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1 /*
2  * Copyright (C) 2011 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_CONTEXT_H_
18 #define ART_RUNTIME_ARCH_CONTEXT_H_
19 
20 #include <stddef.h>
21 #include <stdint.h>
22 
23 #include "base/macros.h"
24 
25 namespace art {
26 
27 class QuickMethodFrameInfo;
28 
29 // Representation of a thread's context on the executing machine, used to implement long jumps in
30 // the quick stack frame layout.
31 class Context {
32  public:
33   // Creates a context for the running architecture
34   static Context* Create();
35 
~Context()36   virtual ~Context() {}
37 
38   // Re-initializes the registers for context re-use.
39   virtual void Reset() = 0;
40 
CalleeSaveAddress(uint8_t * frame,int num,size_t frame_size)41   static uintptr_t* CalleeSaveAddress(uint8_t* frame, int num, size_t frame_size) {
42     // Callee saves are held at the top of the frame
43     uint8_t* save_addr = frame + frame_size - ((num + 1) * sizeof(void*));
44 #if defined(__i386__) || defined(__x86_64__)
45     save_addr -= sizeof(void*);  // account for return address
46 #endif
47     return reinterpret_cast<uintptr_t*>(save_addr);
48   }
49 
50   // Reads values from callee saves in the given frame. The frame also holds
51   // the method that holds the layout.
52   virtual void FillCalleeSaves(uint8_t* frame, const QuickMethodFrameInfo& fr) = 0;
53 
54   // Sets the stack pointer value.
55   virtual void SetSP(uintptr_t new_sp) = 0;
56 
57   // Sets the program counter value.
58   virtual void SetPC(uintptr_t new_pc) = 0;
59 
60   // Sets the first argument register.
61   virtual void SetArg0(uintptr_t new_arg0_value) = 0;
62 
63   // Returns whether the given GPR is accessible (read or write).
64   virtual bool IsAccessibleGPR(uint32_t reg) = 0;
65 
66   // Gets the given GPRs address.
67   virtual uintptr_t* GetGPRAddress(uint32_t reg) = 0;
68 
69   // Reads the given GPR. The caller is responsible for checking the register
70   // is accessible with IsAccessibleGPR.
71   virtual uintptr_t GetGPR(uint32_t reg) = 0;
72 
73   // Sets the given GPR. The caller is responsible for checking the register
74   // is accessible with IsAccessibleGPR.
75   virtual void SetGPR(uint32_t reg, uintptr_t value) = 0;
76 
77   // Returns whether the given FPR is accessible (read or write).
78   virtual bool IsAccessibleFPR(uint32_t reg) = 0;
79 
80   // Reads the given FPR. The caller is responsible for checking the register
81   // is accessible with IsAccessibleFPR.
82   virtual uintptr_t GetFPR(uint32_t reg) = 0;
83 
84   // Sets the given FPR. The caller is responsible for checking the register
85   // is accessible with IsAccessibleFPR.
86   virtual void SetFPR(uint32_t reg, uintptr_t value) = 0;
87 
88   // Smashes the caller save registers. If we're throwing, we don't want to return bogus values.
89   virtual void SmashCallerSaves() = 0;
90 
91   // Set `new_value` to the physical register containing the dex PC pointer in
92   // an nterp frame.
SetNterpDexPC(uintptr_t new_value ATTRIBUTE_UNUSED)93   virtual void SetNterpDexPC(uintptr_t new_value ATTRIBUTE_UNUSED) {
94     abort();
95   }
96 
97   // Switches execution of the executing context to this context
98   NO_RETURN virtual void DoLongJump() = 0;
99 
100   enum {
101     kBadGprBase = 0xebad6070,
102     kBadFprBase = 0xebad8070,
103   };
104 };
105 
106 }  // namespace art
107 
108 #endif  // ART_RUNTIME_ARCH_CONTEXT_H_
109