vfork.S 1.9 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566
  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, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #include <sys/syscall.h>
  16. /* Clone the calling process, but without copying the whole address space.
  17. The calling process is suspended until the new process exits or is
  18. replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
  19. and the process ID of the new process to the old process. */
  20. #ifndef __NR_vfork
  21. /* No vfork so use fork instead */
  22. # define __NR_vfork __NR_fork
  23. #endif
  24. .text
  25. .global __vfork
  26. .hidden __vfork
  27. .type __vfork,%function
  28. __vfork:
  29. /* Pop the return PC value into RDI. We need a register that
  30. is preserved by the syscall and that we're allowed to destroy. */
  31. popq %rdi
  32. #ifdef SAVE_PID
  33. SAVE_PID
  34. #endif
  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. #ifdef RESTORE_PID
  41. RESTORE_PID
  42. #endif
  43. cmpl $-4095, %eax
  44. jae __syscall_error /* Branch forward if it failed. */
  45. /* Normal return. */
  46. ret
  47. .size __vfork,.-__vfork
  48. weak_alias(__vfork,vfork)
  49. libc_hidden_weak(vfork)