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83 lines
2.5 KiB
ArmAsm
83 lines
2.5 KiB
ArmAsm
/* Copyright (C) 2005-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#define _ERRNO_H 1
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#include <bits/errno.h>
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#include <tcb-offsets.h>
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/* Clone the calling process, but without copying the whole address space.
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The calling process is suspended until the new process exits or is
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replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
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and the process ID of the new process to the old process. */
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.Lthread_start: ASM_LINE_SEP
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/* r26, r25, r24, r23 are free since vfork has no arguments */
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ENTRY(__vfork)
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/* We must not create a frame. When the child unwinds to call
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exec it will clobber the same frame that the parent
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needs to unwind. */
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/* Save the PIC register. */
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#ifdef PIC
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copy %r19, %r25 /* parent */
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#endif
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/* Syscall saves and restores all register states */
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ble 0x100(%sr2,%r0)
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ldi __NR_vfork,%r20
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/* Check for error */
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ldi -4096,%r1
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comclr,>>= %r1,%ret0,%r0 /* Note: unsigned compare. */
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b,n .Lerror
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/* Return, and DO NOT restore rp. The child may have called
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functions that updated the frame's rp. This works because
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the kernel ensures rp is preserved across the vfork
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syscall. */
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bv,n %r0(%rp)
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.Lerror:
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/* Now we need a stack to call a function. We are assured
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that there is no child now, so it's safe to create
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a frame. */
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stw %rp, -20(%sp)
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.cfi_offset 2, -20
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stwm %r3, 64(%sp)
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.cfi_def_cfa_offset -64
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.cfi_offset 3, 0
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stw %sp, -4(%sp)
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sub %r0,%ret0,%r3
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SYSCALL_ERROR_HANDLER
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/* Restore the PIC register (in delay slot) on error */
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#ifdef PIC
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copy %r25, %r19 /* parent */
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#else
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nop
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#endif
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/* Write syscall return into errno location */
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stw %r3, 0(%ret0)
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ldw -84(%sp), %rp
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bv %r0(%rp)
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ldwm -64(%sp), %r3
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PSEUDO_END (__vfork)
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libc_hidden_def (__vfork)
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weak_alias (__vfork, vfork)
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