sysdeps/i386/bp-asm.h

   1 /* Bounded-pointer definitions for x86 assembler.
   2    Copyright (C) 2000-2013 Free Software Foundation, Inc.
   3    Contributed by Greg McGary <greg@mcgary.org>
   4    This file is part of the GNU C Library.  Its master source is NOT part of
   5    the C library, however.  The master source lives in the GNU MP Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library 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 GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, see
  19    <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef _bp_asm_h_
  22 # define _bp_asm_h_ 1
  23
  24 # if __ASSEMBLER__
  25
  26 #  if __BOUNDED_POINTERS__
  27
  28 /* Bounded pointers occupy three words.  */
  29 #   define PTR_SIZE 12
  30 /* Bounded pointer return values are passed back through a hidden
  31    argument that points to caller-allocate space.  The hidden arg
  32    occupies one word on the stack.  */
  33 #   define RTN_SIZE 4
  34 /* Although the caller pushes the hidden arg, the callee is
  35    responsible for popping it.  */
  36 #   define RET_PTR ret $RTN_SIZE
  37 /* Maintain frame pointer chain in leaf assembler functions for the benefit
  38    of debugging stack traces when bounds violations occur.  */
  39 #   define ENTER pushl %ebp; movl %esp, %ebp
  40 #   define LEAVE movl %ebp, %esp; popl %ebp
  41 /* Stack space overhead of procedure-call linkage: return address and
  42    frame pointer.  */
  43 #   define LINKAGE 8
  44 /* Stack offset of return address after calling ENTER.  */
  45 #   define PCOFF 4
  46
  47 /* Int 5 is the "bound range" exception also raised by the "bound"
  48    instruction.  */
  49 #   define BOUNDS_VIOLATED int $5
  50
  51 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)    \
  52         cmpl 4+BP_MEM, VAL_REG;                 \
  53         jae 0f; /* continue if value >= low */  \
  54         BOUNDS_VIOLATED;                        \
  55     0:
  56
  57 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)      \
  58         cmpl 8+BP_MEM, VAL_REG;                         \
  59         Jcc 0f; /* continue if value < high */          \
  60         BOUNDS_VIOLATED;                                \
  61     0:
  62
  63 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)   \
  64         cmpl 4+BP_MEM, VAL_REG;                 \
  65         jb 1f; /* die if value < low */         \
  66         cmpl 8+BP_MEM, VAL_REG;                 \
  67         jb 0f; /* continue if value < high */   \
  68     1:  BOUNDS_VIOLATED;                        \
  69     0:
  70
  71 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)      \
  72         CHECK_BOUNDS_LOW(VAL_REG, BP_MEM);                      \
  73         addl LENGTH, VAL_REG;                                   \
  74         cmpl 8+BP_MEM, VAL_REG;                                 \
  75         jbe 0f; /* continue if value <= high */                 \
  76         BOUNDS_VIOLATED;                                        \
  77     0:  subl LENGTH, VAL_REG /* restore value */
  78
  79 /* Take bounds from BP_MEM and affix them to the pointer
  80    value in %eax, stuffing all into memory at RTN(%esp).
  81    Use %edx as a scratch register.  */
  82
  83 #   define RETURN_BOUNDED_POINTER(BP_MEM)       \
  84         movl RTN(%esp), %edx;                   \
  85         movl %eax, 0(%edx);                     \
  86         movl 4+BP_MEM, %eax;                    \
  87         movl %eax, 4(%edx);                     \
  88         movl 8+BP_MEM, %eax;                    \
  89         movl %eax, 8(%edx)
  90
  91 #   define RETURN_NULL_BOUNDED_POINTER          \
  92         movl RTN(%esp), %edx;                   \
  93         movl %eax, 0(%edx);                     \
  94         movl %eax, 4(%edx);                     \
  95         movl %eax, 8(%edx)
  96
  97 /* The caller of __errno_location is responsible for allocating space
  98    for the three-word BP return-value and passing pushing its address
  99    as an implicit first argument.  */
 100 #   define PUSH_ERRNO_LOCATION_RETURN           \
 101         subl $8, %esp;                          \
 102         subl $4, %esp;                          \
 103         pushl %esp
 104
 105 /* __errno_location is responsible for popping the implicit first
 106    argument, but we must pop the space for the BP itself.  We also
 107    dereference the return value in order to dig out the pointer value.  */
 108 #   define POP_ERRNO_LOCATION_RETURN            \
 109         popl %eax;                              \
 110         addl $8, %esp
 111
 112 #  else /* !__BOUNDED_POINTERS__ */
 113
 114 /* Unbounded pointers occupy one word.  */
 115 #   define PTR_SIZE 4
 116 /* Unbounded pointer return values are passed back in the register %eax.  */
 117 #   define RTN_SIZE 0
 118 /* Use simple return instruction for unbounded pointer values.  */
 119 #   define RET_PTR ret
 120 /* Don't maintain frame pointer chain for leaf assembler functions.  */
 121 #   define ENTER
 122 #   define LEAVE
 123 /* Stack space overhead of procedure-call linkage: return address only.  */
 124 #   define LINKAGE 4
 125 /* Stack offset of return address after calling ENTER.  */
 126 #   define PCOFF 0
 127
 128 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)
 129 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)
 130 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)
 131 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)
 132 #   define RETURN_BOUNDED_POINTER(BP_MEM)
 133
 134 #   define RETURN_NULL_BOUNDED_POINTER
 135
 136 #   define PUSH_ERRNO_LOCATION_RETURN
 137 #   define POP_ERRNO_LOCATION_RETURN
 138
 139 #  endif /* !__BOUNDED_POINTERS__ */
 140
 141 # endif /* __ASSEMBLER__ */
 142
 143 #endif /* _bp_asm_h_ */