自学教程：C++ unw_step函数代码示例

/* * ut_dump_backtrace -- dump stacktrace to error log using libunwind */voidut_dump_backtrace(void){	unw_context_t context;	unw_proc_info_t pip;	pip.unwind_info = NULL;	int ret = unw_getcontext(&context);	if (ret) {		ERR("unw_getcontext: %s [%d]", unw_strerror(ret), ret);		return;	}	unw_cursor_t cursor;	ret = unw_init_local(&cursor, &context);	if (ret) {		ERR("unw_init_local: %s [%d]", unw_strerror(ret), ret);		return;	}	ret = unw_step(&cursor);	char procname[PROCNAMELEN];	unsigned i = 0;	while (ret > 0) {		ret = unw_get_proc_info(&cursor, &pip);		if (ret) {			ERR("unw_get_proc_info: %s [%d]", unw_strerror(ret),					ret);			break;		}		unw_word_t off;		ret = unw_get_proc_name(&cursor, procname, PROCNAMELEN, &off);		if (ret && ret != -UNW_ENOMEM) {			if (ret != -UNW_EUNSPEC) {				ERR("unw_get_proc_name: %s [%d]",					unw_strerror(ret), ret);			}			strcpy(procname, "?");		}		void *ptr = (void *)(pip.start_ip + off);		Dl_info dlinfo;		const char *fname = "?";		if (dladdr(ptr, &dlinfo) && dlinfo.dli_fname &&				*dlinfo.dli_fname)			fname = dlinfo.dli_fname;		ERR("%u: %s (%s%s+0x%lx) [%p]", i++, fname, procname,				ret == -UNW_ENOMEM ? "..." : "", off, ptr);		ret = unw_step(&cursor);		if (ret < 0)			ERR("unw_step: %s [%d]", unw_strerror(ret), ret);	}}

int xbt_libunwind_backtrace(void** bt, int size){  int i = 0;  for(i=0; i < size; i++)    bt[i] = nullptr;  i=0;  unw_cursor_t c;  unw_context_t uc;  unw_getcontext (&uc);  unw_init_local (&c, &uc);  unw_word_t ip;  unw_step(&c);  while(unw_step(&c) >= 0 && i < size){    unw_get_reg(&c, UNW_REG_IP, &ip);    bt[i] = (void*)(long)ip;    i++;  }  return i;}

intbacktrace(void **trace, int size){    unw_cursor_t cursor; unw_context_t uc;    unw_word_t ip;    int n = 0;    unw_getcontext(&uc);    unw_init_local(&cursor, &uc);    while (unw_step(&cursor) > 0) {	unw_get_reg(&cursor, UNW_REG_IP, &ip);	trace[n++] = (void *)ip;	{	    char buf[256];	    unw_get_proc_name(&cursor, buf, 256, &ip);	    if (strncmp("_sigtramp", buf, sizeof("_sigtramp")) == 0) {		goto darwin_sigtramp;	    }	}    }    return n;darwin_sigtramp:    /* darwin's bundled libunwind doesn't support signal trampoline */    {	ucontext_t *uctx;	/* get _sigtramp's ucontext_t and set values to cursor	 * http://www.opensource.apple.com/source/Libc/Libc-825.25/i386/sys/_sigtramp.s	 * http://www.opensource.apple.com/source/libunwind/libunwind-35.1/src/unw_getcontext.s	 */	unw_get_reg(&cursor, UNW_X86_64_RBX, &ip);	uctx = (ucontext_t *)ip;	unw_set_reg(&cursor, UNW_X86_64_RAX, uctx->uc_mcontext->__ss.__rax);	unw_set_reg(&cursor, UNW_X86_64_RBX, uctx->uc_mcontext->__ss.__rbx);	unw_set_reg(&cursor, UNW_X86_64_RCX, uctx->uc_mcontext->__ss.__rcx);	unw_set_reg(&cursor, UNW_X86_64_RDX, uctx->uc_mcontext->__ss.__rdx);	unw_set_reg(&cursor, UNW_X86_64_RDI, uctx->uc_mcontext->__ss.__rdi);	unw_set_reg(&cursor, UNW_X86_64_RSI, uctx->uc_mcontext->__ss.__rsi);	unw_set_reg(&cursor, UNW_X86_64_RBP, uctx->uc_mcontext->__ss.__rbp);	unw_set_reg(&cursor, UNW_X86_64_RSP, 8+(uctx->uc_mcontext->__ss.__rsp));	unw_set_reg(&cursor, UNW_X86_64_R8,  uctx->uc_mcontext->__ss.__r8);	unw_set_reg(&cursor, UNW_X86_64_R9,  uctx->uc_mcontext->__ss.__r9);	unw_set_reg(&cursor, UNW_X86_64_R10, uctx->uc_mcontext->__ss.__r10);	unw_set_reg(&cursor, UNW_X86_64_R11, uctx->uc_mcontext->__ss.__r11);	unw_set_reg(&cursor, UNW_X86_64_R12, uctx->uc_mcontext->__ss.__r12);	unw_set_reg(&cursor, UNW_X86_64_R13, uctx->uc_mcontext->__ss.__r13);	unw_set_reg(&cursor, UNW_X86_64_R14, uctx->uc_mcontext->__ss.__r14);	unw_set_reg(&cursor, UNW_X86_64_R15, uctx->uc_mcontext->__ss.__r15);	ip = *(unw_word_t*)uctx->uc_mcontext->__ss.__rsp;	unw_set_reg(&cursor, UNW_REG_IP, ip);	trace[n++] = (void *)uctx->uc_mcontext->__ss.__rip;	trace[n++] = (void *)ip;    }    while (unw_step(&cursor) > 0) {	unw_get_reg(&cursor, UNW_REG_IP, &ip);	trace[n++] = (void *)ip;    }    return n;}

