forked from google/syzkaller
-
Notifications
You must be signed in to change notification settings - Fork 0
/
alloc.go
164 lines (149 loc) · 3.93 KB
/
alloc.go
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
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
// Copyright 2018 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package prog
import (
"fmt"
)
// memAlloc keeps track of allocated objects in a program
// and decides where to allocate new objects.
// It has 2 main methods: noteAlloc which is called for existing allocations
// in a program as we analyze it; and alloc which decides where to allocate
// a new object.
// The implementation is based on a 2-level bitmap where each bit represents
// 64 bytes (memAllocGranule) of program memory.
type memAlloc struct {
size uint64
mem [memAllocL1Size]*[memAllocL0Size]uint64
buf [memAllocL0Size]uint64
}
const (
memAllocGranule = 64 // 1 bit per that many bytes (all allocations are rounded to this size)
memAllocMaxMem = 16 << 20
memAllocL0Size = 64
bitsPerUint64 = 8 * 8
memAllocL0Mem = memAllocL0Size * memAllocGranule * bitsPerUint64
memAllocL1Size = memAllocMaxMem / memAllocL0Mem
)
func newMemAlloc(totalMemSize uint64) *memAlloc {
if totalMemSize > memAllocMaxMem {
panic(fmt.Sprintf("newMemAlloc: too much mem %v (max: %v)", totalMemSize, memAllocMaxMem))
}
if totalMemSize%memAllocL0Mem != 0 {
panic(fmt.Sprintf("newMemAlloc: unaligned size %v (align: %v)", totalMemSize, memAllocL0Mem))
}
ma := &memAlloc{
size: totalMemSize / memAllocGranule,
}
ma.mem[0] = &ma.buf
return ma
}
func (ma *memAlloc) noteAlloc(addr0, size0 uint64) {
addr := addr0 / memAllocGranule
size := (addr0+size0+memAllocGranule-1)/memAllocGranule - addr
for i := uint64(0); i < size; i++ {
ma.set(addr + i)
}
}
func (ma *memAlloc) alloc(r *randGen, size0 uint64) uint64 {
if size0 == 0 {
size0 = 1
}
size := (size0 + memAllocGranule - 1) / memAllocGranule
end := ma.size - size
for start := uint64(0); start < end; start++ {
empty := true
for i := uint64(0); i < size; i++ {
if ma.get(start + i) {
empty = false
break
}
}
if empty {
start0 := start * memAllocGranule
ma.noteAlloc(start0, size0)
return start0
}
}
ma.bankruptcy()
return ma.alloc(r, size0)
}
func (ma *memAlloc) bankruptcy() {
for i1 := uint64(0); i1 < ma.size/(memAllocL0Size*bitsPerUint64); i1++ {
if ma.mem[i1] == nil {
continue
}
for i0 := range ma.mem[i1] {
ma.mem[i1][i0] = 0
}
}
}
func (ma *memAlloc) pos(idx uint64) (i1, i0, bit uint64) {
i1 = idx / (memAllocL0Size * bitsPerUint64)
r1 := idx % (memAllocL0Size * bitsPerUint64)
i0 = r1 / bitsPerUint64
bit = 1 << (r1 % bitsPerUint64)
return
}
func (ma *memAlloc) set(idx uint64) {
i1, i0, bit := ma.pos(idx)
if ma.mem[i1] == nil {
ma.mem[i1] = new([memAllocL0Size]uint64)
}
ma.mem[i1][i0] |= bit
}
func (ma *memAlloc) get(idx uint64) bool {
i1, i0, bit := ma.pos(idx)
if ma.mem[i1] == nil {
return false
}
return ma.mem[i1][i0]&bit != 0
}
type vmaAlloc struct {
numPages uint64
used []uint64
m map[uint64]struct{}
}
func newVmaAlloc(totalPages uint64) *vmaAlloc {
return &vmaAlloc{
numPages: totalPages,
m: make(map[uint64]struct{}),
}
}
func (va *vmaAlloc) noteAlloc(page, size uint64) {
for i := page; i < page+size; i++ {
if _, ok := va.m[i]; ok {
continue
}
va.m[i] = struct{}{}
va.used = append(va.used, i)
}
}
func (va *vmaAlloc) alloc(r *randGen, size uint64) uint64 {
if size > va.numPages {
panic(fmt.Sprintf("vmaAlloc: bad size=%v numPages=%v", size, va.numPages))
}
var page uint64
if len(va.used) == 0 || r.oneOf(5) {
page = r.rand(4)
if !r.oneOf(100) {
page = va.numPages - page - size
}
} else {
page = va.used[r.rand(len(va.used))]
if size > 1 && r.bin() {
off := r.rand(int(size))
if off > page {
off = page
}
page -= off
}
if page+size > va.numPages {
page = va.numPages - size
}
}
if page >= va.numPages || size > va.numPages || page+size > va.numPages {
panic(fmt.Sprintf("vmaAlloc: bad page=%v size=%v numPages=%v", page, size, va.numPages))
}
va.noteAlloc(page, size)
return page
}