clone2.S 3.3 KB

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  1. /* Copyright (C) 2000, 2001, 2003, 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 "sysdep.h"
  16. #include "sysdep.h"
  17. #include <asm/errno.h>
  18. /* int __clone2(int (*fn) (void *arg), void *child_stack_base, */
  19. /* size_t child_stack_size, int flags, void *arg, */
  20. /* pid_t *parent_tid, void *tls, pid_t *child_tid) */
  21. #define CHILD p8
  22. #define PARENT p9
  23. ENTRY(__clone2)
  24. .prologue
  25. alloc r2=ar.pfs,8,1,6,0
  26. cmp.eq p6,p0=0,in0
  27. mov r8=EINVAL
  28. mov out0=in3 /* Flags are first syscall argument. */
  29. mov out1=in1 /* Stack address. */
  30. (p6) br.cond.spnt.many __syscall_error
  31. ;;
  32. mov out2=in2 /* Stack size. */
  33. mov out3=in5 /* Parent TID Pointer */
  34. mov out4=in7 /* Child TID Pointer */
  35. mov out5=in6 /* TLS pointer */
  36. /*
  37. * clone2() is special: the child cannot execute br.ret right
  38. * after the system call returns, because it starts out
  39. * executing on an empty stack. Because of this, we can't use
  40. * the new (lightweight) syscall convention here. Instead, we
  41. * just fall back on always using "break".
  42. *
  43. * Furthermore, since the child starts with an empty stack, we
  44. * need to avoid unwinding past invalid memory. To that end,
  45. * we'll pretend now that __clone2() is the end of the
  46. * call-chain. This is wrong for the parent, but only until
  47. * it returns from clone2() but it's better than the
  48. * alternative.
  49. */
  50. mov r15=SYS_ify (clone2)
  51. .save rp, r0
  52. break __BREAK_SYSCALL
  53. .body
  54. cmp.eq p6,p0=-1,r10
  55. cmp.eq CHILD,PARENT=0,r8 /* Are we the child? */
  56. (p6) br.cond.spnt.many __syscall_error
  57. ;;
  58. (CHILD) mov loc0=gp
  59. (PARENT) ret
  60. ;;
  61. #ifdef RESET_PID
  62. tbit.nz p6,p0=in3,16 /* CLONE_THREAD */
  63. tbit.z p7,p10=in3,8 /* CLONE_VM */
  64. (p6) br.cond.dptk 1f
  65. ;;
  66. mov r15=SYS_ify (getpid)
  67. (p10) addl r8=-1,r0
  68. (p7) break __BREAK_SYSCALL
  69. ;;
  70. add r9=PID,r13
  71. add r10=TID,r13
  72. ;;
  73. st4 [r9]=r8
  74. st4 [r10]=r8
  75. ;;
  76. #endif
  77. 1: ld8 out1=[in0],8 /* Retrieve code pointer. */
  78. mov out0=in4 /* Pass proper argument to fn */
  79. ;;
  80. ld8 gp=[in0] /* Load function gp. */
  81. mov b6=out1
  82. br.call.dptk.many rp=b6 /* Call fn(arg) in the child */
  83. ;;
  84. mov out0=r8 /* Argument to _exit */
  85. mov gp=loc0
  86. .globl HIDDEN_JUMPTARGET(_exit)
  87. br.call.dpnt.many rp=HIDDEN_JUMPTARGET(_exit)
  88. /* call _exit with result from fn. */
  89. ret /* Not reached. */
  90. PSEUDO_END(__clone2)
  91. /* For now we leave __clone undefined. This is unlikely to be a */
  92. /* problem, since at least the i386 __clone in glibc always failed */
  93. /* with a 0 sp (eventhough the kernel explicitly handled it). */
  94. /* Thus all such calls needed to pass an explicit sp, and as a result, */
  95. /* would be unlikely to work on ia64. */