libgcc/config/rs6000/aix-unwind.h

   1 /* DWARF2 EH unwinding support for AIX.
   2    Copyright (C) 2011-2024 Free Software Foundation, Inc.
   3
   4    This file is part of GCC.
   5
   6    GCC is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT
  12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  14    License for more details.
  15
  16    Under Section 7 of GPL version 3, you are granted additional
  17    permissions described in the GCC Runtime Library Exception, version
  18    3.1, as published by the Free Software Foundation.
  19
  20    You should have received a copy of the GNU General Public License and
  21    a copy of the GCC Runtime Library Exception along with this program;
  22    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23    <http://www.gnu.org/licenses/>.  */
  24
  25 /* Useful register numbers.  */
  26
  27 #define R_LR             65
  28 #define R_CR2            70
  29 #define R_XER            76
  30 #define R_FIRST_ALTIVEC  77
  31 #define R_VRSAVE        109
  32 #define R_VSCR          110
  33
  34 /* If the current unwind info (FS) does not contain explicit info
  35    saving R2, then we have to do a minor amount of code reading to
  36    figure out if it was saved.  The big problem here is that the
  37    code that does the save/restore is generated by the linker, so
  38    we have no good way to determine at compile time what to do.  */
  39
  40 #ifdef __64BIT__
  41 #define MD_FROB_UPDATE_CONTEXT(CTX, FS)                                 \
  42   do {                                                                  \
  43     if ((FS)->regs.how[2] == REG_UNSAVED)                               \
  44       {                                                                 \
  45         unsigned int *insn                                              \
  46           = (unsigned int *)                                            \
  47             _Unwind_GetGR ((CTX), R_LR);                                \
  48         if (*insn == 0xE8410028)                                        \
  49           _Unwind_SetGRPtr ((CTX), 2, (CTX)->cfa + 40);                 \
  50       }                                                                 \
  51   } while (0)
  52 #else
  53 #define MD_FROB_UPDATE_CONTEXT(CTX, FS)                                 \
  54   do {                                                                  \
  55     if ((FS)->regs.how[2] == REG_UNSAVED)                               \
  56       {                                                                 \
  57         unsigned int *insn                                              \
  58           = (unsigned int *)                                            \
  59             _Unwind_GetGR ((CTX), R_LR);                                \
  60         if (*insn == 0x80410014)                                        \
  61           _Unwind_SetGRPtr ((CTX), 2, (CTX)->cfa + 20);                 \
  62       }                                                                 \
  63   } while (0)
  64 #endif
  65
  66 /* Now on to MD_FALLBACK_FRAME_STATE_FOR.
  67    32bit AIX 5.2, 5.3, 6.1, 7.X and
  68    64bit AIX 6.1, 7.X only at this stage.  */
  69
  70 #include <stdlib.h>
  71 #include <stddef.h>
  72 #include <signal.h>
  73 #include <sys/machine.h>
  74
  75 #ifdef __64BIT__
  76
  77 typedef struct __context64 mstate_t;
  78
  79 #else
  80
