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/* Copyright (C) 2005-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <tcb-offsets.h>
/* Clone the calling process, but without copying the whole address space.
The calling process is suspended until the new process exits or is
replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
and the process ID of the new process to the old process. */
/* Load the thread register.
Load the saved PID value.
Negate the value.
Store the temporary PID. */
#define SAVE_PID \
mfctl %cr27, %r26 ASM_LINE_SEP \
ldw PID_THREAD_OFFSET(%r26),%r1 ASM_LINE_SEP \
sub %r0,%r1,%r1 ASM_LINE_SEP \
stw %r1,PID_THREAD_OFFSET(%r26) ASM_LINE_SEP
/* If we are the parent...
Get the thread pointer.
Load the saved PID.
Negate the value (got back original)
Restore the PID. */
#define RESTORE_PID \
cmpb,=,n %r0,%ret0,.Lthread_start ASM_LINE_SEP \
mfctl %cr27, %r26 ASM_LINE_SEP \
ldw PID_THREAD_OFFSET(%r26),%r1 ASM_LINE_SEP \
sub %r0,%r1,%r1 ASM_LINE_SEP \
stw %r1,PID_THREAD_OFFSET(%r26) ASM_LINE_SEP \
.Lthread_start: ASM_LINE_SEP
/* r26, r25, r24, r23 are free since vfork has no arguments */
ENTRY(__vfork)
/* We must not create a frame. When the child unwinds to call
exec it will clobber the same frame that the parent
needs to unwind. */
/* Save the PIC register. */
#ifdef PIC
copy %r19, %r25 /* parent */
#endif
/* Save the process PID */
SAVE_PID
/* Syscall saves and restores all register states */
ble 0x100(%sr2,%r0)
ldi __NR_vfork,%r20
/* Conditionally restore the PID */
RESTORE_PID
/* Check for error */
ldi -4096,%r1
comclr,>>= %r1,%ret0,%r0 /* Note: unsigned compare. */
b,n .Lerror
/* Return, and DO NOT restore rp. The child may have called
functions that updated the frame's rp. This works because
the kernel ensures rp is preserved across the vfork
syscall. */
bv,n %r0(%rp)
.Lerror:
/* Now we need a stack to call a function. We are assured
that there is no child now, so it's safe to create
a frame. */
stw %rp, -20(%sp)
stwm %r3, 64(%sp)
stw %sp, -4(%sp)
sub %r0,%ret0,%r3
SYSCALL_ERROR_HANDLER
/* Restore the PIC register (in delay slot) on error */
#ifdef PIC
copy %r25, %r19 /* parent */
#else
nop
#endif
/* Write syscall return into errno location */
stw %r3, 0(%ret0)
ldw -84(%sp), %rp
bv %r0(%rp)
ldwm -64(%sp), %r3
PSEUDO_END (__vfork)
libc_hidden_def (__vfork)
weak_alias (__vfork, vfork)
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