voidfill_in_backtrace(FaultData* fdp){    unw_context_t uc;    unw_cursor_t c;    int i, boff;    memset(&uc, 0, sizeof(uc));    memset(&c, 0, sizeof(c));    if (unw_getcontext(&uc) < 0) {        abort();    }    if (unw_init_local(&c, &uc) < 0) {        abort();    }    // Skip the signal handler, and the signal trampoline    for (i = 0; i < SKIP_FRAME_COUNT; i++) {        if (unw_step(&c) <= 0) {            break;        }    }    memset(fdp->frame, 0, sizeof(fdp->frame));    fdp->frame_count = 0;    boff = 0;    do {        char fn[256];        unw_word_t off, ip;        Dl_info dli;        unw_proc_info_t pi;        unw_get_reg (&c, UNW_REG_IP, &ip);        fdp->frame[fdp->frame_count].addr = (uintptr_t) ip;        fdp->frame[fdp->frame_count].procname = (uintptr_t) &fdp->backtrace_buf[boff];        unw_get_proc_name(&c, (char *) fdp->frame[fdp->frame_count].procname, sizeof(fdp->backtrace_buf) - boff, &off);        unw_get_proc_info(&c, &pi);        boff += strlen((char *) fdp->frame[fdp->frame_count].procname) + 1;        fdp->frame[fdp->frame_count].libname = (uintptr_t) &fdp->backtrace_buf[boff];        dladdr((void *)(uintptr_t) ip, &dli);        strcpy((char *) (uintptr_t) fdp->frame[fdp->frame_count].libname, dli.dli_fname);        boff += strlen((char *) fdp->frame[fdp->frame_count].libname) + 1;        fdp->frame_count++;    } while (unw_step(&c) > 0);}

ssize_t getStackTraceSafe(uintptr_t* addresses, size_t maxAddresses) {  if (maxAddresses == 0) {    return 0;  }  unw_context_t context;  if (unw_getcontext(&context) < 0) {    return -1;  }  unw_cursor_t cursor;  if (unw_init_local(&cursor, &context) < 0) {    return -1;  }  if (!getFrameInfo(&cursor, *addresses)) {    return -1;  }  ++addresses;  size_t count = 1;  for (; count != maxAddresses; ++count, ++addresses) {    int r = unw_step(&cursor);    if (r < 0) {      return -1;    }    if (r == 0) {      break;    }    if (!getFrameInfo(&cursor, *addresses)) {      return -1;    }  }  return count;}

void dumpStack(FILE* file, unw_cursor_t cursor){  int nframe = 0;  char buffer[100];  unw_word_t off;  do {    const char * name = !unw_get_proc_name(&cursor, buffer, 100, &off) ? buffer : "?";    int status;    // Unmangle C++ names:    char* realname = abi::__cxa_demangle(name, 0, 0, &status);#if defined(__x86_64__)    unw_word_t rip = 0;    unw_word_t rsp = 0;    unw_get_reg(&cursor, UNW_X86_64_RIP, &rip);    unw_get_reg(&cursor, UNW_X86_64_RSP, &rsp);    fprintf(file, "  %i: %s (RIP=0x%" PRIx64 " RSP=0x%" PRIx64 ")/n",      nframe, realname ? realname : name, (std::uint64_t) rip, (std::uint64_t) rsp);#else    fprintf(file, "  %i: %s/n", nframe, realname ? realname : name);#endif    free(realname);    ++nframe;  } while(unw_step(&cursor));}

