNAME(_end)
-	.text
-
-ENTRY(sbrk)
-#ifdef PIC
-	movl	4(%esp),%ecx
-	PIC_PROLOGUE
-	movl	PIC_GOT(HIDENAME(curbrk)),%edx
-	movl	(%edx),%eax
-	PIC_EPILOGUE
-	testl	%ecx,%ecx
-	jz	back
-	addl	%eax,4(%esp)
-	mov	$SYS_break,%eax
-	KERNCALL
-	jb	HIDENAME(cerror)
-	PIC_PROLOGUE
-	movl	PIC_GOT(HIDENAME(curbrk)),%edx
-	movl	(%edx),%eax
-	addl	%ecx,(%edx)
-	PIC_EPILOGUE
-back:
-	ret
-
-#else /* !PIC */
-
-	movl	4(%esp),%ecx
-	movl	HIDENAME(curbrk),%eax
-	testl	%ecx,%ecx
-	jz	back
-	addl	%eax,4(%esp)
-	mov	$SYS_break,%eax
-	KERNCALL
-	jb	HIDENAME(cerror)
-	movl	HIDENAME(curbrk),%eax
-	addl	%ecx,HIDENAME(curbrk)
-back:
-	ret
-#endif /* PIC */
-END(sbrk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/mips/Symbol.map b/lib/libc/mips/Symbol.map
index 6663a5f25f5d..4eba7eab57c2 100644
--- a/lib/libc/mips/Symbol.map
+++ b/lib/libc/mips/Symbol.map
@@ -50,7 +50,6 @@ FBSDprivate_1.0 {
 	__siglongjmp;
 	__sys_vfork;
 	_vfork;
-	_end;
 	_brk;
 	_sbrk;
 };
diff --git a/lib/libc/mips/sys/Makefile.inc b/lib/libc/mips/sys/Makefile.inc
index 5e6eec1ee535..d7cc70d01b07 100644
--- a/lib/libc/mips/sys/Makefile.inc
+++ b/lib/libc/mips/sys/Makefile.inc
@@ -2,7 +2,7 @@
 
 SRCS+=	trivial-vdso_tc.c
 
-MDASM=  Ovfork.S brk.S cerror.S sbrk.S syscall.S
+MDASM=  Ovfork.S cerror.S syscall.S
 
