1/* stuff needed for libgcc on win32. 2 * 3 * Copyright (C) 1996, 1998, 2001, 2003 Free Software Foundation, Inc. 4 * Written By Steve Chamberlain 5 * 6 * This file is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the 8 * Free Software Foundation; either version 2, or (at your option) any 9 * later version. 10 * 11 * In addition to the permissions in the GNU General Public License, the 12 * Free Software Foundation gives you unlimited permission to link the 13 * compiled version of this file with other programs, and to distribute 14 * those programs without any restriction coming from the use of this 15 * file. (The General Public License restrictions do apply in other 16 * respects; for example, they cover modification of the file, and 17 * distribution when not linked into another program.) 18 * 19 * This file is distributed in the hope that it will be useful, but 20 * WITHOUT ANY WARRANTY; without even the implied warranty of 21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 * General Public License for more details. 23 * 24 * You should have received a copy of the GNU General Public License 25 * along with this program; see the file COPYING. If not, write to 26 * the Free Software Foundation, 51 Franklin Street, Fifth Floor, 27 * Boston, MA 02110-1301, USA. 28 * 29 * As a special exception, if you link this library with files 30 * compiled with GCC to produce an executable, this does not cause 31 * the resulting executable to be covered by the GNU General Public License. 32 * This exception does not however invalidate any other reasons why 33 * the executable file might be covered by the GNU General Public License. 34 */ 35 36#ifdef L_chkstk 37 38/* Function prologue calls _alloca to probe the stack when allocating more 39 than CHECK_STACK_LIMIT bytes in one go. Touching the stack at 4K 40 increments is necessary to ensure that the guard pages used 41 by the OS virtual memory manger are allocated in correct sequence. */ 42 43 .global ___chkstk 44 .global __alloca 45___chkstk: 46__alloca: 47 pushl %ecx /* save temp */ 48 movl %esp,%ecx /* get sp */ 49 addl $0x8,%ecx /* and point to return addr */ 50 51probe: cmpl $0x1000,%eax /* > 4k ?*/ 52 jb done 53 54 subl $0x1000,%ecx /* yes, move pointer down 4k*/ 55 orl $0x0,(%ecx) /* probe there */ 56 subl $0x1000,%eax /* decrement count */ 57 jmp probe /* and do it again */ 58 59done: subl %eax,%ecx 60 orl $0x0,(%ecx) /* less that 4k, just peek here */ 61 62 movl %esp,%eax 63 movl %ecx,%esp /* decrement stack */ 64 65 movl (%eax),%ecx /* recover saved temp */ 66 movl 4(%eax),%eax /* get return address */ 67 jmp *%eax 68#endif 69