/* * Perform stack unwinding by using the _Unwind_Backtrace. * * User application that wants to use backtrace needs to be * compiled with -fasynchronous-unwind-tables option and -rdynamic to get full * symbols printed. * * Copyright (C) 2009, 2010 STMicroelectronics Ltd. * * Author(s): Giuseppe Cavallaro <peppe.cavallaro@st.com> * - Initial implementation for glibc * * Author(s): Carmelo Amoroso <carmelo.amoroso@st.com> * - Reworked for uClibc * - use dlsym/dlopen from libdl * - rewrite initialisation to not use libc_once * - make it available in static link too * * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. * */ #include <libgcc_s.h> #include <execinfo.h> #include <dlfcn.h> #include <stdlib.h> #include <unwind.h> #include <assert.h> #include <stdio.h> struct trace_arg { void **array; int cnt, size; }; #ifdef SHARED static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *); static void backtrace_init (void) { void *handle = dlopen (LIBGCC_S_SO, RTLD_LAZY); if (handle == NULL || ((unwind_backtrace = dlsym (handle, "_Unwind_Backtrace")) == NULL) || ((unwind_getip = dlsym (handle, "_Unwind_GetIP")) == NULL)) { printf(LIBGCC_S_SO " must be installed for backtrace to work\n"); abort(); } } #else # define unwind_backtrace _Unwind_Backtrace # define unwind_getip _Unwind_GetIP #endif static _Unwind_Reason_Code backtrace_helper (struct _Unwind_Context *ctx, void *a) { struct trace_arg *arg = a; assert (unwind_getip != NULL); /* We are first called with address in the __backtrace function. Skip it. */ if (arg->cnt != -1) arg->array[arg->cnt] = (void *) unwind_getip (ctx); if (++arg->cnt == arg->size) return _URC_END_OF_STACK; return _URC_NO_REASON; } /* * Perform stack unwinding by using the _Unwind_Backtrace. * */ int backtrace (void **array, int size) { struct trace_arg arg = { .array = array, .size = size, .cnt = -1 }; #ifdef SHARED if (unwind_backtrace == NULL) backtrace_init(); #endif if (size >= 1) unwind_backtrace (backtrace_helper, &arg); return arg.cnt != -1 ? arg.cnt : 0; }