| /* ===-- gcc_personality_v0.c - Implement __gcc_personality_v0 -------------=== |
| * |
| * The LLVM Compiler Infrastructure |
| * |
| * This file is dual licensed under the MIT and the University of Illinois Open |
| * Source Licenses. See LICENSE.TXT for details. |
| * |
| * ===----------------------------------------------------------------------=== |
| * |
| */ |
| |
| #include "int_lib.h" |
| |
| #include <unwind.h> |
| #if defined(__arm__) && !defined(__ARM_DWARF_EH__) && !defined(__USING_SJLJ_EXCEPTIONS__) |
| /* |
| * When building with older compilers (e.g. clang <3.9), it is possible that we |
| * have a version of unwind.h which does not provide the EHABI declarations |
| * which are quired for the C personality to conform to the specification. In |
| * order to provide forward compatibility for such compilers, we re-declare the |
| * necessary interfaces in the helper to permit a standalone compilation of the |
| * builtins (which contains the C unwinding personality for historical reasons). |
| */ |
| #include "unwind-ehabi-helpers.h" |
| #endif |
| |
| /* |
| * Pointer encodings documented at: |
| * http://refspecs.freestandards.org/LSB_1.3.0/gLSB/gLSB/ehframehdr.html |
| */ |
| |
| #define DW_EH_PE_omit 0xff /* no data follows */ |
| |
| #define DW_EH_PE_absptr 0x00 |
| #define DW_EH_PE_uleb128 0x01 |
| #define DW_EH_PE_udata2 0x02 |
| #define DW_EH_PE_udata4 0x03 |
| #define DW_EH_PE_udata8 0x04 |
| #define DW_EH_PE_sleb128 0x09 |
| #define DW_EH_PE_sdata2 0x0A |
| #define DW_EH_PE_sdata4 0x0B |
| #define DW_EH_PE_sdata8 0x0C |
| |
| #define DW_EH_PE_pcrel 0x10 |
| #define DW_EH_PE_textrel 0x20 |
| #define DW_EH_PE_datarel 0x30 |
| #define DW_EH_PE_funcrel 0x40 |
| #define DW_EH_PE_aligned 0x50 |
| #define DW_EH_PE_indirect 0x80 /* gcc extension */ |
| |
| |
| |
| /* read a uleb128 encoded value and advance pointer */ |
| static uintptr_t readULEB128(const uint8_t** data) |
| { |
| uintptr_t result = 0; |
| uintptr_t shift = 0; |
| unsigned char byte; |
| const uint8_t* p = *data; |
| do { |
| byte = *p++; |
| result |= (byte & 0x7f) << shift; |
| shift += 7; |
| } while (byte & 0x80); |
| *data = p; |
| return result; |
| } |
| |
| /* read a pointer encoded value and advance pointer */ |
| static uintptr_t readEncodedPointer(const uint8_t** data, uint8_t encoding) |
| { |
| const uint8_t* p = *data; |
| uintptr_t result = 0; |
| |
| if ( encoding == DW_EH_PE_omit ) |
| return 0; |
| |
| /* first get value */ |
| switch (encoding & 0x0F) { |
| case DW_EH_PE_absptr: |
| result = *((const uintptr_t*)p); |
| p += sizeof(uintptr_t); |
| break; |
| case DW_EH_PE_uleb128: |
| result = readULEB128(&p); |
| break; |
| case DW_EH_PE_udata2: |
| result = *((const uint16_t*)p); |
| p += sizeof(uint16_t); |
| break; |
| case DW_EH_PE_udata4: |
| result = *((const uint32_t*)p); |
| p += sizeof(uint32_t); |
| break; |
| case DW_EH_PE_udata8: |
| result = *((const uint64_t*)p); |
| p += sizeof(uint64_t); |
| break; |
| case DW_EH_PE_sdata2: |
| result = *((const int16_t*)p); |
| p += sizeof(int16_t); |
| break; |
| case DW_EH_PE_sdata4: |
| result = *((const int32_t*)p); |
| p += sizeof(int32_t); |
| break; |
| case DW_EH_PE_sdata8: |
| result = *((const int64_t*)p); |
| p += sizeof(int64_t); |
| break; |
| case DW_EH_PE_sleb128: |
| default: |
| /* not supported */ |
| compilerrt_abort(); |
| break; |
| } |
| |
| /* then add relative offset */ |
| switch ( encoding & 0x70 ) { |
| case DW_EH_PE_absptr: |
| /* do nothing */ |
| break; |
| case DW_EH_PE_pcrel: |
| result += (uintptr_t)(*data); |
| break; |
| case DW_EH_PE_textrel: |
| case DW_EH_PE_datarel: |
| case DW_EH_PE_funcrel: |
| case DW_EH_PE_aligned: |
| default: |
| /* not supported */ |
| compilerrt_abort(); |
| break; |
| } |
| |
| /* then apply indirection */ |
| if (encoding & DW_EH_PE_indirect) { |
| result = *((const uintptr_t*)result); |
| } |
| |
| *data = p; |
| return result; |
| } |
| |
| #if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \ |
| !defined(__ARM_DWARF_EH__) |
| #define USING_ARM_EHABI 1 |
| _Unwind_Reason_Code __gnu_unwind_frame(struct _Unwind_Exception *, |
| struct _Unwind_Context *); |
