1/* DWARF2 EH unwinding support for AIX. 2 Copyright (C) 2011-2020 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.reg[2].how == 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.reg[2].how == 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 77typedef struct __context64 mstate_t; 78 79#else 80 81typedef 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 95typedef unsigned int uint; 96typedef struct { uint v[4]; } vreg_t; 97typedef 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 109typedef struct { 110 uint pad1 [4]; 111 vstate_t vstate; 112 char bumper [BUMPER_SIZE]; 113 int mark; 114} extended_context_t; 115 116typedef 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 125static ucontext_t * 126ucontext_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)\ 209do { \ 210(FS)->regs.reg[REGNO].how = REG_SAVED_OFFSET; \ 211(FS)->regs.reg[REGNO].loc.offset = (long) (ADDR) - (CFA); \ 212} while (0) 213 214static _Unwind_Reason_Code 215ppc_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} 280