vfork.S 1.7 KB

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  1. /* Copyright (C) 2001, 2002, 2004, 2008 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, see
  13. <http://www.gnu.org/licenses/>. */
  14. #include <sys/syscall.h>
  15. /* Clone the calling process, but without copying the whole address space.
  16. The calling process is suspended until the new process exits or is
  17. replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
  18. and the process ID of the new process to the old process. */
  19. #ifndef __NR_vfork
  20. /* No vfork so use fork instead */
  21. # define __NR_vfork __NR_fork
  22. #endif
  23. .text
  24. .global __vfork
  25. .hidden __vfork
  26. .type __vfork,%function
  27. __vfork:
  28. /* Pop the return PC value into RDI. We need a register that
  29. is preserved by the syscall and that we're allowed to destroy. */
  30. popq %rdi
  31. /* Stuff the syscall number in RAX and enter into the kernel. */
  32. movl $__NR_vfork, %eax
  33. syscall
  34. /* Push back the return PC. */
  35. pushq %rdi
  36. cmpl $-4095, %eax
  37. jae __syscall_error /* Branch forward if it failed. */
  38. /* Normal return. */
  39. ret
  40. .size __vfork,.-__vfork
  41. weak_alias(__vfork,vfork)
  42. libc_hidden_def(vfork)