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Merge "Don't ask libc for PT feature w/o kernel support."

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This commit is contained in:
Mitch Phillips
2020-04-07 15:38:56 +00:00
committed by Android (Google) Code Review
parent bcff0b9284 6dabec7b3b
commit 60ec63d646
4 changed files with 23 additions and 5 deletions
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7
core/java/com/android/internal/os/Zygote.java
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@@ -1065,4 +1065,11 @@ public final class Zygote {
* Returns whether the hardware supports memory tagging (ARM MTE).
*/
public static native boolean nativeSupportsMemoryTagging();
/**
* Returns whether the kernel supports tagged pointers. Present in the
* Android Common Kernel from 4.14 and up. By default, you should prefer
* fully-feature Memory Tagging, rather than the static Tagged Pointers.
*/
public static native boolean nativeSupportsTaggedPointers();
}

4
core/java/com/android/internal/os/ZygoteInit.java
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@@ -754,9 +754,9 @@ public class ZygoteInit {
/* The system server is more privileged than regular app processes, so it has async
* tag checks enabled on hardware that supports memory tagging. */
parsedArgs.mRuntimeFlags |= Zygote.MEMORY_TAG_LEVEL_ASYNC;
} else {
} else if (Zygote.nativeSupportsTaggedPointers()) {
/* Enable pointer tagging in the system server. Hardware support for this is present
* in all ARMv8 CPUs; this flag has no effect on other platforms. */
* in all ARMv8 CPUs. */
parsedArgs.mRuntimeFlags |= Zygote.MEMORY_TAG_LEVEL_TBI;
}

11
core/jni/com_android_internal_os_Zygote.cpp
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@@ -2456,6 +2456,15 @@ static jboolean com_android_internal_os_Zygote_nativeSupportsMemoryTagging(JNIEn
#endif
}
static jboolean com_android_internal_os_Zygote_nativeSupportsTaggedPointers(JNIEnv* env, jclass) {
#ifdef __aarch64__
int res = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0);
return res >= 0 && res & PR_TAGGED_ADDR_ENABLE;
#else
return false;
#endif
}
static const JNINativeMethod gMethods[] = {
{"nativeForkAndSpecialize",
"(II[II[[IILjava/lang/String;Ljava/lang/String;[I[IZLjava/lang/String;Ljava/lang/"
@@ -2493,6 +2502,8 @@ static const JNINativeMethod gMethods[] = {
(void*)com_android_internal_os_Zygote_nativeParseSigChld},
{"nativeSupportsMemoryTagging", "()Z",
(void*)com_android_internal_os_Zygote_nativeSupportsMemoryTagging},
{"nativeSupportsTaggedPointers", "()Z",
(void*)com_android_internal_os_Zygote_nativeSupportsTaggedPointers},
};
int register_com_android_internal_os_Zygote(JNIEnv* env) {

6
services/core/java/com/android/server/am/ProcessList.java
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@@ -1862,9 +1862,9 @@ public final class ProcessList {
|| mPlatformCompat.isChangeEnabled(NATIVE_MEMORY_TAGGING, app.info)) {
runtimeFlags |= Zygote.MEMORY_TAG_LEVEL_ASYNC;
}
} else {
// Enable heap pointer tagging, unless disabled by the app manifest, target sdk
// level, or the compat feature.
} else if (Zygote.nativeSupportsTaggedPointers()) {
// Enable heap pointer tagging if supported by the kernel, unless disabled by the
// app manifest, target sdk level, or compat feature.
if (app.info.allowsNativeHeapPointerTagging()
&& mPlatformCompat.isChangeEnabled(NATIVE_HEAP_POINTER_TAGGING, app.info)) {
runtimeFlags |= Zygote.MEMORY_TAG_LEVEL_TBI;