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brk.S

brk.S 2.0 KB
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  1. /* Copyright (C) 1993, 1995, 1996, 1997 Free Software Foundation, Inc.
    2. 

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

  3.    Contributed by Brendan Kehoe <brendan@zen.org>, 1993.
    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, write to the Free
    17. 

  17.    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    18. 

  18.    02111-1307 USA.  */
    19. 

  19. 

  20. /* __brk is a special syscall under Linux since it never returns an
    21. 

  21.    error.  Instead, the error condition is indicated by returning the old
    22. 

  22.    break value (instead of the new, requested one).  */
    23. 

  23. 

  24. #include <features.h>
    25. 

  25. #define _ERRNO_H
    26. 

  26. #include <bits/errno.h>
    27. 

  27. #include <sys/syscall.h>
    28. 

  28. 

  29. #ifdef __PIC__
    30. 

  30. .section .bss
    31. 

  31. 	.align 3
    32. 

  32. 	.globl __curbrk
    33. 

  33. 	.hidden __curbrk
    34. 

  34. __curbrk: .skip 8
    35. 

  35. 	.type __curbrk,@object
    36. 

  36. 	.size __curbrk,8
    37. 

  37. #else
    38. 

  38. .comm __curbrk, 8
    39. 

  39. #endif
    40. 

  40. 

  41. 	.text
    42. 

  42. .globl  brk;
    43. 

  43. .align 3;
    44. 

  44. .ent  brk , 0;
    45. 

  45. 

  46. brk:
    47. 

  47.     .frame $30 ,   8 , $26
    48. 

  48. 	ldgp	$29, 0($27)
    49. 

  49. 	subq	$30, 8, $30
    50. 

  50. 	.prologue 1
    51. 

  51. 

  52. 	/* Save the requested brk across the system call.  */
    53. 

  53. 	stq	$16, 0($30)
    54. 

  54. 

  55. 	ldiq	$0, __NR_brk
    56. 

  56. 	call_pal 131
    57. 

  57. 

  58. 	ldq	$16, 0($30)
    59. 

  59. 

  60. 	/* Be prepared for an OSF-style brk.  */
    61. 

  61. 	bne	$19, $err1
    62. 

  62. 	beq	$0, $ok
    63. 

  63. 

  64. 	/* Correctly handle the brk(0) query case.  */
    65. 

  65. 	cmoveq	$16, $0, $16
    66. 

  66. 	xor	$16, $0, $1
    67. 

  67. 	bne	$1, $err0
    68. 

  68. 

  69. 	/* Update __curbrk and return cleanly.  */
    70. 

  70. 	mov	$31, $0
    71. 

  71. $ok:	stq	$16, __curbrk
    72. 

  72. 	addq	$30, 8, $30
    73. 

  73. 	ret
    74. 

  74. 

  75. 	/* What a horrible way to die.  */
    76. 

  76. $err0:	ldi	$0, ENOMEM
    77. 

  77. $err1:	addq	$30, 8, $30
    78. 

  78. 	jmp	$31, __syscall_error
    79. 

  79. 

  80. 	.end brk
    81. 

  81. 

  82. libc_hidden_def(brk)
    83.