1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/* prmci3li.c: PROTECTION MUTATOR CONTEXT INTEL 386 (LINUX)
 *
 * $Id: //info.ravenbrook.com/project/mps/version/1.110/code/prmci3li.c#1 $
 * Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
 *
 * .purpose: This module implements the part of the protection module
 * that decodes the MutatorFaultContext. 
 *
 *
 * SOURCES
 *
 * .source.i486: Intel486 Microprocessor Family Programmer's
 * Reference Manual
 *
 * .source.linux.kernel: Linux kernel source files.
 *
 *
 * ASSUMPTIONS
 *
 * .sp: The stack pointer in the context is uc_stack.ss_sp.
 *
 * .context.regroots: The root regs are assumed to be recorded in the context
 * at pointer-aligned boundaries.
 *
 * .assume.regref: The resisters in the context can be modified by
 * storing into an MRef pointer.
 */

#include "prmcix.h"
#include "prmci3.h"

SRCID(prmci3li, "$Id: //info.ravenbrook.com/project/mps/version/1.110/code/prmci3li.c#1 $");


/* Prmci3AddressHoldingReg -- return an address of a register in a context */

MRef Prmci3AddressHoldingReg(MutatorFaultContext mfc, unsigned int regnum)
{
  AVER(regnum <= 7);
  AVER(regnum >= 0);

  /* .source.i486 */
  /* .assume.regref */
  /* The REG_EAX etc. symbols are only present if _GNU_SOURCE is defined.
     Currently this is in lii3gc.gmk in PFMDEFS. */
  /* TODO: The current arrangement of the fix operation (taking a Ref *)
     forces us to pun these registers (actually `int` on LII3GC).  We can
     suppress the warning my casting through `char *` and this might make
     it safe, but does it really?  RB 2012-09-10 */
  switch (regnum) {
    case 0: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_EAX]);
    case 1: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_ECX]);
    case 2: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_EDX]);
    case 3: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_EBX]);
    case 4: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_ESP]);
    case 5: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_EBP]);
    case 6: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_ESI]);
    case 7: return (MRef)((char *)&mfc->ucontext->uc_mcontext.gregs[REG_EDI]);
  }
  NOTREACHED;
  return (MRef)NULL;  /* Avoids compiler warning. */
}


/* Prmci3DecodeFaultContext -- decode fault to find faulting address and IP */

void Prmci3DecodeFaultContext(MRef *faultmemReturn,
                              Byte **insvecReturn,
                              MutatorFaultContext mfc)
{
  /* .source.linux.kernel (linux/arch/i386/mm/fault.c). */
  *faultmemReturn = (MRef)mfc->info->si_addr;
  *insvecReturn = (Byte*)mfc->ucontext->uc_mcontext.gregs[REG_EIP];
}


/* Prmci3StepOverIns -- modify context to step over instruction */

void Prmci3StepOverIns(MutatorFaultContext mfc, Size inslen)
{
  mfc->ucontext->uc_mcontext.gregs[REG_EIP] += (unsigned long)inslen;
}


Addr MutatorFaultContextSP(MutatorFaultContext mfc)
{
  return (Addr)mfc->ucontext->uc_stack.ss_sp;
}


Res MutatorFaultContextScan(ScanState ss, MutatorFaultContext mfc)
{
  mcontext_t *mc;
  Res res;

  /* This scans the root registers (.context.regroots).  It also
     unnecessarily scans the rest of the context.  The optimisation
     to scan only relevant parts would be machine dependent. */
  mc = &mfc->ucontext->uc_mcontext;
  res = TraceScanAreaTagged(ss,
                            (Addr *)mc,
                            (Addr *)((char *)mc + sizeof(*mc)));
  return res;
}


/* C. COPYRIGHT AND LICENSE
 *
 * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
 * All rights reserved.  This is an open source license.  Contact
 * Ravenbrook for commercial licensing options.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * 3. Redistributions in any form must be accompanied by information on how
 * to obtain complete source code for this software and any accompanying
 * software that uses this software.  The source code must either be
 * included in the distribution or be available for no more than the cost
 * of distribution plus a nominal fee, and must be freely redistributable
 * under reasonable conditions.  For an executable file, complete source
 * code means the source code for all modules it contains. It does not
 * include source code for modules or files that typically accompany the
 * major components of the operating system on which the executable file
 * runs.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */