1 /*
2  * Copyright (C) 2014 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_ARCH_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
18 #define ART_RUNTIME_ARCH_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
19 
20 #include "arch/instruction_set_features.h"
21 #include "base/macros.h"
22 
23 namespace art HIDDEN {
24 
25 class ArmInstructionSetFeatures;
26 using ArmFeaturesUniquePtr = std::unique_ptr<const ArmInstructionSetFeatures>;
27 
28 // Instruction set features relevant to the ARM architecture.
29 class ArmInstructionSetFeatures final : public InstructionSetFeatures {
30  public:
31   // Process a CPU variant string like "krait" or "cortex-a15" and create InstructionSetFeatures.
32   static ArmFeaturesUniquePtr FromVariant(const std::string& variant, std::string* error_msg);
33 
34   // Parse a bitmap and create an InstructionSetFeatures.
35   static ArmFeaturesUniquePtr FromBitmap(uint32_t bitmap);
36 
37   // Turn C pre-processor #defines into the equivalent instruction set features.
38   static ArmFeaturesUniquePtr FromCppDefines();
39 
40   // Process /proc/cpuinfo and use kRuntimeISA to produce InstructionSetFeatures.
41   static ArmFeaturesUniquePtr FromCpuInfo();
42 
43   // Process the auxiliary vector AT_HWCAP entry and use kRuntimeISA to produce
44   // InstructionSetFeatures.
45   static ArmFeaturesUniquePtr FromHwcap();
46 
47   // Use assembly tests of the current runtime (ie kRuntimeISA) to determine the
48   // InstructionSetFeatures. This works around kernel bugs in AT_HWCAP and /proc/cpuinfo.
49   static ArmFeaturesUniquePtr FromAssembly();
50 
51   // Use external cpu_features library.
52   static ArmFeaturesUniquePtr FromCpuFeatures();
53 
54   bool Equals(const InstructionSetFeatures* other) const override;
55 
56   bool HasAtLeast(const InstructionSetFeatures* other) const override;
57 
GetInstructionSet()58   InstructionSet GetInstructionSet() const override {
59     return InstructionSet::kArm;
60   }
61 
62   uint32_t AsBitmap() const override;
63 
64   // Return a string of the form "div,lpae" or "none".
65   std::string GetFeatureString() const override;
66 
67   // Is the divide instruction feature enabled?
HasDivideInstruction()68   bool HasDivideInstruction() const {
69       return has_div_;
70   }
71 
72   // Are the ldrd and strd instructions atomic? This is commonly true when the Large Physical
73   // Address Extension (LPAE) is present.
HasAtomicLdrdAndStrd()74   bool HasAtomicLdrdAndStrd() const {
75     return has_atomic_ldrd_strd_;
76   }
77 
78   // Are ARMv8-A instructions available?
HasARMv8AInstructions()79   bool HasARMv8AInstructions() const {
80     return has_armv8a_;
81   }
82 
~ArmInstructionSetFeatures()83   virtual ~ArmInstructionSetFeatures() {}
84 
85  protected:
86   // Parse a vector of the form "div", "lpae" adding these to a new ArmInstructionSetFeatures.
87   std::unique_ptr<const InstructionSetFeatures>
88       AddFeaturesFromSplitString(const std::vector<std::string>& features,
89                                  std::string* error_msg) const override;
90 
91  private:
ArmInstructionSetFeatures(bool has_div,bool has_atomic_ldrd_strd,bool has_armv8a)92   ArmInstructionSetFeatures(bool has_div,
93                             bool has_atomic_ldrd_strd,
94                             bool has_armv8a)
95       : InstructionSetFeatures(),
96         has_div_(has_div),
97         has_atomic_ldrd_strd_(has_atomic_ldrd_strd),
98         has_armv8a_(has_armv8a) {}
99 
100   // Bitmap positions for encoding features as a bitmap.
101   enum {
102     kDivBitfield = 1 << 0,
103     kAtomicLdrdStrdBitfield = 1 << 1,
104     kARMv8A = 1 << 2,
105   };
106 
107   const bool has_div_;
108   const bool has_atomic_ldrd_strd_;
109   const bool has_armv8a_;
110 
111   DISALLOW_COPY_AND_ASSIGN(ArmInstructionSetFeatures);
112 };
113 
114 }  // namespace art
115 
116 #endif  // ART_RUNTIME_ARCH_ARM_INSTRUCTION_SET_FEATURES_ARM_H_
117