tpf-unwind.h revision 1.1 
1/* DWARF2 EH unwinding support for TPF OS.
2   Copyright (C) 2004-2013 Free Software Foundation, Inc.
3   Contributed by P.J. Darcy (darcypj@us.ibm.com).
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 3, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17Under Section 7 of GPL version 3, you are granted additional
18permissions described in the GCC Runtime Library Exception, version
193.1, as published by the Free Software Foundation.
20
21You should have received a copy of the GNU General Public License and
22a copy of the GCC Runtime Library Exception along with this program;
23see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24<http://www.gnu.org/licenses/>.  */
25
26#include <dlfcn.h>
27
28/* Function Name: __isPATrange
29   Parameters passed into it:  address to check
30   Return Value: A 1 if address is in pat code "range", 0 if not
31   Description: This function simply checks to see if the address
32   passed to it is in the CP pat code range.  */
33
34#define MIN_PATRANGE 0x10000
35#define MAX_PATRANGE 0x800000
36
37static inline unsigned int
38__isPATrange (void *addr)
39{
40  if (addr > (void *)MIN_PATRANGE && addr < (void *)MAX_PATRANGE)
41    return 1;
42  else
43    return 0;
44}
45
46/* TPF return address offset from start of stack frame.  */
47#define TPFRA_OFFSET 168
48
49/* Exceptions macro defined for TPF so that functions without
50   dwarf frame information can be used with exceptions.  */
51#define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
52
53static _Unwind_Reason_Code
54s390_fallback_frame_state (struct _Unwind_Context *context,
55			   _Unwind_FrameState *fs)
56{
57  unsigned long int regs;
58  unsigned long int new_cfa;
59  int i;
60
61  regs = *((unsigned long int *)
62        (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
63
64  /* Are we going through special linkage code?  */
65  if (__isPATrange (context->ra))
66    {
67
68      /* Our return register isn't zero for end of stack, so
69         check backward stackpointer to see if it is zero.  */
70      if (regs == NULL)
71         return _URC_END_OF_STACK;
72
73      /* No stack frame.  */
74      fs->regs.cfa_how = CFA_REG_OFFSET;
75      fs->regs.cfa_reg = 15;
76      fs->regs.cfa_offset = STACK_POINTER_OFFSET;
77
78      /* All registers remain unchanged ...  */
79      for (i = 0; i < 32; i++)
80	{
81	  fs->regs.reg[i].how = REG_SAVED_REG;
82	  fs->regs.reg[i].loc.reg = i;
83	}
84
85      /* ... except for %r14, which is stored at CFA-112
86	 and used as return address.  */
87      fs->regs.reg[14].how = REG_SAVED_OFFSET;
88      fs->regs.reg[14].loc.offset = TPFRA_OFFSET - STACK_POINTER_OFFSET;
89      fs->retaddr_column = 14;
90
91      return _URC_NO_REASON;
92    }
93
94  regs = *((unsigned long int *)
95        (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
96  new_cfa = regs + STACK_POINTER_OFFSET;
97
98  fs->regs.cfa_how = CFA_REG_OFFSET;
99  fs->regs.cfa_reg = 15;
100  fs->regs.cfa_offset = new_cfa -
101        (unsigned long int) context->cfa + STACK_POINTER_OFFSET;
102
103  for (i = 0; i < 16; i++)
104    {
105      fs->regs.reg[i].how = REG_SAVED_OFFSET;
106      fs->regs.reg[i].loc.offset = regs + i*8 - new_cfa;
107    }
108
109  for (i = 0; i < 4; i++)
110    {
111      fs->regs.reg[16 + i].how = REG_SAVED_OFFSET;
112      fs->regs.reg[16 + i].loc.offset = regs + 16*8 + i*8 - new_cfa;
113    }
114
115  fs->retaddr_column = 14;
116
117  return _URC_NO_REASON;