 # Don't generate default code for these syscalls:
-NOASM+=	vfork.o
+NOASM+=	sbrk.o vfork.o
diff --git a/lib/libc/mips/sys/brk.S b/lib/libc/mips/sys/brk.S
deleted file mode 100644
index 68f0bd45b32a..000000000000
--- a/lib/libc/mips/sys/brk.S
+++ /dev/null
@@ -1,71 +0,0 @@
-/*	$NetBSD: brk.S,v 1.16 2003/08/07 16:42:17 agc Exp $	*/
-
-/*-
- * Copyright (c) 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Ralph Campbell.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-#include "SYS.h"
-
-#if defined(LIBC_SCCS) && !defined(lint)
-	ASMSTR("from: @(#)brk.s	8.1 (Berkeley) 6/4/93")
-	ASMSTR("$NetBSD: brk.S,v 1.16 2003/08/07 16:42:17 agc Exp $")
-#endif /* LIBC_SCCS and not lint */
-
-	.globl	_C_LABEL(minbrk)
-	.globl	_C_LABEL(__curbrk)
-	.globl	_C_LABEL(_end)
-
-	.data
-_C_LABEL(minbrk):
-	PTR_WORD	_C_LABEL(_end)
-
-	.text
-LEAF(__sys_brk)
-	WEAK_ALIAS(brk, __sys_brk)
-	WEAK_ALIAS(_brk, __sys_brk)
-	PIC_PROLOGUE(__sys_brk)
-	PTR_LA	v0, _C_LABEL(minbrk)
-	PTR_L	v0, 0(v0)
-	bgeu	a0, v0, 1f
-	move	a0, v0		# dont allow break < minbrk
-1:
-	li	v0, SYS_break
-	syscall
-	bne	a3, zero, 2f
-	PTR_LA	t0, _C_LABEL(__curbrk)
-	PTR_S	a0, 0(t0)
-	move	v0, zero
-	PIC_RETURN()
-2:
-	PIC_TAILCALL(__cerror)
-END(__sys_brk)
diff --git a/lib/libc/mips/sys/sbrk.S b/lib/libc/mips/sys/sbrk.S
deleted file mode 100644
index 0989493a6172..000000000000
--- a/lib/libc/mips/sys/sbrk.S
+++ /dev/null
@@ -1,73 +0,0 @@
-/*	$NetBSD: sbrk.S,v 1.16 2005/04/22 06:58:01 simonb Exp $	*/
-
-/*-
- * Copyright (c) 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Ralph Campbell.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-#include "SYS.h"
-
-#if defined(LIBC_SCCS) && !defined(lint)
-	ASMSTR("from: @(#)sbrk.s	8.1 (Berkeley) 6/4/93")
-	ASMSTR("$NetBSD: sbrk.S,v 1.16 2005/04/22 06:58:01 simonb Exp $")
-#endif /* LIBC_SCCS and not lint */
-
-	.globl	_C_LABEL(__curbrk)
-	.globl	_C_LABEL(_end)
-
-	.data
-_C_LABEL(__curbrk):
-	PTR_WORD	_C_LABEL(_end)
-	.text
-
-LEAF(__sys_sbrk)
-	WEAK_ALIAS(sbrk, __sys_sbrk)
-	WEAK_ALIAS(_sbrk, __sys_sbrk)
-	PIC_PROLOGUE(__sys_sbrk)
-	PTR_LA	t0, _C_LABEL(__curbrk)
-	PTR_L	t0, 0(t0)
-	PTR_ADDU a0, a0, t0
-
-	li	v0, SYS_break
-	syscall
-
-	bne	a3, zero, 1f
-	nop
-	move	v0, t0			# return old val of curbrk from above
-	PTR_LA	t0, _C_LABEL(__curbrk)
-	PTR_S	a0, 0(t0)		# save current val of curbrk from above
-	PIC_RETURN()
-	j	ra
-
-1:
-	PIC_TAILCALL(__cerror)
-END(__sys_sbrk)
diff --git a/lib/libc/powerpc/Symbol.map b/lib/libc/powerpc/Symbol.map
index ae0da985463b..38f9bf579cfb 100644
--- a/lib/libc/powerpc/Symbol.map
+++ b/lib/libc/powerpc/Symbol.map
@@ -54,5 +54,4 @@ FBSDprivate_1.0 {
 	signalcontext;
 	__signalcontext;
 	__syncicache;
-	_end;
 };
diff --git a/lib/libc/powerpc/sys/Makefile.inc b/lib/libc/powerpc/sys/Makefile.inc
index f2b5e794120c..ac7f38cb863b 100644
--- a/lib/libc/powerpc/sys/Makefile.inc
+++ b/lib/libc/powerpc/sys/Makefile.inc
@@ -1,3 +1,3 @@
 # $FreeBSD$
 
