74 lines
2.3 KiB
ArmAsm
74 lines
2.3 KiB
ArmAsm
/* Copyright (C) 2001-2015 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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ENTRY (__vfork)
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/* Pop the return PC value into RDI. We need a register that
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is preserved by the syscall and that we're allowed to destroy. */
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popq %rdi
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cfi_adjust_cfa_offset(-8)
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cfi_register(%rip, %rdi)
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/* Save the TCB-cached PID away in %esi, and then negate the TCB
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field. But if it's zero, set it to 0x80000000 instead. See
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raise.c for the logic that relies on this value. */
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movl %fs:PID, %esi
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movl $0x80000000, %ecx
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movl %esi, %edx
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negl %edx
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cmove %ecx, %edx
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movl %edx, %fs:PID
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/* Stuff the syscall number in RAX and enter into the kernel. */
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movl $SYS_ify (vfork), %eax
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syscall
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/* Push back the return PC. */
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pushq %rdi
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cfi_adjust_cfa_offset(8)
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/* Restore the original value of the TCB cache of the PID, if we're
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the parent. But in the child (syscall return value equals zero),
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leave things as they are. */
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testq %rax, %rax
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je 1f
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movl %esi, %fs:PID
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1:
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cmpl $-4095, %eax
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jae SYSCALL_ERROR_LABEL /* Branch forward if it failed. */
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/* Normal return. */
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ret
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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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strong_alias (__vfork, __libc_vfork)
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