Merge "Remove the workaround for old vendor blobs." am: 55bbd5d8ff am: 935c0cebe9

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2518435

Change-Id: I095ef53250db2a46e9646f631273071c759824f9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

core/jni/com_android_internal_os_ZygoteInit.cpp

@@ -23,43 +23,13 @@
 
 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();
 }