-MDASM+=	brk.S cerror.S sbrk.S
+MDASM+=	cerror.S
diff --git a/lib/libc/powerpc/sys/brk.S b/lib/libc/powerpc/sys/brk.S
deleted file mode 100644
index e14be1058b51..000000000000
--- a/lib/libc/powerpc/sys/brk.S
+++ /dev/null
@@ -1,76 +0,0 @@
-/*-
- * Copyright (c) 2002 Peter Grehan.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-/*      $NetBSD: brk.S,v 1.9 2000/06/26 06:25:43 kleink Exp $   */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-        .globl  HIDENAME(curbrk)
-        .globl  HIDENAME(minbrk)
-        .globl  CNAME(_end)
-
-        .data
-HIDENAME(minbrk):
-        .long   CNAME(_end)
-
-        .text
-
-ENTRY(brk)
-#ifdef PIC
-	mflr    %r10
-	bl	_GLOBAL_OFFSET_TABLE_@local-4
-	mflr	%r9
-	mtlr	%r10
-	lwz	%r5,HIDENAME(minbrk)@got(%r9)
-	lwz	%r6,0(%r5)
-#else
-	lis	%r5,HIDENAME(minbrk)@ha
-	lwz	%r6,HIDENAME(minbrk)@l(%r5)
-#endif
-	cmplw   %r6,%r3			/* if (minbrk <= r3) */
-	bgt     0f
-	mr	%r6,%r3			/* r6 = r3 */
-0:
-	mr      %r3,%r6			/* new break value */
-	li      %r0,SYS_break
-	sc				/* assume, that r5 is kept */
-	bso	1f
-#ifdef PIC
-	lwz	%r7,HIDENAME(curbrk)@got(%r9)
-	stw	%r6,0(%r7)
-#else
-	lis	%r7,HIDENAME(curbrk)@ha /* record new break */
-	stw	%r6,HIDENAME(curbrk)@l(%r7)
-#endif
-	blr				/* return 0 */
-
-1:
-	b	PIC_PLT(HIDENAME(cerror))
-END(brk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/powerpc/sys/sbrk.S b/lib/libc/powerpc/sys/sbrk.S
deleted file mode 100644
index f058d112e863..000000000000
--- a/lib/libc/powerpc/sys/sbrk.S
+++ /dev/null
@@ -1,73 +0,0 @@
-/*-
- * Copyright (c) 2002 Peter Grehan.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-/*      $NetBSD: sbrk.S,v 1.8 2000/06/26 06:25:44 kleink Exp $  */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	HIDENAME(curbrk)
-	.globl	CNAME(_end)
-
-	.data
-HIDENAME(curbrk):
-	.long	CNAME(_end)
-
-	.text
-ENTRY(sbrk)
-
-#ifdef PIC
-	mflr	%r10
-	bl	_GLOBAL_OFFSET_TABLE_@local-4
-	mflr	%r5
-	mtlr	%r10
-	lwz	%r5,HIDENAME(curbrk)@got(%r5)
-	lwz	%r6,0(%r5)
-#else
-	lis	%r5,HIDENAME(curbrk)@ha
-	lwz	%r6,HIDENAME(curbrk)@l(%r5)	/* r6 = old break */
-#endif
-	cmpwi	%r3,0				/* sbrk(0) - return curbrk */
-	beq	1f
-	add	%r3,%r3,%r6
-	mr	%r7,%r3				/* r7 = new break */
-	li	%r0,SYS_break
-	sc					/* break(new_break) */
-	bso	2f
-#ifdef PIC
-	stw     %r7,0(%r5)
-#else
-	stw     %r7,HIDENAME(curbrk)@l(%r5)	/* record new break */
-#endif
-1:
-	mr      %r3,%r6				/* set return value */
-	blr
-2:
-	b	PIC_PLT(HIDENAME(cerror))
-END(sbrk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/powerpc64/Symbol.map b/lib/libc/powerpc64/Symbol.map
index a45cd055157a..c1e2d9ce8e69 100644
--- a/lib/libc/powerpc64/Symbol.map
+++ b/lib/libc/powerpc64/Symbol.map
@@ -50,5 +50,4 @@ FBSDprivate_1.0 {
 	signalcontext;
 	__signalcontext;
 	__syncicache;
-	_end;
 };
diff --git a/lib/libc/powerpc64/sys/Makefile.inc b/lib/libc/powerpc64/sys/Makefile.inc
index f2b5e794120c..ac7f38cb863b 100644
--- a/lib/libc/powerpc64/sys/Makefile.inc
+++ b/lib/libc/powerpc64/sys/Makefile.inc
@@ -1,3 +1,3 @@
 # $FreeBSD$
 