void backtrace() {  unw_cursor_t cursor;  unw_context_t context;  // Initialize cursor to current frame for local unwinding.  unw_getcontext(&context);  unw_init_local(&cursor, &context);  // Unwind frames one by one, going up the frame stack.  while (unw_step(&cursor) > 0) {    unw_word_t offset, pc;    unw_get_reg(&cursor, UNW_REG_IP, &pc);    if (pc == 0) {      break;    }    printf("0x%lx:", pc);    char sym[256];    if (unw_get_proc_name(&cursor, sym, sizeof(sym), &offset) == 0) {      char* nameptr = sym;      int status;      char* demangled = abi::__cxa_demangle(sym, nullptr, nullptr, &status);      if (status == 0) {        nameptr = demangled;      }	char file[256];	int line = 0;	getFileAndLine((long)pc, file, 256, &line);      printf(" (%s+0x%lx) in %s:%d/n", nameptr, offset, file, line);      free(demangled);    } else {      printf(" -- error: unable to obtain symbol name for this frame/n");    }  }}

static voidprint_trace (void){#ifdef HAVE_LIBUNWIND  unw_context_t uc;  unw_cursor_t cursor;  guint stack_num = 0;  if (!display_filter (DISPLAY_FLAG_BACKTRACE))    return;  unw_getcontext (&uc);  unw_init_local (&cursor, &uc);  while (unw_step (&cursor) > 0)    {      gchar name[129];      unw_word_t off;      int result;      result = unw_get_proc_name (&cursor, name, sizeof (name) - 1, &off);      if (result < 0 && result != UNW_ENOMEM)        {          g_print ("Error getting proc name/n");          break;        }      g_print ("#%d  %s + [0x%08x]/n", stack_num++, name, (unsigned int)off);    }}

int getCurrentStackTrace(size_t skip, StackTrace* trace) {  trace->frameIPs = NULL;  trace->frameCount = 0;  struct Context ctx;  ctx.trace = trace;  ctx.skip = skip;  ctx.capacity = 0;  unw_context_t uctx;  int r = unw_getcontext(&uctx);  int err = checkError("unw_get_context", r);  if (err) return err;  unw_cursor_t cursor;  r = unw_init_local(&cursor, &uctx);  err = checkError("unw_init_local", r);  if (err) return err;  while ((r = unw_step(&cursor)) > 0) {    if ((err = addIP(&ctx, &cursor)) != 0) {      destroyStackTrace(trace);      return err;    }  }  err = checkError("unw_step", r);  if (err) return err;  return 0;}

        static void handler(int sig) {            unw_context_t context;            unw_getcontext(&context);            unw_cursor_t cursor;            unw_init_local(&cursor, &context);            SkDebugf("/nSignal %d:/n", sig);            while (unw_step(&cursor) > 0) {                static const size_t kMax = 256;                char mangled[kMax], demangled[kMax];                unw_word_t offset;                unw_get_proc_name(&cursor, mangled, kMax, &offset);                int ok;                size_t len = kMax;                abi::__cxa_demangle(mangled, demangled, &len, &ok);                SkDebugf("%s (+0x%zx)/n", ok == 0 ? demangled : mangled, (size_t)offset);            }            SkDebugf("/n");            // Exit NOW.  Don't notify other threads, don't call anything registered with atexit().            _Exit(sig);        }

static int vmprof_unw_step(unw_cursor_t *cp, int first_run) {	void* ip;    void* sp;    ptrdiff_t sp_offset;    unw_get_reg (cp, UNW_REG_IP, (unw_word_t*)&ip);    unw_get_reg (cp, UNW_REG_SP, (unw_word_t*)&sp);	if (!first_run)		// make sure we're pointing to the CALL and not to the first		// instruction after. If the callee adjusts the stack for us		// it's not safe to be at the instruction after		ip -= 1;    sp_offset = vmprof_unw_get_custom_offset(ip, cp);    if (sp_offset == -1) {        // it means that the ip is NOT in JITted code, so we can use the        // stardard unw_step        return unw_step(cp);    }    else {        // this is a horrible hack to manually walk the stack frame, by        // setting the IP and SP in the cursor        vmprof_hacked_unw_cursor_t *cp2 = (vmprof_hacked_unw_cursor_t*)cp;        void* bp = (void*)sp + sp_offset;        cp2->sp = bp;		bp -= sizeof(void*);        cp2->ip = ((void**)bp)[0];        // the ret is on the top of the stack minus WORD        return 1;    }}

