352 lines · c
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//8// Implements gcc extensions to the C++ ABI Exception Handling Level 1.9//10//===----------------------------------------------------------------------===//11 12#include <inttypes.h>13#include <stdbool.h>14#include <stdint.h>15#include <stdio.h>16#include <stdlib.h>17#include <string.h>18 19#include "config.h"20#include "libunwind_ext.h"21#include "libunwind.h"22#include "Unwind-EHABI.h"23#include "unwind.h"24 25#if defined(_AIX)26#include <sys/debug.h>27#endif28 29#if defined(_LIBUNWIND_BUILD_ZERO_COST_APIS)30 31#if defined(_LIBUNWIND_SUPPORT_SEH_UNWIND)32#define PRIVATE_1 private_[0]33#elif defined(_LIBUNWIND_ARM_EHABI)34#define PRIVATE_1 unwinder_cache.reserved135#else36#define PRIVATE_1 private_137#endif38 39/// Called by __cxa_rethrow().40_LIBUNWIND_EXPORT _Unwind_Reason_Code41_Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) {42 _LIBUNWIND_TRACE_API(43 "_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%" PRIdPTR,44 (void *)exception_object, (intptr_t)exception_object->PRIVATE_1);45 46 // If this is non-forced and a stopping place was found, then this is a47 // re-throw.48 // Call _Unwind_RaiseException() as if this was a new exception49 if (exception_object->PRIVATE_1 == 0) {50 return _Unwind_RaiseException(exception_object);51 // Will return if there is no catch clause, so that __cxa_rethrow can call52 // std::terminate().53 }54 55 // Call through to _Unwind_Resume() which distinguishes between forced and56 // regular exceptions.57 _Unwind_Resume(exception_object);58 _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()"59 " which unexpectedly returned");60}61 62/// Called by personality handler during phase 2 to get base address for data63/// relative encodings.64_LIBUNWIND_EXPORT uintptr_t65_Unwind_GetDataRelBase(struct _Unwind_Context *context) {66 _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)", (void *)context);67#if defined(_AIX)68 return unw_get_data_rel_base((unw_cursor_t *)context);69#else70 (void)context;71 _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented");72#endif73}74 75/// Called by personality handler during phase 2 to get base address for text76/// relative encodings.77_LIBUNWIND_EXPORT uintptr_t78_Unwind_GetTextRelBase(struct _Unwind_Context *context) {79 (void)context;80 _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)", (void *)context);81 _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented");82}83 84 85/// Scans unwind information to find the function that contains the86/// specified code address "pc".87_LIBUNWIND_EXPORT void *_Unwind_FindEnclosingFunction(void *pc) {88 _LIBUNWIND_TRACE_API("_Unwind_FindEnclosingFunction(pc=%p)", pc);89#if defined(_AIX)90 if (pc == NULL)91 return NULL;92 93 // Get the start address of the enclosing function from the function's94 // traceback table.95 uint32_t *p = (uint32_t *)pc;96 97 // Keep looking forward until a word of 0 is found. The traceback98 // table starts at the following word.99 while (*p)100 ++p;101 struct tbtable *TBTable = (struct tbtable *)(p + 1);102 103 // Get the address of the traceback table extension.104 p = (uint32_t *)&TBTable->tb_ext;105 106 // Skip field parminfo if it exists.107 if (TBTable->tb.fixedparms || TBTable->tb.floatparms)108 ++p;109 110 if (TBTable->tb.has_tboff)111 // *p contains the offset from the function start to traceback table.112 return (void *)((uintptr_t)TBTable - *p - sizeof(uint32_t));113 return NULL;114#else115 // This is slow, but works.116 // We create an unwind cursor then alter the IP to be pc117 unw_cursor_t cursor;118 unw_context_t uc;119 unw_proc_info_t info;120 __unw_getcontext(&uc);121 __unw_init_local(&cursor, &uc);122 __unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(intptr_t)pc);123 if (__unw_get_proc_info(&cursor, &info) == UNW_ESUCCESS)124 return (void *)(intptr_t) info.start_ip;125 else126 return NULL;127#endif128}129 130/// Walk every frame and call trace function at each