blob: dac66373f84a8d7336d7163e4eb7aebc767e056c (
plain)
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
|
// Copyright 2018 Google Inc.
//
// 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.
// +build i386 amd64
package pagetables
// Opts are pagetable options.
type Opts struct {
EnablePCID bool
}
// archPageTables has x86-specific features.
type archPageTables struct {
// pcids is the PCID database.
pcids *PCIDs
// pcid is the globally unique identifier, or zero if none were
// available or pcids is nil.
pcid uint16
}
// init initializes arch-specific features.
func (a *archPageTables) init(opts Opts) {
if opts.EnablePCID {
a.pcids = NewPCIDs()
a.pcid = a.pcids.allocate()
}
}
// initFrom initializes arch-specific features from an existing entry.'
func (a *archPageTables) initFrom(other *archPageTables) {
a.pcids = other.pcids // Refer to the same PCID database.
if a.pcids != nil {
a.pcid = a.pcids.allocate()
}
}
// release is called from Release.
func (a *archPageTables) release() {
// Return the PCID.
if a.pcids != nil {
a.pcids.free(a.pcid)
}
}
// CR3 returns the CR3 value for these tables.
//
// This may be called in interrupt contexts.
//
//go:nosplit
func (p *PageTables) CR3() uint64 {
// Bit 63 is set to avoid flushing the PCID (per SDM 4.10.4.1).
const noFlushBit uint64 = 0x8000000000000000
if p.pcid != 0 {
return noFlushBit | uint64(p.root.physical) | uint64(p.pcid)
}
return uint64(p.root.physical)
}
// FlushCR3 returns the CR3 value that flushes the TLB.
//
// This may be called in interrupt contexts.
//
//go:nosplit
func (p *PageTables) FlushCR3() uint64 {
return uint64(p.root.physical) | uint64(p.pcid)
}
|
