Add some MTE-related helpers.
mte_supported() lets code efficiently detect the presence of MTE, and
ScopedDisableMTE lets code disable MTE RAII-style in a particular region
of code.
Bug: 135772972
Change-Id: I628a054b50d79f67f39f35d44232b7a2ae166afb
diff --git a/libc/Android.bp b/libc/Android.bp
index ef1bbe8..78d2e71 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1797,7 +1797,7 @@
name: "bionic_libc_platform_headers",
visibility: [
"//art:__subpackages__",
- "//bionic/libc:__subpackages__",
+ "//bionic:__subpackages__",
"//frameworks:__subpackages__",
"//external/perfetto:__subpackages__",
"//external/scudo:__subpackages__",
diff --git a/libc/bionic/getauxval.cpp b/libc/bionic/getauxval.cpp
index f865f97..d6f75f8 100644
--- a/libc/bionic/getauxval.cpp
+++ b/libc/bionic/getauxval.cpp
@@ -31,6 +31,7 @@
#include <sys/auxv.h>
#include <private/bionic_auxv.h>
#include <private/bionic_globals.h>
+#include <private/bionic_ifuncs.h>
#include <elf.h>
#include <errno.h>
diff --git a/libc/platform/bionic/mte.h b/libc/platform/bionic/mte.h
new file mode 100644
index 0000000..661664a
--- /dev/null
+++ b/libc/platform/bionic/mte.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#pragma once
+
+#include <sys/auxv.h>
+#include <bionic/mte_kernel.h>
+
+#ifdef __aarch64__
+inline bool mte_supported() {
+#ifdef ANDROID_EXPERIMENTAL_MTE
+ static bool supported = getauxval(AT_HWCAP2) & HWCAP2_MTE;
+#else
+ static bool supported = false;
+#endif
+ return supported;
+}
+#endif
+
+struct ScopedDisableMTE {
+ ScopedDisableMTE() {
+#ifdef __aarch64__
+ if (mte_supported()) {
+ __asm__ __volatile__(".arch_extension mte; msr tco, #1");
+ }
+#endif
+ }
+
+ ~ScopedDisableMTE() {
+#ifdef __aarch64__
+ if (mte_supported()) {
+ __asm__ __volatile__(".arch_extension mte; msr tco, #0");
+ }
+#endif
+ }
+};