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
|
// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package kernel
import (
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/futex"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
"gvisor.googlesource.com/gvisor/pkg/syserror"
)
// Futex returns t's futex manager.
//
// Preconditions: The caller must be running on the task goroutine, or t.mu
// must be locked.
func (t *Task) Futex() *futex.Manager {
return t.tc.fu
}
// FutexChecker returns a futex.Checker that interprets addresses in t's
// address space.
//
// Preconditions: All uses of the returned futex.Checker must be on the task
// goroutine.
func (t *Task) FutexChecker() futex.Checker {
return futexChecker{t}
}
type futexChecker struct {
t *Task
}
// Check implements futex.Checker.Check.
func (f futexChecker) Check(addr uintptr, val uint32) error {
// FIXME
in := f.t.CopyScratchBuffer(4)
_, err := f.t.CopyInBytes(usermem.Addr(addr), in)
if err != nil {
return err
}
nval := usermem.ByteOrder.Uint32(in)
if val != nval {
return syserror.EAGAIN
}
return nil
}
func (f futexChecker) atomicOp(addr uintptr, op func(uint32) uint32) (uint32, error) {
// FIXME
in := f.t.CopyScratchBuffer(4)
_, err := f.t.CopyInBytes(usermem.Addr(addr), in)
if err != nil {
return 0, err
}
o := usermem.ByteOrder.Uint32(in)
mm := f.t.MemoryManager()
for {
n := op(o)
r, err := mm.CompareAndSwapUint32(f.t, usermem.Addr(addr), o, n, usermem.IOOpts{
AddressSpaceActive: true,
})
if err != nil {
return 0, err
}
if r == o {
return o, nil
}
o = r
}
}
// Op implements futex.Checker.Op, interpreting opIn consistently with Linux.
func (f futexChecker) Op(addr uintptr, opIn uint32) (bool, error) {
op := (opIn >> 28) & 0xf
cmp := (opIn >> 24) & 0xf
opArg := (opIn >> 12) & 0xfff
cmpArg := opIn & 0xfff
if op&linux.FUTEX_OP_OPARG_SHIFT != 0 {
opArg = 1 << opArg
op &^= linux.FUTEX_OP_OPARG_SHIFT // clear flag
}
var oldVal uint32
var err error
switch op {
case linux.FUTEX_OP_SET:
oldVal, err = f.t.MemoryManager().SwapUint32(f.t, usermem.Addr(addr), opArg, usermem.IOOpts{
AddressSpaceActive: true,
})
case linux.FUTEX_OP_ADD:
oldVal, err = f.atomicOp(addr, func(a uint32) uint32 {
return a + opArg
})
case linux.FUTEX_OP_OR:
oldVal, err = f.atomicOp(addr, func(a uint32) uint32 {
return a | opArg
})
case linux.FUTEX_OP_ANDN:
oldVal, err = f.atomicOp(addr, func(a uint32) uint32 {
return a &^ opArg
})
case linux.FUTEX_OP_XOR:
oldVal, err = f.atomicOp(addr, func(a uint32) uint32 {
return a ^ opArg
})
default:
return false, syserror.ENOSYS
}
if err != nil {
return false, err
}
switch cmp {
case linux.FUTEX_OP_CMP_EQ:
return oldVal == cmpArg, nil
case linux.FUTEX_OP_CMP_NE:
return oldVal != cmpArg, nil
case linux.FUTEX_OP_CMP_LT:
return oldVal < cmpArg, nil
case linux.FUTEX_OP_CMP_LE:
return oldVal <= cmpArg, nil
case linux.FUTEX_OP_CMP_GT:
return oldVal > cmpArg, nil
case linux.FUTEX_OP_CMP_GE:
return oldVal >= cmpArg, nil
default:
return false, syserror.ENOSYS
}
}
// GetSharedKey implements futex.Checker.GetSharedKey.
func (f futexChecker) GetSharedKey(addr uintptr) (futex.Key, error) {
return f.t.MemoryManager().GetSharedFutexKey(f.t, usermem.Addr(addr))
}
|
