implement posix_madvise

Bug: 18472477
Change-Id: I8183de6c281acf69ed5f7f88351b056b9827b162

libc/Android.mk

@@ -153,6 +153,7 @@ libc_bionic_src_files := \
     bionic/poll.cpp \
     bionic/posix_fadvise.cpp \
     bionic/posix_fallocate.cpp \
+    bionic/posix_madvise.cpp \
     bionic/posix_timers.cpp \
     bionic/pthread_atfork.cpp \
     bionic/pthread_attr.cpp \

libc/bionic/posix_madvise.cpp

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2014 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 <errno.h>
+#include <sys/mman.h>
+
+#include "private/ErrnoRestorer.h"
+
+int posix_madvise(void* addr, size_t len, int advice) {
+  ErrnoRestorer errno_restorer;
+
+  // Don't call madvise() on POSIX_MADV_DONTNEED, it will make the space not available.
+  if (advice == POSIX_MADV_DONTNEED) {
+    return 0;
+  }
+  return (madvise(addr, len, advice) == 0 ? 0 : errno);
+}

libc/include/machine/posix_limits.h

@@ -32,7 +32,7 @@
 
 /* Any constant values here other than -1 or 200809L are explicitly specified by POSIX.1-2008. */
 /* Keep it sorted. */
-#define _POSIX_ADVISORY_INFO        -1  /* posix_madvise() not implemented */
+#define _POSIX_ADVISORY_INFO        200809L
 #define _POSIX_AIO_LISTIO_MAX       2
 #define _POSIX_AIO_MAX              1
 #define _POSIX_ARG_MAX              4096

libc/include/sys/mman.h

@@ -43,6 +43,12 @@ __BEGIN_DECLS
 #define MREMAP_MAYMOVE  1
 #define MREMAP_FIXED    2
 
+#define POSIX_MADV_NORMAL     MADV_NORMAL
+#define POSIX_MADV_RANDOM     MADV_RANDOM
+#define POSIX_MADV_SEQUENTIAL MADV_SEQUENTIAL
+#define POSIX_MADV_WILLNEED   MADV_WILLNEED
+#define POSIX_MADV_DONTNEED   MADV_DONTNEED
+
 extern void* mmap(void*, size_t, int, int, int, off_t);
 extern void* mmap64(void*, size_t, int, int, int, off64_t);
 extern int munmap(void*, size_t);
@@ -61,6 +67,8 @@ extern int munlock(const void*, size_t);
 
 extern int mincore(void*, size_t, unsigned char*);
 
+extern int posix_madvise(void*, size_t, int);
+
 __END_DECLS
 
 #endif /* _SYS_MMAN_H_ */

tests/sys_mman_test.cpp

@@ -172,3 +172,46 @@ TEST(sys_mman, mmap_file_write_at_offset) {
   ASSERT_STREQ(NEWPAGE2_MSG, buf);
   ASSERT_STREQ(END_MSG, buf+pagesize-sizeof(END_MSG));
 }
+
+TEST(sys_mman, posix_madvise) {
+  TemporaryFile tempfile;
+  size_t pagesize = sysconf(_SC_PAGESIZE);
+  char buf[pagesize];
+
+  // Prepare environment.
+  ASSERT_EQ(static_cast<ssize_t>(pagesize), write(tempfile.fd, buf, pagesize));
+  void* map = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_SHARED, tempfile.fd, 0);
+  ASSERT_NE(MAP_FAILED, map);
+
+  // Verify different options of posix_madvise.
+  ASSERT_EQ(0, posix_madvise(map, pagesize, POSIX_MADV_NORMAL));
+  ASSERT_EQ(0, posix_madvise(map, pagesize, POSIX_MADV_SEQUENTIAL));
+  ASSERT_EQ(0, posix_madvise(map, pagesize, POSIX_MADV_RANDOM));
+  ASSERT_EQ(0, posix_madvise(map, pagesize, POSIX_MADV_WILLNEED));
+
+  ASSERT_EQ(0, munmap(map, pagesize));
+}
+
+// Verify that memory can still access after posix_madvise(POSIX_MADV_DONTNEED).
+// We should test on MAP_ANONYMOUS memory to verify whether the memory is discarded,
+// because the content of non MAP_ANONYMOUS memory can be reread from file.
+TEST(sys_mman, posix_madvise_POSIX_MADV_DONTNEED) {
+  size_t pagesize = sysconf(_SC_PAGESIZE);
+
+  void* map = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  ASSERT_NE(MAP_FAILED, map);
+
+  int* int_ptr = reinterpret_cast<int*>(map);
+  for (int i = 0; i < static_cast<int>(pagesize / sizeof(int)); ++i) {
+    *int_ptr++ = i;
+  }
+
+  ASSERT_EQ(0, posix_madvise(map, pagesize, POSIX_MADV_DONTNEED));
+
+  int_ptr = reinterpret_cast<int*>(map);
+  for (int i = 0; i < static_cast<int>(pagesize / sizeof(int)); ++i) {
+    ASSERT_EQ(i, *int_ptr++);
+  }
+
+  ASSERT_EQ(0, munmap(map, pagesize));
+}

tests/unistd_test.cpp

@@ -523,6 +523,7 @@ TEST(unistd, _POSIX_macros_smoke) {
   // Verify according to POSIX.1-2008.
   EXPECT_EQ(200809L, _POSIX_VERSION);
 
+  EXPECT_EQ(_POSIX_VERSION, _POSIX_ADVISORY_INFO);
   EXPECT_GT(_POSIX_AIO_LISTIO_MAX, 0);
   EXPECT_GT(_POSIX_AIO_MAX, 0);
   EXPECT_GT(_POSIX_ARG_MAX, 0);
@@ -611,8 +612,7 @@ TEST(unistd, _POSIX_macros_smoke) {
 
 #if defined(__BIONIC__)
   // These tests only pass on bionic, as bionic and glibc has different support on these macros.
-  // Macros like _POSIX_ADVISORY_INFO are not supported on bionic yet.
-  EXPECT_EQ(-1, _POSIX_ADVISORY_INFO);
+  // Macros like _POSIX_ASYNCHRONOUS_IO are not supported on bionic yet.
   EXPECT_EQ(-1, _POSIX_ASYNCHRONOUS_IO);
   EXPECT_EQ(-1, _POSIX_BARRIERS);
   EXPECT_EQ(-1, _POSIX_MESSAGE_PASSING);
@@ -658,6 +658,7 @@ static void VerifySysconf(int option, const char *option_name, bool (*verify)(lo
 }
 
 TEST(unistd, sysconf) {
+  VERIFY_SYSCONF_POSIX_VERSION(_SC_ADVISORY_INFO);
   VERIFY_SYSCONF_POSITIVE(_SC_ARG_MAX);
   VERIFY_SYSCONF_POSITIVE(_SC_BC_BASE_MAX);
   VERIFY_SYSCONF_POSITIVE(_SC_BC_DIM_MAX);
@@ -773,7 +774,6 @@ TEST(unistd, sysconf) {
 #if defined(__BIONIC__)
   // Tests can only run on bionic, as bionic and glibc have different support for these options.
   // Below options are not supported on bionic yet.
-  VERIFY_SYSCONF_NOT_SUPPORT(_SC_ADVISORY_INFO);
   VERIFY_SYSCONF_NOT_SUPPORT(_SC_ASYNCHRONOUS_IO);
   VERIFY_SYSCONF_NOT_SUPPORT(_SC_BARRIERS);
   VERIFY_SYSCONF_NOT_SUPPORT(_SC_MESSAGE_PASSING);