Split libc_debug.so into two .so modules loaded on demand from libc.so

This change is intended to eliminate need to replace libc.so with libc_debug.so in order to enablememory allocation debugging.
This is also the first step towards implementing extended memoryallocation debugging using emulator's capabilities in monitoring memory access.

1 files changed, 432 insertions, 0 deletions

diff --git a/libc/bionic/malloc_debug_common.c b/libc/bionic/malloc_debug_common.c
new file mode 100644
index 0000000..4210915
--- /dev/null
+++ b/libc/bionic/malloc_debug_common.c
@@ -0,0 +1,432 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Contains definition of global variables and implementation of routines
+ * that are used by malloc leak detection code and other components in
+ * the system. The trick is that some components expect these data and
+ * routines to be defined / implemented in libc.so library, regardless
+ * whether or not MALLOC_LEAK_CHECK macro is defined. To make things even
+ * more tricky, malloc leak detection code, implemented in
+ * libc_malloc_debug.so also requires access to these variables and routines
+ * (to fill allocation entry hash table, for example). So, all relevant
+ * variables and routines are defined / implemented here and exported
+ * to all, leak detection code and other components via dynamic (libc.so),
+ * or static (libc.a) linking.
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include "dlmalloc.h"
+#include "malloc_debug_common.h"
+
+/*
+ * In a VM process, this is set to 1 after fork()ing out of zygote.
+ */
+int gMallocLeakZygoteChild = 0;
+
+pthread_mutex_t gAllocationsMutex = PTHREAD_MUTEX_INITIALIZER;
+HashTable gHashTable;
+
+// =============================================================================
+// output functions
+// =============================================================================
+
+static int hash_entry_compare(const void* arg1, const void* arg2)
+{
+    HashEntry* e1 = *(HashEntry**)arg1;
+    HashEntry* e2 = *(HashEntry**)arg2;
+
+    size_t nbAlloc1 = e1->allocations;
+    size_t nbAlloc2 = e2->allocations;
+    size_t size1 = e1->size & ~SIZE_FLAG_MASK;
+    size_t size2 = e2->size & ~SIZE_FLAG_MASK;
+    size_t alloc1 = nbAlloc1 * size1;
+    size_t alloc2 = nbAlloc2 * size2;
+
+    // sort in descending order by:
+    // 1) total size
+    // 2) number of allocations
+    //
+    // This is used for sorting, not determination of equality, so we don't
+    // need to compare the bit flags.
+    int result;
+    if (alloc1 > alloc2) {
+        result = -1;
+    } else if (alloc1 < alloc2) {
+        result = 1;
+    } else {
+        if (nbAlloc1 > nbAlloc2) {
+            result = -1;
+        } else if (nbAlloc1 < nbAlloc2) {
+            result = 1;
+        } else {
+            result = 0;
+        }
+    }
+    return result;
+}
+
+/*
+ * Retrieve native heap information.
