bionic: add function to name memory

Only works on some kernels, and only on page-aligned regions of
anonymous memory.  It will show up in /proc/pid/maps as
[anon:<name>] and in /proc/pid/smaps as Name: <name>

Change-Id: If31667cf45ff41cc2a79a140ff68707526def80e

libc/Android.mk

@@ -104,6 +104,7 @@ libc_common_src_files := \
 	bionic/md5.c \
 	bionic/memmem.c \
 	bionic/memswap.c \
+	bionic/name_mem.c \
 	bionic/openat.c \
 	bionic/open.c \
 	bionic/pathconf.c \

libc/bionic/name_mem.c

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#include "private/bionic_name_mem.h"
+
+/*
+ * Local definitions of custom prctl arguments to set a vma name in some kernels
+ */
+#define BIONIC_PR_SET_VMA               0x53564d41
+#define BIONIC_PR_SET_VMA_ANON_NAME     0
+
+/*
+ * Names a region of memory.  The name is expected to show up in /proc/pid/maps
+ * and /proc/pid/smaps.  There is no guarantee that it will work, and it if it
+ * does work it is likely to only work on memory that was allocated with
+ * mmap(MAP_ANONYMOUS), and only on regions that are page aligned.  name should
+ * be a pointer to a string that is valid for as long as the memory is mapped,
+ * preferably a compile-time constant string.
+ *
+ * Returns -1 on error and sets errno.  If it returns an error naming page
+ * aligned anonymous memory the kernel doesn't support naming, and an alternate
+ * method of naming memory should be used (like ashmem).
+ */
+int __bionic_name_mem(void *addr, size_t len, const char *name)
+{
+    return prctl(BIONIC_PR_SET_VMA, BIONIC_PR_SET_VMA_ANON_NAME,
+                 addr, len, name);
+}

libc/private/bionic_name_mem.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+#ifndef _BIONIC_NAME_MEM_H
+#define _BIONIC_NAME_MEM_H
+
+#include <sys/cdefs.h>
+#include <stddef.h>
+
+__BEGIN_DECLS
+
+int __bionic_name_mem(void *addr, size_t len, const char *name);
+
+__END_DECLS
+
+#endif