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Diffstat (limited to 'contrib/llvm-project/compiler-rt/lib/builtins/gcc_personality_v0.c')
| -rw-r--r-- | contrib/llvm-project/compiler-rt/lib/builtins/gcc_personality_v0.c | 272 |
1 files changed, 272 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/builtins/gcc_personality_v0.c b/contrib/llvm-project/compiler-rt/lib/builtins/gcc_personality_v0.c new file mode 100644 index 000000000000..3437205a1cc4 --- /dev/null +++ b/contrib/llvm-project/compiler-rt/lib/builtins/gcc_personality_v0.c @@ -0,0 +1,272 @@ +//===-- gcc_personality_v0.c - Implement __gcc_personality_v0 -------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#include "int_lib.h" +#include <stddef.h> + +#include <unwind.h> +/* + * XXX On FreeBSD, this file is compiled into three libraries: + * - libcompiler_rt + * - libgcc_eh + * - libgcc_s + * + * In the former, the include path points to the contrib/libcxxrt/unwind-arm.h + * copy of unwind.h. In the latter, the include path points to the + * contrib/libunwind/include/unwind.h header (LLVM libunwind). + * + * Neither (seemingly redundant) variant of unwind.h needs the redefinitions + * provided in the "helpful" header below, and libcxxrt's unwind-arm.h provides + * *no* useful distinguishing macros, so just forcibly disable the helper + * header on FreeBSD. + */ +#if defined(__arm__) && !defined(__ARM_DWARF_EH__) && \ + !defined(__USING_SJLJ_EXCEPTIONS__) && !defined(__FreeBSD__) +// 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 + +#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) +#include <windows.h> +#include <winnt.h> + +EXCEPTION_DISPOSITION _GCC_specific_handler(PEXCEPTION_RECORD, void *, PCONTEXT, + PDISPATCHER_CONTEXT, + _Unwind_Personality_Fn); +#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 size_t readULEB128(const uint8_t **data) { + size_t result = 0; + size_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__) && !defined(__SEH__) +#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) +#elif defined(__SEH__) +static _Unwind_Reason_Code __gcc_personality_imp( + int version, _Unwind_Action actions, uint64_t exceptionClass, + 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 = (uintptr_t)_Unwind_GetIP(context) - 1; + uintptr_t funcStart = (uintptr_t)_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++; + size_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); + size_t length = readEncodedPointer(&p, callSiteEncoding); + size_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); +} + +#if defined(__SEH__) && !defined(__USING_SJLJ_EXCEPTIONS__) +COMPILER_RT_ABI EXCEPTION_DISPOSITION +__gcc_personality_seh0(PEXCEPTION_RECORD ms_exc, void *this_frame, + PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp) { + return _GCC_specific_handler(ms_exc, this_frame, ms_orig_context, ms_disp, + __gcc_personality_imp); +} +#endif |