1/* Supporting functions for C exception handling. 2 Copyright (C) 2002-2015 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 "unwind.h" 30#define NO_SIZE_OF_ENCODED_VALUE 31#include "unwind-pe.h" 32 33typedef struct 34{ 35 _Unwind_Ptr Start; 36 _Unwind_Ptr LPStart; 37 _Unwind_Ptr ttype_base; 38 const unsigned char *TType; 39 const unsigned char *action_table; 40 unsigned char ttype_encoding; 41 unsigned char call_site_encoding; 42} lsda_header_info; 43 44static const unsigned char * 45parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p, 46 lsda_header_info *info) 47{ 48 _uleb128_t tmp; 49 unsigned char lpstart_encoding; 50 51 info->Start = (context ? _Unwind_GetRegionStart (context) : 0); 52 53 /* Find @LPStart, the base to which landing pad offsets are relative. */ 54 lpstart_encoding = *p++; 55 if (lpstart_encoding != DW_EH_PE_omit) 56 p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart); 57 else 58 info->LPStart = info->Start; 59 60 /* Find @TType, the base of the handler and exception spec type data. */ 61 info->ttype_encoding = *p++; 62 if (info->ttype_encoding != DW_EH_PE_omit) 63 { 64 p = read_uleb128 (p, &tmp); 65 info->TType = p + tmp; 66 } 67 else 68 info->TType = 0; 69 70 /* The encoding and length of the call-site table; the action table 71 immediately follows. */ 72 info->call_site_encoding = *p++; 73 p = read_uleb128 (p, &tmp); 74 info->action_table = p + tmp; 75 76 return p; 77} 78 79#ifdef __ARM_EABI_UNWINDER__ 80/* ARM EABI personality routines must also unwind the stack. */ 81#define CONTINUE_UNWINDING \ 82 do \ 83 { \ 84 if (__gnu_unwind_frame (ue_header, context) != _URC_OK) \ 85 return _URC_FAILURE; \ 86 return _URC_CONTINUE_UNWIND; \ 87 } \ 88 while (0) 89#else 90#define CONTINUE_UNWINDING return _URC_CONTINUE_UNWIND 91#endif 92 93#ifdef __USING_SJLJ_EXCEPTIONS__ 94#define PERSONALITY_FUNCTION __gcc_personality_sj0 95#define __builtin_eh_return_data_regno(x) x 96#elif defined(__SEH__) 97#define PERSONALITY_FUNCTION __gcc_personality_imp 98#else 99#define PERSONALITY_FUNCTION __gcc_personality_v0 100#endif 101 102#ifdef __ARM_EABI_UNWINDER__ 103_Unwind_Reason_Code 104PERSONALITY_FUNCTION (_Unwind_State, struct _Unwind_Exception *, 105 struct _Unwind_Context *); 106 107_Unwind_Reason_Code 108PERSONALITY_FUNCTION (_Unwind_State state, 109 struct _Unwind_Exception * ue_header, 110 struct _Unwind_Context * context) 111#else 112#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__) 113static 114#endif 115_Unwind_Reason_Code 116PERSONALITY_FUNCTION (int, _Unwind_Action, _Unwind_Exception_Class, 117 struct _Unwind_Exception *, struct _Unwind_Context *); 118 119_Unwind_Reason_Code 120PERSONALITY_FUNCTION (int version, 121 _Unwind_Action actions, 122 _Unwind_Exception_Class exception_class ATTRIBUTE_UNUSED, 123 struct _Unwind_Exception *ue_header, 124 struct _Unwind_Context *context) 125#endif 126{ 127 lsda_header_info info; 128 const unsigned char *language_specific_data, *p; 129 _Unwind_Ptr landing_pad, ip; 130 int ip_before_insn = 0; 131 132#ifdef __ARM_EABI_UNWINDER__ 133 if ((state & _US_ACTION_MASK) != _US_UNWIND_FRAME_STARTING) 134 CONTINUE_UNWINDING; 135 136 /* The dwarf unwinder assumes the context structure holds things like the 137 function and LSDA pointers. The ARM implementation caches these in 138 the exception header (UCB). To avoid rewriting everything we make a 139 virtual scratch register point at the UCB. */ 140 ip = (_Unwind_Ptr) ue_header; 141 _Unwind_SetGR (context, UNWIND_POINTER_REG, ip); 142#else 143 if (version != 1) 144 return _URC_FATAL_PHASE1_ERROR; 145 146 /* Currently we only support cleanups for C. */ 147 if ((actions & _UA_CLEANUP_PHASE) == 0) 148 CONTINUE_UNWINDING; 149#endif 150 151 language_specific_data = (const unsigned char *) 152 _Unwind_GetLanguageSpecificData (context); 153 154 /* If no LSDA, then there are no handlers or cleanups. */ 155 if (! language_specific_data) 156 CONTINUE_UNWINDING; 157 158 /* Parse the LSDA header. */ 159 p = parse_lsda_header (context, language_specific_data, &info); 160#ifdef HAVE_GETIPINFO 161 ip = _Unwind_GetIPInfo (context, &ip_before_insn); 162#else 163 ip = _Unwind_GetIP (context); 164#endif 165 if (! ip_before_insn) 166 --ip; 167 landing_pad = 0; 168 169#ifdef __USING_SJLJ_EXCEPTIONS__ 170 /* The given "IP" is an index into the call-site table, with two 171 exceptions -- -1 means no-action, and 0 means terminate. But 172 since we're using uleb128 values, we've not got random access 173 to the array. */ 174 if ((int) ip <= 0) 175 return _URC_CONTINUE_UNWIND; 176 else 177 { 178 _uleb128_t cs_lp, cs_action; 179 do 180 { 181 p = read_uleb128 (p, &cs_lp); 182 p = read_uleb128 (p, &cs_action); 183 } 184 while (--ip); 185 186 /* Can never have null landing pad for sjlj -- that would have 187 been indicated by a -1 call site index. */ 188 landing_pad = (_Unwind_Ptr)cs_lp + 1; 189 goto found_something; 190 } 191#else 192 /* Search the call-site table for the action associated with this IP. */ 193 while (p < info.action_table) 194 { 195 _Unwind_Ptr cs_start, cs_len, cs_lp; 196 _uleb128_t cs_action; 197 198 /* Note that all call-site encodings are "absolute" displacements. */ 199 p = read_encoded_value (0, info.call_site_encoding, p, &cs_start); 200 p = read_encoded_value (0, info.call_site_encoding, p, &cs_len); 201 p = read_encoded_value (0, info.call_site_encoding, p, &cs_lp); 202 p = read_uleb128 (p, &cs_action); 203 204 /* The table is sorted, so if we've passed the ip, stop. */ 205 if (ip < info.Start + cs_start) 206 p = info.action_table; 207 else if (ip < info.Start + cs_start + cs_len) 208 { 209 if (cs_lp) 210 landing_pad = info.LPStart + cs_lp; 211 goto found_something; 212 } 213 } 214#endif 215 216 /* IP is not in table. No associated cleanups. */ 217 /* ??? This is where C++ calls std::terminate to catch throw 218 from a destructor. */ 219 CONTINUE_UNWINDING; 220 221 found_something: 222 if (landing_pad == 0) 223 { 224 /* IP is present, but has a null landing pad. 225 No handler to be run. */ 226 CONTINUE_UNWINDING; 227 } 228 229 _Unwind_SetGR (context, __builtin_eh_return_data_regno (0), 230 (_Unwind_Ptr) ue_header); 231 _Unwind_SetGR (context, __builtin_eh_return_data_regno (1), 0); 232 _Unwind_SetIP (context, landing_pad); 233 return _URC_INSTALL_CONTEXT; 234} 235 236#if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__) 237EXCEPTION_DISPOSITION 238__gcc_personality_seh0 (PEXCEPTION_RECORD ms_exc, void *this_frame, 239 PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp) 240{ 241 return _GCC_specific_handler (ms_exc, this_frame, ms_orig_context, 242 ms_disp, __gcc_personality_imp); 243} 244#endif /* SEH */ 245