one. If trace function131/// returns anything other than _URC_NO_REASON, then walk is terminated.132_LIBUNWIND_EXPORT _Unwind_Reason_Code133_Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) {134 unw_cursor_t cursor;135 unw_context_t uc;136 __unw_getcontext(&uc);137 __unw_init_local(&cursor, &uc);138 139 _LIBUNWIND_TRACE_API("_Unwind_Backtrace(callback=%p)",140 (void *)(uintptr_t)callback);141 142#if defined(_LIBUNWIND_ARM_EHABI)143 // Create a mock exception object for force unwinding.144 _Unwind_Exception ex;145 memset(&ex, '\0', sizeof(ex));146 memcpy(&ex.exception_class, "CLNGUNW", sizeof(ex.exception_class));147#endif148 149 // walk each frame150 while (true) {151 _Unwind_Reason_Code result;152 153#if !defined(_LIBUNWIND_ARM_EHABI)154 // ask libunwind to get next frame (skip over first frame which is155 // _Unwind_Backtrace())156 if (__unw_step(&cursor) <= 0) {157 _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because cursor reached "158 "bottom of stack, returning %d",159 _URC_END_OF_STACK);160 return _URC_END_OF_STACK;161 }162#else163 // Get the information for this frame.164 unw_proc_info_t frameInfo;165 if (__unw_get_proc_info(&cursor, &frameInfo) != UNW_ESUCCESS) {166 return _URC_END_OF_STACK;167 }168 169 // Update the pr_cache in the mock exception object.170 uint32_t *unwindInfo = (uint32_t *)frameInfo.unwind_info;171 ex.pr_cache.fnstart = frameInfo.start_ip;172 ex.pr_cache.ehtp = (_Unwind_EHT_Header *) unwindInfo;173 ex.pr_cache.additional= frameInfo.flags;174 175 struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor;176 // Get and call the personality function to unwind the frame.177 _Unwind_Personality_Fn handler = (_Unwind_Personality_Fn)frameInfo.handler;178 if (handler == NULL) {179 return _URC_END_OF_STACK;180 }181 if (handler(_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, &ex, context) !=182 _URC_CONTINUE_UNWIND) {183 return _URC_END_OF_STACK;184 }185#endif // defined(_LIBUNWIND_ARM_EHABI)186 187 // debugging188 if (_LIBUNWIND_TRACING_UNWINDING) {189 char functionName[512];190 unw_proc_info_t frame;191 unw_word_t offset;192 __unw_get_proc_name(&cursor, functionName, 512, &offset);193 __unw_get_proc_info(&cursor, &frame);194 _LIBUNWIND_TRACE_UNWINDING(195 " _backtrace: start_ip=0x%" PRIxPTR ", func=%s, lsda=0x%" PRIxPTR ", context=%p",196 frame.start_ip, functionName, frame.lsda,197 (void *)&cursor);198 }199 200 // call trace function with this frame201 result = (*callback)((struct _Unwind_Context *)(&cursor), ref);202 if (result != _URC_NO_REASON) {203 _LIBUNWIND_TRACE_UNWINDING(204 " _backtrace: ended because callback returned %d", result);205 return result;206 }207 }208}209 210 211/// Find DWARF unwind info for an address 'pc' in some function.212_LIBUNWIND_EXPORT const void *_Unwind_Find_FDE(const void *pc,213 struct dwarf_eh_bases *bases) {214 // This is slow, but works.215 // We create an unwind cursor then alter the IP to be pc216 unw_cursor_t cursor;217 unw_context_t uc;218 unw_proc_info_t info;219 __unw_getcontext(&uc);220 __unw_init_local(&cursor, &uc);221 __unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(intptr_t)pc);222 __unw_get_proc_info(&cursor, &info);223 bases->tbase = (uintptr_t)info.extra;224 bases->dbase = 0; // dbase not used on Mac OS X225 bases->func = (uintptr_t)info.start_ip;226 _LIBUNWIND_TRACE_API("_Unwind_Find_FDE(pc=%p) => %p", pc,227 (void *)(intptr_t) info.unwind_info);228 return (void *)(intptr_t) info.unwind_info;229}230 231/// Returns the CFA (call frame area, or stack pointer at start of function)232/// for the current context.233_LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) {234 unw_cursor_t *cursor = (unw_cursor_t *)context;235 unw_word_t result;236 __unw_get_reg(cursor, UNW_REG_SP, &result);237 _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIxPTR,238 (void *)context, result);239 return (uintptr_t)result;240}241 242 243/// Called by personality handler during phase 2 to get instruction pointer.244/// ipBefore is a boolean