gcc/config/rs6000/linux-unwind.h

   1 /* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.
   2    Copyright (C) 2004, 2005, 2006, 2007 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
   8    by the Free Software Foundation; either version 2, or (at your
   9    option) any later version.
  10
  11    In addition to the permissions in the GNU General Public License,
  12    the Free Software Foundation gives you unlimited permission to link
  13    the compiled version of this file with other programs, and to
  14    distribute those programs without any restriction coming from the
  15    use of this file.  (The General Public License restrictions do
  16    apply in other respects; for example, they cover modification of
  17    the file, and distribution when not linked into another program.)
  18
  19    GCC is distributed in the hope that it will be useful, but WITHOUT
  20    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  21    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  22    License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with GCC; see the file COPYING.  If not, write to the
  26    Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  27    MA 02110-1301, USA.  */
  28
  29 /* This file defines our own versions of various kernel and user
  30    structs, so that system headers are not needed, which otherwise
  31    can make bootstrapping a new toolchain difficult.  Do not use
  32    these structs elsewhere;  Many fields are missing, particularly
  33    from the end of the structures.  */
  34
  35 #define R_LR            65
  36 #define R_CR2           70
  37 #define R_VR0           77
  38 #define R_VRSAVE        109
  39 #define R_VSCR          110
  40
  41 struct gcc_vregs
  42 {
  43   __attribute__ ((vector_size (16))) int vr[32];
  44 #ifdef __powerpc64__
  45   unsigned int pad1[3];
  46   unsigned int vscr;
  47   unsigned int vsave;
  48   unsigned int pad2[3];
  49 #else
  50   unsigned int vsave;
  51   unsigned int pad[2];
  52   unsigned int vscr;
  53 #endif
  54 };
  55
  56 struct gcc_regs
  57 {
  58   unsigned long gpr[32];
  59   unsigned long nip;
  60   unsigned long msr;
  61   unsigned long orig_gpr3;
  62   unsigned long ctr;
  63   unsigned long link;
  64   unsigned long xer;
  65   unsigned long ccr;
  66   unsigned long softe;
  67   unsigned long trap;
  68   unsigned long dar;
  69   unsigned long dsisr;
  70   unsigned long result;
  71   unsigned long pad1[4];
  72   double fpr[32];
  73   unsigned int pad2;
  74   unsigned int fpscr;
  75 #ifdef __powerpc64__
  76   struct gcc_vregs *vp;
  77 #else
  78   unsigned int pad3[2];
  79 #endif
  80   struct gcc_vregs vregs;
  81 };
  82
  83 struct gcc_ucontext
  84 {
  85 #ifdef __powerpc64__
  86   unsigned long pad[28];
  87 #else
  88   unsigned long pad[12];
  89 #endif
  90   struct gcc_regs *regs;
  91   struct gcc_regs rsave;
  92 };
  93
  94 #ifdef __powerpc64__
  95
  96 enum { SIGNAL_FRAMESIZE = 128 };
  97
  98 /* If PC is at a sigreturn trampoline, return a pointer to the
  99    regs.  Otherwise return NULL.  */
 100
 101 static struct gcc_regs *
 102 get_regs (struct _Unwind_Context *context)
 103 {
 104   const unsigned char *pc = context->ra;
 105
 106   /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */
 107   /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */
 108   if (*(unsigned int *) (pc + 0) != 0x38210000 + SIGNAL_FRAMESIZE
 109       || *(unsigned int *) (pc + 8) != 0x44000002)
 110     return NULL;
 111   if (*(unsigned int *) (pc + 4) == 0x38000077)
 112     {
 113       struct sigframe {
 114         char gap[SIGNAL_FRAMESIZE];
 115         unsigned long pad[7];
 116         struct gcc_regs *regs;
 117       } *frame = (struct sigframe *) context->cfa;
 118       return frame->regs;
 119     }
 120   else if (*(unsigned int *) (pc + 4) == 0x380000AC)
 121     {
 122       /* This works for 2.4 kernels, but not for 2.6 kernels with vdso
 123          because pc isn't pointing into the stack.  Can be removed when
 124          no one is running 2.4.19 or 2.4.20, the first two ppc64
 125          kernels released.  */
 126       struct rt_sigframe_24 {
