diff --git a/cmds/keystore/test-keystore b/cmds/keystore/test-keystore
index 82b276f..3be51b3 100755
--- a/cmds/keystore/test-keystore
+++ b/cmds/keystore/test-keystore
@@ -116,11 +116,12 @@
     expect "1 No error"
     expect "baz"
 
-    log "system does not have access to read any keys"
+    log "get baz"
     keystore system g baz
-    expect "6 Permission denied"
-    
-    log "however, root can read system user keys (as can wifi or vpn users)"
+    expect "1 No error"
+    expect "quux"
+
+    log "root can read system user keys (as can wifi or vpn users)"
     keystore root g baz
     expect "1 No error"
     expect "quux"
diff --git a/include/binder/IMemory.h b/include/binder/IMemory.h
index 74d2cc7..2d0db00 100644
--- a/include/binder/IMemory.h
+++ b/include/binder/IMemory.h
@@ -43,6 +43,7 @@
     virtual void*       getBase() const = 0;
     virtual size_t      getSize() const = 0;
     virtual uint32_t    getFlags() const = 0;
+    virtual uint32_t    getOffset() const = 0;
 
     // these are there just for backward source compatibility
     int32_t heapID() const { return getHeapID(); }
diff --git a/include/binder/MemoryHeapBase.h b/include/binder/MemoryHeapBase.h
index 2f2e31b..bbbda9c 100644
--- a/include/binder/MemoryHeapBase.h
+++ b/include/binder/MemoryHeapBase.h
@@ -27,7 +27,7 @@
 
 // ---------------------------------------------------------------------------
 
-class MemoryHeapBase : public virtual BnMemoryHeap 
+class MemoryHeapBase : public virtual BnMemoryHeap
 {
 public:
     enum {
@@ -38,12 +38,12 @@
         NO_CACHING = 0x00000200
     };
 
-    /* 
+    /*
      * maps the memory referenced by fd. but DOESN'T take ownership
      * of the filedescriptor (it makes a copy with dup()
      */
     MemoryHeapBase(int fd, size_t size, uint32_t flags = 0, uint32_t offset = 0);
-    
+
     /*
      * maps memory from the given device
      */
@@ -61,9 +61,10 @@
     virtual void*       getBase() const;
     virtual size_t      getSize() const;
     virtual uint32_t    getFlags() const;
+    virtual uint32_t      getOffset() const;
 
     const char*         getDevice() const;
-    
+
     /* this closes this heap -- use carefully */
     void dispose();
 
@@ -74,12 +75,12 @@
             mDevice = device;
         return mDevice ? NO_ERROR : ALREADY_EXISTS;
     }
-    
+
 protected:
             MemoryHeapBase();
     // init() takes ownership of fd
     status_t init(int fd, void *base, int size,
-            int flags = 0, const char* device = NULL);    
+            int flags = 0, const char* device = NULL);
 
 private:
     status_t mapfd(int fd, size_t size, uint32_t offset = 0);
@@ -90,6 +91,7 @@
     uint32_t    mFlags;
     const char* mDevice;
     bool        mNeedUnmap;
+    uint32_t    mOffset;
 };
 
