mirror of
https://github.com/golang/go
synced 2024-11-20 03:24:41 -07:00
6ad33be2d9
The motivation is that sysAlloc/Free() currently aren't safe to be called without a valid G, because arm's xadd64() uses locks that require a valid G. The solution here was proposed by Dmitry Vyukov: use xadduintptr() instead of xadd64(), until arm can support xadd64 on all of its architectures (not a trivial task for arm). Change-Id: I250252079357ea2e4360e1235958b1c22051498f Reviewed-on: https://go-review.googlesource.com/9002 Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
83 lines
1.9 KiB
Go
83 lines
1.9 KiB
Go
// Copyright 2015 The Go 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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package runtime
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import "unsafe"
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//go:noescape
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func xadd(ptr *uint32, delta int32) uint32
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//go:noescape
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func xadd64(ptr *uint64, delta int64) uint64
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//go:noescape
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//go:linkname xadduintptr runtime.xadd64
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func xadduintptr(ptr *uintptr, delta uintptr) uintptr
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//go:noescape
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func xchg(ptr *uint32, new uint32) uint32
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//go:noescape
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func xchg64(ptr *uint64, new uint64) uint64
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// NO go:noescape annotation; see atomic_pointer.go.
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func xchgp1(ptr unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer
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//go:noescape
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func xchguintptr(ptr *uintptr, new uintptr) uintptr
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//go:noescape
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func atomicload(ptr *uint32) uint32
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//go:noescape
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func atomicload64(ptr *uint64) uint64
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//go:noescape
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func atomicloadp(ptr unsafe.Pointer) unsafe.Pointer
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//go:nosplit
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func atomicor8(addr *uint8, v uint8) {
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// TODO(dfc) implement this in asm.
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// Align down to 4 bytes and use 32-bit CAS.
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uaddr := uintptr(unsafe.Pointer(addr))
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addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
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word := uint32(v) << ((uaddr & 3) * 8) // little endian
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for {
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old := *addr32
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if cas(addr32, old, old|word) {
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return
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}
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}
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}
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//go:nosplit
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func atomicand8(addr *uint8, v uint8) {
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// TODO(dfc) implement this in asm.
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// Align down to 4 bytes and use 32-bit CAS.
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uaddr := uintptr(unsafe.Pointer(addr))
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addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
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word := uint32(v) << ((uaddr & 3) * 8) // little endian
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mask := uint32(0xFF) << ((uaddr & 3) * 8) // little endian
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word |= ^mask
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for {
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old := *addr32
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if cas(addr32, old, old&word) {
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return
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}
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}
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}
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//go:noescape
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func cas64(ptr *uint64, old, new uint64) bool
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//go:noescape
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func atomicstore(ptr *uint32, val uint32)
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//go:noescape
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func atomicstore64(ptr *uint64, val uint64)
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// NO go:noescape annotation; see atomic_pointer.go.
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func atomicstorep1(ptr unsafe.Pointer, val unsafe.Pointer)
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