sysdeps/i386/bp-asm.h

   1 /* Bounded-pointer definitions for x86 assembler.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    Contributed by Greg McGary <greg@mcgary.org>
   4
   5    This file is part of the GNU C Library.  Its master source is NOT part of
   6    the C library, however.  The master source lives in the GNU MP Library.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Library General Public License as
  10    published by the Free Software Foundation; either version 2 of the
  11    License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Library General Public License for more details.
  17
  18    You should have received a copy of the GNU Library General Public
  19    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  20    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #ifndef _bp_asm_h_
  24 # define _bp_asm_h_ 1
  25
  26 # if __ASSEMBLER__
  27
  28 #  if __BOUNDED_POINTERS__
  29
  30 /* Bounded pointers occupy three words.  */
  31 #   define PTR_SIZE 12
  32 /* Bounded pointer return values are passed back through a hidden
  33    argument that points to caller-allocate space.  The hidden arg
  34    occupies one word on the stack.  */
  35 #   define RTN_SIZE 4
  36 /* Although the caller pushes the hidden arg, the callee is
  37    responsible for popping it.  */
  38 #   define RET_PTR ret $RTN_SIZE
  39 /* Maintain frame pointer chain in leaf assembler functions for the benefit
  40    of debugging stack traces when bounds violations occur.  */
  41 #   define ENTER pushl %ebp; movl %esp, %ebp
  42 #   define LEAVE movl %ebp, %esp; popl %ebp
  43 /* Stack space overhead of procedure-call linkage: return address and
  44    frame pointer.  */
  45 #   define LINKAGE 8
  46 /* Stack offset of return address after calling ENTER.  */
  47 #   define PCOFF 4
  48
  49 /* Int 5 is the "bound range" exception also raised by the "bound"
  50    instruction.  */
  51 #   define BOUNDS_VIOLATED int $5
  52
  53 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)    \
  54         cmpl 4+BP_MEM, VAL_REG;                 \
  55         jae 0f; /* continue if value >= low */  \
  56         BOUNDS_VIOLATED;                        \
  57     0:
  58
  59 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)      \
  60         cmpl 8+BP_MEM, VAL_REG;                         \
  61         Jcc 0f; /* continue if value < high */          \
  62         BOUNDS_VIOLATED;                                \
  63     0:
  64
  65 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)   \
  66         cmpl 4+BP_MEM, VAL_REG;                 \
  67         jb 1f; /* die if value < low */         \
  68         cmpl 8+BP_MEM, VAL_REG;                 \
  69         jb 0f; /* continue if value < high */   \
  70     1:  BOUNDS_VIOLATED;                        \
  71     0:
  72
  73 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)      \
  74         CHECK_BOUNDS_LOW(VAL_REG, BP_MEM);                      \
  75         addl LENGTH, VAL_REG;                                   \
  76         cmpl 8+BP_MEM, VAL_REG;                                 \
  77         jbe 0f; /* continue if value <= high */                 \
  78         BOUNDS_VIOLATED;                                        \
  79     0:  subl LENGTH, VAL_REG /* restore value */
  80
  81 /* Take bounds from BP_MEM and affix them to the pointer
  82    value in %eax, stuffing all into memory at RTN(%esp).
  83    Use %edx as a scratch register.  */
  84
  85 #   define RETURN_BOUNDED_POINTER(BP_MEM)       \
  86         movl RTN(%esp), %edx;                   \
  87         movl %eax, 0(%edx);                     \
  88         movl 4+BP_MEM, %eax;                    \
  89         movl %eax, 4(%edx);                     \
  90         movl 8+BP_MEM, %eax;                    \
  91         movl %eax, 8(%edx)
  92
  93 #   define RETURN_NULL_BOUNDED_POINTER          \
  94         movl RTN(%esp), %edx;                   \
  95         movl %eax, 0(%edx);                     \
  96         movl %eax, 4(%edx);                     \
  97         movl %eax, 8(%edx)
  98
  99 /* The caller of __errno_location is responsible for allocating space
 100    for the three-word BP return-value and passing pushing its address
 101    as an implicit first argument.  */
 102 #   define PUSH_ERRNO_LOCATION_RETURN           \
 103         subl $8, %esp;                          \
 104         subl $4, %esp;                          \
 105         pushl %esp
 106
 107 /* __errno_location is responsible for popping the implicit first
 108    argument, but we must pop the space for the BP itself.  We also
 109    dereference the return value in order to dig out the pointer value.  */
 110 #   define POP_ERRNO_LOCATION_RETURN            \
 111         popl %eax;                              \
 112         addl $8, %esp
 113
 114 #  else /* !__BOUNDED_POINTERS__ */
 115
 116 /* Unbounded pointers occupy one word.  */
 117 #   define PTR_SIZE 4
 118 /* Unbounded pointer return values are passed back in the register %eax.  */
 119 #   define RTN_SIZE 0
 120 /* Use simple return instruction for unbounded pointer values.  */
 121 #   define RET_PTR ret
 122 /* Don't maintain frame pointer chain for leaf assembler functions.  */
 123 #   define ENTER
 124 #   define LEAVE
 125 /* Stack space overhead of procedure-call linkage: return address only.  */
 126 #   define LINKAGE 4
 127 /* Stack offset of return address after calling ENTER.  */
 128 #   define PCOFF 0
 129
 130 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)
 131 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)
 132 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)
 133 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)
 134 #   define RETURN_BOUNDED_POINTER(BP_MEM)
 135
 136 #   define RETURN_NULL_BOUNDED_POINTER
 137
 138 #   define PUSH_ERRNO_LOCATION_RETURN
 139 #   define POP_ERRNO_LOCATION_RETURN
 140
 141 #  endif /* !__BOUNDED_POINTERS__ */
 142
 143 # endif /* __ASSEMBLER__ */
 144
 145 #endif /* _bp_asm_h_ */