vfork.S 1.9 KB

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  1. /* Copyright (C) 2001, 2002, 2004 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, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #include <features.h>
  16. #include <sys/syscall.h>
  17. /* Clone the calling process, but without copying the whole address space.
  18. The calling process is suspended until the new process exits or is
  19. replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
  20. and the process ID of the new process to the old process. */
  21. #ifndef __NR_vfork
  22. /* No vfork so use fork instead */
  23. hidden_strong_alias(__fork,__vfork)
  24. weak_alias(vfork,__libc_fork)
  25. #else
  26. .text
  27. .global __vfork
  28. .hidden __vfork
  29. .type __vfork,%function
  30. .align 16
  31. __vfork:
  32. /* Pop the return PC value into RDI. We need a register that
  33. is preserved by the syscall and that we're allowed to destroy. */
  34. popq %rdi
  35. /* Stuff the syscall number in RAX and enter into the kernel. */
  36. movl $__NR_vfork, %eax
  37. syscall
  38. /* Push back the return PC. */
  39. pushq %rdi
  40. cmpl $-4095, %eax
  41. jae __error /* Branch forward if it failed. */
  42. /* Normal return. */
  43. ret
  44. __error:
  45. jmp __syscall_error
  46. .size __vfork,.-__vfork
  47. #endif /* __NR_vfork */
  48. strong_alias(__vfork,vfork)