clone.S 3.6 KB

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  1. /* Wrapper around clone system call.
  2. Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
  3. This file is part of the GNU C Library.
  4. The GNU C Library is free software; you can redistribute it and/or
  5. modify it under the terms of the GNU Lesser General Public
  6. License as published by the Free Software Foundation; either
  7. version 2.1 of the License, or (at your option) any later version.
  8. The GNU C Library is distributed in the hope that it will be useful,
  9. but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11. Lesser General Public License for more details.
  12. You should have received a copy of the GNU Lesser General Public
  13. License along with the GNU C Library; if not, write to the Free
  14. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  15. 02111-1307 USA. */
  16. #include <features.h>
  17. #define _ERRNO_H 1
  18. #include <bits/errno.h>
  19. #include <sysdep.h>
  20. #define CLONE_VM 0x00000100
  21. #define CLONE_THREAD 0x00010000
  22. /* This is the only really unusual system call in PPC linux, but not
  23. because of any weirdness in the system call itself; because of
  24. all the freaky stuff we have to do to make the call useful. */
  25. /* int [r3] clone(int (*fn)(void *arg) [r3], void *child_stack [r4],
  26. int flags [r5], void *arg [r6], void *parent_tid [r7],
  27. void *tls [r8], void *child_tid [r9]); */
  28. #ifdef __NR_clone
  29. .globl __clone
  30. .type __clone,@function
  31. .align 2
  32. __clone:
  33. /* Check for child_stack == NULL || fn == NULL. */
  34. cmpwi cr0,r4,0
  35. cmpwi cr1,r3,0
  36. cror cr0*4+eq,cr1*4+eq,cr0*4+eq
  37. beq- cr0,.Lbadargs
  38. /* Set up stack frame for parent. */
  39. stwu r1,-32(r1)
  40. cfi_adjust_cfa_offset (32)
  41. #ifdef RESET_PID
  42. stmw r28,16(r1)
  43. #else
  44. # ifdef __ASSUME_FIXED_CLONE_SYSCALL
  45. stmw r29,16(r1)
  46. # else
  47. stmw r30,16(r1)
  48. # endif
  49. #endif
  50. /* Set up stack frame for child. */
  51. clrrwi r4,r4,4
  52. li r0,0
  53. stwu r0,-16(r4)
  54. /* Save fn, args, stack across syscall. */
  55. mr r30,r3 /* Function in r30. */
  56. #ifndef __ASSUME_FIXED_CLONE_SYSCALL
  57. mr r29,r4 /* Stack pointer in r29. */
  58. #endif
  59. #ifdef RESET_PID
  60. mr r28,r5
  61. #endif
  62. mr r31,r6 /* Argument in r31. */
  63. /* 'flags' argument is first parameter to clone syscall. (The other
  64. argument is the stack pointer, already in r4.) */
  65. mr r3,r5
  66. /* Move the parent_tid, child_tid and tls arguments. */
  67. mr r5,r7
  68. mr r6,r8
  69. mr r7,r9
  70. /* End FDE now, because in the child the unwind info will be wrong. */
  71. cfi_endproc
  72. /* Do the call. */
  73. li 0, __NR_clone
  74. sc
  75. /* Check for child process. */
  76. cmpwi cr1,r3,0
  77. crandc cr1*4+eq,cr1*4+eq,cr0*4+so
  78. bne- cr1,.Lparent /* The '-' is to minimise the race. */
  79. #ifndef __ASSUME_FIXED_CLONE_SYSCALL
  80. /* On at least mklinux DR3a5, clone() doesn't actually change
  81. the stack pointer. I'm pretty sure this is a bug, because
  82. it adds a race condition if a signal is sent to a thread
  83. just after it is created (in the previous three instructions). */
  84. mr r1,r29
  85. #endif
  86. #ifdef RESET_PID
  87. andis. r0,r28,CLONE_THREAD>>16
  88. bne+ r0,.Loldpid
  89. andi. r0,r28,CLONE_VM
  90. li r3,-1
  91. bne- r0,.Lnomoregetpid
  92. .Lnomoregetpid:
  93. stw r3,TID(r2)
  94. stw r3,PID(r2)
  95. .Loldpid:
  96. #endif
  97. /* Call procedure. */
  98. mtctr r30
  99. mr r3,r31
  100. bctrl
  101. /* Call _exit with result from procedure. */
  102. b HIDDEN_JUMPTARGET(_exit)
  103. .Lparent:
  104. /* Parent. Restore registers & return. */
  105. #ifdef RESET_PID
  106. lmw r28,16(r1)
  107. #else
  108. # ifndef __ASSUME_FIXED_CLONE_SYSCALL
  109. lmw r29,16(r1)
  110. # else
  111. lmw r30,16(r1)
  112. # endif
  113. #endif
  114. addi r1,r1,32
  115. bnslr+
  116. b __syscall_error
  117. .Lbadargs:
  118. li r3,EINVAL
  119. b __syscall_error
  120. cfi_startproc
  121. .size __clone,.-__clone
  122. weak_alias(__clone, clone)
  123. #endif