UINT64 Extrae_get_caller (int offset){	int current_deep = 0;	unw_cursor_t cursor;	unw_context_t uc;	unw_word_t ip;	if (unw_getcontext(&uc) < 0)		return 0;	if (unw_init_local(&cursor, &uc))		return 0;	offset --; /* Don't compute call to unw_getcontext */	while (current_deep <= offset)	{		if (unw_get_reg(&cursor, UNW_REG_IP, &ip) < 0)			break;#if defined(DEBUG)		fprintf (stderr, "DEBUG: offset %d depth %d address %08llx %c/n", offset, current_deep, ip, (offset == current_deep)?'*':' ');#endif		if (unw_step (&cursor) <= 0)			return 0;		current_deep ++;	}	return (UINT64) ip;}

static void _adjust_stack_pre_safepoint(hlt_execution_context* ctx){    // Climb up the stack and adjust the reference counts for live objects    // referenced there so that it reflects reality.    unw_cursor_t cursor;    unw_context_t uc;    unw_word_t ip, sp;    unw_getcontext(&uc);    unw_init_local(&cursor, &uc);    int level = 0;    while ( unw_step(&cursor) > 0 ) {        unw_get_reg(&cursor, UNW_REG_IP, &ip);        unw_get_reg(&cursor, UNW_REG_SP, &sp);        printf("level = %d ip = %lx, sp = %lx/n", level, (long)ip, (long)sp);        level++;    }#ifdef DEBUG// DBG_LOG("hilti-mem", "%10s stack-adjust-ctor %p %d %s::%s = %s", obj, level, func, id, render);#endif}

void VSDebugLib::printStack() {  unw_cursor_t cursor;   unw_context_t uc;  unw_word_t ip, sp, off;  unw_proc_info_t pi;  char file[256], name[256];  int line;  int status;  unw_getcontext(&uc);  unw_init_local(&cursor, &uc);  while (unw_step(&cursor) > 0) {    unw_get_reg(&cursor, UNW_REG_IP, &ip);    unw_get_reg(&cursor, UNW_REG_SP, &sp);    unw_get_proc_name (&cursor, name, sizeof (name), &off);    getFileAndLine((long)ip, file, 256, &line);    if (line >= 0) {      char *realname;      realname = abi::__cxa_demangle(name, 0, 0, &status);            if (realname) {	printf("%s: %s, %d/n", realname, file, line);	free(realname);      } else {	printf("%s: %s, %d/n", name, file, line);      }    }  }}

static ALWAYS_INLINE intslow_backtrace (void **buffer, int size, unw_context_t *uc, int skip){  unw_cursor_t cursor;  unw_word_t ip;  int n = 0;  if (unlikely (unw_init_local (&cursor, uc) < 0))    return 0;  while (unw_step (&cursor) > 0)    {      if (n >= size)	return n;      if (unw_get_reg (&cursor, UNW_REG_IP, &ip) < 0)	return n;      if (skip > 0)        skip--;      else        buffer[n++] = (void *) (uintptr_t) ip;    }  return n;}

int dwarf_backtrace(CallStack **returnStack) {  *returnStack = calloc(1, sizeof(CallStack));  CallStack *callStack = *returnStack;  callStack->stack = calloc(INITIAL_LIVE_FUNCTION_SIZE, sizeof(LiveFunction));  callStack->count = 0;  callStack->capacity = INITIAL_LIVE_FUNCTION_SIZE;  unw_cursor_t cursor;  unw_context_t uc;  unw_word_t ip, sp;  unw_getcontext(&uc);  unw_init_local(&cursor, &uc);  while (unw_step(&cursor) > 0) {    unw_get_reg(&cursor, UNW_REG_IP, &ip);    unw_get_reg(&cursor, UNW_REG_SP, &sp);    if (callStack->count >= callStack->capacity) {      callStack->capacity *= 2;      callStack->stack = realloc(callStack->stack,                                 callStack->capacity * sizeof(LiveFunction *));    }    callStack->stack[callStack->count].cursor = cursor;    callStack->stack[callStack->count].pc = (void *)ip;    callStack->stack[callStack->count].sp = (void *)sp;    printf("%p => %p/n", (void *)ip, (void *)sp);    callStack->count++;  }  return callStack->count;}