+ *
+ * "*info" is set to a buffer we allocate
+ * "*overallSize" is set to the size of the "info" buffer
+ * "*infoSize" is set to the size of a single entry
+ * "*totalMemory" is set to the sum of all allocations we're tracking; does
+ *   not include heap overhead
+ * "*backtraceSize" is set to the maximum number of entries in the back trace
+ */
+void get_malloc_leak_info(uint8_t** info, size_t* overallSize,
+        size_t* infoSize, size_t* totalMemory, size_t* backtraceSize)
+{
+    // don't do anything if we have invalid arguments
+    if (info == NULL || overallSize == NULL || infoSize == NULL ||
+            totalMemory == NULL || backtraceSize == NULL) {
+        return;
+    }
+
+    pthread_mutex_lock(&gAllocationsMutex);
+
+    if (gHashTable.count == 0) {
+        *info = NULL;
+        *overallSize = 0;
+        *infoSize = 0;
+        *totalMemory = 0;
+        *backtraceSize = 0;
+        goto done;
+    }
+
+    void** list = (void**)dlmalloc(sizeof(void*) * gHashTable.count);
+
+    // get the entries into an array to be sorted
+    int index = 0;
+    int i;
+    for (i = 0 ; i < HASHTABLE_SIZE ; i++) {
+        HashEntry* entry = gHashTable.slots[i];
+        while (entry != NULL) {
+            list[index] = entry;
+            *totalMemory = *totalMemory +
+                ((entry->size & ~SIZE_FLAG_MASK) * entry->allocations);
+            index++;
+            entry = entry->next;
+        }
+    }
+
+    // XXX: the protocol doesn't allow variable size for the stack trace (yet)
+    *infoSize = (sizeof(size_t) * 2) + (sizeof(intptr_t) * BACKTRACE_SIZE);
+    *overallSize = *infoSize * gHashTable.count;
+    *backtraceSize = BACKTRACE_SIZE;
+
+    // now get A byte array big enough for this
+    *info = (uint8_t*)dlmalloc(*overallSize);
+
+    if (*info == NULL) {
+        *overallSize = 0;
+        goto done;
+    }
+
+    qsort((void*)list, gHashTable.count, sizeof(void*), hash_entry_compare);
+
+    uint8_t* head = *info;
+    const int count = gHashTable.count;
+    for (i = 0 ; i < count ; i++) {
+        HashEntry* entry = list[i];
+        size_t entrySize = (sizeof(size_t) * 2) + (sizeof(intptr_t) * entry->numEntries);
+        if (entrySize < *infoSize) {
+            /* we're writing less than a full entry, clear out the rest */
+            /* TODO: only clear out the part we're not overwriting? */
+            memset(head, 0, *infoSize);
+        } else {
+            /* make sure the amount we're copying doesn't exceed the limit */
+            entrySize = *infoSize;
+        }
+        memcpy(head, &(entry->size), entrySize);
+        head += *infoSize;
+    }
+
+    dlfree(list);
+
+done:
+    pthread_mutex_unlock(&gAllocationsMutex);
+}
+
+void free_malloc_leak_info(uint8_t* info)
+{
+    dlfree(info);
+}
+
+struct mallinfo mallinfo()
+{
+    return dlmallinfo();
+}
+
+void* valloc(size_t bytes) {
+    /* assume page size of 4096 bytes */
+    return memalign( getpagesize(), bytes );
+}
+
+/* Support for malloc debugging.
+ * Note that if USE_DL_PREFIX is not defined, it's assumed that memory
+ * allocation routines are implemented somewhere else, so all our custom
+ * malloc routines should not be compiled at all.
+ */
+#ifdef USE_DL_PREFIX
+
+/* Table for dispatching malloc calls, initialized with default dispatchers. */
+const MallocDebug __libc_malloc_default_dispatch __attribute__((aligned(32))) =
+{
+    dlmalloc, dlfree, dlcalloc, dlrealloc, dlmemalign
+};
+
+/* Selector of dispatch table to use for dispatching malloc calls. */
+const MallocDebug* __libc_malloc_dispatch = &__libc_malloc_default_dispatch;
+
+void* malloc(size_t bytes) {
+    return __libc_malloc_dispatch->malloc(bytes);
+}
+void free(void* mem) {
+    __libc_malloc_dispatch->free(mem);
+}
+void* calloc(size_t n_elements, size_t elem_size) {
+    return __libc_malloc_dispatch->calloc(n_elements, elem_size);
+}
+void* realloc(void* oldMem, size_t bytes) {
+    return __libc_malloc_dispatch->realloc(oldMem, bytes);
+}
+void* memalign(size_t alignment, size_t bytes) {
+    return __libc_malloc_dispatch->memalign(alignment, bytes);
+}
+
+/* We implement malloc debugging only in libc.so, so code bellow
+ * must be excluded if we compile this file for static libc.a
+ */
+#ifndef LIBC_STATIC
+#include <sys/system_properties.h>
+#include <dlfcn.h>
+#include "logd.h"
+
+// =============================================================================
+// log functions
+// =============================================================================
+
+#define debug_log(format, ...)  \
+    __libc_android_log_print(ANDROID_LOG_DEBUG, "libc", (format), ##__VA_ARGS__ )
+#define error_log(format, ...)  \
+    __libc_android_log_print(ANDROID_LOG_ERROR, "libc", (format), ##__VA_ARGS__ )
+#define info_log(format, ...)  \
+    __libc_android_log_print(ANDROID_LOG_INFO, "libc", (format), ##__VA_ARGS__ )
+
+/* Table for dispatching malloc calls, depending on environment. */
+static MallocDebug gMallocUse __attribute__((aligned(32))) = {
+    dlmalloc, dlfree, dlcalloc, dlrealloc, dlmemalign
+};
+
+extern char*  __progname;
+
+/* Handle to shared library where actual memory allocation is implemented.
