Revert "Replaces vfork() implementation with fork()"

We're getting cold feet on this one... let's put it back.

This reverts commit 210331d9762037afb9b5ed8413079c6f65872df9.

Change-Id: I6b0d3c2b1dbf7f1dc9566979a91b7504c2189269
(cherry picked from commit 6a918870bab1a55a5f57dd7954abd9a8a27c1bc2)

libc/SYSCALLS.TXT

@@ -77,6 +77,7 @@ int prlimit64(pid_t, int, struct rlimit64*, const struct rlimit64*)  arm,mips,x8
 int     setgroups:setgroups32(int, const gid_t*)   arm,x86
 int     setgroups:setgroups(int, const gid_t*)     arm64,mips,mips64,x86_64
 int     setpgid(pid_t, pid_t)  all
+pid_t   vfork(void)  arm
 int     setregid:setregid32(gid_t, gid_t)  arm,x86
 int     setregid:setregid(gid_t, gid_t)    arm64,mips,mips64,x86_64
 int     chroot(const char*)  all

libc/arch-arm/syscalls/vfork.S

@@ -0,0 +1,14 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(vfork)
+    mov     ip, r7
+    ldr     r7, =__NR_vfork
+    swi     #0
+    mov     r7, ip
+    cmn     r0, #(MAX_ERRNO + 1)
+    bxls    lr
+    neg     r0, r0
+    b       __set_errno
+END(vfork)

libc/arch-arm64/arm64.mk

@@ -36,6 +36,7 @@ libc_bionic_src_files_arm64 := \
     arch-arm64/bionic/__set_tls.c \
     arch-arm64/bionic/sigsetjmp.S \
     arch-arm64/bionic/syscall.S \
+    arch-arm64/bionic/vfork.S \
 
 
 libc_crt_target_cflags_arm64 := \

libc/arch-arm64/bionic/vfork.S

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <private/bionic_asm.h>
+#include <asm/signal.h>
+#include <linux/sched.h>
+
+ENTRY(vfork)
+    mov     x0, #(CLONE_VM | CLONE_VFORK | SIGCHLD)
+    mov     x1, xzr
+    mov     x2, xzr
+    mov     x3, xzr
+    mov     x4, xzr
+
+    mov     x8, __NR_clone
+    svc     #0
+
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno
+
+    ret
+END(vfork)

libc/arch-mips/bionic/vfork.S

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <private/bionic_asm.h>
+#include <linux/sched.h>
+
+// TODO: mips' uapi signal.h is missing #ifndef __ASSEMBLY__.
+// #include <asm/signal.h>
+#define SIGCHLD 18
+
+ENTRY(vfork)
+	.set	noreorder
+	.cpload	t9
+
+	li	a0, (CLONE_VM | CLONE_VFORK | SIGCHLD)
+	li	a1, 0
+	li	a2, 0
+	li	a3, 0
+	subu	sp, 8
+	sw	$0, 16(sp)
+	li	v0, __NR_clone
+	syscall
+	addu	sp, 8
+	bnez	a3, 1f
+	 move	a0, v0
+
+	j	ra
+	 nop
+1:
+	la	t9, __set_errno
+	j	t9
+	 nop
+END(vfork)

libc/arch-mips/mips.mk

@@ -59,6 +59,7 @@ libc_bionic_src_files_mips += \
     arch-mips/bionic/setjmp.S \
     arch-mips/bionic/sigsetjmp.S \
     arch-mips/bionic/syscall.S \
+    arch-mips/bionic/vfork.S \
 