void fakegc(){  std::cout << "GC/n";  unw_cursor_t cursor;  unw_word_t ip, sp;  unw_context_t uc;  root_info_t root_info_ptr;  unw_getcontext(&uc);  unw_init_local(&cursor, &uc);  do    {      unw_get_reg(&cursor, UNW_REG_IP, &ip);      unw_get_reg(&cursor, UNW_REG_SP, &sp);      // printf("ip=%p sp=%p/n", ip, sp);      if (stk_map.find_root_info((void*)ip, root_info_ptr))        {          for(auto it : root_info_ptr)            {              int *cptr = *((int**)sp - it);              printf("x=%p/n", cptr);              printf("i=%d/n", *cptr);              *cptr = *cptr + 1;            }        }    } while (unw_step(&cursor) > 0);}

void              _dump_crash_report(unsigne pid)// shortened code from android's debuggerd// to get a backtrace on ARM{    unw_addr_space_t as;    struct UPT_info *ui;    unw_cursor_t     cursor;    as = unw_create_addr_space(&_UPT_accessors, 0);    ui = _UPT_create(pid);    int ret = unw_init_remote(&cursor, as, ui);    if (ret < 0) {        PRINTF("WARNING: unw_init_remote() failed [pid %i]/n", pid);        _UPT_destroy(ui);        return;    }    PRINTF("DEBUG: backtrace of the remote process (pid %d) using libunwind-ptrace:/n", pid);    do {        unw_word_t ip, sp, offp;        char buf[512];        unw_get_reg(&cursor, UNW_REG_IP, &ip);        unw_get_reg(&cursor, UNW_REG_SP, &sp);        unw_get_proc_name(&cursor, buf, sizeof (buf), &offp);        PRINTF("DEBUG:   ip: %10p, sp: %10p   %s/n", (void*) ip, (void*) sp, buf);    } while ((ret = unw_step (&cursor)) > 0);    _UPT_destroy (ui);}

static void findRealErrorOnStack (ShockerScriptableControlObject* obj) {	unw_context_t uc;	unw_cursor_t cursor, prev;	unw_word_t bp;	unw_getcontext(&uc);	unw_init_local(&cursor, &uc);	char framename [1024];	int count = 0;	while (unw_step(&cursor) > 0 && count < 18) {		count++;		unw_get_proc_name (&cursor, framename, sizeof(framename), 0);		if (!*framename)			continue;		if (strstr (framename, "js_ReportErrorAgain")) {#if (__i386__)			unw_get_reg(&prev, UNW_X86_EBP, &bp);#elif (__amd64__)			unw_get_reg(&prev, UNW_X86_64_RBP, &bp);#endif			bp += 12;			char ** n = (char**)bp;			obj->GetLogProvider ()->LogError (*n);			break;		}		prev = cursor;	}}

void collectStackRoots(TraceStack *stack) {    unw_cursor_t cursor;    unw_context_t uc;    unw_word_t ip, sp, bp;    // force callee-save registers onto the stack:    // Actually, I feel like this is pretty brittle:    // collectStackRoots itself is allowed to save the callee-save registers    // on its own stack.    jmp_buf registers __attribute__((aligned(sizeof(void*))));#ifdef VALGRIND    memset(&registers, 0, sizeof(registers));    memset(&cursor, 0, sizeof(cursor));    memset(&uc, 0, sizeof(uc));    memset(&ip, 0, sizeof(ip));    memset(&sp, 0, sizeof(sp));    memset(&bp, 0, sizeof(bp));#endif    setjmp(registers);    assert(sizeof(registers) % 8 == 0);    //void* stack_bottom = __builtin_frame_address(0);    collectRoots(&registers, &registers + 1, stack);    unw_getcontext(&uc);    unw_init_local(&cursor, &uc);    TraceStackGCVisitor visitor(stack);    int code;    while (true) {        int code = unw_step(&cursor);        assert(code > 0 && "something broke unwinding!");        unw_get_reg(&cursor, UNW_REG_IP, &ip);        unw_get_reg(&cursor, UNW_REG_SP, &sp);        unw_get_reg(&cursor, UNW_TDEP_BP, &bp);        void* cur_sp = (void*)sp;        void* cur_bp = (void*)bp;        //std::string name = g.func_addr_registry.getFuncNameAtAddress((void*)ip, true);        //if (VERBOSITY()) printf("ip = %lx (%s), stack = [%p, %p)/n", (long) ip, name.c_str(), cur_sp, cur_bp);        unw_proc_info_t pip;        unw_get_proc_info(&cursor, &pip);        if (pip.start_ip == (uintptr_t)&__libc_start_main) {            break;        }        if (pip.start_ip == (intptr_t)interpretFunction) {            // TODO Do we still need to crawl the interpreter itself?            gatherInterpreterRootsForFrame(&visitor, cur_bp);        }        collectRoots(cur_sp, (char*)cur_bp, stack);    }}

