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pt-vfork.S

pt-vfork.S 2.1 KB
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  1. /* Copyright (C) 1999, 2002, 2004 Free Software Foundation, Inc.
    2. 

  2.    This file is part of the GNU C Library.
    3. 

  3.    Contributed by Andreas Schwab <schwab@gnu.org>.
    4. 

  4. 

  5.    The GNU C Library is free software; you can redistribute it and/or
    6. 

  6.    modify it under the terms of the GNU Lesser General Public
    7. 

  7.    License as published by the Free Software Foundation; either
    8. 

  8.    version 2.1 of the License, or (at your option) any later version.
    9. 

  9. 

  10.    The GNU C Library is distributed in the hope that it will be useful,
    11. 

  11.    but WITHOUT ANY WARRANTY; without even the implied warranty of
    12. 

  12.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13. 

  13.    Lesser General Public License for more details.
    14. 

  14. 

  15.    You should have received a copy of the GNU Lesser General Public
    16. 

  16.    License along with the GNU C Library; if not, see
    17. 

  17.    <http://www.gnu.org/licenses/>.  */
    18. 

  18. 

  19. #include <sysdep.h>
    20. 

  20. #define _ERRNO_H	1
    21. 

  21. #include <bits/errno.h>
    22. 

  22. #include <bits/kernel-features.h>
    23. 

  23. #include <tcb-offsets.h>
    24. 

  24. 

  25. /* Save the PID value.  */
    26. 

  26. #define SAVE_PID \
    27. 

  27. 	movl	%gs:PID, %edx; 						      \
    28. 

  28. 	movl	%edx, %eax;						      \
    29. 

  29. 	negl	%eax;							      \
    30. 

  30. 	movl	%eax, %gs:PID
    31. 

  31. 

  32. /* Restore the old PID value in the parent.  */
    33. 

  33. #define RESTORE_PID \
    34. 

  34. 	testl	%eax, %eax;						      \
    35. 

  35. 	je	1f;							      \
    36. 

  36. 	movl	%edx, %gs:PID;						      \
    37. 

  37. 1:
    38. 

  38. 

  39. /* Clone the calling process, but without copying the whole address space.
    40. 

  40.    The calling process is suspended until the new process exits or is
    41. 

  41.    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
    42. 

  42.    and the process ID of the new process to the old process.  */
    43. 

  43. 

  44. ENTRY (__vfork)
    45. 

  45. 	/* Pop the return PC value into ECX.  */
    46. 

  46. 	popl	%ecx
    47. 

  47. 

  48. 	SAVE_PID
    49. 

  49. 

  50. 	/* Stuff the syscall number in EAX and enter into the kernel.  */
    51. 

  51. 	movl	$SYS_ify (vfork), %eax
    52. 

  52. 	int	$0x80
    53. 

  53. 

  54. 	RESTORE_PID
    55. 

  55. 

  56. 	/* Jump to the return PC.  Don't jump directly since this
    57. 

  57. 	   disturbs the branch target cache.  Instead push the return
    58. 

  58. 	   address back on the stack.  */
    59. 

  59. 	pushl	%ecx
    60. 

  60. 

  61. 	cmpl	$-4095, %eax
    62. 

  62. 	jae	SYSCALL_ERROR_LABEL	/* Branch forward if it failed.  */
    63. 

  63. L(pseudo_end):
    64. 

  64. 	ret
    65. 

  65. PSEUDO_END (__vfork)
    66. 

  66. 

  67. weak_alias (__vfork, vfork)
    68.