 // ---------------------------------------------------------------------------
diff --git a/include/binder/Permission.h b/include/binder/Permission.h
deleted file mode 100644
index 9542d50..0000000
--- a/include/binder/Permission.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright (C) 2009 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.
- */
-
-#ifndef BINDER_PERMISSION_H
-#define BINDER_PERMISSION_H
-
-#include <stdint.h>
-#include <unistd.h>
-
-#include <utils/SortedVector.h>
-#include <utils/String16.h>
-#include <utils/threads.h>
-
-namespace android {
-// ---------------------------------------------------------------------------
-
-/*
- * Permission caches the result of the permission check for the given
- * permission name and the provided uid/pid. It also handles a few
- * known cases efficiently (caller is in the same process or is root).
- * The package manager does something similar but lives in dalvik world
- * and is therefore extremely slow to access.
- */
-
-class Permission
-{
-public:
-            Permission(char const* name);
-            Permission(const String16& name);
-            Permission(const Permission& rhs);
-    virtual ~Permission();
-
-    bool operator < (const Permission& rhs) const;
-
-    // checks the current binder call's caller has access to this permission
-    bool checkCalling() const;
-    
-    // checks the specified pid/uid has access to this permission
-    bool check(pid_t pid, uid_t uid) const;
-    
-protected:
-    virtual bool doCheckPermission(pid_t pid, uid_t uid) const;
-
-private:
-    Permission& operator = (const Permission& rhs) const;
-    const String16 mPermissionName;
-    mutable SortedVector<uid_t> mGranted;
-    const pid_t mPid;
-    mutable Mutex mLock;
-};
-
-// ---------------------------------------------------------------------------
-}; // namespace android
-
-#endif /* BINDER_PERMISSION_H */
diff --git a/include/binder/PermissionCache.h b/include/binder/PermissionCache.h
new file mode 100644
index 0000000..1171d48
--- /dev/null
+++ b/include/binder/PermissionCache.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2009 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.
+ */
+
+#ifndef BINDER_PERMISSION_H
+#define BINDER_PERMISSION_H
+
+#include <stdint.h>
+#include <unistd.h>
+
+#include <utils/String16.h>
+#include <utils/Singleton.h>
+
+namespace android {
+// ---------------------------------------------------------------------------
+
+/*
+ * PermissionCache caches permission checks for a given uid.
+ *
+ * Currently the cache is not updated when there is a permission change,
+ * for instance when an application is uninstalled.
+ *
+ * IMPORTANT: for the reason stated above, only system permissions are safe
+ * to cache. This restriction may be lifted at a later time.
+ *
+ */
+
+class PermissionCache : Singleton<PermissionCache> {
+    struct Entry {
+        String16    name;
+        uid_t       uid;
+        bool        granted;
+        inline bool operator < (const Entry& e) const {
+            return (uid == e.uid) ? (name < e.name) : (uid < e.uid);
+        }
+    };
+    mutable Mutex mLock;
+    // we pool all the permission names we see, as many permissions checks
+    // will have identical names
+    SortedVector< String16 > mPermissionNamesPool;
+    // this is our cache per say. it stores pooled names.
+    SortedVector< Entry > mCache;
+
+    // free the whole cache, but keep the permission name pool
+    void purge();
+
+    status_t check(bool* granted,
+            const String16& permission, uid_t uid) const;
+
+    void cache(const String16& permission, uid_t uid, bool granted);
+
+public:
+    PermissionCache();
+
+    static bool checkCallingPermission(const String16& permission);
+
+    static bool checkCallingPermission(const String16& permission,
+                                int32_t* outPid, int32_t* outUid);
+
+    static bool checkPermission(const String16& permission,
+            pid_t pid, uid_t uid);
+};
+
+// ---------------------------------------------------------------------------
+}; // namespace android
+
+#endif /* BINDER_PERMISSION_H */
diff --git a/libs/binder/Android.mk b/libs/binder/Android.mk
index f9d9f25..3a12e96 100644
--- a/libs/binder/Android.mk
+++ b/libs/binder/Android.mk
@@ -27,7 +27,7 @@
     MemoryHeapBase.cpp \
     MemoryHeapPmem.cpp \
     Parcel.cpp \
-    Permission.cpp \
+    PermissionCache.cpp \
     ProcessState.cpp \
     Static.cpp
 
diff --git a/libs/binder/IMemory.cpp b/libs/binder/IMemory.cpp
index bc8c412..1ace8f8 100644
--- a/libs/binder/IMemory.cpp
+++ b/libs/binder/IMemory.cpp
@@ -42,11 +42,11 @@
 public:
     HeapCache();
     virtual ~HeapCache();
-    
+
     virtual void binderDied(const wp<IBinder>& who);
 
-    sp<IMemoryHeap> find_heap(const sp<IBinder>& binder); 
-    void free_heap(const sp<IBinder>& binder); 
+    sp<IMemoryHeap> find_heap(const sp<IBinder>& binder);
+    void free_heap(const sp<IBinder>& binder);
     sp<IMemoryHeap> get_heap(const sp<IBinder>& binder);
     void dump_heaps();
 
@@ -57,7 +57,7 @@
         int32_t         count;
     };
 
-    void free_heap(const wp<IBinder>& binder); 
+    void free_heap(const wp<IBinder>& binder);
 
