Adding kuser_helper on note to all arm32 binaries.
A kernel change is going in for 64bit arm to disable kuser_helper vector
pages for 32bit processes. This change adds a special elf note to
all arm32 binaries built with bionic. This note tells the kernel to
load the kuser_helper vector page for the process.
Bug: 33689037
Test: Manual - Phone boots, 32bit binaries have the notes, 64bit
binaries do not.
Change-Id: Ib8366e2a0810092b71381d57dee4bdaa56369a24
diff --git a/libc/arch-arm/bionic/kuser_helper_on.S b/libc/arch-arm/bionic/kuser_helper_on.S
new file mode 100644
index 0000000..e59d0d5
--- /dev/null
+++ b/libc/arch-arm/bionic/kuser_helper_on.S
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+ .section .note.android.kuser_helper_off,"a",%note
+ .align 2
+ .type abitag, %object
+abitag:
+ .long 2f-1f /* int32_t namesz */
+ .long 3f-2f /* int32_t descsz */
+ .long 3 /* int32_t type */
+1: .ascii "Android\0" /* char name[] */
+2: .long 1 /* int32_t on */
+3:
+ .size abitag, .-abitag