 127         int tramp[6];
 128         void *pinfo;
 129         struct gcc_ucontext *puc;
 130       } *frame24 = (struct rt_sigframe_24 *) pc;
 131
 132       /* Test for magic value in *puc of vdso.  */
 133       if ((long) frame24->puc != -21 * 8)
 134         return frame24->puc->regs;
 135       else
 136         {
 137           /* This works for 2.4.21 and later kernels.  */
 138           struct rt_sigframe {
 139             char gap[SIGNAL_FRAMESIZE];
 140             struct gcc_ucontext uc;
 141             unsigned long pad[2];
 142             int tramp[6];
 143             void *pinfo;
 144             struct gcc_ucontext *puc;
 145           } *frame = (struct rt_sigframe *) context->cfa;
 146           return frame->uc.regs;
 147         }
 148     }
 149   return NULL;
 150 }
 151
 152 #else  /* !__powerpc64__ */
 153
 154 enum { SIGNAL_FRAMESIZE = 64 };
 155
 156 static struct gcc_regs *
 157 get_regs (struct _Unwind_Context *context)
 158 {
 159   const unsigned char *pc = context->ra;
 160
 161   /* li r0, 0x7777; sc  (sigreturn old)  */
 162   /* li r0, 0x0077; sc  (sigreturn new)  */
 163   /* li r0, 0x6666; sc  (rt_sigreturn old)  */
 164   /* li r0, 0x00AC; sc  (rt_sigreturn new)  */
 165   if (*(unsigned int *) (pc + 4) != 0x44000002)
 166     return NULL;
 167   if (*(unsigned int *) (pc + 0) == 0x38007777
 168       || *(unsigned int *) (pc + 0) == 0x38000077)
 169     {
 170       struct sigframe {
 171         char gap[SIGNAL_FRAMESIZE];
 172         unsigned long pad[7];
 173         struct gcc_regs *regs;
 174       } *frame = (struct sigframe *) context->cfa;
 175       return frame->regs;
 176     }
 177   else if (*(unsigned int *) (pc + 0) == 0x38006666
 178            || *(unsigned int *) (pc + 0) == 0x380000AC)
 179     {
 180       struct rt_sigframe {
 181         char gap[SIGNAL_FRAMESIZE + 16];
 182         char siginfo[128];
 183         struct gcc_ucontext uc;
 184       } *frame = (struct rt_sigframe *) context->cfa;
 185       return frame->uc.regs;
 186     }
 187   return NULL;
 188 }
 189 #endif
 190
 191 /* Find an entry in the process auxiliary vector.  The canonical way to
 192    test for VMX is to look at AT_HWCAP.  */
 193
 194 static long
 195 ppc_linux_aux_vector (long which)
 196 {
 197   /* __libc_stack_end holds the original stack passed to a process.  */
 198   extern long *__libc_stack_end;
 199   long argc;
 200   char **argv;
 201   char **envp;
 202   struct auxv
 203   {
 204     long a_type;
 205     long a_val;
 206   } *auxp;
 207
 208   /* The Linux kernel puts argc first on the stack.  */
 209   argc = __libc_stack_end[0];
 210   /* Followed by argv, NULL terminated.  */
 211   argv = (char **) __libc_stack_end + 1;
 212   /* Followed by environment string pointers, NULL terminated. */
 213   envp = argv + argc + 1;
 214   while (*envp++)
 215     continue;
 216   /* Followed by the aux vector, zero terminated.  */
 217   for (auxp = (struct auxv *) envp; auxp->a_type != 0; ++auxp)
 218     if (auxp->a_type == which)
 219       return auxp->a_val;
 220   return 0;
 221 }
 222
 223 /* Do code reading to identify a signal frame, and set the frame
 224    state data appropriately.  See unwind-dw2.c for the structs.  */
 225
 226 #define MD_FALLBACK_FRAME_STATE_FOR ppc_fallback_frame_state
 227
 228 static _Unwind_Reason_Code
 229 ppc_fallback_frame_state (struct _Unwind_Context *context,
 230                           _Unwind_FrameState *fs)
 231 {
 232   static long hwcap = 0;
 233   struct gcc_regs *regs = get_regs (context);
 234   long new_cfa;
 235   int i;
 236
 237   if (regs == NULL)
 238     return _URC_END_OF_STACK;
 239
 240   new_cfa = regs->gpr[STACK_POINTER_REGNUM];
 241   fs->regs.cfa_how = CFA_REG_OFFSET;
 242   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
 243   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 244
 245   for (i = 0; i < 32; i++)
 246     if (i != STACK_POINTER_REGNUM)
 247       {
 248         fs->regs.reg[i].how = REG_SAVED_OFFSET;
 249         fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
 250       }
 251
 252   fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