     Mutex mHeapCacheLock;
     KeyedVector< wp<IBinder>, heap_info_t > mHeapCache;
@@ -81,11 +81,12 @@
     virtual void* getBase() const;
     virtual size_t getSize() const;
     virtual uint32_t getFlags() const;
+    virtual uint32_t getOffset() const;
 
 private:
     friend class IMemory;
     friend class HeapCache;
-    
+
     // for debugging in this module
     static inline sp<IMemoryHeap> find_heap(const sp<IBinder>& binder) {
         return gHeapCache->find_heap(binder);
@@ -97,7 +98,7 @@
         return gHeapCache->get_heap(binder);
     }
     static inline void dump_heaps() {
-        gHeapCache->dump_heaps();       
+        gHeapCache->dump_heaps();
     }
 
     void assertMapped() const;
@@ -107,6 +108,7 @@
     mutable void*       mBase;
     mutable size_t      mSize;
     mutable uint32_t    mFlags;
+    mutable uint32_t    mOffset;
     mutable bool        mRealHeap;
     mutable Mutex       mLock;
 };
@@ -123,7 +125,7 @@
     BpMemory(const sp<IBinder>& impl);
     virtual ~BpMemory();
     virtual sp<IMemoryHeap> getMemory(ssize_t* offset=0, size_t* size=0) const;
-    
+
 private:
     mutable sp<IMemoryHeap> mHeap;
     mutable ssize_t mOffset;
@@ -203,7 +205,7 @@
 BnMemory::BnMemory() {
 }
 
-BnMemory::~BnMemory() { 
+BnMemory::~BnMemory() {
 }
 
 status_t BnMemory::onTransact(
@@ -229,7 +231,7 @@
 
 BpMemoryHeap::BpMemoryHeap(const sp<IBinder>& impl)
     : BpInterface<IMemoryHeap>(impl),
-        mHeapId(-1), mBase(MAP_FAILED), mSize(0), mFlags(0), mRealHeap(false)
+        mHeapId(-1), mBase(MAP_FAILED), mSize(0), mFlags(0), mOffset(0), mRealHeap(false)
 {
 }
 
@@ -242,7 +244,7 @@
                 sp<IBinder> binder = const_cast<BpMemoryHeap*>(this)->asBinder();
 
                 if (VERBOSE) {
-                    LOGD("UNMAPPING binder=%p, heap=%p, size=%d, fd=%d", 
+                    LOGD("UNMAPPING binder=%p, heap=%p, size=%d, fd=%d",
                             binder.get(), this, mSize, mHeapId);
                     CallStack stack;
                     stack.update();
@@ -270,6 +272,7 @@
             if (mHeapId == -1) {
                 mBase   = heap->mBase;
                 mSize   = heap->mSize;
+                mOffset = heap->mOffset;
                 android_atomic_write( dup( heap->mHeapId ), &mHeapId );
             }
         } else {
@@ -286,13 +289,14 @@
         // remote call without mLock held, worse case scenario, we end up
         // calling transact() from multiple threads, but that's not a problem,
         // only mmap below must be in the critical section.
-        
+
         Parcel data, reply;
         data.writeInterfaceToken(IMemoryHeap::getInterfaceDescriptor());
         status_t err = remote()->transact(HEAP_ID, data, &reply);
         int parcel_fd = reply.readFileDescriptor();
         ssize_t size = reply.readInt32();
         uint32_t flags = reply.readInt32();
+        uint32_t offset = reply.readInt32();
 
         LOGE_IF(err, "binder=%p transaction failed fd=%d, size=%ld, err=%d (%s)",
                 asBinder().get(), parcel_fd, size, err, strerror(-err));
@@ -309,7 +313,7 @@
         Mutex::Autolock _l(mLock);
         if (mHeapId == -1) {
             mRealHeap = true;
-            mBase = mmap(0, size, access, MAP_SHARED, fd, 0);
+            mBase = mmap(0, size, access, MAP_SHARED, fd, offset);
             if (mBase == MAP_FAILED) {
                 LOGE("cannot map BpMemoryHeap (binder=%p), size=%ld, fd=%d (%s)",
                         asBinder().get(), size, fd, strerror(errno));
@@ -317,6 +321,7 @@
             } else {
                 mSize = size;
                 mFlags = flags;
+                mOffset = offset;
                 android_atomic_write(fd, &mHeapId);
             }
         }
@@ -343,14 +348,19 @@
     return mFlags;
 }
 
+uint32_t BpMemoryHeap::getOffset() const {
+    assertMapped();
+    return mOffset;
+}
+
 // ---------------------------------------------------------------------------
 
