1/* Supporting functions for C exception handling. 2 Copyright (C) 2002-2020 Free Software Foundation, Inc. 3 Contributed by Aldy Hernandez <aldy@quesejoda.com>. 4 Shamelessly stolen from the Java front end. 5 6This file is part of GCC. 7 8GCC is free software; you can redistribute it and/or modify it under 9the terms of the GNU General Public License as published by the Free 10Software Foundation; either version 3, or (at your option) any later 11version. 12 13GCC is distributed in the hope that it will be useful, but WITHOUT ANY 14WARRANTY; without even the implied warranty of MERCHANTABILITY or 15FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 16for more details. 17 18Under Section 7 of GPL version 3, you are granted additional 19permissions described in the GCC Runtime Library Exception, version 203.1, as published by the Free Software Foundation. 21 22You should have received a copy of the GNU General Public License and 23a copy of the GCC Runtime Library Exception along with this program; 24see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 25<http://www.gnu.org/licenses/>. */ 26 27#include "tconfig.h" 28#include "tsystem.h" 29#include "auto-target.h" 30#include "unwind.h" 31#define NO_SIZE_OF_ENCODED_VALUE 32#include "unwind-pe.h" 33 34typedef struct 35{ 36 _Unwind_Ptr Start; 37 _Unwind_Ptr LPStart; 38 _Unwind_Ptr ttype_base; 39 const unsigned char *TType; 40 const unsigned char *action_table; 41 unsigned char ttype_encoding; 42 unsigned char call_site_encoding; 43} lsda_header_info; 44 45static const unsigned char * 46parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p, 47 lsda_header_info *info) 48{ 49 _uleb128_t tmp; 50 unsigned char lpstart_encoding; 51 52 info->Start = (context ? _Unwind_GetRegionStart (context) : 0); 53 54 /* Find @LPStart, the base to which landing pad offsets are relative. */ 55 lpstart_encoding = *p++; 56 if (lpstart_encoding != DW_EH_PE_omit) 57 p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart); 58 else 59 info->LPStart = info->Start; 60 61 /* Find @TType, the base of the handler and exception spec type data. */ 62 info->ttype_encoding = *p++; 63 if (info->ttype_encoding != DW_EH_PE_omit) 64 { 65 p = read_uleb128 (p, &tmp); 66 info->TType = p + tmp; 67 } 68 else 69 info->TType = 0; 70 71 /* The encoding and length of the call-site table; the action table 72 immediately follows. */ 73 info->call_site_encoding = *p++; 74 p = read_uleb128 (p, &tmp); 75 info->action_table = p + tmp; 76 77 return p; 78} 79 80#ifdef __ARM_EABI_UNWINDER__ 81/* ARM EABI personality routines must also unwind the stack. */ 82#define CONTINUE_UNWINDING \ 83 do \ 84 { \ 85 if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \ 86 return _URC_FAILURE; \ 87 return _URC_CONTINUE_UNWIND; \ 88 } \ 89 while (0) 90#else 91#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND 92#endif 93 94#ifdef __USING_SJLJ_EXCEPTIONS__ 95#define PERSONALITY_FUNCTION __gcc_personality_sj0 96#define __builtin_eh_return_data_regno(x) x 97#elif defined(__SEH__) 98#define PERSONALITY_FUNCTION __gcc_personality_imp 99#else 100#define PERSONALITY_FUNCTION __gcc_personality_v0 101#endif 102 103#ifdef __ARM_EABI_UNWINDER__ 104_Unwind_Reason_Code 105PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *, 106 struct _Unwind_Context *); 107 108_Unwind_Reason_Code 109__attribute__((target ("general-regs-only"))) 110PERSONALITY_FUNCTION (_Unwind_State state, 111 struct _Unwind_Exception * ue_header, 112 struct _Unwind_Context * context) 113#else 114#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__) 115static 116#endif 117_Unwind_Reason_Code 118PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class, 119 struct _Unwind_Exception *, struct _Unwind_Context *); 120 121_Unwind_Reason_Code 122PERSONALITY_FUNCTION (int version, 123 _Unwind_Action actions, 124 _Unwind_Exception_Class exception_class