-MDASM+=	brk.S cerror.S sbrk.S
+MDASM+=	cerror.S
diff --git a/lib/libc/powerpc64/sys/brk.S b/lib/libc/powerpc64/sys/brk.S
deleted file mode 100644
index cbcecc7abb11..000000000000
--- a/lib/libc/powerpc64/sys/brk.S
+++ /dev/null
@@ -1,74 +0,0 @@
-/*-
- * Copyright (c) 2002 Peter Grehan.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-/*      $NetBSD: brk.S,v 1.9 2000/06/26 06:25:43 kleink Exp $   */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-        .globl  HIDENAME(curbrk)
-        .globl  HIDENAME(minbrk)
-        .globl  CNAME(_end)
-
-        .data
-        .align 3
-HIDENAME(minbrk):
-        .llong   CNAME(_end)
-
-        .text
-
-ENTRY(brk)
-	addis	%r6,%r2,HIDENAME(minbrk)@toc@ha
-	ld	%r6,HIDENAME(minbrk)@toc@l(%r6)
-	cmpld   %r6,%r3			/* if (minbrk <= r3) */
-	bgt     0f
-	mr	%r6,%r3			/* r6 = r3 */
-0:
-	mr      %r3,%r6			/* new break value */
-	li      %r0,SYS_break
-	sc				/* assume, that r5 is kept */
-	bso	1f
-
-	/* record new break */
-	addis	%r7,%r2,HIDENAME(curbrk)@toc@ha
-	std	%r6,HIDENAME(curbrk)@toc@l(%r7)
-
-	blr				/* return 0 */
-
-1:
-	mflr	%r0
-	std	%r0,16(%r1)
-	stdu	%r1,-48(%r1)
-	bl	HIDENAME(cerror)
-	nop
-	ld	%r1,0(%r1)
-	ld	%r0,16(%r1)
-	mtlr	%r0
-	blr
-END(brk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/powerpc64/sys/sbrk.S b/lib/libc/powerpc64/sys/sbrk.S
deleted file mode 100644
index 4e3b57abf458..000000000000
--- a/lib/libc/powerpc64/sys/sbrk.S
+++ /dev/null
@@ -1,69 +0,0 @@
-/*-
- * Copyright (c) 2002 Peter Grehan.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-/*      $NetBSD: sbrk.S,v 1.8 2000/06/26 06:25:44 kleink Exp $  */
-
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	HIDENAME(curbrk)
-	.globl	CNAME(_end)
-
-	.data
-	.align 3
-HIDENAME(curbrk):
-	.llong	CNAME(_end)
-
-	.text
-ENTRY(sbrk)
-	addis	%r5,%r2,HIDENAME(curbrk)@toc@ha
-	addi	%r5,%r5,HIDENAME(curbrk)@toc@l
-	ld	%r6,0(%r5)			/* r6 = old break */
-	cmpdi	%r3,0				/* sbrk(0) - return curbrk */
-	beq	1f
-	add	%r3,%r3,%r6
-	mr	%r7,%r3				/* r7 = new break */
-	li	%r0,SYS_break
-	sc					/* break(new_break) */
-	bso	2f
-	std     %r7,0(%r5)
-1:
-	mr      %r3,%r6				/* set return value */
-	blr
-2:
-	mflr	%r0
-	std	%r0,16(%r1)
-	stdu	%r1,-48(%r1)
-	bl	HIDENAME(cerror)
-	nop
-	ld	%r1,0(%r1)
-	ld	%r0,16(%r1)
-	mtlr	%r0
-	blr
-END(sbrk)
-
-	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/riscv/sys/Makefile.inc b/lib/libc/riscv/sys/Makefile.inc
index 34d81b618dc9..0e94e6652645 100644
--- a/lib/libc/riscv/sys/Makefile.inc
+++ b/lib/libc/riscv/sys/Makefile.inc
@@ -7,4 +7,4 @@ MDASM=	cerror.S \
 	vfork.S
 
 # Don't generate default code for these syscalls:
-NOASM+=	vfork.o
+NOASM+=	sbrk.o vfork.o
diff --git a/lib/libc/sparc64/Symbol.map b/lib/libc/sparc64/Symbol.map
index e81b07753cce..551fae915158 100644
--- a/lib/libc/sparc64/Symbol.map
+++ b/lib/libc/sparc64/Symbol.map
@@ -81,7 +81,6 @@ FBSDprivate_1.0 {
 	__siglongjmp;
 	__sys_brk;
 	_brk;
-	_end;
 	__sys_sbrk;
 	_sbrk;
 	__sys_vfork;
diff --git a/lib/libc/sparc64/sys/Makefile.inc b/lib/libc/sparc64/sys/Makefile.inc
index e0f8d24b2e7f..fd6368c4de7a 100644
--- a/lib/libc/sparc64/sys/Makefile.inc
+++ b/lib/libc/sparc64/sys/Makefile.inc
@@ -12,4 +12,4 @@ SRCS+=	__sparc_sigtramp_setup.c \
 
