sysdeps/x86_64/bp-asm.h

   1 /* Bounded-pointer definitions for x86-64 assembler.
   2    Copyright (C) 2001 Free Software Foundation, Inc.
   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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #ifndef _bp_asm_h_
  20 # define _bp_asm_h_ 1
  21
  22 # if __ASSEMBLER__
  23
  24 #  if __BOUNDED_POINTERS__
  25
  26 /* Bounded pointers occupy three words.  */
  27 #   define PTR_SIZE 24
  28 /* Bounded pointer return values are passed back through a hidden
  29    argument that points to caller-allocate space.  The hidden arg
  30    occupies one word on the stack.  */
  31 #   define RTN_SIZE 6
  32 /* Although the caller pushes the hidden arg, the callee is
  33    responsible for popping it.  */
  34 #   define RET_PTR ret $RTN_SIZE
  35 /* Maintain frame pointer chain in leaf assembler functions for the benefit
  36    of debugging stack traces when bounds violations occur.  */
  37 #   define ENTER pushq %rbp; movq %rsp, %rbp
  38 #   define LEAVE movq %rbp, %rsp; popq %rbp
  39 /* Stack space overhead of procedure-call linkage: return address and
  40    frame pointer.  */
  41 #   define LINKAGE 16
  42 /* Stack offset of return address after calling ENTER.  */
  43 #   define PCOFF 8
  44
  45 /* Int 5 is the "bound range" exception also raised by the "bound"
  46    instruction.  */
  47 #   define BOUNDS_VIOLATED int $5
  48
  49 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)    \
  50         cmpq 8+BP_MEM, VAL_REG;                 \
  51         jae 0f; /* continue if value >= low */  \
  52         BOUNDS_VIOLATED;                        \
  53     0:
  54
  55 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)      \
  56         cmpq 16+BP_MEM, VAL_REG;                        \
  57         Jcc 0f; /* continue if value < high */          \
  58         BOUNDS_VIOLATED;                                \
  59     0:
  60
  61 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)   \
  62         cmpq 8+BP_MEM, VAL_REG;                 \
  63         jb 1f; /* die if value < low */         \
  64         cmpq 16+BP_MEM, VAL_REG;                \
  65         jb 0f; /* continue if value < high */   \
  66     1:  BOUNDS_VIOLATED;                        \
  67     0:
  68
  69 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)      \
  70         CHECK_BOUNDS_LOW(VAL_REG, BP_MEM);                      \
  71         addl LENGTH, VAL_REG;                                   \
  72         cmpq 16+BP_MEM, VAL_REG;                                        \
  73         jbe 0f; /* continue if value <= high */                 \
  74         BOUNDS_VIOLATED;                                        \
  75     0:  subq LENGTH, VAL_REG /* restore value */
  76
  77 /* Take bounds from BP_MEM and affix them to the pointer
  78    value in %rax, stuffing all into memory at RTN(%esp).
  79    Use %rdx as a scratch register.  */
  80
  81 #   define RETURN_BOUNDED_POINTER(BP_MEM)       \
  82         movq RTN(%rsp), %rdx;                   \
  83         movq %rax, 0(%rdx);                     \
  84         movq 8+BP_MEM, %rax;                    \
  85         movq %rax, 4(%rdx);                     \
  86         movq 16+BP_MEM, %rax;                   \
  87         movq %rax, 8(%rdx)
  88
  89 #   define RETURN_NULL_BOUNDED_POINTER          \
  90         movl RTN(%rsp), %rdx;                   \
  91         movl %rax, 0(%rdx);                     \
  92         movl %rax, 4(%rdx);                     \
  93         movl %rax, 8(%rdx)
  94
  95 /* The caller of __errno_location is responsible for allocating space
  96    for the three-word BP return-value and passing pushing its address
  97    as an implicit first argument.  */
  98 #   define PUSH_ERRNO_LOCATION_RETURN           \
  99         subl $16, %esp;                         \
 100         subl $8, %esp;                          \
 101         pushq %rsp
 102
 103 /* __errno_location is responsible for popping the implicit first
 104    argument, but we must pop the space for the BP itself.  We also
 105    dereference the return value in order to dig out the pointer value.  */
 106 #   define POP_ERRNO_LOCATION_RETURN            \
 107         popq %rax;                              \
 108         addq $16, %rsp
 109
 110 #  else /* !__BOUNDED_POINTERS__ */
 111
 112 /* Unbounded pointers occupy one word.  */
 113 #   define PTR_SIZE 8
 114 /* Unbounded pointer return values are passed back in the register %rax.  */
 115 #   define RTN_SIZE 0
 116 /* Use simple return instruction for unbounded pointer values.  */
 117 #   define RET_PTR ret
 118 /* Don't maintain frame pointer chain for leaf assembler functions.  */
 119 #   define ENTER
 120 #   define LEAVE
 121 /* Stack space overhead of procedure-call linkage: return address only.  */
 122 #   define LINKAGE 8
 123 /* Stack offset of return address after calling ENTER.  */
 124 #   define PCOFF 0
 125
 126 #   define CHECK_BOUNDS_LOW(VAL_REG, BP_MEM)
 127 #   define CHECK_BOUNDS_HIGH(VAL_REG, BP_MEM, Jcc)
 128 #   define CHECK_BOUNDS_BOTH(VAL_REG, BP_MEM)
 129 #   define CHECK_BOUNDS_BOTH_WIDE(VAL_REG, BP_MEM, LENGTH)
 130 #   define RETURN_BOUNDED_POINTER(BP_MEM)
 131
 132 #   define RETURN_NULL_BOUNDED_POINTER
 133
 134 #   define PUSH_ERRNO_LOCATION_RETURN
 135 #   define POP_ERRNO_LOCATION_RETURN
 136
 137 #  endif /* !__BOUNDED_POINTERS__ */
 138
 139 # endif /* __ASSEMBLER__ */
 140
 141 #endif /* _bp_asm_h_ */