 253   fs->regs.reg[R_CR2].loc.offset = (long) &regs->ccr - new_cfa;
 254
 255   fs->regs.reg[R_LR].how = REG_SAVED_OFFSET;
 256   fs->regs.reg[R_LR].loc.offset = (long) &regs->link - new_cfa;
 257
 258   fs->regs.reg[ARG_POINTER_REGNUM].how = REG_SAVED_OFFSET;
 259   fs->regs.reg[ARG_POINTER_REGNUM].loc.offset = (long) &regs->nip - new_cfa;
 260   fs->retaddr_column = ARG_POINTER_REGNUM;
 261   fs->signal_frame = 1;
 262
 263   if (hwcap == 0)
 264     {
 265       hwcap = ppc_linux_aux_vector (16);
 266       /* These will already be set if we found AT_HWCAP.  A nonzero
 267          value stops us looking again if for some reason we couldn't
 268          find AT_HWCAP.  */
 269 #ifdef __powerpc64__
 270       hwcap |= 0xc0000000;
 271 #else
 272       hwcap |= 0x80000000;
 273 #endif
 274     }
 275
 276   /* If we have a FPU...  */
 277   if (hwcap & 0x08000000)
 278     for (i = 0; i < 32; i++)
 279       {
 280         fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
 281         fs->regs.reg[i + 32].loc.offset = (long) &regs->fpr[i] - new_cfa;
 282       }
 283
 284   /* If we have a VMX unit...  */
 285   if (hwcap & 0x10000000)
 286     {
 287       struct gcc_vregs *vregs;
 288 #ifdef __powerpc64__
 289       vregs = regs->vp;
 290 #else
 291       vregs = &regs->vregs;
 292 #endif
 293       if (regs->msr & (1 << 25))
 294         {
 295           for (i = 0; i < 32; i++)
 296             {
 297               fs->regs.reg[i + R_VR0].how = REG_SAVED_OFFSET;
 298               fs->regs.reg[i + R_VR0].loc.offset
 299                 = (long) &vregs->vr[i] - new_cfa;
 300             }
 301
 302           fs->regs.reg[R_VSCR].how = REG_SAVED_OFFSET;
 303           fs->regs.reg[R_VSCR].loc.offset = (long) &vregs->vscr - new_cfa;
 304         }
 305
 306       fs->regs.reg[R_VRSAVE].how = REG_SAVED_OFFSET;
 307       fs->regs.reg[R_VRSAVE].loc.offset = (long) &vregs->vsave - new_cfa;
 308     }
 309
 310   /* If we have SPE register high-parts... we check at compile-time to
 311      avoid expanding the code for all other PowerPC.  */
 312 #ifdef __SPE__
 313   for (i = 0; i < 32; i++)
 314     {
 315       fs->regs.reg[i + FIRST_PSEUDO_REGISTER - 1].how = REG_SAVED_OFFSET;
 316       fs->regs.reg[i + FIRST_PSEUDO_REGISTER - 1].loc.offset
 317         = (long) &regs->vregs - new_cfa + 4 * i;
 318     }
 319 #endif
 320
 321   return _URC_NO_REASON;
 322 }
 323
 324 #define MD_FROB_UPDATE_CONTEXT frob_update_context
 325
 326 static void
 327 frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATTRIBUTE_UNUSED)
 328 {
 329   const unsigned int *pc = (const unsigned int *) context->ra;
 330
 331   /* Fix up for 2.6.12 - 2.6.16 Linux kernels that have vDSO, but don't
 332      have S flag in it.  */
 333 #ifdef __powerpc64__
 334   /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */
 335   /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */
 336   if (pc[0] == 0x38210000 + SIGNAL_FRAMESIZE
 337       && (pc[1] == 0x38000077 || pc[1] == 0x380000AC)
 338       && pc[2] == 0x44000002)
 339     _Unwind_SetSignalFrame (context, 1);
 340 #else
 341   /* li r0, 0x7777; sc  (sigreturn old)  */
 342   /* li r0, 0x0077; sc  (sigreturn new)  */
 343   /* li r0, 0x6666; sc  (rt_sigreturn old)  */
 344   /* li r0, 0x00AC; sc  (rt_sigreturn new)  */
 345   if ((pc[0] == 0x38007777 || pc[0] == 0x38000077
 346        || pc[0] == 0x38006666 || pc[0] == 0x380000AC)
 347       && pc[1] == 0x44000002)
 348     _Unwind_SetSignalFrame (context, 1);
 349 #endif
 350
 351 #ifdef __powerpc64__
 352   if (fs->regs.reg[2].how == REG_UNSAVED)
 353     {
 354       /* If the current unwind info (FS) does not contain explicit info
 355          saving R2, then we have to do a minor amount of code reading to
 356          figure out if it was saved.  The big problem here is that the
 357          code that does the save/restore is generated by the linker, so
 358          we have no good way to determine at compile time what to do.  */
 359       unsigned int *insn
 360         = (unsigned int *) _Unwind_GetGR (context, R_LR);
 361       if (*insn == 0xE8410028)
 362         _Unwind_SetGRPtr (context, 2, context->cfa + 40);
 363     }
 364 #endif
 365 }