From afab3ffcce1054ec887fb347700819d69a9c8151 Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Tue, 28 Jul 2015 14:58:37 -0700
Subject: [PATCH] Move PAGE_MASK into <sys/user.h>.

I'm removing the TODO on the assumption that being compatible with glibc
is more useful than BSD. The new internal "bionic_page.h" header factors
out some duplication between libc and the linker.

Bug: http://b/22735893
Change-Id: I4aec4dcba5886fb6f6b9290a8f85660643261321
---
 libc/bionic/libc_init_static.cpp |  8 +-------
 libc/include/limits.h            |  3 ---
 libc/include/sys/user.h          |  3 +++
 libc/private/bionic_page.h       | 33 ++++++++++++++++++++++++++++++++
 linker/linker.h                  | 15 +++------------
 5 files changed, 40 insertions(+), 22 deletions(-)
 create mode 100644 libc/private/bionic_page.h

diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index ef57af650..2b1a8cb2c 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -49,16 +49,10 @@
 #include "libc_init_common.h"
 #include "pthread_internal.h"
 
+#include "private/bionic_page.h"
 #include "private/bionic_tls.h"
 #include "private/KernelArgumentBlock.h"
 
-// Returns the address of the page containing address 'x'.
-#define PAGE_START(x)  ((x) & PAGE_MASK)
-
-// Returns the address of the next page after address 'x', unless 'x' is
-// itself at the start of a page.
-#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
-
 extern "C" int __cxa_atexit(void (*)(void *), void *, void *);
 
 static void call_array(void(**list)()) {
diff --git a/libc/include/limits.h b/libc/include/limits.h
index 6ae629be7..685e1847d 100644
--- a/libc/include/limits.h
+++ b/libc/include/limits.h
@@ -89,9 +89,6 @@
 #define  PAGESIZE  PAGE_SIZE
 #endif
 
-/* glibc's PAGE_MASK is the bitwise negation of BSD's! TODO: remove? */
-#define PAGE_MASK (~(PAGE_SIZE - 1))
-
 #define SEM_VALUE_MAX 0x3fffffff
 
 /* POSIX says these belong in <unistd.h> but BSD has some in <limits.h>. */
diff --git a/libc/include/sys/user.h b/libc/include/sys/user.h
index d63fe6aa5..12af664d5 100644
--- a/libc/include/sys/user.h
+++ b/libc/include/sys/user.h
@@ -35,6 +35,9 @@
 
 __BEGIN_DECLS
 
+#define PAGE_SIZE 4096
+#define PAGE_MASK (~(PAGE_SIZE - 1))
+
 #if __i386__
 
 struct user_fpregs_struct {
diff --git a/libc/private/bionic_page.h b/libc/private/bionic_page.h
new file mode 100644
index 000000000..0beb70843
--- /dev/null
+++ b/libc/private/bionic_page.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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 _BIONIC_PAGE_H_
+#define _BIONIC_PAGE_H_
+
+// Get PAGE_SIZE and PAGE_MASK.
+#include <sys/user.h>
+
+// Returns the address of the page containing address 'x'.
+#define PAGE_START(x) ((x) & PAGE_MASK)
+
+// Returns the offset of address 'x' in its page.
+#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
+
+// Returns the address of the next page after address 'x', unless 'x' is
+// itself at the start of a page.
+#define PAGE_END(x) PAGE_START((x) + (PAGE_SIZE-1))
+
+#endif // _BIONIC_PAGE_H_
diff --git a/linker/linker.h b/linker/linker.h
index b1d256677..6f8bf1fdf 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -29,13 +29,14 @@
 #ifndef _LINKER_H_
 #define _LINKER_H_
 
+#include <android/dlext.h>
 #include <elf.h>
 #include <inttypes.h>
 #include <link.h>
-#include <unistd.h>
-#include <android/dlext.h>
 #include <sys/stat.h>
+#include <unistd.h>
 
+#include "private/bionic_page.h"
 #include "private/libc_logging.h"
 #include "linked_list.h"
 
@@ -77,16 +78,6 @@
 #define ELF64_R_TYPE(info)  (((info) >> 56) & 0xff)
 #endif
 
-// Returns the address of the page containing address 'x'.
-#define PAGE_START(x)  ((x) & PAGE_MASK)
-
-// Returns the offset of address 'x' in its page.
-#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
-
-// Returns the address of the next page after address 'x', unless 'x' is
-// itself at the start of a page.
-#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
-
 #define FLAG_LINKED     0x00000001
 #define FLAG_EXE        0x00000004 // The main executable
 #define FLAG_LINKER     0x00000010 // The linker itself