sysdeps/mach/hurd/i386/____longjmp_chk.S

   1 /* Copyright (C) 2001-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <sysdep.h>
  19 #include <jmpbuf-offsets.h>
  20 #include <asm-syntax.h>
  21
  22 #include <signal-defines.h>
  23 /* #include <signal.h> */
  24 #define SS_ONSTACK 1
  25
  26
  27         .section .rodata.str1.1,"aMS",@progbits,1
  28         .type   longjmp_msg,@object
  29 longjmp_msg:
  30         .string "longjmp causes uninitialized stack frame"
  31         .size   longjmp_msg, .-longjmp_msg
  32
  33
  34 #ifdef PIC
  35 # define CALL_FAIL      movl    %ebx, %ecx; /* TODO: what's this mov good for? */ \
  36                         cfi_register(%ebx,%ecx);                              \
  37                         LOAD_PIC_REG (bx);                                    \
  38                         leal    longjmp_msg@GOTOFF(%ebx), %eax;               \
  39                         call    HIDDEN_JUMPTARGET(__fortify_fail)
  40 #else
  41 # define CALL_FAIL      movl    $longjmp_msg, %eax;                           \
  42                         call    HIDDEN_JUMPTARGET(__fortify_fail)
  43 #endif
  44
  45
  46         .text
  47 ENTRY (____longjmp_chk)
  48         movl    4(%esp), %ecx   /* User's jmp_buf in %ecx.  */
  49
  50         /* Save the return address now.  */
  51         movl    (JB_PC*4)(%ecx), %edx
  52         /* Get the stack pointer.  */
  53         movl    (JB_SP*4)(%ecx), %edi
  54         cfi_undefined(%edi)
  55 #ifdef PTR_DEMANGLE
  56         PTR_DEMANGLE (%edx)
  57         PTR_DEMANGLE (%edi)
  58 #endif
  59
  60         cmpl    %edi, %esp
  61         /* Jumping to a higher-address frame is always allowed.  */
  62         jbe     .Lok
  63
  64         /* Passing here, we're either about to do something invalid, or we're
  65         executing on an alternative signal stack.  */
  66
  67         /* TODO: need locking?  */
  68         /* struct hurd_sigstate * _hurd_self_sigstate (void) */
  69 #ifdef PIC
  70         call    1f
  71 1:      popl    %ebx
  72         addl    $_GLOBAL_OFFSET_TABLE_+[.-1b], %ebx
  73 #endif
  74         call    JUMPTARGET(_hurd_self_sigstate)
  75         /* TODO: %eax and %eax->sigaltstack are always valid?  */
  76
  77         testl   $SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%eax)
  78         /* Fail if SS_ONSTACK is not set.  */
  79         jz      .Lfail
  80
  81         movl    (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%eax), %ebx
  82         addl    (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%eax), %ebx
  83         subl    %edi, %ebx
  84         cmpl    (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%eax), %ebx
  85         /* TODO: comment this calculation.  */
  86         jae     .Lok
  87
  88 .Lfail: CALL_FAIL
  89
  90 .Lok:   /* We add unwind information for the target here.  */
  91         cfi_def_cfa(%ecx, 0)
  92         cfi_register(%eip, %edx)
  93         cfi_register(%esp, %edi)
  94         cfi_offset(%ebx, JB_BX*4)
  95         cfi_offset(%esi, JB_SI*4)
  96         cfi_offset(%edi, JB_DI*4)
  97         cfi_offset(%ebp, JB_BP*4)
  98
  99         movl    8(%esp), %eax   /* Second argument is return value.  */
 100         movl    %edi, %esp
 101
 102         /* Restore registers.  */
 103         movl    (JB_BX*4)(%ecx), %ebx
 104         movl    (JB_SI*4)(%ecx), %esi
 105         movl    (JB_DI*4)(%ecx), %edi
 106         movl    (JB_BP*4)(%ecx), %ebp
 107         cfi_restore(%ebx)
 108         cfi_restore(%esi)
 109         cfi_restore(%edi)
 110         cfi_restore(%ebp)
 111
 112         /* Jump to saved PC.  */
 113         jmp     *%edx
 114 END (____longjmp_chk)