 CFLAGS+= -I${LIBC_SRCTOP}/sparc64/fpu
 
-MDASM+=	brk.S cerror.S sbrk.S sigaction1.S
+MDASM+=	cerror.S sigaction1.S
diff --git a/lib/libc/sparc64/sys/brk.S b/lib/libc/sparc64/sys/brk.S
deleted file mode 100644
index dc99b2239a32..000000000000
--- a/lib/libc/sparc64/sys/brk.S
+++ /dev/null
@@ -1,65 +0,0 @@
-/*
- * Copyright (c) 1992, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * This software was developed by the Computer Systems Engineering group
- * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
- * contributed to Berkeley.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * from: Header: brk.s,v 1.3 92/06/25 12:56:05 mccanne Exp
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)brk.s	8.1 (Berkeley) 6/4/93"
-#if 0
-	RCSID("$NetBSD: brk.S,v 1.9 2000/07/25 20:15:40 mycroft Exp $")
-#endif
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.globl	HIDENAME(curbrk)
-	.globl	HIDENAME(minbrk)
-
-_SYSENTRY(brk)
-	PIC_PROLOGUE(%o3, %o2)
-	SET(HIDENAME(minbrk), %o2, %o3)
-	ldx	[%o3], %o4
-	cmp	%o4, %o0
-	movg	%xcc, %o4, %o0
-	mov	%o0, %o4
-	mov	SYS_break, %g1
-	ta	%xcc, ST_SYSCALL
-	bcc,a,pt %xcc, 1f
-	 nop
-	ERROR()
-1:	SET(HIDENAME(curbrk), %o2, %o3)
-	retl
-	 stx	%o4, [%o3]
-_SYSEND(brk)
diff --git a/lib/libc/sparc64/sys/sbrk.S b/lib/libc/sparc64/sys/sbrk.S
deleted file mode 100644
index 671bdc10d6fe..000000000000
--- a/lib/libc/sparc64/sys/sbrk.S
+++ /dev/null
@@ -1,71 +0,0 @@
-/*
- * Copyright (c) 1992, 1993
- *	The Regents of the University of California.  All rights reserved.
- *
- * This software was developed by the Computer Systems Engineering group
- * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
- * contributed to Berkeley.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * from: Header: brk.s,v 1.3 92/06/25 12:56:05 mccanne Exp
- */
-
-#if defined(SYSLIBC_SCCS) && !defined(lint)
-	.asciz "@(#)sbrk.s	8.1 (Berkeley) 6/4/93"
-#if 0
-	RCSID("$NetBSD: sbrk.S,v 1.7 2000/07/25 15:14:46 mycroft Exp $")
-#endif
-#endif /* SYSLIBC_SCCS and not lint */
-#include <machine/asm.h>
-__FBSDID("$FreeBSD$");
-
-#include "SYS.h"
-
-	.data
-	.globl	HIDENAME(curbrk)
-	.globl	HIDENAME(minbrk)
-	.type	HIDENAME(curbrk),@object
-	.type	HIDENAME(minbrk),@object
-	.align	8
-HIDENAME(curbrk):
-	.xword	CNAME(_end)
-HIDENAME(minbrk):
-	.xword	CNAME(_end)
-
-_SYSENTRY(sbrk)
-	PIC_PROLOGUE(%o3, %o2)
-	SET(HIDENAME(curbrk), %o2, %o3)
-	ldx	[%o3], %o4
-	add	%o4, %o0, %o5
-	mov	%o5, %o0
-	mov	SYS_break, %g1
-	ta	%xcc, ST_SYSCALL
-	bcc,a,pt %xcc, 1f
-	 mov	%o4, %o0
-	ERROR()
-1:	retl
-	 stx	%o5, [%o3]
-_SYSEND(sbrk)
diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 84a9be128082..98a2233bcd9a 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -17,8 +17,7 @@
 # While historically machine dependent, all architectures have the following
 # declarations in common:
 #
-NOASM=	break.o \
-	exit.o \
+NOASM=	exit.o \
 	getlogin.o \
 	sstk.o \
 	yield.o
@@ -45,6 +44,7 @@ SRCS+= getdirentries.c
 NOASM+= getdirentries.o
 PSEUDO+= _getdirentries.o
 
