98 lines
1.9 KiB
Go
98 lines
1.9 KiB
Go
// Copyright 2011 Evan Shaw. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE-MMAP-GO file.
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// Modifications (c) 2024 The Memory Authors.
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// Copyright 2024 The Memory Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build openbsd && (386 || amd64 || arm64)
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package memory
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import (
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"fmt"
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"os"
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"sync"
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"unsafe"
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"golang.org/x/sys/unix"
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)
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// track what can be unmapped
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var allocmap map[uintptr][]byte
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var m sync.Mutex
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const pageSizeLog = 20
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var (
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osPageMask = osPageSize - 1
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osPageSize = os.Getpagesize()
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)
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func init() {
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allocmap = make(map[uintptr][]byte)
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}
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func unmap(addr uintptr, size int) error {
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if trace {
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fmt.Fprintf(os.Stderr, "unmap %#x\n", addr)
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}
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a, ok := allocmap[addr]
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if !ok {
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if trace {
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fmt.Fprintf(os.Stderr, "unmap %#x: not found\n", addr)
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}
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// panic("unmap called on unknown mapping")
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return nil
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}
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if err := unix.Munmap(a); err != nil {
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if trace {
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fmt.Fprintf(os.Stderr, "unmap: %s\n", err.Error())
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}
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// panic(err.Error())
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return err
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}
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m.Lock()
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delete(allocmap, addr)
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m.Unlock()
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return nil
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}
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func mmap(size int) (uintptr, int, error) {
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roundsize := roundup(size, osPageSize) + pageSize
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b, err := unix.Mmap(-1, 0, roundsize, unix.PROT_READ|unix.PROT_WRITE, unix.MAP_PRIVATE|unix.MAP_ANON)
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if err != nil {
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return 0, 0, err
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}
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p := uintptr(unsafe.Pointer(&b[0]))
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if trace {
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fmt.Fprintf(os.Stderr, "mmap actual @%#x size: %#x\n", p, roundsize)
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}
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// waste all the space until the next page
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r := (p + uintptr(pageSize)) &^ uintptr(pageMask)
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nsize := (roundsize) - int((r - p))
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if nsize < size {
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panic("didn't allocate enough to meet initial request!")
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}
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if trace {
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fmt.Fprintf(os.Stderr, "mmap page-rounded @%#x size: %#x\n", r, nsize)
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}
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m.Lock()
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allocmap[r] = b
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m.Unlock()
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return r, nsize, nil
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}
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