 ifndef ARCH_MIPS_REV6
 libc_bionic_src_files_mips += \

libc/arch-mips64/bionic/vfork.S

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <private/bionic_asm.h>
+#include <linux/sched.h>
+
+// TODO: mips' uapi signal.h is missing #ifndef __ASSEMBLY__.
+// #include <asm/signal.h>
+#define SIGCHLD 18
+
+	.text
+
+#if (_MIPS_SIM == _ABIO32) || (_MIPS_SIM == _ABI32)
+FRAMESZ		=	MKFSIZ(5,0)
+#else
+FRAMESZ		=	MKFSIZ(0,0)
+#endif
+
+LEAF(vfork,FRAMESZ)
+#if FRAMESZ!=0
+	PTR_SUBU sp, FRAMESZ
+#endif
+	SETUP_GP64(a5, vfork)
+	LI	a0, (CLONE_VM | CLONE_VFORK | SIGCHLD)
+	move	a1, $0
+	move	a2, $0
+	move	a3, $0
+#if (_MIPS_SIM == _ABIO32) || (_MIPS_SIM == _ABI32)
+	REG_S	$0, 4*REGSZ(sp)
+#else
+	move	a4, $0
+#endif
+	LI	v0, __NR_clone
+	syscall
+#if FRAMESZ!=0
+	PTR_ADDU sp,FRAMESZ
+#endif
+	move	a0, v0
+	bnez	a3, 1f
+	RESTORE_GP64
+	j	ra
+1:
+	LA	t9,__set_errno
+	RESTORE_GP64
+	j	t9
+	END(vfork)

libc/arch-mips64/mips64.mk

@@ -46,6 +46,7 @@ libc_bionic_src_files_mips64 := \
     arch-mips64/bionic/setjmp.S \
     arch-mips64/bionic/sigsetjmp.S \
     arch-mips64/bionic/syscall.S \
+    arch-mips64/bionic/vfork.S \
 
 # FIXME TODO
 ## libc_bionic_src_files_mips64 += arch-mips64/string/memcpy.S

libc/arch-x86/bionic/vfork.S

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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 COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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 <private/bionic_asm.h>
+
+// This custom code preserves the return address across the system call.
+
+ENTRY(vfork)
+  popl    %ecx  // Grab the return address.
+  movl    $__NR_vfork, %eax
+  int     $0x80
+  cmpl    $-MAX_ERRNO, %eax
+  jb      1f
+  negl    %eax
+  pushl   %eax
+  call    __set_errno
+1:
+  jmp     *%ecx  // Jump to the stored return address.
+END(vfork)

libc/arch-x86/x86.mk

@@ -31,6 +31,7 @@ libc_bionic_src_files_x86 += \
     arch-x86/bionic/__set_tls.c \
     arch-x86/bionic/sigsetjmp.S \
     arch-x86/bionic/syscall.S \
+    arch-x86/bionic/vfork.S \
 
 ## ARCH variant specific source files
 arch_variant_mk := $(LOCAL_PATH)/arch-x86/$(TARGET_ARCH_VARIANT)/$(TARGET_ARCH_VARIANT).mk

libc/arch-x86_64/bionic/vfork.S

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 The Android Open Source Project
+ * Copyright (C) 2013 The Android Open Source Project
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,10 +26,20 @@
  * SUCH DAMAGE.
  */
 
-#include <unistd.h>
+#include <private/bionic_asm.h>
 
-// vfork(2) was removed from POSIX 2008, but it's common enough that we can't
+// This custom code preserves the return address across the system call.
-// actually remove it entirely.
+
-extern "C" pid_t vfork(void) {
+ENTRY(vfork)
-  return fork();
+  popq    %rdi  // Grab the return address.
-}
+  movl    $__NR_vfork, %eax
+  syscall
+  pushq   %rdi  // Restore the return address.
+  cmpq    $-MAX_ERRNO, %rax
+  jb      1f
+  negl    %eax
+  movl    %eax, %edi
+  call    __set_errno
+1:
+  ret
+END(vfork)

libc/arch-x86_64/x86_64.mk

@@ -37,6 +37,7 @@ libc_bionic_src_files_x86_64 := \
     arch-x86_64/bionic/__set_tls.c \
     arch-x86_64/bionic/sigsetjmp.S \
     arch-x86_64/bionic/syscall.S \
+    arch-x86_64/bionic/vfork.S \
 
 libc_bionic_src_files_x86_64 += \
     arch-x86_64/string/sse2-memcpy-slm.S \