+ * This library is loaded and memory allocation calls are redirected there
+ * when libc.debug.malloc environment variable contains value other than
+ * zero:
+ * 1  - For memory leak detections.
+ * 5  - For filling allocated / freed memory with patterns defined by
+ *      CHK_SENTINEL_VALUE, and CHK_FILL_FREE macros.
+ * 10 - For adding pre-, and post- allocation stubs in order to detect
+ *      buffer overruns.
+ * 20 - For enabling emulator memory allocation instrumentation detecting
+ *      memory leaks and buffer overruns.
+ * Actual functionality for debug levels 1-10 is implemented in
+ * libc_malloc_debug_leak.so, while functionality for debug level 20 is
+ * implemented in libc_malloc_debug_qemu.so and can be run inside the
+ * emulator only.
+ */
+static void* libc_malloc_impl_handle = NULL;
+
+/* Initializes memory allocation framework once per process. */
+static void malloc_init_impl(void)
+{
+    const char* so_name = NULL;
+    unsigned int debug_level = 0;
+    unsigned int qemu_running = 0;
+    int len;
+    char env[PROP_VALUE_MAX];
+
+    // Get custom malloc debug level.
+    len = __system_property_get("libc.debug.malloc", env);
+    if (len) {
+        debug_level = atoi(env);
+    }
+
+    /* Debug level 0 means that we should use dlxxx allocation
+     * routines (default).
+     */
+    if (!debug_level) {
+        return;
+    }
+
+    // Get emulator running status.
+    len = __system_property_get("ro.kernel.qemu", env);
+    if (len) {
+        qemu_running = atoi(env);
+    }
+
+    // Lets see which .so must be loaded for the requested debug level
+    switch (debug_level) {
+        case 1:
+        case 5:
+        case 10:
+            so_name = "/system/lib/libc_malloc_debug_leak.so";
+            break;
+        case 20:
+            // Quick check: debug level 20 can only be handled in emulator
+            if (!qemu_running) {
+                info_log("%s: Debug level %d can only be set in emulator\n",
+                         __progname, debug_level);
+                return;
+            }
+            so_name = "/system/lib/libc_malloc_debug_qemu.so";
+            break;
+        default:
+            info_log("%s: Debug level %d is unknown\n",
+                     __progname, debug_level);
+            return;
+    }
+
+    // Load .so that implements the required malloc debugging functionality.
+    libc_malloc_impl_handle = dlopen(so_name, RTLD_LAZY);
+    if (libc_malloc_impl_handle == NULL) {
+        error_log("%s: Missing module %s required for malloc debug level %d\n",
+                 __progname, so_name, debug_level);
+        return;
+    }
+
+    // Initialize malloc dispatch table with appropriate routines.