 IMPLEMENT_META_INTERFACE(MemoryHeap, "android.utils.IMemoryHeap");
 
-BnMemoryHeap::BnMemoryHeap() { 
+BnMemoryHeap::BnMemoryHeap() {
 }
 
-BnMemoryHeap::~BnMemoryHeap() { 
+BnMemoryHeap::~BnMemoryHeap() {
 }
 
 status_t BnMemoryHeap::onTransact(
@@ -362,6 +372,7 @@
             reply->writeFileDescriptor(getHeapID());
             reply->writeInt32(getSize());
             reply->writeInt32(getFlags());
+            reply->writeInt32(getOffset());
             return NO_ERROR;
         } break;
         default:
@@ -383,17 +394,17 @@
 void HeapCache::binderDied(const wp<IBinder>& binder)
 {
     //LOGD("binderDied binder=%p", binder.unsafe_get());
-    free_heap(binder); 
+    free_heap(binder);
 }
 
-sp<IMemoryHeap> HeapCache::find_heap(const sp<IBinder>& binder) 
+sp<IMemoryHeap> HeapCache::find_heap(const sp<IBinder>& binder)
 {
     Mutex::Autolock _l(mHeapCacheLock);
     ssize_t i = mHeapCache.indexOfKey(binder);
     if (i>=0) {
         heap_info_t& info = mHeapCache.editValueAt(i);
         LOGD_IF(VERBOSE,
-                "found binder=%p, heap=%p, size=%d, fd=%d, count=%d", 
+                "found binder=%p, heap=%p, size=%d, fd=%d, count=%d",
                 binder.get(), info.heap.get(),
                 static_cast<BpMemoryHeap*>(info.heap.get())->mSize,
                 static_cast<BpMemoryHeap*>(info.heap.get())->mHeapId,
@@ -415,7 +426,7 @@
     free_heap( wp<IBinder>(binder) );
 }
 
-void HeapCache::free_heap(const wp<IBinder>& binder) 
+void HeapCache::free_heap(const wp<IBinder>& binder)
 {
     sp<IMemoryHeap> rel;
     {
@@ -426,7 +437,7 @@
             int32_t c = android_atomic_dec(&info.count);
             if (c == 1) {
                 LOGD_IF(VERBOSE,
-                        "removing binder=%p, heap=%p, size=%d, fd=%d, count=%d", 
+                        "removing binder=%p, heap=%p, size=%d, fd=%d, count=%d",
                         binder.unsafe_get(), info.heap.get(),
                         static_cast<BpMemoryHeap*>(info.heap.get())->mSize,
                         static_cast<BpMemoryHeap*>(info.heap.get())->mHeapId,
@@ -450,7 +461,7 @@
     return realHeap;
 }
 
-void HeapCache::dump_heaps() 
+void HeapCache::dump_heaps()
 {
     Mutex::Autolock _l(mHeapCacheLock);
     int c = mHeapCache.size();
@@ -459,7 +470,7 @@
         BpMemoryHeap const* h(static_cast<BpMemoryHeap const *>(info.heap.get()));
         LOGD("hey=%p, heap=%p, count=%d, (fd=%d, base=%p, size=%d)",
                 mHeapCache.keyAt(i).unsafe_get(),
-                info.heap.get(), info.count, 
+                info.heap.get(), info.count,
                 h->mHeapId, h->mBase, h->mSize);
     }
 }
diff --git a/libs/binder/MemoryHeapBase.cpp b/libs/binder/MemoryHeapBase.cpp
index 9f501e2..bf4a73f 100644
--- a/libs/binder/MemoryHeapBase.cpp
+++ b/libs/binder/MemoryHeapBase.cpp
@@ -40,15 +40,15 @@
 
 // ---------------------------------------------------------------------------
 
-MemoryHeapBase::MemoryHeapBase() 
+MemoryHeapBase::MemoryHeapBase()
     : mFD(-1), mSize(0), mBase(MAP_FAILED),
-      mDevice(NULL), mNeedUnmap(false) 
+      mDevice(NULL), mNeedUnmap(false), mOffset(0)
 {
 }
 
 MemoryHeapBase::MemoryHeapBase(size_t size, uint32_t flags, char const * name)
     : mFD(-1), mSize(0), mBase(MAP_FAILED), mFlags(flags),
-      mDevice(0), mNeedUnmap(false)
+      mDevice(0), mNeedUnmap(false), mOffset(0)
 {
     const size_t pagesize = getpagesize();
     size = ((size + pagesize-1) & ~(pagesize-1));
@@ -65,7 +65,7 @@
 