ATTRIBUTE_UNUSED, 125 struct _Unwind_Exception *ue_header, 126 struct _Unwind_Context *context) 127#endif 128{ 129 lsda_header_info info; 130 const unsigned char *language_specific_data, *p; 131 _Unwind_Ptr landing_pad, ip; 132 int ip_before_insn = 0; 133 134#ifdef __ARM_EABI_UNWINDER__ 135 if ((state & _US_ACTION_MASK) != _US_UNWIND_FRAME_STARTING) 136 CONTINUE_UNWINDING; 137 138 /* The dwarf unwinder assumes the context structure holds things like the 139 function and LSDA pointers. The ARM implementation caches these in 140 the exception header (UCB). To avoid rewriting everything we make a 141 virtual scratch register point at the UCB. */ 142 ip = (_Unwind_Ptr) ue_header; 143 _Unwind_SetGR (context, UNWIND_POINTER_REG, ip); 144#else 145 if (version != 1) 146 return _URC_FATAL_PHASE1_ERROR; 147 148 /* Currently we only support cleanups for C. */ 149 if ((actions & _UA_CLEANUP_PHASE) == 0) 150 CONTINUE_UNWINDING; 151#endif 152 153 language_specific_data = (const unsigned char *) 154 _Unwind_GetLanguageSpecificData (context); 155 156 /* If no LSDA, then there are no handlers or cleanups. */ 157 if (! language_specific_data) 158 CONTINUE_UNWINDING; 159 160 /* Parse the LSDA header. */ 161 p = parse_lsda_header (context, language_specific_data, &info); 162#ifdef HAVE_GETIPINFO 163 ip = _Unwind_GetIPInfo (context, &ip_before_insn); 164#else 165 ip = _Unwind_GetIP (context); 166#endif 167 if (! ip_before_insn) 168 --ip; 169 landing_pad = 0; 170 171#ifdef __USING_SJLJ_EXCEPTIONS__ 172 /* The given "IP" is an index into the call-site table, with two 173 exceptions -- -1 means no-action, and 0 means terminate. But 174 since we're using uleb128 values, we've not got random access 175 to the array. */ 176 if ((int) ip <= 0) 177 return _URC_CONTINUE_UNWIND; 178 else 179 { 180 _uleb128_t cs_lp, cs_action; 181 do 182 { 183 p = read_uleb128 (p, &cs_lp); 184 p = read_uleb128 (p, &cs_action); 185 } 186 while (--ip); 187 188 /* Can never have null landing pad for sjlj -- that would have 189 been indicated by a -1 call site index. */ 190 landing_pad = (_Unwind_Ptr)cs_lp + 1; 191 goto found_something; 192 } 193#else 194 /* Search the call-site table for the action associated with this IP. */ 195 while (p < info.action_table) 196 { 197 _Unwind_Ptr cs_start, cs_len, cs_lp; 198 _uleb128_t cs_action; 199 200 /* Note that all call-site encodings are "absolute" displacements. */ 201 p = read_encoded_value (0, info.call_site_encoding, p, &cs_start); 202 p = read_encoded_value (0, info.call_site_encoding, p, &cs_len); 203 p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp); 204 p = read_uleb128 (p, &cs_action); 205 206 /* The table is sorted, so if we've passed the ip, stop. */ 207 if (ip < info.Start + cs_start) 208 p = info.action_table; 209 else if (ip < info.Start + cs_start + cs_len) 210 { 211 if (cs_lp) 212 landing_pad = info.LPStart + cs_lp; 213 goto found_something; 214 } 215 } 216#endif 217 218 /* IP is not in table. No associated cleanups. */ 219 /* ??? This is where C++ calls std::terminate to catch throw 220 from a destructor. */ 221 CONTINUE_UNWINDING; 222 223 found_something: 224 if (landing_pad == 0) 225 { 226 /* IP is present, but has a null landing pad. 227 No handler to be run. */ 228 CONTINUE_UNWINDING; 229 } 230 231 _Unwind_SetGR (context, __builtin_eh_return_data_regno (0), 232 (_Unwind_Ptr) ue_header); 233 _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0); 234 _Unwind_SetIP (context, landing_pad); 235 return _URC_INSTALL_CONTEXT; 236} 237 238#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__) 239EXCEPTION_DISPOSITION 240__gcc_personality_seh0 (PEXCEPTION_RECORD ms_exc, void *this_frame, 241 PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp) 242{ 243 return _GCC_specific_handler (ms_exc, this_frame, ms_orig_context, 244 ms_disp, __gcc_personality_imp); 245} 246#endif /* SEH */ 247