55 lines
1.8 KiB
Go
55 lines
1.8 KiB
Go
// Copyright 2021 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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// Package fpu provides basic floating point helpers.
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package fpu
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import (
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"fmt"
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"reflect"
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)
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// State represents floating point state.
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//
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// This is a simple byte slice, but may have architecture-specific methods
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// attached to it.
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type State []byte
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// ErrLoadingState indicates a failed restore due to unusable floating point
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// state.
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type ErrLoadingState struct {
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// supported is the supported floating point state.
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supportedFeatures uint64
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// saved is the saved floating point state.
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savedFeatures uint64
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}
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// Error returns a sensible description of the restore error.
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func (e ErrLoadingState) Error() string {
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return fmt.Sprintf("floating point state contains unsupported features; supported: %#x saved: %#x", e.supportedFeatures, e.savedFeatures)
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}
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// alignedBytes returns a slice of size bytes, aligned in memory to the given
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// alignment. This is used because we require certain structures to be aligned
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// in a specific way (for example, the X86 floating point data).
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func alignedBytes(size, alignment uint) []byte {
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data := make([]byte, size+alignment-1)
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offset := uint(reflect.ValueOf(data).Index(0).Addr().Pointer() % uintptr(alignment))
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if offset == 0 {
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return data[:size:size]
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}
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return data[alignment-offset:][:size:size]
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}
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