1 /*
2  * Copyright 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ART_RUNTIME_JIT_JIT_SCOPED_CODE_CACHE_WRITE_H_
18 #define ART_RUNTIME_JIT_JIT_SCOPED_CODE_CACHE_WRITE_H_
19 
20 #include <sys/mman.h>
21 
22 #include "base/systrace.h"
23 #include "base/utils.h"  // For CheckedCall
24 
25 namespace art {
26 namespace jit {
27 
28 class JitMemoryRegion;
29 
30 static constexpr int kProtR = PROT_READ;
31 static constexpr int kProtRW = PROT_READ | PROT_WRITE;
32 static constexpr int kProtRWX = PROT_READ | PROT_WRITE | PROT_EXEC;
33 static constexpr int kProtRX = PROT_READ | PROT_EXEC;
34 
35 // Helper for toggling JIT memory R <-> RW.
36 class ScopedCodeCacheWrite : ScopedTrace {
37  public:
ScopedCodeCacheWrite(const JitMemoryRegion & region)38   explicit ScopedCodeCacheWrite(const JitMemoryRegion& region)
39       : ScopedTrace("ScopedCodeCacheWrite"),
40         region_(region) {
41     ScopedTrace trace("mprotect all");
42     const MemMap* const updatable_pages = region.GetUpdatableCodeMapping();
43     if (updatable_pages != nullptr) {
44       int prot = region.HasDualCodeMapping() ? kProtRW : kProtRWX;
45       CheckedCall(mprotect, "Cache +W", updatable_pages->Begin(), updatable_pages->Size(), prot);
46     }
47   }
48 
~ScopedCodeCacheWrite()49   ~ScopedCodeCacheWrite() {
50     ScopedTrace trace("mprotect code");
51     const MemMap* const updatable_pages = region_.GetUpdatableCodeMapping();
52     if (updatable_pages != nullptr) {
53       int prot = region_.HasDualCodeMapping() ? kProtR : kProtRX;
54       CheckedCall(mprotect, "Cache -W", updatable_pages->Begin(), updatable_pages->Size(), prot);
55     }
56   }
57 
58  private:
59   const JitMemoryRegion& region_;
60 
61   DISALLOW_COPY_AND_ASSIGN(ScopedCodeCacheWrite);
62 };
63 
64 }  // namespace jit
65 }  // namespace art
66 
67 #endif  // ART_RUNTIME_JIT_JIT_SCOPED_CODE_CACHE_WRITE_H_
68