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Jamie LiuandgVisor bot
b8de7c720c
- Use the correct instruction in safecopy.checkXstate(). Before this CL: ``` TEXT pkg/sentry/arch/fpu/fpu.initX86FPState.abi0(SB) ... fpu_amd64.s:78 0x7661b2 480fae2f XRSTOR64 0(DI) TEXT pkg/safecopy/safecopy.checkXstate.abi0(SB) ... xrstor_amd64.s:54 0x7648a0 0fae2f XRSTOR 0(DI) ``` I'm not sure what the actual difference between XRSTOR and XRSTOR64 is, but Linux is careful to use XRSTOR64 (arch/x86/kernel/fpu/xstate.h:XRSTOR, REX_PREFIX) so it probably matters. - When an AfterLoad callback fails, log the error message before the failing object, since the latter can be huge and prevent the error message from being logged. - Include additional information in the error message emitted by fpu.State.AfterLoad(). PiperOrigin-RevId: 605534648
60 lines
2.0 KiB
ArmAsm
60 lines
2.0 KiB
ArmAsm
// Copyright 2023 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "textflag.h"
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// handleCheckXstateFault returns (the value stored in AX, the value stored in DI).
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// Control is transferred to it when checkXstate below receives SIGSEGV or SIGBUS,
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// with the faulting address stored in AX and the signal number stored in DI.
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//
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// It must have the same frame configuration as memcpy so that it can undo any
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// potential call frame set up by the assembler.
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TEXT handleCheckXstateFault(SB), NOSPLIT|NOFRAME, $0-26
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MOVQ AX, addr+8(FP)
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MOVL DI, sig+16(FP)
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LDMXCSR mxcsr+20(FP)
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BYTE $0xDB; BYTE $0xE2; // FNCLEX
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FLDCW cw+24(FP)
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RET
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// ·checkXstate verifies that the specified floating point state can be loaded.
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TEXT ·checkXstate(SB),NOSPLIT|NOFRAME,$0-26
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// Store 0 as the returned signal number. If we run to completion,
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// this is the value the caller will see; if a signal is received,
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// handleMemcpyFault will store a different value in this address.
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MOVL $0, sig+16(FP)
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// MXCSR and the x87 control word are the only floating point state
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// that is callee-save and thus we must save.
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STMXCSR mxcsr+20(FP)
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FSTCW cw+24(FP)
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MOVQ addr+0(FP), DI
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MOVL $0xffffffff, AX
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MOVL $0xffffffff, DX
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XRSTOR64 (DI)
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// Restore MXCSR and the x87 control word.
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LDMXCSR mxcsr+20(FP)
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BYTE $0xDB; BYTE $0xE2; // FNCLEX
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FLDCW cw+24(FP)
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RET
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// func addrOfCheckXstate() uintptr
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TEXT ·addrOfCheckXstate(SB), $0-8
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MOVQ $·checkXstate(SB), AX
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MOVQ AX, ret+0(FP)
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RET
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