libgcc/config/s390/tpf-unwind.h

   1 /* DWARF2 EH unwinding support for TPF OS.
   2    Copyright (C) 2004-2022 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 under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include <dlfcn.h>
  27 #include <stdbool.h>
  28
  29 /* Function Name: __isPATrange
  30    Parameters passed into it:  address to check
  31    Return Value: A 1 if address is in pat code "range", 0 if not
  32    Description: This function simply checks to see if the address
  33    passed to it is in the CP pat code range.  */
  34
  35 #define CP_CNF  0x000000000000c18u /* location of BSS CINFC pointer */
  36 #define cinfc_fast(TAG) (void *) \
  37   *((unsigned long *) *(unsigned long *) (CP_CNF) + (TAG))
  38 #define CINFC_CMRESET 187
  39 #define CINTFC_CMCENBKST 431
  40 #define CINTFC_CMCENBKED 432
  41
  42 static inline unsigned int
  43 __isPATrange (void *addr)
  44 {
  45   return !!(addr > cinfc_fast (CINTFC_CMCENBKST)
  46             && addr < cinfc_fast (CINTFC_CMCENBKED));
  47 }
  48
  49 static inline unsigned int
  50 __isSkipResetAddr (void *addr)
  51 {
  52   return !!(addr == cinfc_fast (CINFC_CMRESET));
  53 }
  54
  55 /* TPF return address offset from start of stack frame.  */
  56 #define ICST_CRET 168
  57 #define ICST_SRET 320
  58
  59 /* Exceptions macro defined for TPF so that functions without
  60    dwarf frame information can be used with exceptions.  */
  61 #define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
  62
  63 static _Unwind_Reason_Code
  64 s390_fallback_frame_state (struct _Unwind_Context *context,
  65                            _Unwind_FrameState *fs)
  66 {
  67   unsigned long int regs;
  68   unsigned long int new_cfa;
  69   int i;
  70
  71   regs = *((unsigned long int *)
  72         (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
  73
  74   /* Are we going through special linkage code?  */
  75   if (__isPATrange (context->ra) || __isSkipResetAddr (context->ra))
  76     {
  77
  78       /* Our return register isn't zero for end of stack, so
  79          check backward stackpointer to see if it is zero.  */
  80       if (regs == 0)
  81          return _URC_END_OF_STACK;
  82
  83       /* No stack frame.  */
  84       fs->regs.cfa_how = CFA_REG_OFFSET;
  85       fs->regs.cfa_reg = 15;
  86       fs->regs.cfa_offset = STACK_POINTER_OFFSET;
  87
  88       /* All registers remain unchanged ...  */
  89       for (i = 0; i < 32; i++)
  90         {
  91           fs->regs.how[i] = REG_SAVED_REG;
  92           fs->regs.reg[i].loc.reg = i;
  93         }
  94
  95       /* ... except for %r14, which is stored at CFA+offset where offset
  96          is displacment of ICST_CRET or ICST_SRET from CFA */
  97       if ( __isPATrange(context->ra) )  {
  98            fs->regs.how[14] = REG_SAVED_OFFSET;
  99            fs->regs.reg[14].loc.offset = ICST_CRET - STACK_POINTER_OFFSET;
 100            fs->retaddr_column = 14;
 101       }  else  {
 102            fs->regs.how[14] = REG_SAVED_OFFSET;
 103            fs->regs.reg[14].loc.offset = ICST_SRET - STACK_POINTER_OFFSET;
 104            fs->retaddr_column = 14;
 105
 106       }
 107
 108       return _URC_NO_REASON;
 109     }
 110
 111   regs = *((unsigned long int *)
 112         (((unsigned long int) context->cfa) - STACK_POINTER_OFFSET));
 113   new_cfa = regs + STACK_POINTER_OFFSET;
 114
 115   fs->regs.cfa_how = CFA_REG_OFFSET;
 116   fs->regs.cfa_reg = 15;
 117   fs->regs.cfa_offset = new_cfa -
 118         (unsigned long int) context->cfa + STACK_POINTER_OFFSET;
 119
 120   for (i = 0; i < 16; i++)
 121     {
 122       fs->regs.how[i] = REG_SAVED_OFFSET;
 123       fs->regs.reg[i].loc.offset = regs + i*8 - new_cfa;
 124     }
 125
 126   for (i = 0; i < 4; i++)
 127     {
 128       fs->regs.how[16 + i] = REG_SAVED_OFFSET;
 129       fs->regs.reg[16 + i].loc.offset = regs + 16*8 + i*8 - new_cfa;
 130     }
 131
 132   fs->retaddr_column = 14;
 133
 134   return _URC_NO_REASON;