+    switch (debug_level) {
+        case 1:
+            __libc_android_log_print(ANDROID_LOG_INFO, "libc",
+                    "%s using MALLOC_DEBUG = %d (leak checker)\n",
+                    __progname, debug_level);
+            gMallocUse.malloc =
+                dlsym(libc_malloc_impl_handle, "leak_malloc");
+            gMallocUse.free =
+                dlsym(libc_malloc_impl_handle, "leak_free");
+            gMallocUse.calloc =
+                dlsym(libc_malloc_impl_handle, "leak_calloc");
+            gMallocUse.realloc =
+                dlsym(libc_malloc_impl_handle, "leak_realloc");
+            gMallocUse.memalign =
+                dlsym(libc_malloc_impl_handle, "leak_memalign");
+            break;
+        case 5:
+            __libc_android_log_print(ANDROID_LOG_INFO, "libc",
+                    "%s using MALLOC_DEBUG = %d (fill)\n",
+                    __progname, debug_level);
+            gMallocUse.malloc =
+                dlsym(libc_malloc_impl_handle, "fill_malloc");
+            gMallocUse.free =
+                dlsym(libc_malloc_impl_handle, "fill_free");
+            gMallocUse.calloc = dlcalloc;
+            gMallocUse.realloc =
+                dlsym(libc_malloc_impl_handle, "fill_realloc");
+            gMallocUse.memalign =
+                dlsym(libc_malloc_impl_handle, "fill_memalign");
+            break;
+        case 10:
+            __libc_android_log_print(ANDROID_LOG_INFO, "libc",
+                    "%s using MALLOC_DEBUG = %d (sentinels, fill)\n",
+                    __progname, debug_level);
+            gMallocUse.malloc =
+                dlsym(libc_malloc_impl_handle, "chk_malloc");
+            gMallocUse.free =
+                dlsym(libc_malloc_impl_handle, "chk_free");
+            gMallocUse.calloc =
+                dlsym(libc_malloc_impl_handle, "chk_calloc");
+            gMallocUse.realloc =
+                dlsym(libc_malloc_impl_handle, "chk_realloc");
+            gMallocUse.memalign =
+                dlsym(libc_malloc_impl_handle, "chk_memalign");
+            break;
+        case 20:
+            __libc_android_log_print(ANDROID_LOG_INFO, "libc",
+                    "%s using MALLOC_DEBUG = %d (instrumented for emulator)\n",
+                    __progname, debug_level);
+            gMallocUse.malloc =
+                dlsym(libc_malloc_impl_handle, "qemu_instrumented_malloc");
+            gMallocUse.free =
+                dlsym(libc_malloc_impl_handle, "qemu_instrumented_free");
+            gMallocUse.calloc =
+                dlsym(libc_malloc_impl_handle, "qemu_instrumented_calloc");
+            gMallocUse.realloc =
+                dlsym(libc_malloc_impl_handle, "qemu_instrumented_realloc");
+            gMallocUse.memalign =
+                dlsym(libc_malloc_impl_handle, "qemu_instrumented_memalign");
+            break;
+        default:
+            break;
+    }
+
+    // Make sure dispatch table is initialized
+    if ((gMallocUse.malloc == NULL) ||
+        (gMallocUse.free == NULL) ||
+        (gMallocUse.calloc == NULL) ||
+        (gMallocUse.realloc == NULL) ||
+        (gMallocUse.memalign == NULL)) {
+        error_log("%s: Cannot initialize malloc dispatch table for debug level"
+                  " %d: %p, %p, %p, %p, %p\n",
+                  __progname, debug_level,
+                  gMallocUse.malloc, gMallocUse.free,
+                  gMallocUse.calloc, gMallocUse.realloc,
+                  gMallocUse.memalign);
+        dlclose(libc_malloc_impl_handle);
+        libc_malloc_impl_handle = NULL;
+    } else {
+        __libc_malloc_dispatch = &gMallocUse;
+    }
+}
+
+static pthread_once_t  malloc_init_once_ctl = PTHREAD_ONCE_INIT;
+
+#endif  // !LIBC_STATIC
+#endif  // USE_DL_PREFIX
+
+/* Initializes memory allocation framework.
+ * This routine is called from __libc_init routines implemented
+ * in libc_init_static.c and libc_init_dynamic.c files.
+ */
+void malloc_debug_init(void)
+{
+    /* We need to initialize malloc iff we impelement here custom
+     * malloc routines (i.e. USE_DL_PREFIX is defined) for libc.so
+     */
+#if defined(USE_DL_PREFIX) && !defined(LIBC_STATIC)
+    if (pthread_once(&malloc_init_once_ctl, malloc_init_impl)) {
+        error_log("Unable to initialize malloc_debug component.");
+    }
+#endif  // USE_DL_PREFIX && !LIBC_STATIC
+}