libgcc/config/rs6000/linux-unwind.h

   1 /* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux.
   2    Copyright (C) 2004-2014 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 3, or (at your
   9    option) 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 #define R_LR            65
  26 #define R_CR2           70
  27 #define R_CR3           71
  28 #define R_CR4           72
  29 #define R_VR0           77
  30 #define R_VRSAVE        109
  31
  32 #ifdef __powerpc64__
  33 #if _CALL_ELF == 2
  34 #define TOC_SAVE_SLOT   24
  35 #else
  36 #define TOC_SAVE_SLOT   40
  37 #endif
  38 #endif
  39
  40 struct gcc_vregs
  41 {
  42   __attribute__ ((vector_size (16))) int vr[32];
  43 #ifdef __powerpc64__
  44   unsigned int pad1[3];
  45   unsigned int vscr;
  46   unsigned int vsave;
  47   unsigned int pad2[3];
  48 #else
  49   unsigned int vsave;
  50   unsigned int pad[2];
  51   unsigned int vscr;
  52 #endif
  53 };
  54
  55 struct gcc_regs
  56 {
  57   unsigned long gpr[32];
  58   unsigned long nip;
  59   unsigned long msr;
  60   unsigned long orig_gpr3;
  61   unsigned long ctr;
  62   unsigned long link;
  63   unsigned long xer;
  64   unsigned long ccr;
  65   unsigned long softe;
  66   unsigned long trap;
  67   unsigned long dar;
  68   unsigned long dsisr;
  69   unsigned long result;
  70   unsigned long pad1[4];
  71   double fpr[32];
  72   unsigned int pad2;
  73   unsigned int fpscr;
  74 #ifdef __powerpc64__
  75   struct gcc_vregs *vp;
  76 #else
  77   unsigned int pad3[2];
  78 #endif
  79   struct gcc_vregs vregs;
  80 };
  81
  82 struct gcc_ucontext
  83 {
  84 #ifdef __powerpc64__
  85   unsigned long pad[28];
  86 #else
  87   unsigned long pad[12];
  88 #endif
  89   struct gcc_regs *regs;
  90   struct gcc_regs rsave;
  91 };
  92
  93 #ifdef __powerpc64__
  94
  95 enum { SIGNAL_FRAMESIZE = 128 };
  96
  97 /* If PC is at a sigreturn trampoline, return a pointer to the
  98    regs.  Otherwise return NULL.  */
  99
 100 static struct gcc_regs *
 101 get_regs (struct _Unwind_Context *context)
 102 {
 103   const unsigned int *pc = context->ra;
 104
 105   /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */
 106   /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */
 107   if (pc[0] != 0x38210000 + SIGNAL_FRAMESIZE || pc[2] != 0x44000002)
 108     return NULL;
 109   if (pc[1] == 0x38000077)
 110     {
 111       struct sigframe {
 112         char gap[SIGNAL_FRAMESIZE];
 113         unsigned long pad[7];
 114         struct gcc_regs *regs;
 115       } *frame = (struct sigframe *) context->cfa;
 116       return frame->regs;
 117     }
 118   else if (pc[1] == 0x380000AC)
 119     {
 120 #if _CALL_ELF != 2
 121       /* These old kernel versions never supported ELFv2.  */
 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       const struct rt_sigframe_24 {
 127         int tramp[6];
 128         void *pinfo;
 129         struct gcc_ucontext *puc;
 130       } *frame24 = (const struct rt_sigframe_24 *) context->ra;
 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 #endif
 137         {
 138           /* This works for 2.4.21 and later kernels.  */
 139           struct rt_sigframe {
 140             char gap[SIGNAL_FRAMESIZE];
 141             struct gcc_ucontext uc;
 142             unsigned long pad[2];
 143             int tramp[6];
 144             void *pinfo;
 145             struct gcc_ucontext *puc;
 146           } *frame = (struct rt_sigframe *) context->cfa;
 147           return frame->uc.regs;
 148         }
 149     }
 150   return NULL;
 151 }
 152
 153 #else  /* !__powerpc64__ */
 154
 155 enum { SIGNAL_FRAMESIZE = 64 };