 MemoryHeapBase::MemoryHeapBase(const char* device, size_t size, uint32_t flags)
     : mFD(-1), mSize(0), mBase(MAP_FAILED), mFlags(flags),
-      mDevice(0), mNeedUnmap(false)
+      mDevice(0), mNeedUnmap(false), mOffset(0)
 {
     int open_flags = O_RDWR;
     if (flags & NO_CACHING)
@@ -84,7 +84,7 @@
 
 MemoryHeapBase::MemoryHeapBase(int fd, size_t size, uint32_t flags, uint32_t offset)
     : mFD(-1), mSize(0), mBase(MAP_FAILED), mFlags(flags),
-      mDevice(0), mNeedUnmap(false)
+      mDevice(0), mNeedUnmap(false), mOffset(0)
 {
     const size_t pagesize = getpagesize();
     size = ((size + pagesize-1) & ~(pagesize-1));
@@ -141,6 +141,7 @@
     }
     mFD = fd;
     mSize = size;
+    mOffset = offset;
     return NO_ERROR;
 }
 
@@ -183,5 +184,9 @@
     return mDevice;
 }
 
+uint32_t MemoryHeapBase::getOffset() const {
+    return mOffset;
+}
+
 // ---------------------------------------------------------------------------
 }; // namespace android
diff --git a/libs/binder/Permission.cpp b/libs/binder/Permission.cpp
deleted file mode 100644
index fd8fe69..0000000
--- a/libs/binder/Permission.cpp
+++ /dev/null
@@ -1,88 +0,0 @@
-/*
- * Copyright (C) 2009 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.
- */
-
-#include <stdint.h>
-#include <utils/Log.h>
-#include <binder/IPCThreadState.h>
-#include <binder/IServiceManager.h>
-#include <binder/Permission.h>
-
-namespace android {
-// ---------------------------------------------------------------------------
-
-Permission::Permission(char const* name)
-    : mPermissionName(name), mPid(getpid())
-{
-}
-
-Permission::Permission(const String16& name)
-    : mPermissionName(name), mPid(getpid())
-{
-}
-
-Permission::Permission(const Permission& rhs)
-    : mPermissionName(rhs.mPermissionName),
-    mGranted(rhs.mGranted),
-    mPid(rhs.mPid)
-{
-}
-
-Permission::~Permission()
-{
-}
-
-bool Permission::operator < (const Permission& rhs) const
-{
-    return mPermissionName < rhs.mPermissionName;
-}
-
-bool Permission::checkCalling() const
-{
-    IPCThreadState* ipcState = IPCThreadState::self();
-    pid_t pid = ipcState->getCallingPid();
-    uid_t uid = ipcState->getCallingUid();
-    return doCheckPermission(pid, uid);
-}
-
-bool Permission::check(pid_t pid, uid_t uid) const
-{
-    return doCheckPermission(pid, uid);
-}
-
-bool Permission::doCheckPermission(pid_t pid, uid_t uid) const
-{
-    if ((uid == 0) || (pid == mPid)) {
-        // root and ourselves is always okay
-        return true;
-    } else {
-        // see if we already granted this permission for this uid
-        Mutex::Autolock _l(mLock);
-        if (mGranted.indexOf(uid) >= 0)
-            return true;
-    }
-
-    bool granted = checkPermission(mPermissionName, pid, uid);
-    if (granted) {
-        Mutex::Autolock _l(mLock);
-        // no need to check again, the old item will be replaced if it is
-        // already there.
-        mGranted.add(uid);
-    }
-    return granted;
-}
-
-// ---------------------------------------------------------------------------
-}; // namespace android
diff --git a/libs/binder/PermissionCache.cpp b/libs/binder/PermissionCache.cpp
new file mode 100644
index 0000000..7278187
--- /dev/null
+++ b/libs/binder/PermissionCache.cpp
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2009 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 "PermissionCache"
+