118}
119
120/* Function Name: __tpf_eh_return
121   Parameters passed into it: Destination address to jump to.
122   Return Value: Converted Destination address if a Pat Stub exists.
123   Description: This function swaps the unwinding return address
124      with the cp stub code.  The original target return address is
125      then stored into the tpf return address field.  The cp stub
126      code is searched for by climbing back up the stack and
127      comparing the tpf stored return address object address to
128      that of the targets object address.  */
129
130#define CURRENT_STACK_PTR() \
131  ({ register unsigned long int *stack_ptr asm ("%r15"); stack_ptr; })
132
133#define PREVIOUS_STACK_PTR() \
134  ((unsigned long int *)(*(CURRENT_STACK_PTR())))
135
136#define RA_OFFSET 112
137#define R15_OFFSET 120
138#define TPFAREA_OFFSET 160
139#define TPFAREA_SIZE STACK_POINTER_OFFSET-TPFAREA_OFFSET
140#define INVALID_RETURN 0
141
142void * __tpf_eh_return (void *target);
143
144void *
145__tpf_eh_return (void *target)
146{
147  Dl_info targetcodeInfo, currentcodeInfo;
148  int retval;
149  void *current, *stackptr, *destination_frame;
150  unsigned long int shifter, is_a_stub;
151
152  is_a_stub = 0;
153
154  /* Get code info for target return's address.  */
155  retval = dladdr (target, &targetcodeInfo);
156
157  /* Ensure the code info is valid (for target).  */
158  if (retval != INVALID_RETURN)
159    {
160
161      /* Get the stack pointer of the stack frame to be modified by
162         the exception unwinder.  So that we can begin our climb
163         there.  */
164      stackptr = (void *) *((unsigned long int *) (*(PREVIOUS_STACK_PTR())));
165
166      /* Begin looping through stack frames.  Stop if invalid
167         code information is retrieved or if a match between the
168         current stack frame iteration shared object's address
169         matches that of the target, calculated above.  */
170      do
171        {
172          /* Get return address based on our stackptr iterator.  */
173          current = (void *) *((unsigned long int *)
174                      (stackptr+RA_OFFSET));
175
176          /* Is it a Pat Stub?  */
177          if (__isPATrange (current))
178            {
179              /* Yes it was, get real return address
180                 in TPF stack area.  */
181              current = (void *) *((unsigned long int *)
182                          (stackptr+TPFRA_OFFSET));
183              is_a_stub = 1;
184            }
185
186          /* Get codeinfo on RA so that we can figure out
187             the module address.  */
188          retval = dladdr (current, &currentcodeInfo);
189
190          /* Check that codeinfo for current stack frame is valid.
191             Then compare the module address of current stack frame
192             to target stack frame to determine if we have the pat
193             stub address we want.  Also ensure we are dealing
194             with a module crossing, stub return address. */
195          if (is_a_stub && retval != INVALID_RETURN
196             && targetcodeInfo.dli_fbase == currentcodeInfo.dli_fbase)
197             {
198               /* Yes! They are in the same module.
199                  Force copy of TPF private stack area to
200                  destination stack frame TPF private area. */
201               destination_frame = (void *) *((unsigned long int *)
202                   (*PREVIOUS_STACK_PTR() + R15_OFFSET));
203
204               /* Copy TPF linkage area from current frame to
205                  destination frame.  */
206               memcpy((void *) (destination_frame + TPFAREA_OFFSET),
207                 (void *) (stackptr + TPFAREA_OFFSET), TPFAREA_SIZE);
208
209               /* Now overlay the
210                  real target address into the TPF stack area of
211                  the target frame we are jumping to.  */
212               *((unsigned long int *) (destination_frame +
213                   TPFRA_OFFSET)) = (unsigned long int) target;
214
215               /* Before returning the desired pat stub address to
216                  the exception handling unwinder so that it can
217                  actually do the "leap" shift out the low order
218                  bit designated to determine if we are in 64BIT mode.
219                  This is necessary for CTOA stubs.
220                  Otherwise we leap one byte past where we want to
221                  go to in the TPF pat stub linkage code.  */
222               shifter = *((unsigned long int *)
223                     (stackptr + RA_OFFSET));
224
225               shifter &= ~1ul;
226
227               /* Store Pat Stub Address in destination Stack Frame.  */
228               *((unsigned long int *) (destination_frame +
229                   RA_OFFSET)) = shifter;
230
231               /* Re-adjust pat stub address to go to correct place
232                  in linkage.  */
233               shifter = shifter - 4;
234
235               return (void *) shifter;
236             }
237
238          /* Desired module pat stub not found ...
239             Bump stack frame iterator.  */
240          stackptr = (void *) *(unsigned long int *) stackptr;
241
242          is_a_stub = 0;
243
244        }  while (stackptr && retval != INVALID_RETURN
245                && targetcodeInfo.dli_fbase != currentcodeInfo.dli_fbase);
246    }
247
248  /* No pat stub found, could be a problem?  Simply return unmodified
249     target address.  */
250  return target;
251}
252
253