gcc/config/s390/tpf-eh.c

   1 /* Exception handling routines for TPF.
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3    Contributed by P.J. Darcy (darcypj@us.ibm.com).
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    In addition to the permissions in the GNU General Public License, the
  13    Free Software Foundation gives you unlimited permission to link the
  14    compiled version of this file into combinations with other programs,
  15    and to distribute those combinations without any restriction coming
  16    from the use of this file.  (The General Public License restrictions
  17    do apply in other respects; for example, they cover modification of
  18    the file, and distribution when not linked into a combined
  19    executable.)
  20
  21    GCC is distributed in the hope that it will be useful, but WITHOUT
  22    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  23    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  24    License for more details.
  25
  26    You should have received a copy of the GNU General Public License
  27    along with GCC; see the file COPYING.  If not, write to the Free
  28    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  29    02111-1307, USA.  */
  30
  31 #define __USE_GNU 1
  32 #define _GNU_SOURCE
  33 #include <dlfcn.h>
  34 #undef __USE_GNU
  35 #undef _GNU_SOURCE
  36
  37 #define CURRENT_STACK_PTR() \
  38   ({ register unsigned long int *stack_ptr asm ("%r15"); stack_ptr; })
  39
  40 #define PREVIOUS_STACK_PTR() \
  41   ((unsigned long int *)(*(CURRENT_STACK_PTR())))
  42
  43 #define RA_OFFSET_FROM_START_OF_STACK_FRAME 112
  44 #define CURRENT_STACK_PTR_OFFSET 120
  45 #define TPFRA_OFFSET_FROM_START_OF_STACK_FRAME 168
  46 #define MIN_PATRANGE 0x10000
  47 #define MAX_PATRANGE 0x800000
  48 #define INVALID_RETURN 0
  49
  50 /* Function Name: __isPATrange
  51    Parameters passed into it:  address to check
  52    Return Value: A 1 if address is in pat code "range", 0 if not
  53    Description: This function simply checks to see if the address
  54    passed to it is in the CP pat code range.  */
  55
  56 unsigned int __isPATrange(void *addr)
  57 {
  58   if (addr > (void *)MIN_PATRANGE && addr < (void *)MAX_PATRANGE)
  59     return 1;
  60   else
  61     return 0;
  62 }
  63
  64 /* Function Name: __tpf_eh_return
  65    Parameters passed into it: Destination address to jump to.
  66    Return Value: Converted Destination address if a Pat Stub exists.
  67    Description: This function swaps the unwinding return address
  68       with the cp stub code.  The original target return address is
  69       then stored into the tpf return address field.  The cp stub
  70       code is searched for by climbing back up the stack and
  71       comparing the tpf stored return address object address to
  72       that of the targets object address.  */
  73
  74 void *__tpf_eh_return (void *target)
  75 {
  76   Dl_info targetcodeInfo, currentcodeInfo;
  77   int retval;
  78   void *current, *stackptr;
  79   unsigned long int shifter;
  80
  81   /* Get code info for target return's address.  */
  82   retval = dladdr (target, &targetcodeInfo);
  83
  84   /* Get the return address of the stack frame to be replaced by
  85      the exception unwinder.  So that the __cxa_throw return is
  86      replaced by the target return.  */
  87   current = (void *) *((unsigned long int *)
  88                  ((*((unsigned long int *)*(PREVIOUS_STACK_PTR())))
  89                              + RA_OFFSET_FROM_START_OF_STACK_FRAME));
  90
  91   /* Ensure the code info is valid (for target).  */
  92   if (retval != INVALID_RETURN)
  93     {
  94       /* Now check to see if the current RA is a PAT
  95          stub return address.  */
  96       if ( __isPATrange(current))
  97         {
  98           /* It was!  Then go into the TPF private stack area and fetch
  99              the real address.  */
 100           current = (void *) *((unsigned long int *)
 101                            ((unsigned long int)*((unsigned long int *)
 102                            *(PREVIOUS_STACK_PTR()))
 103                            +TPFRA_OFFSET_FROM_START_OF_STACK_FRAME));
 104         }
 105
 106       /* Get code info for current return address.  */
 107       retval = dladdr (current, &currentcodeInfo);
 108
 109       /* Ensure the code info is valid (for current frame).  */
 110       if (retval != INVALID_RETURN)
 111         {
 112           /* Get the stack pointer of the stack frame to be replaced by
 113              the exception unwinder.  So that we can begin our climb
 114              there.  */
 115           stackptr = (void *) (*((unsigned long int *)
 116                       (*((unsigned long int *)(*(PREVIOUS_STACK_PTR()))))));
 117
 118           /* Begin looping through stack frames.  Stop if invalid
 119              code information is retrieved or if a match between the
 120              current stack frame iteration shared object's address
 121              matches that of the target, calculated above.  */
 122           while (retval != INVALID_RETURN
 123                  && targetcodeInfo.dli_fbase != currentcodeInfo.dli_fbase)
 124             {
 125               /* Get return address based on our stackptr iterator.  */
 126               current = (void *) *((unsigned long int *)
 127                      (stackptr+RA_OFFSET_FROM_START_OF_STACK_FRAME));
 128
 129               /* Is it a Pat Stub?  */
 130               if (__isPATrange (current))
 131                 {
 132                   /* Yes it was, get real return address
 133                      in TPF stack area.  */
 134                   current = (void *) *((unsigned long int *)
 135                          (stackptr+TPFRA_OFFSET_FROM_START_OF_STACK_FRAME));
 136                 }
 137
 138               /* Get codeinfo on RA so that we can figure out
 139                  the module address.  */
 140               retval = dladdr (current, &currentcodeInfo);
 141
 142               /* Check that codeinfo for current stack frame is valid.
 143                  Then compare the module address of current stack frame
 144                  to target stack frame to determine if we have the pat
 145                  stub address we want.  */
 146               if (retval != INVALID_RETURN
 147                   && targetcodeInfo.dli_fbase == currentcodeInfo.dli_fbase)
 148                 {
 149                   /* Yes!  They are in the same module.  Now store the
 150                      real target address into the TPF stack area of
 151                      the target frame we are jumping to.  */
 152                   *((unsigned long int *)(*((unsigned long int *)
 153                           (*PREVIOUS_STACK_PTR() + CURRENT_STACK_PTR_OFFSET))
 154                           + TPFRA_OFFSET_FROM_START_OF_STACK_FRAME))
 155                           = (unsigned long int) target;
 156
 157                   /* Before returning the desired pat stub address to
 158                      the exception handling unwinder so that it can
 159                      actually do the "leap" shift out the low order
 160                      bit designated to determine if we are in 64BIT mode.
 161                      This is necessary for CTOA stubs.
 162                      Otherwise we leap one byte past where we want to
 163                      go to in the TPF pat stub linkage code.  */
 164                   shifter = *((unsigned long int *)
 165                        (stackptr + RA_OFFSET_FROM_START_OF_STACK_FRAME));
 166
 167                   shifter &= ~1ul;
 168
 169                   return (void *) shifter;
 170                 }
 171
 172               /* Desired module pat stub not found ...
 173                  Bump stack frame iterator.  */
 174               stackptr = (void *) *(unsigned long int *) stackptr;
 175             }
 176         }
 177     }
 178
 179   /* No pat stub found, could be a problem?  Simply return unmodified
 180      target address.  */
 181   return target;
 182 }
 183