| /* |
| * Copyright (C) 2017 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. |
| */ |
| |
| #define LOG_TAG "Zygote" |
| |
| #include <android/graphics/jni_runtime.h> |
| #include <ui/GraphicBufferMapper.h> |
| |
| #include "core_jni_helpers.h" |
| |
| namespace { |
| |
| // Shadow call stack (SCS) is a security mitigation that uses a separate stack |
| // (the SCS) for return addresses. In versions of Android newer than P, the |
| // compiler cooperates with the system to ensure that the SCS address is always |
| // stored in register x18, as long as the app was compiled with a new enough |
| // compiler and does not use features that rely on SP-HALs (this restriction is |
| // because the SP-HALs might not preserve x18 due to potentially having been |
| // compiled with an old compiler as a consequence of Treble; it generally means |
| // that the app must be a system app without a UI). This struct is used to |
| // temporarily store the address on the stack while preloading the SP-HALs, so |
| // that such apps can use the same zygote as everything else. |
| struct ScopedSCSExit { |
| #ifdef __aarch64__ |
| void* scs; |
| |
| ScopedSCSExit() { |
| __asm__ __volatile__("str x18, [%0]" ::"r"(&scs)); |
| } |
| |
| ~ScopedSCSExit() { |
| __asm__ __volatile__("ldr x18, [%0]; str xzr, [%0]" ::"r"(&scs)); |
| } |
| #else |
| // Silence unused variable warnings in non-SCS builds. |
| ScopedSCSExit() {} |
| ~ScopedSCSExit() {} |
| #endif |
| }; |
| |
| void android_internal_os_ZygoteInit_nativePreloadAppProcessHALs(JNIEnv* env, jclass) { |
| ScopedSCSExit x; |
| android::GraphicBufferMapper::preloadHal(); |
| // Add preloading here for other HALs that are (a) always passthrough, and |
| // (b) loaded by most app processes. |
| } |
| |
| void android_internal_os_ZygoteInit_nativePreloadGraphicsDriver(JNIEnv* env, jclass) { |
| ScopedSCSExit x; |
| zygote_preload_graphics(); |
| } |
| |
| const JNINativeMethod gMethods[] = { |
| { "nativePreloadAppProcessHALs", "()V", |
| (void*)android_internal_os_ZygoteInit_nativePreloadAppProcessHALs }, |
| { "nativePreloadGraphicsDriver", "()V", |
| (void*)android_internal_os_ZygoteInit_nativePreloadGraphicsDriver }, |
| }; |
| |
| } // anonymous namespace |
| |
| namespace android { |
| |
| int register_com_android_internal_os_ZygoteInit(JNIEnv* env) { |
| return RegisterMethodsOrDie(env, "com/android/internal/os/ZygoteInit", |
| gMethods, NELEM(gMethods)); |
| } |
| |
| } // namespace android |