+SRCS+= brk.c
 SRCS+= pipe.c
 SRCS+= vadvise.c
 
diff --git a/lib/libc/sys/brk.2 b/lib/libc/sys/brk.2
index a5247c9227d9..fc10e2ccf65a 100644
--- a/lib/libc/sys/brk.2
+++ b/lib/libc/sys/brk.2
@@ -28,7 +28,7 @@
 .\"     @(#)brk.2	8.4 (Berkeley) 5/1/95
 .\" $FreeBSD$
 .\"
-.Dd May 24, 2018
+.Dd June 2, 2018
 .Dt BRK 2
 .Os
 .Sh NAME
@@ -183,3 +183,8 @@ is sometimes used to monitor heap use by calling with an argument of 0.
 The result is unlikely to reflect actual utilization in combination with an
 .Xr mmap 2
 based malloc.
+.Pp
+.Fn brk
+and
+.Fn sbrk
+are not thread-safe.
diff --git a/lib/libc/sys/brk.c b/lib/libc/sys/brk.c
new file mode 100644
index 000000000000..7e50737d3e18
--- /dev/null
+++ b/lib/libc/sys/brk.c
@@ -0,0 +1,107 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/syscall.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void *__sys_break(char *nsize);
+
+static uintptr_t curbrk, minbrk;
+static int curbrk_initted;
+
+static int
+initbrk(void)
+{
+	void *newbrk;
+
+	if (!curbrk_initted) {
+		newbrk = __sys_break(NULL);
+		if (newbrk == (void *)-1)
+			return (-1);
+		curbrk = minbrk = (uintptr_t)newbrk;
+		curbrk_initted = 1;
+	}
+	return (0);
+}
+
+static void *
+mvbrk(void *addr)
+{
+	uintptr_t oldbrk;
+
+	if ((uintptr_t)addr < minbrk) {
+		/* Emulate legacy error handling in the syscall. */
+		errno = EINVAL;
+		return ((void *)-1);
+	}
+	if (__sys_break(addr) == (void *)-1)
+		return ((void *)-1);
+	oldbrk = curbrk;
+	curbrk = (uintptr_t)addr;
+	return ((void *)oldbrk);
+}
+
+int
+brk(const void *addr)
+{
+
+	if (initbrk() == -1)
+		return (-1);
+	if ((uintptr_t)addr < minbrk)
+		addr = (void *)minbrk;
+	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
+}
+
+int
+_brk(const void *addr)
+{
+
+	if (initbrk() == -1)
+		return (-1);
+	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
+}
+
+void *
+sbrk(intptr_t incr)
+{
+
+	if (initbrk() == -1)
+		return ((void *)-1);
+	if ((incr > 0 && curbrk + incr < curbrk) ||
+	    (incr < 0 && curbrk + incr > curbrk)) {
+		/* Emulate legacy error handling in the syscall. */
+		errno = EINVAL;
+		return ((void *)-1);
+	}
+	return (mvbrk((void *)(curbrk + incr)));
+}
diff --git a/lib/libc/tests/sys/Makefile b/lib/libc/tests/sys/Makefile
index 5b1a867bf29a..3abcb9924ee5 100644
--- a/lib/libc/tests/sys/Makefile
+++ b/lib/libc/tests/sys/Makefile
@@ -4,6 +4,7 @@ PACKAGE=			tests
 