+#include <stdint.h>
+#include <utils/Log.h>
+#include <binder/IPCThreadState.h>
+#include <binder/IServiceManager.h>
+#include <binder/PermissionCache.h>
+#include <utils/String8.h>
+
+namespace android {
+
+// ----------------------------------------------------------------------------
+
+ANDROID_SINGLETON_STATIC_INSTANCE(PermissionCache) ;
+
+// ----------------------------------------------------------------------------
+
+PermissionCache::PermissionCache() {
+}
+
+status_t PermissionCache::check(bool* granted,
+        const String16& permission, uid_t uid) const {
+    Mutex::Autolock _l(mLock);
+    Entry e;
+    e.name = permission;
+    e.uid  = uid;
+    ssize_t index = mCache.indexOf(e);
+    if (index >= 0) {
+        *granted = mCache.itemAt(index).granted;
+        return NO_ERROR;
+    }
+    return NAME_NOT_FOUND;
+}
+
+void PermissionCache::cache(const String16& permission,
+        uid_t uid, bool granted) {
+    Mutex::Autolock _l(mLock);
+    Entry e;
+    ssize_t index = mPermissionNamesPool.indexOf(permission);
+    if (index > 0) {
+        e.name = mPermissionNamesPool.itemAt(index);
+    } else {
+        mPermissionNamesPool.add(permission);
+        e.name = permission;
+    }
+    // note, we don't need to store the pid, which is not actually used in
+    // permission checks
+    e.uid  = uid;
+    e.granted = granted;
+    index = mCache.indexOf(e);
+    if (index < 0) {
+        mCache.add(e);
+    }
+}
+
+void PermissionCache::purge() {
+    Mutex::Autolock _l(mLock);
+    mCache.clear();
+}
+
+bool PermissionCache::checkCallingPermission(const String16& permission) {
+    return PermissionCache::checkCallingPermission(permission, NULL, NULL);
+}
+
+bool PermissionCache::checkCallingPermission(
+        const String16& permission, int32_t* outPid, int32_t* outUid) {
+    IPCThreadState* ipcState = IPCThreadState::self();
+    pid_t pid = ipcState->getCallingPid();
+    uid_t uid = ipcState->getCallingUid();
+    if (outPid) *outPid = pid;
+    if (outUid) *outUid = uid;
+    return PermissionCache::checkPermission(permission, pid, uid);
+}
+
+bool PermissionCache::checkPermission(
+        const String16& permission, pid_t pid, uid_t uid) {
+    if ((uid == 0) || (pid == getpid())) {
+        // root and ourselves is always okay
+        return true;
+    }
+
+    PermissionCache& pc(PermissionCache::getInstance());
+    bool granted = false;
+    if (pc.check(&granted, permission, uid) != NO_ERROR) {
+        nsecs_t t = -systemTime();
+        granted = android::checkPermission(permission, pid, uid);
+        t += systemTime();
+        LOGD("checking %s for uid=%d => %s (%d us)",
+                String8(permission).string(), uid,
+                granted?"granted":"denied", (int)ns2us(t));
+        pc.cache(permission, uid, granted);
+    }
+    return granted;
+}
+
+// ---------------------------------------------------------------------------
+}; // namespace android
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 97edfee..f0b19f2 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -32,6 +32,7 @@
 #include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <binder/MemoryHeapBase.h>
+#include <binder/PermissionCache.h>
 
 #include <utils/String8.h>
 #include <utils/String16.h>
@@ -67,6 +68,13 @@
 namespace android {
 // ---------------------------------------------------------------------------
 
