1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
using ARMeilleure.Memory;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Threading;
namespace ARMeilleure.Translation
{
class JumpTable
{
// The jump table is a block of (guestAddress, hostAddress) function mappings.
// Each entry corresponds to one branch in a JIT compiled function. The entries are
// reserved specifically for each call.
// The _dependants dictionary can be used to update the hostAddress for any functions that change.
public const int JumpTableStride = 16; // 8 byte guest address, 8 byte host address
private const int JumpTableSize = 1048576;
private const int JumpTableByteSize = JumpTableSize * JumpTableStride;
// The dynamic table is also a block of (guestAddress, hostAddress) function mappings.
// The main difference is that indirect calls and jumps reserve _multiple_ entries on the table.
// These start out as all 0. When an indirect call is made, it tries to find the guest address on the table.
// If we get to an empty address, the guestAddress is set to the call that we want.
// If we get to a guestAddress that matches our own (or we just claimed it), the hostAddress is read.
// If it is non-zero, we immediately branch or call the host function.
// If it is 0, NativeInterface is called to find the rejited address of the call.
// If none is found, the hostAddress entry stays at 0. Otherwise, the new address is placed in the entry.
// If the table size is exhausted and we didn't find our desired address, we fall back to requesting
// the function from the JIT.
private const int DynamicTableSize = 1048576;
public const int DynamicTableElems = 1;
public const int DynamicTableStride = DynamicTableElems * JumpTableStride;
private const int DynamicTableByteSize = DynamicTableSize * JumpTableStride * DynamicTableElems;
private int _tableEnd = 0;
private int _dynTableEnd = 0;
private ConcurrentDictionary<ulong, TranslatedFunction> _targets;
private ConcurrentDictionary<ulong, LinkedList<int>> _dependants; // TODO: Attach to TranslatedFunction or a wrapper class.
private ReservedRegion _jumpRegion;
private ReservedRegion _dynamicRegion;
public IntPtr JumpPointer => _jumpRegion.Pointer;
public IntPtr DynamicPointer => _dynamicRegion.Pointer;
public JumpTable(IJitMemoryAllocator allocator)
{
_jumpRegion = new ReservedRegion(allocator, JumpTableByteSize);
_dynamicRegion = new ReservedRegion(allocator, DynamicTableByteSize);
_targets = new ConcurrentDictionary<ulong, TranslatedFunction>();
_dependants = new ConcurrentDictionary<ulong, LinkedList<int>>();
}
public void RegisterFunction(ulong address, TranslatedFunction func)
{
address &= ~3UL;
_targets.AddOrUpdate(address, func, (key, oldFunc) => func);
long funcPtr = func.GetPointer().ToInt64();
// Update all jump table entries that target this address.
if (_dependants.TryGetValue(address, out LinkedList<int> myDependants))
{
lock (myDependants)
{
foreach (var entry in myDependants)
{
IntPtr addr = _jumpRegion.Pointer + entry * JumpTableStride;
Marshal.WriteInt64(addr, 8, funcPtr);
}
}
}
}
public int ReserveDynamicEntry(bool isJump)
{
int entry = Interlocked.Increment(ref _dynTableEnd);
if (entry >= DynamicTableSize)
{
throw new OutOfMemoryException("JIT Dynamic Jump Table exhausted.");
}
_dynamicRegion.ExpandIfNeeded((ulong)((entry + 1) * DynamicTableStride));
// Initialize all host function pointers to the indirect call stub.
IntPtr addr = _dynamicRegion.Pointer + entry * DynamicTableStride;
long stubPtr = (long)DirectCallStubs.IndirectCallStub(isJump);
for (int i = 0; i < DynamicTableElems; i++)
{
Marshal.WriteInt64(addr, i * JumpTableStride + 8, stubPtr);
}
return entry;
}
public int ReserveTableEntry(long ownerAddress, long address, bool isJump)
{
int entry = Interlocked.Increment(ref _tableEnd);
if (entry >= JumpTableSize)
{
throw new OutOfMemoryException("JIT Direct Jump Table exhausted.");
}
_jumpRegion.ExpandIfNeeded((ulong)((entry + 1) * JumpTableStride));
// Is the address we have already registered? If so, put the function address in the jump table.
// If not, it will point to the direct call stub.
long value = (long)DirectCallStubs.DirectCallStub(isJump);
if (_targets.TryGetValue((ulong)address, out TranslatedFunction func))
{
value = func.GetPointer().ToInt64();
}
// Make sure changes to the function at the target address update this jump table entry.
LinkedList<int> targetDependants = _dependants.GetOrAdd((ulong)address, (addr) => new LinkedList<int>());
lock (targetDependants)
{
targetDependants.AddLast(entry);
}
IntPtr addr = _jumpRegion.Pointer + entry * JumpTableStride;
Marshal.WriteInt64(addr, 0, address);
Marshal.WriteInt64(addr, 8, value);
return entry;
}
}
}
|
