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Diffstat (limited to 'src/UnwindLevel1-gcc-ext.c')
| -rw-r--r-- | src/UnwindLevel1-gcc-ext.c | 316 |
1 files changed, 316 insertions, 0 deletions
diff --git a/src/UnwindLevel1-gcc-ext.c b/src/UnwindLevel1-gcc-ext.c new file mode 100644 index 000000000000..28ba0928121f --- /dev/null +++ b/src/UnwindLevel1-gcc-ext.c @@ -0,0 +1,316 @@ +//===--------------------- UnwindLevel1-gcc-ext.c -------------------------===// +// +// 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. +// +// +// Implements gcc extensions to the C++ ABI Exception Handling Level 1. +// +//===----------------------------------------------------------------------===// + +#include <inttypes.h> +#include <stdbool.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "config.h" +#include "libunwind_ext.h" +#include "libunwind.h" +#include "Unwind-EHABI.h" +#include "unwind.h" + +#if _LIBUNWIND_BUILD_ZERO_COST_APIS + +/// Called by __cxa_rethrow(). +_LIBUNWIND_EXPORT _Unwind_Reason_Code +_Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) { +#if _LIBUNWIND_ARM_EHABI + _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%ld\n", + (void *)exception_object, + (long)exception_object->unwinder_cache.reserved1); +#else + _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%ld\n", + (void *)exception_object, + (long)exception_object->private_1); +#endif + +#if _LIBUNWIND_ARM_EHABI + // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0, + // which is in the same position as private_1 below. + return _Unwind_RaiseException(exception_object); +#else + // If this is non-forced and a stopping place was found, then this is a + // re-throw. + // Call _Unwind_RaiseException() as if this was a new exception + if (exception_object->private_1 == 0) { + return _Unwind_RaiseException(exception_object); + // Will return if there is no catch clause, so that __cxa_rethrow can call + // std::terminate(). + } + + // Call through to _Unwind_Resume() which distiguishes between forced and + // regular exceptions. + _Unwind_Resume(exception_object); + _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()" + " which unexpectedly returned"); +#endif +} + + +/// Called by personality handler during phase 2 to get base address for data +/// relative encodings. +_LIBUNWIND_EXPORT uintptr_t +_Unwind_GetDataRelBase(struct _Unwind_Context *context) { + (void)context; + _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)\n", (void *)context); + _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented"); +} + + +/// Called by personality handler during phase 2 to get base address for text +/// relative encodings. +_LIBUNWIND_EXPORT uintptr_t +_Unwind_GetTextRelBase(struct _Unwind_Context *context) { + (void)context; + _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)\n", (void *)context); + _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented"); +} + + +/// Scans unwind information to find the function that contains the +/// specified code address "pc". +_LIBUNWIND_EXPORT void *_Unwind_FindEnclosingFunction(void *pc) { + _LIBUNWIND_TRACE_API("_Unwind_FindEnclosingFunction(pc=%p)\n", pc); + // This is slow, but works. + // We create an unwind cursor then alter the IP to be pc + unw_cursor_t cursor; + unw_context_t uc; + unw_proc_info_t info; + unw_getcontext(&uc); + unw_init_local(&cursor, &uc); + unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); + if (unw_get_proc_info(&cursor, &info) == UNW_ESUCCESS) + return (void *)(long) info.start_ip; + else + return NULL; +} + +/// Walk every frame and call trace function at each one. If trace function +/// returns anything other than _URC_NO_REASON, then walk is terminated. +_LIBUNWIND_EXPORT _Unwind_Reason_Code +_Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) { + unw_cursor_t cursor; + unw_context_t uc; + unw_getcontext(&uc); + unw_init_local(&cursor, &uc); + + _LIBUNWIND_TRACE_API("_Unwind_Backtrace(callback=%p)\n", + (void *)(uintptr_t)callback); + +#if _LIBUNWIND_ARM_EHABI + // Create a mock exception object for force unwinding. + _Unwind_Exception ex; + memset(&ex, '\0', sizeof(ex)); + ex.exception_class = 0x434C4E47554E5700; // CLNGUNW\0 +#endif + + // walk each frame + while (true) { + _Unwind_Reason_Code result; + +#if !_LIBUNWIND_ARM_EHABI + // ask libuwind to get next frame (skip over first frame which is + // _Unwind_Backtrace()) + if (unw_step(&cursor) <= 0) { + _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because cursor reached " + "bottom of stack, returning %d\n", + _URC_END_OF_STACK); + return _URC_END_OF_STACK; + } +#else + // Get the information for this frame. + unw_proc_info_t frameInfo; + if (unw_get_proc_info(&cursor, &frameInfo) != UNW_ESUCCESS) { + return _URC_END_OF_STACK; + } + + // Update the pr_cache in the mock exception object. + const uint32_t* unwindInfo = (uint32_t *) frameInfo.unwind_info; + ex.pr_cache.fnstart = frameInfo.start_ip; + ex.pr_cache.ehtp = (_Unwind_EHT_Header *) unwindInfo; + ex.pr_cache.additional= frameInfo.flags; + + struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor; + // Get and call the personality function to unwind the frame. + __personality_routine handler = (__personality_routine) frameInfo.handler; + if (handler == NULL) { + return _URC_END_OF_STACK; + } + if (handler(_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, &ex, context) != + _URC_CONTINUE_UNWIND) { + return _URC_END_OF_STACK; + } +#endif // _LIBUNWIND_ARM_EHABI + + // debugging + if (_LIBUNWIND_TRACING_UNWINDING) { + char functionName[512]; + unw_proc_info_t frame; + unw_word_t offset; + unw_get_proc_name(&cursor, functionName, 512, &offset); + unw_get_proc_info(&cursor, &frame); + _LIBUNWIND_TRACE_UNWINDING( + " _backtrace: start_ip=0x%llX, func=%s, lsda=0x%llX, context=%p\n", + (long long)frame.start_ip, functionName, (long long)frame.lsda, + (void *)&cursor); + } + + // call trace function with this frame + result = (*callback)((struct _Unwind_Context *)(&cursor), ref); + if (result != _URC_NO_REASON) { + _LIBUNWIND_TRACE_UNWINDING( + " _backtrace: ended because callback returned %d\n", result); + return result; + } + } +} + + +/// Find dwarf unwind info for an address 'pc' in some function. +_LIBUNWIND_EXPORT const void *_Unwind_Find_FDE(const void *pc, + struct dwarf_eh_bases *bases) { + // This is slow, but works. + // We create an unwind cursor then alter the IP to be pc + unw_cursor_t cursor; + unw_context_t uc; + unw_proc_info_t info; + unw_getcontext(&uc); + unw_init_local(&cursor, &uc); + unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); + unw_get_proc_info(&cursor, &info); + bases->tbase = (uintptr_t)info.extra; + bases->dbase = 0; // dbase not used on Mac OS X + bases->func = (uintptr_t)info.start_ip; + _LIBUNWIND_TRACE_API("_Unwind_Find_FDE(pc=%p) => %p\n", pc, + (void *)(long) info.unwind_info); + return (void *)(long) info.unwind_info; +} + +/// Returns the CFA (call frame area, or stack pointer at start of function) +/// for the current context. +_LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) { + unw_cursor_t *cursor = (unw_cursor_t *)context; + unw_word_t result; + unw_get_reg(cursor, UNW_REG_SP, &result); + _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIx64 "\n", + (void *)context, (uint64_t)result); + return (uintptr_t)result; +} + + +/// Called by personality handler during phase 2 to get instruction pointer. +/// ipBefore is a boolean that says if IP is already adjusted to be the call +/// site address. Normally IP is the return address. +_LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context, + int *ipBefore) { + _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p)\n", (void *)context); + *ipBefore = 0; + return _Unwind_GetIP(context); +} + +#if _LIBUNWIND_SUPPORT_DWARF_UNWIND + +/// Called by programs with dynamic code generators that want +/// to register a dynamically generated FDE. +/// This function has existed on Mac OS X since 10.4, but +/// was broken until 10.6. +_LIBUNWIND_EXPORT void __register_frame(const void *fde) { + _LIBUNWIND_TRACE_API("__register_frame(%p)\n", fde); + _unw_add_dynamic_fde((unw_word_t)(uintptr_t) fde); +} + + +/// Called by programs with dynamic code generators that want +/// to unregister a dynamically generated FDE. +/// This function has existed on Mac OS X since 10.4, but +/// was broken until 10.6. +_LIBUNWIND_EXPORT void __deregister_frame(const void *fde) { + _LIBUNWIND_TRACE_API("__deregister_frame(%p)\n", fde); + _unw_remove_dynamic_fde((unw_word_t)(uintptr_t) fde); +} + + +// The following register/deregister functions are gcc extensions. +// They have existed on Mac OS X, but have never worked because Mac OS X +// before 10.6 used keymgr to track known FDEs, but these functions +// never got updated to use keymgr. +// For now, we implement these as do-nothing functions to keep any existing +// applications working. We also add the not in 10.6 symbol so that nwe +// application won't be able to use them. + +#if _LIBUNWIND_SUPPORT_FRAME_APIS +_LIBUNWIND_EXPORT void __register_frame_info_bases(const void *fde, void *ob, + void *tb, void *db) { + (void)fde; + (void)ob; + (void)tb; + (void)db; + _LIBUNWIND_TRACE_API("__register_frame_info_bases(%p,%p, %p, %p)\n", + fde, ob, tb, db); + // do nothing, this function never worked in Mac OS X +} + +_LIBUNWIND_EXPORT void __register_frame_info(const void *fde, void *ob) { + (void)fde; + (void)ob; + _LIBUNWIND_TRACE_API("__register_frame_info(%p, %p)\n", fde, ob); + // do nothing, this function never worked in Mac OS X +} + +_LIBUNWIND_EXPORT void __register_frame_info_table_bases(const void *fde, + void *ob, void *tb, + void *db) { + (void)fde; + (void)ob; + (void)tb; + (void)db; + _LIBUNWIND_TRACE_API("__register_frame_info_table_bases" + "(%p,%p, %p, %p)\n", fde, ob, tb, db); + // do nothing, this function never worked in Mac OS X +} + +_LIBUNWIND_EXPORT void __register_frame_info_table(const void *fde, void *ob) { + (void)fde; + (void)ob; + _LIBUNWIND_TRACE_API("__register_frame_info_table(%p, %p)\n", fde, ob); + // do nothing, this function never worked in Mac OS X +} + +_LIBUNWIND_EXPORT void __register_frame_table(const void *fde) { + (void)fde; + _LIBUNWIND_TRACE_API("__register_frame_table(%p)\n", fde); + // do nothing, this function never worked in Mac OS X +} + +_LIBUNWIND_EXPORT void *__deregister_frame_info(const void *fde) { + (void)fde; + _LIBUNWIND_TRACE_API("__deregister_frame_info(%p)\n", fde); + // do nothing, this function never worked in Mac OS X + return NULL; +} + +_LIBUNWIND_EXPORT void *__deregister_frame_info_bases(const void *fde) { + (void)fde; + _LIBUNWIND_TRACE_API("__deregister_frame_info_bases(%p)\n", fde); + // do nothing, this function never worked in Mac OS X + return NULL; +} +#endif // _LIBUNWIND_SUPPORT_FRAME_APIS + +#endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND + +#endif // _LIBUNWIND_BUILD_ZERO_COST_APIS |