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     if (kIsDebugBuild || !region.HasDualCodeMapping()) {
42       ScopedTrace trace("mprotect all");
43       const MemMap* const updatable_pages = region.GetUpdatableCodeMapping();
44       if (updatable_pages != nullptr) {
45         int prot = region.HasDualCodeMapping() ? kProtRW : kProtRWX;
46         CheckedCall(mprotect, "Cache +W", updatable_pages->Begin(), updatable_pages->Size(), prot);
47       }
48     }
49   }
50 
~ScopedCodeCacheWrite()51   ~ScopedCodeCacheWrite() {
52     if (kIsDebugBuild || !region_.HasDualCodeMapping()) {
53       ScopedTrace trace("mprotect code");
54       const MemMap* const updatable_pages = region_.GetUpdatableCodeMapping();
55       if (updatable_pages != nullptr) {
56         int prot = region_.HasDualCodeMapping() ? kProtR : kProtRX;
57         CheckedCall(mprotect, "Cache -W", updatable_pages->Begin(), updatable_pages->Size(), prot);
58       }
59     }
60   }
61 
62  private:
63   const JitMemoryRegion& region_;
64 
65   DISALLOW_COPY_AND_ASSIGN(ScopedCodeCacheWrite);
66 };
67 
68 }  // namespace jit
69 }  // namespace art
70 
71 #endif  // ART_RUNTIME_JIT_JIT_SCOPED_CODE_CACHE_WRITE_H_
72