that says if IP is already adjusted to be the call245/// site address. Normally IP is the return address.246_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context,247 int *ipBefore) {248 _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p)", (void *)context);249 int isSignalFrame = __unw_is_signal_frame((unw_cursor_t *)context);250 // Negative means some kind of error (probably UNW_ENOINFO), but we have no251 // good way to report that, and this maintains backward compatibility with the252 // implementation that hard-coded zero in every case, even signal frames.253 if (isSignalFrame <= 0)254 *ipBefore = 0;255 else256 *ipBefore = 1;257 return _Unwind_GetIP(context);258}259 260#if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)261 262/// Called by programs with dynamic code generators that want263/// to register a dynamically generated FDE.264/// This function has existed on Mac OS X since 10.4, but265/// was broken until 10.6.266_LIBUNWIND_EXPORT void __register_frame(const void *fde) {267 _LIBUNWIND_TRACE_API("__register_frame(%p)", fde);268 __unw_add_dynamic_fde((unw_word_t)(uintptr_t)fde);269}270 271 272/// Called by programs with dynamic code generators that want273/// to unregister a dynamically generated FDE.274/// This function has existed on Mac OS X since 10.4, but275/// was broken until 10.6.276_LIBUNWIND_EXPORT void __deregister_frame(const void *fde) {277 _LIBUNWIND_TRACE_API("__deregister_frame(%p)", fde);278 __unw_remove_dynamic_fde((unw_word_t)(uintptr_t)fde);279}280 281 282// The following register/deregister functions are gcc extensions.283// They have existed on Mac OS X, but have never worked because Mac OS X284// before 10.6 used keymgr to track known FDEs, but these functions285// never got updated to use keymgr.286// For now, we implement these as do-nothing functions to keep any existing287// applications working. We also add the not in 10.6 symbol so that nwe288// application won't be able to use them.289 290#if defined(_LIBUNWIND_SUPPORT_FRAME_APIS)291_LIBUNWIND_EXPORT void __register_frame_info_bases(const void *fde, void *ob,292 void *tb, void *db) {293 (void)fde;294 (void)ob;295 (void)tb;296 (void)db;297 _LIBUNWIND_TRACE_API("__register_frame_info_bases(%p,%p, %p, %p)",298 fde, ob, tb, db);299 // do nothing, this function never worked in Mac OS X300}301 302_LIBUNWIND_EXPORT void __register_frame_info(const void *fde, void *ob) {303 (void)fde;304 (void)ob;305 _LIBUNWIND_TRACE_API("__register_frame_info(%p, %p)", fde, ob);306 // do nothing, this function never worked in Mac OS X307}308 309_LIBUNWIND_EXPORT void __register_frame_info_table_bases(const void *fde,310 void *ob, void *tb,311 void *db) {312 (void)fde;313 (void)ob;314 (void)tb;315 (void)db;316 _LIBUNWIND_TRACE_API("__register_frame_info_table_bases"317 "(%p,%p, %p, %p)", fde, ob, tb, db);318 // do nothing, this function never worked in Mac OS X319}320 321_LIBUNWIND_EXPORT void __register_frame_info_table(const void *fde, void *ob) {322 (void)fde;323 (void)ob;324 _LIBUNWIND_TRACE_API("__register_frame_info_table(%p, %p)", fde, ob);325 // do nothing, this function never worked in Mac OS X326}327 328_LIBUNWIND_EXPORT void __register_frame_table(const void *fde) {329 (void)fde;330 _LIBUNWIND_TRACE_API("__register_frame_table(%p)", fde);331 // do nothing, this function never worked in Mac OS X332}333 334_LIBUNWIND_EXPORT void *__deregister_frame_info(const void *fde) {335 (void)fde;336 _LIBUNWIND_TRACE_API("__deregister_frame_info(%p)", fde);337 // do nothing, this function never worked in Mac OS X338 return NULL;339}340 341_LIBUNWIND_EXPORT void *__deregister_frame_info_bases(const void *fde) {342 (void)fde;343 _LIBUNWIND_TRACE_API("__deregister_frame_info_bases(%p)", fde);344 // do nothing, this function never worked in Mac OS X345 return NULL;346}347#endif // defined(_LIBUNWIND_SUPPORT_FRAME_APIS)348 349#endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND)350 351#endif // defined(_LIBUNWIND_BUILD_ZERO_COST_APIS)352