sysdeps/unix/sysv/linux/alpha/brk.S

   1 /* Copyright (C) 1993-2016 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Brendan Kehoe <brendan@zen.org>, 1993.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /* __brk is a special syscall under Linux since it never returns an
  20    error.  Instead, the error condition is indicated by returning the old
  21    break value (instead of the new, requested one).  */
  22
  23 #include <sysdep.h>
  24 #define _ERRNO_H
  25 #include <bits/errno.h>
  26
  27 #ifdef PIC
  28 .section .bss
  29         .align 3
  30         .globl __curbrk
  31 __curbrk: .skip 8
  32         .type __curbrk,@object
  33         .size __curbrk,8
  34 #else
  35 .comm __curbrk, 8
  36 #endif
  37
  38         .text
  39         .align  4
  40         .globl  __brk
  41         .ent    __brk
  42         .usepv  __brk, std
  43
  44         cfi_startproc
  45 __brk:
  46         ldgp    gp, 0(t12)
  47         subq    sp, 16, sp
  48         cfi_adjust_cfa_offset (16)
  49 #ifdef PROF
  50         .set noat
  51         lda     AT, _mcount
  52         jsr     AT, (AT), _mcount
  53         .set at
  54 #endif
  55
  56         /* Save the requested brk across the system call.  */
  57         stq     a0, 0(sp)
  58
  59         ldiq    v0, __NR_brk
  60         call_pal PAL_callsys
  61
  62         ldq     a0, 0(sp)
  63         addq    sp, 16, sp
  64         cfi_adjust_cfa_offset (-16)
  65
  66         /* Be prepared for an OSF-style brk.  */
  67         bne     a3, SYSCALL_ERROR_LABEL
  68         beq     v0, $ok
  69
  70         /* Correctly handle the brk(0) query case.  */
  71         cmoveq  a0, v0, a0
  72         xor     a0, v0, t0
  73         lda     v0, ENOMEM
  74         bne     t0, SYSCALL_ERROR_LABEL
  75
  76         /* Update __curbrk and return cleanly.  */
  77         lda     v0, 0
  78 $ok:    stq     a0, __curbrk
  79         ret
  80
  81 PSEUDO_END(__brk)
  82         cfi_endproc
  83
  84 weak_alias (__brk, brk)