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
|
// Copyright 2023 The gVisor Authors.
//
// 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.
#include "textflag.h"
// handleCheckXstateFault returns (the value stored in AX, the value stored in DI).
// Control is transferred to it when checkXstate below receives SIGSEGV or SIGBUS,
// with the faulting address stored in AX and the signal number stored in DI.
//
// It must have the same frame configuration as memcpy so that it can undo any
// potential call frame set up by the assembler.
TEXT handleCheckXstateFault(SB), NOSPLIT|NOFRAME, $0-26
MOVQ AX, addr+8(FP)
MOVL DI, sig+16(FP)
LDMXCSR mxcsr+20(FP)
BYTE $0xDB; BYTE $0xE2; // FNCLEX
FLDCW cw+24(FP)
RET
// ·checkXstate verifies that the specified floating point state can be loaded.
TEXT ·checkXstate(SB),NOSPLIT|NOFRAME,$0-26
// Store 0 as the returned signal number. If we run to completion,
// this is the value the caller will see; if a signal is received,
// handleMemcpyFault will store a different value in this address.
MOVL $0, sig+16(FP)
// MXCSR and the x87 control word are the only floating point state
// that is callee-save and thus we must save.
STMXCSR mxcsr+20(FP)
FSTCW cw+24(FP)
MOVQ addr+0(FP), DI
MOVL $0xffffffff, AX
MOVL $0xffffffff, DX
XRSTOR64 (DI)
// Restore MXCSR and the x87 control word.
LDMXCSR mxcsr+20(FP)
BYTE $0xDB; BYTE $0xE2; // FNCLEX
FLDCW cw+24(FP)
RET
// func addrOfCheckXstate() uintptr
TEXT ·addrOfCheckXstate(SB), $0-8
MOVQ $·checkXstate(SB), AX
MOVQ AX, ret+0(FP)
RET
|
