1/* DWARF2 EH unwinding support for PowerPC and PowerPC64 Linux. 2 Copyright (C) 2004-2015 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 40struct 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 55struct 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 82struct 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 95enum { SIGNAL_FRAMESIZE = 128 }; 96 97/* If PC is at a sigreturn trampoline, return a pointer to the 98 regs. Otherwise return NULL. */ 99 100static struct gcc_regs * 101get_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 155enum { SIGNAL_FRAMESIZE = 64 }; 156 157static struct gcc_regs * 158get_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 195static _Unwind_Reason_Code 196ppc_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[__LIBGCC_STACK_POINTER_REGNUM__]; 209 fs->regs.cfa_how = CFA_REG_OFFSET; 210 fs->regs.cfa_reg = __LIBGCC_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) ®s->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) ®s->gpr[i] - new_cfa; 221 } 222 223 /* The CR is saved in the low 32 bits of regs->ccr. */ 224 cr_offset = (long) ®s->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) ®s->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) ®s->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) ®s->fpr[i] - new_cfa; 252 } 253 254 /* If we have a VMX unit... */ 255#ifdef __powerpc64__ 256 vregs = regs->vp; 257#else 258 vregs = ®s->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) ®s->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 288static void 289frob_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} 355