  81 typedef struct mstsave mstate_t;
  82
  83 #endif
  84
  85 #define MD_FALLBACK_FRAME_STATE_FOR ppc_aix_fallback_frame_state
  86
  87 /* If we are compiling on AIX < 5.3, the VMX related datastructs are not
  88    defined and we take measures to obtain proper runtime behavior if the
  89    compiled code happens to run on a later version with VMX enabled.  */
  90
  91 #ifndef MSR_VMX
  92 #define MSR_VMX 0x2000000
  93 #endif
  94
  95 typedef unsigned int uint;
  96 typedef struct { uint v[4]; } vreg_t;
  97 typedef struct {
  98   vreg_t regs[32];
  99   uint   pad1 [3];
 100   uint   vscr;
 101   uint   vrsave;
 102   uint   pad2 [3];
 103 } vstate_t;
 104
 105 #define EXT_CONTEXT_MARK 0x45435458
 106 #define EXT_CONTEXT_SIZE 4096
 107 #define BUMPER_SIZE (EXT_CONTEXT_SIZE - sizeof(vstate_t) - (5 * sizeof(int)))
 108
 109 typedef struct {
 110   uint     pad1 [4];
 111   vstate_t vstate;
 112   char     bumper [BUMPER_SIZE];
 113   int      mark;
 114 } extended_context_t;
 115
 116 typedef struct {
 117   char bumper [offsetof (ucontext_t, uc_stack) + sizeof (stack_t)];
 118   extended_context_t * ectx;
 119   int mark;
 120 } vmx_ucontext_t;
 121
 122 /* Determine whether CONTEXT designates a signal handler, and return the
 123    associated ucontext_t address if so.  Return NULL otherwise.  */
 124
 125 static ucontext_t *
 126 ucontext_for (struct _Unwind_Context *context)
 127 {
 128   const unsigned int * ra = context->ra;
 129
 130   /* AIX 5.2, 5.3, 6.1 and 7.X, threaded or not, share common patterns
 131      and feature variants depending on the configured kernel (unix_mp
 132      or unix_64).  */
 133
 134 #ifdef __64BIT__
 135   if (*(ra - 5) == 0x4c00012c     /* isync             */
 136       && *(ra - 4) == 0xe8ec0000  /* ld      r7,0(r12) */
 137       && *(ra - 3) == 0xe84c0008  /* ld      r2,8(r12) */
 138       && *(ra - 2) == 0x7ce903a6  /* mtctr   r7        */
 139       && *(ra - 1) == 0x4e800421  /* bctrl             */
 140       && *(ra - 0) == 0x7de27b78) /* mr      r2,r15   <-- context->ra */
 141     {
 142       /* unix_64 */
 143       if (*(ra - 6) == 0x7d000164)  /* mtmsrd  r8 */
 144         {
 145           /* AIX 6.1, 7.1 and 7.2 */
 146           return (ucontext_t *)(context->cfa + 0x70);
 147         }
 148     }
 149 #else
 150   if (*(ra - 5) == 0x4c00012c     /* isync             */
 151       && *(ra - 4) == 0x80ec0000  /* lwz     r7,0(r12) */
 152       && *(ra - 3) == 0x804c0004  /* lwz     r2,4(r12) */
 153       && *(ra - 2) == 0x7ce903a6  /* mtctr   r7        */
 154       && *(ra - 1) == 0x4e800421  /* bctrl             */
 155       && *(ra - 0) == 0x7dc37378) /* mr      r3,r14   <-- context->ra */
 156     {
 157       /* unix_64 */
 158       if (*(ra - 6) == 0x7d000164)  /* mtmsrd  r8 */
 159         {
 160           switch (*(ra + 18))
 161             {
 162               /* AIX 5.2 */
 163             case 0x835a0520: /* lwz r26,1312(r26) */
 164               return (ucontext_t *)(context->cfa + 0x70);
 165
 166               /* AIX 5.3 */
 167             case 0x835a0570:  /* lwz r26,1392(r26) */
 168               return (ucontext_t *)(context->cfa + 0x40);
 169
 170               /* AIX 6.1 and 7.1 */
 171             case 0x2c1a0000:  /* cmpwi   r26,0 */
 172               return (ucontext_t *)(context->cfa + 0x40);
 173
 174               /* AIX 7.2 */
 175             case 0x3800000a:  /* li   r0,A */