 156
 157 static struct gcc_regs *
 158 get_regs (struct _Unwind_Context *context)
 159 {
 160   const unsigned int *pc = context->ra;
 161
 162   /* li r0, 0x7777; sc  (sigreturn old)  */
 163   /* li r0, 0x0077; sc  (sigreturn new)  */
 164   /* li r0, 0x6666; sc  (rt_sigreturn old)  */
 165   /* li r0, 0x00AC; sc  (rt_sigreturn new)  */
 166   if (pc[1] != 0x44000002)
 167     return NULL;
 168   if (pc[0] == 0x38007777 || 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 (pc[0] == 0x38006666 || pc[0] == 0x380000AC)
 178     {
 179       struct rt_sigframe {
 180         char gap[SIGNAL_FRAMESIZE + 16];
 181         char siginfo[128];
 182         struct gcc_ucontext uc;
 183       } *frame = (struct rt_sigframe *) context->cfa;
 184       return frame->uc.regs;
 185     }
 186   return NULL;
 187 }
 188 #endif
 189
 190 /* Do code reading to identify a signal frame, and set the frame
 191    state data appropriately.  See unwind-dw2.c for the structs.  */
 192
 193 #define MD_FALLBACK_FRAME_STATE_FOR ppc_fallback_frame_state
 194
 195 static _Unwind_Reason_Code
 196 ppc_fallback_frame_state (struct _Unwind_Context *context,
 197                           _Unwind_FrameState *fs)
 198 {
 199   struct gcc_regs *regs = get_regs (context);
 200   struct gcc_vregs *vregs;
 201   long cr_offset;
 202   long new_cfa;
 203   int i;
 204
 205   if (regs == NULL)
 206     return _URC_END_OF_STACK;
 207
 208   new_cfa = regs->gpr[STACK_POINTER_REGNUM];
 209   fs->regs.cfa_how = CFA_REG_OFFSET;
 210   fs->regs.cfa_reg = STACK_POINTER_REGNUM;
 211   fs->regs.cfa_offset = new_cfa - (long) context->cfa;
 212
 213 #ifdef __powerpc64__
 214   fs->regs.reg[2].how = REG_SAVED_OFFSET;
 215   fs->regs.reg[2].loc.offset = (long) &regs->gpr[2] - new_cfa;
 216 #endif
 217   for (i = 14; i < 32; i++)
 218     {
 219       fs->regs.reg[i].how = REG_SAVED_OFFSET;
 220       fs->regs.reg[i].loc.offset = (long) &regs->gpr[i] - new_cfa;
 221     }
 222
 223   /* The CR is saved in the low 32 bits of regs->ccr.  */
 224   cr_offset = (long) &regs->ccr - new_cfa;
 225 #ifndef __LITTLE_ENDIAN__
 226   cr_offset += sizeof (long) - 4;
 227 #endif
 228   /* In the ELFv1 ABI, CR2 stands in for the whole CR.  */
 229   fs->regs.reg[R_CR2].how = REG_SAVED_OFFSET;
 230   fs->regs.reg[R_CR2].loc.offset = cr_offset;
 231 #if _CALL_ELF == 2
 232   /* In the ELFv2 ABI, every CR field has a separate CFI entry.  */
 233   fs->regs.reg[R_CR3].how = REG_SAVED_OFFSET;
 234   fs->regs.reg[R_CR3].loc.offset = cr_offset;
 235   fs->regs.reg[R_CR4].how = REG_SAVED_OFFSET;
 236   fs->regs.reg[R_CR4].loc.offset = cr_offset;
 237 #endif
 238
 239   fs->regs.reg[R_LR].how = REG_SAVED_OFFSET;
 240   fs->regs.reg[R_LR].loc.offset = (long) &regs->link - new_cfa;
 241
 242   fs->regs.reg[ARG_POINTER_REGNUM].how = REG_SAVED_OFFSET;
 243   fs->regs.reg[ARG_POINTER_REGNUM].loc.offset = (long) &regs->nip - new_cfa;
 244   fs->retaddr_column = ARG_POINTER_REGNUM;
 245   fs->signal_frame = 1;
 246
 247   /* If we have a FPU...  */
 248   for (i = 14; i < 32; i++)
 249     {
 250       fs->regs.reg[i + 32].how = REG_SAVED_OFFSET;
 251       fs->regs.reg[i + 32].loc.offset = (long) &regs->fpr[i] - new_cfa;
 252     }
 253
 254   /* If we have a VMX unit...  */
 255 #ifdef __powerpc64__
 256   vregs = regs->vp;
 257 #else
 258   vregs = &regs->vregs;
 259 #endif
 260   if (regs->msr & (1 << 25))
 261     {
 262       for (i = 20; i < 32; i++)
 263         {
 264           fs->regs.reg[i + R_VR0].how = REG_SAVED_OFFSET;
 265           fs->regs.reg[i + R_VR0].loc.offset = (long) &vregs->vr[i] - new_cfa;
 266         }
 267     }
 268
