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authorSalvatore Cro <salvatore.cro@st.com>2010-09-09 15:45:44 +0200
committerCarmelo Amoroso <carmelo.amoroso@st.com>2010-09-15 12:31:22 +0200
commit37eb913ed8c4798b736e678f4dbd9f4a91a68f74 (patch)
tree63fc2c1dbb887a043a7291c9c6215d2db7b5ba5a /libubacktrace/sysdeps
parent7ac7be14eb4c8927fddffbe01fed74c605bf8597 (diff)
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 <carmelo.amoroso@st.com>
Diffstat (limited to 'libubacktrace/sysdeps')
-rw-r--r--libubacktrace/sysdeps/sh/Makefile.arch12
-rw-r--r--libubacktrace/sysdeps/sh/backtrace.c84
2 files changed, 96 insertions, 0 deletions
diff --git a/libubacktrace/sysdeps/sh/Makefile.arch b/libubacktrace/sysdeps/sh/Makefile.arch
new file mode 100644
index 000000000..9b0de385b
--- /dev/null
+++ b/libubacktrace/sysdeps/sh/Makefile.arch
@@ -0,0 +1,12 @@
+# Makefile for uClibc (sh/libubacktrace)
+#
+# Copyright (C) 2010 STMicroelectronics Ltd
+# Author: Carmelo Amoroso <carmelo.amoroso@st.com>
+
+# Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+#
+
+libubacktrace_ARCH_SRC-y := backtrace.c
+
+# -fexections is required for backtrace to work using dwarf2
+CFLAGS-backtrace.c := -fexceptions
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 <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 <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_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;
+}