 176               return (ucontext_t *)(context->cfa + 0x40);
 177
 178             default:
 179               return 0;
 180             }
 181         }
 182
 183       /* unix_mp */
 184       if (*(ra - 6) == 0x7d000124)  /* mtmsr  r8 */
 185         {
 186           typedef struct {
 187             char pad[56];
 188             ucontext_t ucontext;
 189             siginfo_t siginfo;
 190           } aix52_stack_t;
 191
 192           aix52_stack_t * frame = (aix52_stack_t *) context->cfa;
 193           return &frame->ucontext;
 194         }
 195     }
 196 #endif
 197   return 0;
 198 }
 199
 200 /* The fallback proper.  */
 201
 202 #ifdef __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
 203 #define RETURN_COLUMN __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__
 204 #else
 205 #define RETURN_COLUMN ARG_POINTER_REGNUM
 206 #endif
 207
 208 #define REGISTER_CFA_OFFSET_FOR(FS,REGNO,ADDR,CFA)\
 209 do { \
 210 (FS)->regs.how[REGNO] = REG_SAVED_OFFSET; \
 211 (FS)->regs.reg[REGNO].loc.offset = (long) (ADDR) - (CFA); \
 212 } while (0)
 213
 214 static _Unwind_Reason_Code
 215 ppc_aix_fallback_frame_state (struct _Unwind_Context *context,
 216                               _Unwind_FrameState *fs)
 217 {
 218   ucontext_t * uctx = ucontext_for (context);
 219   mstate_t * mctx;
 220
 221   long new_cfa;
 222   int i;
 223
 224   if (uctx == NULL)
 225     return _URC_END_OF_STACK;
 226
 227   mctx = &uctx->uc_mcontext.jmp_context;
 228
 229   /* The "kernel" frame cfa is the stack pointer at the signal occurrence
 230      point.  */
 231   new_cfa = mctx->gpr[__LIBGCC_STACK_POINTER_REGNUM__];
 232
 233   fs->regs.cfa_how = CFA_REG_OFFSET;
 234   fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
 235   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 236
 237   /* And we state how to find the various registers it has saved with
 238      relative offset rules from there.  */
 239
 240   for (i = 0; i < 32; i++)
 241     if (i != __LIBGCC_STACK_POINTER_REGNUM__)
 242       REGISTER_CFA_OFFSET_FOR (fs, i, &mctx->gpr[i], new_cfa);
 243
 244   REGISTER_CFA_OFFSET_FOR (fs, R_CR2, &mctx->cr, new_cfa);
 245   REGISTER_CFA_OFFSET_FOR (fs, R_XER, &mctx->xer, new_cfa);
 246   REGISTER_CFA_OFFSET_FOR (fs, R_LR, &mctx->lr, new_cfa);
 247
 248   fs->retaddr_column = RETURN_COLUMN;
 249   REGISTER_CFA_OFFSET_FOR (fs, RETURN_COLUMN, &mctx->iar, new_cfa);
 250   fs->signal_frame = 1;
 251
 252   /* Honor FP Ever Used ...   */
 253   if (mctx->fpeu)
 254     {
 255       for (i = 0; i < 32; i++)
 256         REGISTER_CFA_OFFSET_FOR (fs, i+32, &mctx->fpr[i], new_cfa);
 257     }
 258
 259   /* Honor VMX context, if any.  We expect the msr bit never to be set in
 260      environments where there is no VMX support, e.g. on AIX < 5.3.  */
 261   if (mctx->msr & MSR_VMX)
 262     {
 263       vmx_ucontext_t * uc = (vmx_ucontext_t *) uctx;
 264
 265       if (uc->mark == EXT_CONTEXT_MARK && uc->ectx->mark == EXT_CONTEXT_MARK)
 266         {
 267           vstate_t * vstate = &uc->ectx->vstate;
 268
 269           for (i = 0; i < 32; i++)
 270             REGISTER_CFA_OFFSET_FOR
 271             (fs, i+R_FIRST_ALTIVEC, &vstate->regs[i], new_cfa);
 272
 273           REGISTER_CFA_OFFSET_FOR (fs, R_VSCR, &vstate->vscr, new_cfa);
 274           REGISTER_CFA_OFFSET_FOR (fs, R_VRSAVE, &vstate->vrsave, new_cfa);
 275         }
 276     }
 277
 278   return _URC_NO_REASON;
 279 }