 269   fs->regs.reg[R_VRSAVE].how = REG_SAVED_OFFSET;
 270   fs->regs.reg[R_VRSAVE].loc.offset = (long) &vregs->vsave - new_cfa;
 271
 272   /* If we have SPE register high-parts... we check at compile-time to
 273      avoid expanding the code for all other PowerPC.  */
 274 #ifdef __SPE__
 275   for (i = 14; i < 32; i++)
 276     {
 277       fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].how = REG_SAVED_OFFSET;
 278       fs->regs.reg[i + FIRST_SPE_HIGH_REGNO - 4].loc.offset
 279         = (long) &regs->vregs - new_cfa + 4 * i;
 280     }
 281 #endif
 282
 283   return _URC_NO_REASON;
 284 }
 285
 286 #define MD_FROB_UPDATE_CONTEXT frob_update_context
 287
 288 static void
 289 frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATTRIBUTE_UNUSED)
 290 {
 291   const unsigned int *pc = (const unsigned int *) context->ra;
 292
 293   /* Fix up for 2.6.12 - 2.6.16 Linux kernels that have vDSO, but don't
 294      have S flag in it.  */
 295 #ifdef __powerpc64__
 296   /* addi r1, r1, 128; li r0, 0x0077; sc  (sigreturn) */
 297   /* addi r1, r1, 128; li r0, 0x00AC; sc  (rt_sigreturn) */
 298   if (pc[0] == 0x38210000 + SIGNAL_FRAMESIZE
 299       && (pc[1] == 0x38000077 || pc[1] == 0x380000AC)
 300       && pc[2] == 0x44000002)
 301     _Unwind_SetSignalFrame (context, 1);
 302 #else
 303   /* li r0, 0x7777; sc  (sigreturn old)  */
 304   /* li r0, 0x0077; sc  (sigreturn new)  */
 305   /* li r0, 0x6666; sc  (rt_sigreturn old)  */
 306   /* li r0, 0x00AC; sc  (rt_sigreturn new)  */
 307   if ((pc[0] == 0x38007777 || pc[0] == 0x38000077
 308        || pc[0] == 0x38006666 || pc[0] == 0x380000AC)
 309       && pc[1] == 0x44000002)
 310     _Unwind_SetSignalFrame (context, 1);
 311 #endif
 312
 313 #ifdef __powerpc64__
 314   if (fs->regs.reg[2].how == REG_UNSAVED)
 315     {
 316       /* If the current unwind info (FS) does not contain explicit info
 317          saving R2, then we have to do a minor amount of code reading to
 318          figure out if it was saved.  The big problem here is that the
 319          code that does the save/restore is generated by the linker, so
 320          we have no good way to determine at compile time what to do.  */
 321       if (pc[0] == 0xF8410000 + TOC_SAVE_SLOT
 322 #if _CALL_ELF != 2
 323           /* The ELFv2 linker never generates the old PLT stub form.  */
 324           || ((pc[0] & 0xFFFF0000) == 0x3D820000
 325               && pc[1] == 0xF8410000 + TOC_SAVE_SLOT)
 326 #endif
 327           )
 328         {
 329           /* We are in a plt call stub or r2 adjusting long branch stub,
 330              before r2 has been saved.  Keep REG_UNSAVED.  */
 331         }
 332       else
 333         {
 334           unsigned int *insn
 335             = (unsigned int *) _Unwind_GetGR (context, R_LR);
 336           if (insn && *insn == 0xE8410000 + TOC_SAVE_SLOT)
 337             _Unwind_SetGRPtr (context, 2, context->cfa + TOC_SAVE_SLOT);
 338 #if _CALL_ELF != 2
 339           /* ELFv2 does not use this function pointer call sequence.  */
 340           else if (pc[0] == 0x4E800421
 341                    && pc[1] == 0xE8410000 + TOC_SAVE_SLOT)
 342             {
 343               /* We are at the bctrl instruction in a call via function
 344                  pointer.  gcc always emits the load of the new R2 just
 345                  before the bctrl so this is the first and only place
 346                  we need to use the stored R2.  */
 347               _Unwind_Word sp = _Unwind_GetGR (context, 1);
 348               _Unwind_SetGRPtr (context, 2, (void *)(sp + TOC_SAVE_SLOT));
 349             }
 350 #endif
 351         }
 352     }
 353 #endif
 354 }