/* * Perform stack unwinding by using the _Unwind_Backtrace. * * User application that wants to use backtrace needs to be * compiled with -fasynchronous-unwid-tables option and -rdynamic i * to get full symbols printed. * * Author(s): Khem Raj <raj.khem@gmail.com> * - ARM specific implementation of backtrace * * 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; }; static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); static _Unwind_VRS_Result (*unwind_vrs_get) (_Unwind_Context *, _Unwind_VRS_RegClass, _uw, _Unwind_VRS_DataRepresentation, void *); static void backtrace_init (void) { void *handle = dlopen (LIBGCC_S_SO, RTLD_LAZY); if (handle == NULL || ((unwind_backtrace = dlsym (handle, "_Unwind_Backtrace")) == NULL) || ((unwind_vrs_get = dlsym (handle, "_Unwind_VRS_Get")) == NULL)) { printf(LIBGCC_S_SO " must be installed for backtrace to work\n"); abort(); } } /* This function is identical to "_Unwind_GetGR", except that it uses "unwind_vrs_get" instead of "_Unwind_VRS_Get". */ static inline _Unwind_Word unwind_getgr (_Unwind_Context *context, int regno) { _uw val; unwind_vrs_get (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val); return val; } /* This macro is identical to the _Unwind_GetIP macro, except that it uses "unwind_getgr" instead of "_Unwind_GetGR". */ #define unwind_getip(context) \ (unwind_getgr (context, 15) & ~(_Unwind_Word)1) static _Unwind_Reason_Code backtrace_helper (struct _Unwind_Context *ctx, void *a) { struct trace_arg *arg = a; assert (unwind_getip(ctx) != 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 }; if (unwind_backtrace == NULL) backtrace_init(); if (size >= 1) unwind_backtrace (backtrace_helper, &arg); return arg.cnt != -1 ? arg.cnt : 0; }