reactos/ntoskrnl/kdbg/i386/longjmp.S

   1         .file   "longjmp.S"
   2 /*
   3  * Copyright (C) 1998, 1999, Jonathan S. Shapiro.
   4  *
   5  * This file is part of the EROS Operating System.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2,
  10  * or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  */
  21
  22         /*
  23          * typedef struct {
  24          *  unsigned long ebx, esi, edi;
  25          *  unsigned long ebp;
  26          *  unsigned long sp;
  27          *  unsigned long pc;
  28          * } jmp_buf[1];
  29          */
  30
  31         /*
  32          * On entry, the stack to longjmp looks like:
  33          *
  34          *     value
  35          *     ptr to jmp_buf
  36          *     return PC
  37          */
  38
  39 .globl _longjmp
  40 _longjmp:
  41         pushl   %ebp
  42         movl    %esp,%ebp
  43
  44         movl    8(%ebp),%ecx            /* address of jmp_buf to ecx */
  45         movl    12(%ebp),%eax           /* return value to %eax */
  46         testl   %eax,%eax
  47         jne     1f
  48         incl    %eax                    /* return 1 if handed 0 */
  49
  50 1:
  51         movl    (%ecx),%ebx             /* restore %ebx */
  52         movl    4(%ecx),%esi            /* restore %esi */
  53         movl    8(%ecx),%edi            /* restore %edi */
  54
  55         /*
  56          * From this instant on we are not running in a valid frame
  57          */
  58
  59         movl    12(%ecx),%ebp           /* restore %ebp */
  60         movl    16(%ecx),%esp           /* restore %esp */
  61         /* movl 20(%ecx),%eax           return PC */
  62
  63         /*
  64          * Since we are abandoning the stack in any case,
  65          * there isn't much point in doing the usual return
  66          * discipline.
  67          */
  68
  69         jmpl    *20(%ecx)
  70