+const String16 sHardwareTest("android.permission.HARDWARE_TEST");
+const String16 sAccessSurfaceFlinger("android.permission.ACCESS_SURFACE_FLINGER");
+const String16 sReadFramebuffer("android.permission.READ_FRAME_BUFFER");
+const String16 sDump("android.permission.DUMP");
+
+// ---------------------------------------------------------------------------
+
 SurfaceFlinger::SurfaceFlinger()
     :   BnSurfaceComposer(), Thread(false),
         mTransactionFlags(0),
@@ -74,10 +82,6 @@
         mResizeTransationPending(false),
         mLayersRemoved(false),
         mBootTime(systemTime()),
-        mHardwareTest("android.permission.HARDWARE_TEST"),
-        mAccessSurfaceFlinger("android.permission.ACCESS_SURFACE_FLINGER"),
-        mReadFramebuffer("android.permission.READ_FRAME_BUFFER"),
-        mDump("android.permission.DUMP"),
         mVisibleRegionsDirty(false),
         mHwWorkListDirty(false),
         mDeferReleaseConsole(false),
@@ -1464,7 +1468,8 @@
     const size_t SIZE = 4096;
     char buffer[SIZE];
     String8 result;
-    if (!mDump.checkCalling()) {
+
+    if (!PermissionCache::checkCallingPermission(sDump)) {
         snprintf(buffer, SIZE, "Permission Denial: "
                 "can't dump SurfaceFlinger from pid=%d, uid=%d\n",
                 IPCThreadState::self()->getCallingPid(),
@@ -1596,7 +1601,8 @@
             IPCThreadState* ipc = IPCThreadState::self();
             const int pid = ipc->getCallingPid();
             const int uid = ipc->getCallingUid();
-            if ((uid != AID_GRAPHICS) && !mAccessSurfaceFlinger.check(pid, uid)) {
+            if ((uid != AID_GRAPHICS) &&
+                    !PermissionCache::checkPermission(sAccessSurfaceFlinger, pid, uid)) {
                 LOGE("Permission Denial: "
                         "can't access SurfaceFlinger pid=%d, uid=%d", pid, uid);
                 return PERMISSION_DENIED;
@@ -1609,7 +1615,8 @@
             IPCThreadState* ipc = IPCThreadState::self();
             const int pid = ipc->getCallingPid();
             const int uid = ipc->getCallingUid();
-            if ((uid != AID_GRAPHICS) && !mReadFramebuffer.check(pid, uid)) {
+            if ((uid != AID_GRAPHICS) &&
+                    !PermissionCache::checkPermission(sReadFramebuffer, pid, uid)) {
                 LOGE("Permission Denial: "
                         "can't read framebuffer pid=%d, uid=%d", pid, uid);
                 return PERMISSION_DENIED;
@@ -1621,7 +1628,7 @@
     status_t err = BnSurfaceComposer::onTransact(code, data, reply, flags);
     if (err == UNKNOWN_TRANSACTION || err == PERMISSION_DENIED) {
         CHECK_INTERFACE(ISurfaceComposer, data, reply);
-        if (UNLIKELY(!mHardwareTest.checkCalling())) {
+        if (UNLIKELY(!PermissionCache::checkCallingPermission(sHardwareTest))) {
             IPCThreadState* ipc = IPCThreadState::self();
             const int pid = ipc->getCallingPid();
             const int uid = ipc->getCallingUid();
@@ -2404,8 +2411,7 @@
      const int self_pid = getpid();
      if (UNLIKELY(pid != self_pid && uid != AID_GRAPHICS && uid != 0)) {
          // we're called from a different process, do the real check
-         if (!checkCallingPermission(
-                 String16("android.permission.ACCESS_SURFACE_FLINGER")))
+         if (!PermissionCache::checkCallingPermission(sAccessSurfaceFlinger))
          {
              LOGE("Permission Denial: "
                      "can't openGlobalTransaction pid=%d, uid=%d", pid, uid);
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index af1ef04..45f80ae 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -20,21 +20,20 @@
 #include <stdint.h>
 #include <sys/types.h>
 
-#include <utils/SortedVector.h>
-#include <utils/KeyedVector.h>
-#include <utils/threads.h>
 #include <utils/Atomic.h>
 #include <utils/Errors.h>
+#include <utils/KeyedVector.h>
 #include <utils/RefBase.h>
+#include <utils/SortedVector.h>
+#include <utils/threads.h>
 
-#include <binder/IMemory.h>
-#include <binder/Permission.h>
 #include <binder/BinderService.h>
+#include <binder/IMemory.h>
 
 #include <ui/PixelFormat.h>
+#include <surfaceflinger/IGraphicBufferAlloc.h>
 #include <surfaceflinger/ISurfaceComposer.h>
 #include <surfaceflinger/ISurfaceComposerClient.h>
-#include <surfaceflinger/IGraphicBufferAlloc.h>
 
 #include "Barrier.h"
 #include "Layer.h"
@@ -353,11 +352,7 @@
                 surface_flinger_cblk_t*     mServerCblk;
                 GLuint                      mWormholeTexName;
                 nsecs_t                     mBootTime;
-                Permission                  mHardwareTest;
-                Permission                  mAccessSurfaceFlinger;
-                Permission                  mReadFramebuffer;
-                Permission                  mDump;
-                
+
                 // Can only accessed from the main thread, these members
                 // don't need synchronization
                 State                       mDrawingState;