static voidthrow_exception (MonoObject *exc, guint64 rethrow){	unw_context_t unw_ctx;	MonoContext ctx;	MonoJitInfo *ji;	unw_word_t ip, sp;	int res;	if (mono_object_isinst (exc, mono_defaults.exception_class)) {		MonoException *mono_ex = (MonoException*)exc;		if (!rethrow) {			mono_ex->stack_trace = NULL;			mono_ex->trace_ips = NULL;		}	}	res = unw_getcontext (&unw_ctx);	g_assert (res == 0);	res = unw_init_local (&ctx.cursor, &unw_ctx);	g_assert (res == 0);	/* 	 * Unwind until the first managed frame. This is needed since 	 * mono_handle_exception expects the variables in the original context to	 * correspond to the method returned by mono_find_jit_info.	 */	while (TRUE) {		res = unw_get_reg (&ctx.cursor, UNW_IA64_IP, &ip);		g_assert (res == 0);		res = unw_get_reg (&ctx.cursor, UNW_IA64_SP, &sp);		g_assert (res == 0);		ji = mini_jit_info_table_find (mono_domain_get (), (gpointer)ip, NULL);		//printf ("UN: %s %lx %lx/n", ji ? jinfo_get_method (ji)->name : "", ip, sp);		if (ji)			break;		res = unw_step (&ctx.cursor);		if (res == 0) {			/*			 * This means an unhandled exception during the compilation of a			 * topmost method like Main			 */			break;		}		g_assert (res >= 0);	}	ctx.precise_ip = FALSE;	mono_handle_exception (&ctx, exc);	restore_context (&ctx);	g_assert_not_reached ();}

__SHIM__CALLER __SHIM__get_caller(){	unw_cursor_t cursor;	unw_word_t sp;	unw_word_t ip;	unw_context_t uc;	unw_getcontext(&uc);	unw_init_local(&cursor, &uc);	if((unw_step(&cursor) > 0) && (unw_step(&cursor) > 0)) {		unw_get_reg(&cursor, UNW_REG_IP, &ip);		return ip - CALLER0;	} else {		perror("caller");		exit(1);	}}

bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, bool resolve) {  // The cursor structure is pretty large, do not put it on the stack.  unw_cursor_t* cursor = new unw_cursor_t;  int ret = unw_init_local(cursor, &context_);  if (ret < 0) {    BACK_LOGW("unw_init_local failed %d", ret);    delete cursor;    return false;  }  std::vector<backtrace_frame_data_t>* frames = GetFrames();  frames->reserve(MAX_BACKTRACE_FRAMES);  size_t num_frames = 0;  do {    unw_word_t pc;    ret = unw_get_reg(cursor, UNW_REG_IP, &pc);    if (ret < 0) {      BACK_LOGW("Failed to read IP %d", ret);      break;    }    unw_word_t sp;    ret = unw_get_reg(cursor, UNW_REG_SP, &sp);    if (ret < 0) {      BACK_LOGW("Failed to read SP %d", ret);      break;    }    if (num_ignore_frames == 0) {      frames->resize(num_frames+1);      backtrace_frame_data_t* frame = &frames->at(num_frames);      frame->num = num_frames;      frame->pc = static_cast<uintptr_t>(pc);      frame->sp = static_cast<uintptr_t>(sp);      frame->stack_size = 0;      if (num_frames > 0) {        // Set the stack size for the previous frame.        backtrace_frame_data_t* prev = &frames->at(num_frames-1);        prev->stack_size = frame->sp - prev->sp;      }      if (resolve) {        frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);        frame->map = FindMap(frame->pc);      } else {        frame->map = NULL;        frame->func_offset = 0;      }      num_frames++;    } else {      num_ignore_frames--;    }    ret = unw_step (cursor);  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);  delete cursor;  return true;}