 135 }
 136
 137 /* Function Name: __tpf_eh_return
 138    Parameters passed into it: Destination address to jump to.
 139    Return Value: Converted Destination address if a Pat Stub exists.
 140    Description: This function swaps the unwinding return address
 141       with the cp stub code.  The original target return address is
 142       then stored into the tpf return address field.  The cp stub
 143       code is searched for by climbing back up the stack and
 144       comparing the tpf stored return address object address to
 145       that of the targets object address.  */
 146
 147 #define CURRENT_STACK_PTR() \
 148   ({ register unsigned long int *stack_ptr asm ("%r15"); stack_ptr; })
 149
 150 #define PREVIOUS_STACK_PTR() \
 151   ((unsigned long int *)(*(CURRENT_STACK_PTR())))
 152
 153 #define RA_OFFSET 112
 154 #define R15_OFFSET 120
 155 #define TPFAREA_OFFSET 160
 156 #define TPFAREA_SIZE STACK_POINTER_OFFSET-TPFAREA_OFFSET
 157 #define INVALID_RETURN 0
 158
 159 #define LOWCORE_PAGE3_ADDR 4032
 160 #define PG3_SKIPPING_OFFSET 18
 161
 162 void * __tpf_eh_return (void *target, void *origRA);
 163
 164 void *
 165 __tpf_eh_return (void *target, void *origRA)
 166 {
 167   Dl_info targetcodeInfo, currentcodeInfo;
 168   int retval;
 169   void *current, *stackptr, *destination_frame;
 170   unsigned char *skipFlagAddress;
 171   unsigned long int shifter;
 172   bool is_a_stub;
 173
 174   is_a_stub = false;
 175
 176   /* Get code info for target return's address.  */
 177   retval = dladdr (target, &targetcodeInfo);
 178
 179   /* Ensure the code info is valid (for target).  */
 180   if (retval != INVALID_RETURN)
 181     {
 182       /* Begin climbing stack searching for target address. */
 183       stackptr = (void *) *(CURRENT_STACK_PTR());
 184
 185       /* Get return address based on our stackptr. */
 186       current = (void *) *(unsigned long *) (stackptr + RA_OFFSET);
 187
 188       /* Is current return address our initiating exception stack
 189          frame? If not, climb the stack one more frame. */
 190       if (current != origRA)  {
 191            stackptr = (void *) *(unsigned long *) stackptr;
 192       }
 193
 194       /* Begin looping through stack frames.  Stop if invalid
 195          code information is retrieved or if a match between the
 196          current stack frame iteration shared object's address
 197          matches that of the target, calculated above.  */
 198       do
 199         {
 200           /* Get return address based on our stackptr iterator.  */
 201           current = (void *) *(unsigned long *) (stackptr + RA_OFFSET);
 202
 203           /* Is it a Pat Stub?  */
 204           if (__isPATrange (current)
 205               || (__isSkipResetAddr (current)
 206                   && __isPATrange ((void *) *(unsigned long *) (stackptr
 207                                                                 + ICST_SRET))))
 208             {
 209               /* Yes it was, get real return address in TPF stack area.  */
 210               current = (void *) *(unsigned long *) (stackptr + ICST_CRET);
 211               is_a_stub = true;
 212             }
 213
 214           /* Get codeinfo on RA so that we can figure out
 215              the module address.  */
 216           retval = dladdr (current, &currentcodeInfo);
 217
 218           /* Check that codeinfo for current stack frame is valid.
 219              Then compare the module address of current stack frame
 220              to target stack frame to determine if we have the pat
 221              stub address we want.  Also ensure we are dealing
 222              with a module crossing, stub return address. */
 223           if (is_a_stub && retval != INVALID_RETURN
 224              && targetcodeInfo.dli_fbase == currentcodeInfo.dli_fbase)
 225              {
 226                /* Yes! They are in the same module.
 227                   Force copy of TPF private stack area to
 228                   destination stack frame TPF private area. */
 229                destination_frame = (void *) *((unsigned long int *)
 230                    (*PREVIOUS_STACK_PTR() + R15_OFFSET));
 231
 232                /* Copy TPF linkage area from current frame to
 233                   destination frame.  */
 234                memcpy((void *) (destination_frame + TPFAREA_OFFSET),
 235                  (void *) (stackptr + TPFAREA_OFFSET), TPFAREA_SIZE);
 236
 237                /* Now overlay the
 238                   real target address into the TPF stack area of
 239                   the target frame we are jumping to.  */
 240                *(unsigned long *) (destination_frame + ICST_CRET) =
 241                  (unsigned long) target;
 242
 243                /* Before returning the desired pat stub address to
 244                   the exception handling unwinder so that it can
 245                   actually do the "leap" shift out the low order
 246                   bit designated to determine if we are in 64BIT mode.
 247                   This is necessary for CTOA stubs.
 248                   Otherwise we leap one byte past where we want to
 249                   go to in the TPF pat stub linkage code.  */
 250                shifter = *(unsigned long *) (stackptr + RA_OFFSET);
 251
 252                shifter &= ~1ul;
 253
 254                /* Store Pat Stub Address in destination Stack Frame.  */
 255                *((unsigned long int *) (destination_frame +
 256                    RA_OFFSET)) = shifter;
 257
 258                /* Re-adjust pat stub address to go to correct place
 259                   in linkage.  */
 260                shifter = shifter - 4;
 261
 262                /* Reset the Function Trace Skipping Switch to re-enable */
 263                /* recording Trace entries if it was turned off. */
 264                skipFlagAddress =
 265                  (unsigned char *) *(unsigned long *) LOWCORE_PAGE3_ADDR;
 266                skipFlagAddress += PG3_SKIPPING_OFFSET;
 267                *skipFlagAddress = '\x00';
 268
 269                return (void *) shifter;
 270              }
 271
 272           /* Desired module pat stub not found ...
 273              Bump stack frame iterator.  */
 274           stackptr = (void *) *(unsigned long int *) stackptr;
 275
 276           is_a_stub = false;
 277
 278         }  while (stackptr && retval != INVALID_RETURN
 279                 && targetcodeInfo.dli_fbase != currentcodeInfo.dli_fbase);
 280     }
 281
 282   /* Reset the Function Trace Skipping Switch to re-enable */
 283   /* recording Trace entries if it was turned off. */
 284   skipFlagAddress = (unsigned char *) *(unsigned long *) LOWCORE_PAGE3_ADDR;
 285   skipFlagAddress += PG3_SKIPPING_OFFSET;
 286   *skipFlagAddress = '\x00';
 287
 288   /* No pat stub found, could be a problem?  Simply return unmodified
 289      target address.  */
 290   return target;
 291 }