| #endif |
| |
| static inline _Unwind_Reason_Code |
| continueUnwind(struct _Unwind_Exception *exceptionObject, |
| struct _Unwind_Context *context) { |
| #if USING_ARM_EHABI |
| /* |
| * On ARM EHABI the personality routine is responsible for actually |
| * unwinding a single stack frame before returning (ARM EHABI Sec. 6.1). |
| */ |
| if (__gnu_unwind_frame(exceptionObject, context) != _URC_OK) |
| return _URC_FAILURE; |
| #endif |
| return _URC_CONTINUE_UNWIND; |
| } |
| |
| /* |
| * The C compiler makes references to __gcc_personality_v0 in |
| * the dwarf unwind information for translation units that use |
| * __attribute__((cleanup(xx))) on local variables. |
| * This personality routine is called by the system unwinder |
| * on each frame as the stack is unwound during a C++ exception |
| * throw through a C function compiled with -fexceptions. |
| */ |
| #if __USING_SJLJ_EXCEPTIONS__ |
| /* the setjump-longjump based exceptions personality routine has a |
| * different name */ |
| COMPILER_RT_ABI _Unwind_Reason_Code |
| __gcc_personality_sj0(int version, _Unwind_Action actions, |
| uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject, |
| struct _Unwind_Context *context) |
| #elif USING_ARM_EHABI |
| /* The ARM EHABI personality routine has a different signature. */ |
| COMPILER_RT_ABI _Unwind_Reason_Code __gcc_personality_v0( |
| _Unwind_State state, struct _Unwind_Exception *exceptionObject, |
| struct _Unwind_Context *context) |
| #else |
| COMPILER_RT_ABI _Unwind_Reason_Code |
| __gcc_personality_v0(int version, _Unwind_Action actions, |
| uint64_t exceptionClass, struct _Unwind_Exception* exceptionObject, |
| struct _Unwind_Context *context) |
| #endif |
| { |
| /* Since C does not have catch clauses, there is nothing to do during */ |
| /* phase 1 (the search phase). */ |
| #if USING_ARM_EHABI |
| /* After resuming from a cleanup we should also continue on to the next |
| * frame straight away. */ |
| if ((state & _US_ACTION_MASK) != _US_UNWIND_FRAME_STARTING) |
| #else |
| if ( actions & _UA_SEARCH_PHASE ) |
| #endif |
| return continueUnwind(exceptionObject, context); |
| |
| /* There is nothing to do if there is no LSDA for this frame. */ |
| const uint8_t* lsda = (uint8_t*)_Unwind_GetLanguageSpecificData(context); |
| if ( lsda == (uint8_t*) 0 ) |
| return continueUnwind(exceptionObject, context); |
| |
| uintptr_t pc = _Unwind_GetIP(context)-1; |
| uintptr_t funcStart = _Unwind_GetRegionStart(context); |
| uintptr_t pcOffset = pc - funcStart; |
| |
| /* Parse LSDA header. */ |
| uint8_t lpStartEncoding = *lsda++; |
| if (lpStartEncoding != DW_EH_PE_omit) { |
| readEncodedPointer(&lsda, lpStartEncoding); |
| } |
| uint8_t ttypeEncoding = *lsda++; |
| if (ttypeEncoding != DW_EH_PE_omit) { |
| readULEB128(&lsda); |
| } |
| /* Walk call-site table looking for range that includes current PC. */ |
| uint8_t callSiteEncoding = *lsda++; |
| uint32_t callSiteTableLength = readULEB128(&lsda); |
| const uint8_t* callSiteTableStart = lsda; |
| const uint8_t* callSiteTableEnd = callSiteTableStart + callSiteTableLength; |
| const uint8_t* p=callSiteTableStart; |
| while (p < callSiteTableEnd) { |
| uintptr_t start = readEncodedPointer(&p, callSiteEncoding); |
| uintptr_t length = readEncodedPointer(&p, callSiteEncoding); |
| uintptr_t landingPad = readEncodedPointer(&p, callSiteEncoding); |
| readULEB128(&p); /* action value not used for C code */ |
| if ( landingPad == 0 ) |
| continue; /* no landing pad for this entry */ |
| if ( (start <= pcOffset) && (pcOffset < (start+length)) ) { |
| /* Found landing pad for the PC. |
| * Set Instruction Pointer to so we re-enter function |
| * at landing pad. The landing pad is created by the compiler |
| * to take two parameters in registers. |
| */ |
| _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), |
| (uintptr_t)exceptionObject); |
| _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), 0); |
| _Unwind_SetIP(context, (funcStart + landingPad)); |
| return _URC_INSTALL_CONTEXT; |
| } |
| } |
| |
| /* No landing pad found, continue unwinding. */ |
| return continueUnwind(exceptionObject, context); |
| } |
| |