 .include <bsd.own.mk>
 
+ATF_TESTS_C+=			brk_test
 ATF_TESTS_C+=			queue_test
 
 # TODO: clone, lwp_create, lwp_ctl, posix_fadvise, recvmmsg,
diff --git a/lib/libc/tests/sys/brk_test.c b/lib/libc/tests/sys/brk_test.c
new file mode 100644
index 000000000000..57b3d605e775
--- /dev/null
+++ b/lib/libc/tests/sys/brk_test.c
@@ -0,0 +1,149 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/mman.h>
+
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <atf-c.h>
+
+ATF_TC(brk_basic);
+ATF_TC_HEAD(brk_basic, tc)
+{
+	atf_tc_set_md_var(tc, "descr", "Verify basic brk() functionality");
+}
+ATF_TC_BODY(brk_basic, tc)
+{
+	void *oldbrk, *newbrk;
+	int error;
+
+	/* Reset the break. */
+	error = brk(0);
+	ATF_REQUIRE_MSG(error == 0, "brk: %s", strerror(errno));
+
+	oldbrk = sbrk(0);
+	ATF_REQUIRE(oldbrk != (void *)-1);
+
+	/* Try to allocate a page. */
+	error = brk((void *)((intptr_t)oldbrk + PAGE_SIZE * 2));
+	ATF_REQUIRE_MSG(error == 0, "brk: %s", strerror(errno));
+
+	/*
+	 * Attempt to set the break below minbrk.  This should have no effect.
+	 */
+	error = brk((void *)((intptr_t)oldbrk - 1));
+	ATF_REQUIRE_MSG(error == 0, "brk: %s", strerror(errno));
+	newbrk = sbrk(0);
+	ATF_REQUIRE_MSG(newbrk != (void *)-1, "sbrk: %s", strerror(errno));
+	ATF_REQUIRE(newbrk == oldbrk);
+}
+
+ATF_TC(sbrk_basic);
+ATF_TC_HEAD(sbrk_basic, tc)
+{
+	atf_tc_set_md_var(tc, "descr", "Verify basic sbrk() functionality");
+}
+ATF_TC_BODY(sbrk_basic, tc)
+{
+	void *newbrk, *oldbrk;
+	int *p;
+
+	oldbrk = sbrk(0);
+	ATF_REQUIRE_MSG(oldbrk != (void *)-1, "sbrk: %s", strerror(errno));
+	p = sbrk(sizeof(*p));
+	*p = 0;
+	ATF_REQUIRE(oldbrk == p);
+
+	newbrk = sbrk(-sizeof(*p));
+	ATF_REQUIRE_MSG(newbrk != (void *)-1, "sbrk: %s", strerror(errno));
+	ATF_REQUIRE(oldbrk == sbrk(0));
+
+	oldbrk = sbrk(PAGE_SIZE * 2 + 1);
+	ATF_REQUIRE_MSG(oldbrk != (void *)-1, "sbrk: %s", strerror(errno));
+	memset(oldbrk, 0, PAGE_SIZE * 2 + 1);
+	newbrk = sbrk(-(PAGE_SIZE * 2 + 1));
+	ATF_REQUIRE_MSG(newbrk != (void *)-1, "sbrk: %s", strerror(errno));
+	ATF_REQUIRE(sbrk(0) == oldbrk);
+}
+
+ATF_TC(mlockfuture);
+ATF_TC_HEAD(mlockfuture, tc)
+{
+	atf_tc_set_md_var(tc, "descr",
+	    "Verify that mlockall(MCL_FUTURE) applies to the data segment");
+}
+ATF_TC_BODY(mlockfuture, tc)
+{
+	void *oldbrk, *n, *newbrk;
+	int error;
+	char v;
+
+	error = mlockall(MCL_FUTURE);
+	ATF_REQUIRE_MSG(error == 0,
+	    "mlockall: %s", strerror(errno));
+
+	/*
+	 * Advance the break so that at least one page is added to the data
+	 * segment.  This page should be automatically faulted in to the address
+	 * space.
+	 */
+	oldbrk = sbrk(0);
+	ATF_REQUIRE(oldbrk != (void *)-1);
+	newbrk = sbrk(PAGE_SIZE * 2);
+	ATF_REQUIRE(newbrk != (void *)-1);
+
+	n = (void *)(((uintptr_t)oldbrk + PAGE_SIZE) & ~PAGE_SIZE);
+	v = 0;
+	error = mincore(n, PAGE_SIZE, &v);
+	ATF_REQUIRE_MSG(error == 0,
+	    "mincore: %s", strerror(errno));
+	ATF_REQUIRE_MSG((v & MINCORE_INCORE) != 0,
+	    "unexpected page flags %#x", v);
+
+	error = brk(oldbrk);
+	ATF_REQUIRE(error == 0);
+
+	error = munlockall();
+	ATF_REQUIRE_MSG(error == 0,
+	    "munlockall: %s", strerror(errno));
+}
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, brk_basic);
+	ATF_TP_ADD_TC(tp, sbrk_basic);
+	ATF_TP_ADD_TC(tp, mlockfuture);
+
+	return (atf_no_error());
+}