From 37eb913ed8c4798b736e678f4dbd9f4a91a68f74 Mon Sep 17 00:00:00 2001 From: Salvatore Cro Date: Thu, 9 Sep 2010 15:45:44 +0200 Subject: libubacktrace: Provide uClibc with backtrace functions A new shared object, libubacktrace.so.0 is added to uClibc to provide backtrace functions to support application self-debugging. This set of functions requires to dynamically load libgcc_s.so so they need to call dlopen/dlsym that are provided by libdl. For this reason they cannot be included into libc.so.0 but are provided by a new library. User application that wants to use backtrace needs to be compiled with -fexceptions option and -rdynamic to get full symbols printed and must be linked against libubacktrace.so Signed-off-by: Carmelo Amoroso --- libubacktrace/sysdeps/sh/backtrace.c | 84 ++++++++++++++++++++++++++++++++++++ 1 file changed, 84 insertions(+) create mode 100644 libubacktrace/sysdeps/sh/backtrace.c (limited to 'libubacktrace/sysdeps/sh/backtrace.c') diff --git a/libubacktrace/sysdeps/sh/backtrace.c b/libubacktrace/sysdeps/sh/backtrace.c new file mode 100644 index 000000000..18b91b1bb --- /dev/null +++ b/libubacktrace/sysdeps/sh/backtrace.c @@ -0,0 +1,84 @@ +/* + * Perform stack unwinding by using the _Unwind_Backtrace. + * + * User application that wants to use backtrace needs to be + * compiled with -fexceptions option and -rdynamic to get full + * symbols printed. + * + * Copyright (C) 2009, 2010 STMicroelectronics Ltd. + * + * Author(s): Giuseppe Cavallaro + * - Initial implementation for glibc + * + * Author(s): Carmelo Amoroso + * - 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 +#include +#include +#include +#include +#include + +struct trace_arg +{ + void **array; + int cnt, size; +}; + +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.1", RTLD_LAZY); + + if (handle == NULL + || ((unwind_backtrace = dlsym (handle, "_Unwind_Backtrace")) == NULL) + || ((unwind_getip = dlsym (handle, "_Unwind_GetIP")) == NULL)) { + printf("libgcc_s.so.1 must be installed for backtrace to work\n"); + abort(); + } +} + +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. + * + * User application that wants to use backtrace needs to be + * compiled with -fexceptions option and -rdynamic to get full + * symbols printed. + */ +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; +} -- cgit v1.2.3