static void luw_backtrace(){	unw_cursor_t cursor;	unw_context_t context;	unw_getcontext(&context);	unw_init_local(&cursor, &context);	std::stringstream output;	output << "Traceback (most recent call first):" << std::endl;	while (unw_step(&cursor) > 0)	{		unw_word_t pc;		unw_get_reg(&cursor, UNW_REG_IP, &pc);		if (pc == 0)			break;		const char *file = NULL;		const char *func = NULL;		unsigned line = 0;		resolve(pc, &file, &line, &func);		if (file != NULL)		{			if (strcmp("__cxa_throw", func) == 0) continue;			if (strncmp(func, "_Z", 2) == 0)			{				// This is a C++ mangled name (as per the IA-64 spec)				output << "  0x" << std::hex << pc << std::dec << " " << demangle(func) << " (" << file << ":" << line << ")" << std::endl;			} else {				output << "  0x" << std::hex << pc << std::dec << " " << func << " (" << file << ":" << line << ")" << std::endl;			}			// Try to load the file and print the offending line			std::ifstream f;			f.open(file);			if (!f.is_open())			{				output << "    <unable to find file>" << std::endl;			} else			{				seek_to_line(f, line);				std::string line;				std::getline(f, line);				output << "    " << line << std::endl;			}		} else {			output << "  <unknown> (<unknown file>:<unknown line>)" << std::endl;		}	}	output << std::endl;	__latest_backtrace = output.str();}

voidjffi_longjmp (jmp_buf env, int val){    extern int _jffi_longjmp_cont;    unw_context_t uc;    unw_cursor_t c;    unw_word_t sp, ip, bp = 0;    uintptr_t *wp = (uintptr_t *) env;    int i, setjmp_frame;    if (unw_getcontext (&uc) < 0 || unw_init_local (&c, &uc) < 0) {        debug("failed to get context");        abort ();    }#ifdef __x86_86__# define UNW_REG_BP UNW_X86_64_RBP#else# define UNW_REG_BP UNW_X86_EBP#endif    setjmp_frame = 0;    do {        char name[256];        unw_proc_info_t pi;        unw_word_t off;        if (unw_get_reg (&c, UNW_REG_BP, &bp) < 0) {            abort();        }        if (unw_get_reg (&c, UNW_REG_SP, &sp) < 0) {            abort();        }        if (unw_get_reg (&c, UNW_REG_IP, &ip) < 0) {            abort();        }        unw_get_proc_name(&c, name, sizeof(name), &off);        unw_get_proc_info(&c, &pi);//        debug("frame %s ip=%llx sp=%llx bp=%llx wp[RP]=%p wp[SP]=%p, pi.start_ip=%llx, pi.end_ip=%llx",//            name, (long long) ip, (long long) sp, (long long) bp, (void *) wp[JB_RP], (void *) wp[JB_SP],//            pi.start_ip, pi.end_ip);        if (wp[JB_SP] > sp || wp[JB_RP] < pi.start_ip || wp[JB_RP] > pi.end_ip) continue;        /* found the right frame: *///        debug("found frame to jump back to");        assert (UNW_NUM_EH_REGS >= 2);        if (unw_set_reg (&c, UNW_REG_EH + 0, wp[JB_RP]) < 0            || unw_set_reg (&c, UNW_REG_EH + 1, val) < 0            || unw_set_reg (&c, UNW_REG_IP, (unw_word_t) (uintptr_t) &_jffi_longjmp_cont))            abort ();        unw_resume (&c);        // should not reach here        abort ();    } while (unw_step (&c) > 0);//    debug("failed to find correct frame to jmp to");}

