Runtime dynamic memory tracing

This commit adds a dynamic memory tracer that calls a callback whenever
one of the basic memory allocation functions (malloc, realloc, calloc,
free) is called. The operation of the tracer is guarded by the
'MBED_MEM_TRACING_ENABLED` macro.

Infinite recursion during tracing is guarded by using atomic
increment/decrement primitives on the `trace_level` variable.

Thanks to @c1728p9 and @Heky for their help and  suggestions.

Author: Bogdan Marinescu

hal/api/mbed_mem_trace.h

@@ -0,0 +1,138 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __MBED_MEM_TRACE_H__
+#define __MBED_MEM_TRACE_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stddef.h>
+
+/* Operation types for tracer */
+enum {
+    MBED_MEM_TRACE_MALLOC,
+    MBED_MEM_TRACE_REALLOC,
+    MBED_MEM_TRACE_CALLOC,
+    MBED_MEM_TRACE_FREE
+};
+
+/* Prefix for the output of the default tracer */
+#define MBED_MEM_DEFAULT_TRACER_PREFIX  "#"
+
+/**
+ * Type of the callback used by the memory tracer. This callback is called when a memory
+ * allocation operation (malloc, realloc, calloc, free) is called and tracing is enabled
+ * for that memory allocation function.
+ *
+ * @param op the ID of the operation (MBED_MEM_TRACE_MALLOC, MBED_MEM_TRACE_REALLOC,
+ *           MBED_MEM_TRACE_CALLOC or MBED_MEM_TRACE_FREE).
+ * @param res the result that the memory operation returned (NULL for 'free').
+ * @param caller the caller of the memory operation. Note that the value of 'caller' might be
+ *               unreliable.
+ *
+ * The rest of the parameters passed 'mbed_mem_trace_cb_t' are the same as the memory operations
+ * that triggered its call (see 'man malloc' for details):
+ *
+ * - for malloc: cb(MBED_MEM_TRACE_MALLOC, res, caller, size).
+ * - for realloc: cb(MBED_MEM_TRACE_REALLOC, res, caller, ptr, size).
+ * - for calloc: cb(MBED_MEM_TRACE_CALLOC, res, caller, nmemb, size).
+ * - for free: cb(MBED_MEM_TRACE_FREE, NULL, caller, ptr).
+ */
+typedef void (*mbed_mem_trace_cb_t)(uint8_t op, void *res, void* caller, ...);
+
+/**
+ * Set the callback used by the memory tracer (use NULL for disable tracing).
+ *
+ * @param cb the callback to call on each memory operation.
+ */
+void mbed_mem_trace_set_callback(mbed_mem_trace_cb_t cb);
+
+/**
+ * Trace a call to 'malloc'.
+ * @param res the result of running 'malloc'.
+ * @param size the 'size' argument given to 'malloc'.
+ * @param caller the caller of the memory operation.
+ * @return 'res' (the first argument).
+ */
+void *mbed_mem_trace_malloc(void *res, size_t size, void *caller);
+
+/**
+ * Trace a call to 'realloc'.
+ * @param res the result of running 'realloc'.
+ * @param ptr the 'ptr' argument given to 'realloc'.
+ * @param size the 'size' argument given to 'realloc'.
+ *
+ * @return 'res' (the first argument).
+ */
+void *mbed_mem_trace_realloc(void *res, void *ptr, size_t size, void *caller);
+
+/**
+ * Trace a call to 'calloc'.
+ * @param res the result of running 'calloc'.
+ * @param nmemb the 'nmemb' argument given to 'calloc'.
+ * @param size the 'size' argument given to 'calloc'.
+ * @param caller the caller of the memory operation.
+ * @Return 'res' (the first argument).
+ */
+void *mbed_mem_trace_calloc(void *res, size_t num, size_t size, void *caller);
+
+/**
+ * Trace a call to 'free'.
+ * @param ptr the 'ptr' argument given to 'free'.
+ * @param caller the caller of the memory operation.
+ */
+void mbed_mem_trace_free(void *ptr, void *caller);
+
+/**
+ * Default memory trace callback. DO NOT CALL DIRECTLY. It is meant to be used
+ * as the second argument of 'mbed_mem_trace_setup'.
+ *
+ * The default callback outputs trace data using 'printf', in a format that's
+ * easily parsable by an external tool. For each memory operation, the callback
+ * outputs a line that begins with '#<op>:<0xresult>;<0xcaller>-':
+ *
+ * - 'op' identifies the memory operation ('m' for 'malloc', 'r' for 'realloc',
+ *   'c' for 'calloc' and 'f' for 'free').
+ * - 'result' (base 16) is the result of the memor operation. This is always NULL
+ *   for 'free', since 'free' doesn't return anything.
+ * -'caller' (base 16) is the caller of the memory operation. Note that the value
+ *   of 'caller' might be unreliable.
+ *
+ * The rest of the output depends on the operation being traced:
+ *
+ * - for 'malloc': 'size', where 'size' is the original argument to 'malloc'.
+ * - for 'realloc': '0xptr;size', where 'ptr' (base 16) and 'size' are the original arguments to 'realloc'.
+ * - for 'calloc': 'nmemb;size', where 'nmemb' and 'size' are the original arguments to 'calloc'.
+ * - for 'free': '0xptr', where 'ptr' (base 16) is the original argument to 'free'.
+ *
+ * Examples:
+ *
+ * - '#m:0x20003240;0x600d-50' encodes a 'malloc' that returned 0x20003240, was called
+ *   by the instruction at 0x600D with a the 'size' argument equal to 50.
+ * - '#f:0x0;0x602f-0x20003240' encodes a 'free' that was called by the instruction at
+ *   0x602f with the 'ptr' argument equal to 0x20003240.
+ */
+void mbed_mem_trace_default_callback(uint8_t op, void *res, void *caller, ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif// #ifndef __MBED_MEM_TRACE_H__
+

hal/api/toolchain.h

@@ -240,6 +240,29 @@
  */
 #define MBED_DEPRECATED_SINCE(D, M) MBED_DEPRECATED(M " [since " D "]")
 
+/** MBED_CALLER_ADDR()
+ * Returns the caller of the current function.
+ *
+ * @note
+ * This macro is only implemented for GCC and ARMCC.
+ *
+ * @code
+ * #include "toolchain.h"
+ *
+ * printf("This function was called from %p", MBED_CALLER_ADDR());
+ * @endcode
+ *
+ * @return Address of the calling function
+ */
+#ifndef MBED_CALLER_ADDR
+#if (defined(__GNUC__) || defined(__clang__)) && !defined(__CC_ARM)
+#define MBED_CALLER_ADDR() __builtin_extract_return_addr(__builtin_return_address(0))
+#elif defined(__CC_ARM)
+#define MBED_CALLER_ADDR() __builtin_return_address(0)
+#else
+#define MBED_CALLER_ADDR() (NULL)
+#endif
+#endif
 
 // FILEHANDLE declaration
 #if defined(TOOLCHAIN_ARM)