bool BacktraceOffline::Unwind(size_t num_ignore_frames, ucontext_t* context) {  if (context == nullptr) {    BACK_LOGW("The context is needed for offline backtracing.");    return false;  }  context_ = context;  unw_addr_space_t addr_space = unw_create_addr_space(&accessors, 0);  unw_cursor_t cursor;  int ret = unw_init_remote(&cursor, addr_space, this);  if (ret != 0) {    BACK_LOGW("unw_init_remote failed %d", ret);    unw_destroy_addr_space(addr_space);    return false;  }  size_t num_frames = 0;  do {    unw_word_t pc;    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);    if (ret < 0) {      BACK_LOGW("Failed to read IP %d", ret);      break;    }    unw_word_t sp;    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);    if (ret < 0) {      BACK_LOGW("Failed to read SP %d", ret);      break;    }    if (num_ignore_frames == 0) {      frames_.resize(num_frames + 1);      backtrace_frame_data_t* frame = &frames_[num_frames];      frame->num = num_frames;      frame->pc = static_cast<uintptr_t>(pc);      frame->sp = static_cast<uintptr_t>(sp);      frame->stack_size = 0;      if (num_frames > 0) {        backtrace_frame_data_t* prev = &frames_[num_frames - 1];        prev->stack_size = frame->sp - prev->sp;      }      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);      FillInMap(frame->pc, &frame->map);      num_frames++;    } else {      num_ignore_frames--;    }    ret = unw_step(&cursor);  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);  unw_destroy_addr_space(addr_space);  context_ = nullptr;  return true;}

void log_stack_trace(const char *msg){#ifdef USE_UNWIND  unw_context_t ctx;  unw_cursor_t cur;  unw_word_t ip, off;  unsigned level;  char sym[512], *dsym;  int status;  const char *log = stack_trace_log.empty() ? NULL : stack_trace_log.c_str();#endif  if (msg)    ST_LOG(msg);  ST_LOG("Unwound call stack:");#ifdef USE_UNWIND  if (unw_getcontext(&ctx) < 0) {    ST_LOG("Failed to create unwind context");    return;  }  if (unw_init_local(&cur, &ctx) < 0) {    ST_LOG("Failed to find the first unwind frame");    return;  }  for (level = 1; level < 999; ++level) { // 999 for safety    int ret = unw_step(&cur);    if (ret < 0) {      ST_LOG("Failed to find the next frame");      return;    }    if (ret == 0)      break;    if (unw_get_reg(&cur, UNW_REG_IP, &ip) < 0) {      ST_LOG("  " << std::setw(4) << level);      continue;    }    if (unw_get_proc_name(&cur, sym, sizeof(sym), &off) < 0) {      ST_LOG("  " << std::setw(4) << level << std::setbase(16) << std::setw(20) << "0x" << ip);      continue;    }    dsym = abi::__cxa_demangle(sym, NULL, NULL, &status);    ST_LOG("  " << std::setw(4) << level << std::setbase(16) << std::setw(20) << "0x" << ip << " " << (!status && dsym ? dsym : sym) << " + " << "0x" << off);    free(dsym);  }#else  std::stringstream ss;  ss << el::base::debug::StackTrace();  std::vector<std::string> lines;  std::string s = ss.str();  boost::split(lines, s, boost::is_any_of("/n"));  for (const auto &line: lines)    ST_LOG(line);#endif}

static int jl_unw_step(bt_cursor_t *cursor, uintptr_t *ip, uintptr_t *sp){    unw_word_t reg;    if (unw_get_reg(cursor, UNW_REG_IP, &reg) < 0)        return 0;    *ip = reg;    if (unw_get_reg(cursor, UNW_REG_SP, &reg) < 0)        return 0;    *sp = reg;    return unw_step(cursor) > 0;}

static voidsighandler (int signal){  unw_cursor_t cursor, cursor2;  unw_word_t ip;  unw_context_t uc;  if (verbose)    printf ("caught signal %d/n", signal);  unw_getcontext (&uc);  if (unw_init_local (&cursor, &uc) < 0)    panic ("unw_init() failed!/n");  /* get cursor for caller of sighandler: */  if (unw_step (&cursor) < 0)    panic ("unw_step() failed!/n");  cursor2 = cursor;  while (!unw_is_signal_frame (&cursor2))    if (unw_step (&cursor2) < 0)      panic ("failed to find signal frame!/n");  if (unw_step (&cursor2) < 0)    panic ("unw_step() failed!/n");  if (unw_get_reg (&cursor2, UNW_REG_IP, &ip) < 0)    panic ("failed to get IP!/n");  /* skip faulting instruction (doesn't handle MLX template) */  ++ip;  if ((ip & 0x3) == 0x3)    ip += 13;  if (unw_set_reg (&cursor2, UNW_REG_IP, ip) < 0)    panic ("failed to set IP!/n");  unw_resume (&cursor);	/* update context & return to caller of sighandler() */  panic ("unexpected return from unw_resume()!/n");}