// Copyright 2020 The gVisor Authors. // // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // +build go1.13 // +build !go1.17 // Check function signatures and constants when updating Go version. package sync import ( "fmt" "reflect" "unsafe" ) // Note that go:linkname silently doesn't work if the local name is exported, // necessitating an indirection for exported functions. // Memmove is runtime.memmove, exported for SeqAtomicLoad/SeqAtomicTryLoad<T>. // //go:nosplit func Memmove(to, from unsafe.Pointer, n uintptr) { memmove(to, from, n) } //go:linkname memmove runtime.memmove //go:noescape func memmove(to, from unsafe.Pointer, n uintptr) // Gopark is runtime.gopark. Gopark calls unlockf(pointer to runtime.g, lock); // if unlockf returns true, Gopark blocks until Goready(pointer to runtime.g) // is called. unlockf and its callees must be nosplit and norace, since stack // splitting and race context are not available where it is called. // //go:nosplit func Gopark(unlockf func(uintptr, unsafe.Pointer) bool, lock unsafe.Pointer, reason uint8, traceEv byte, traceskip int) { gopark(unlockf, lock, reason, traceEv, traceskip) } //go:linkname gopark runtime.gopark func gopark(unlockf func(uintptr, unsafe.Pointer) bool, lock unsafe.Pointer, reason uint8, traceEv byte, traceskip int) // Goready is runtime.goready. // //go:nosplit func Goready(gp uintptr, traceskip int) { goready(gp, traceskip) } //go:linkname goready runtime.goready func goready(gp uintptr, traceskip int) // Values for the reason argument to gopark, from Go's src/runtime/runtime2.go. const ( WaitReasonSelect uint8 = 9 ) // Values for the traceEv argument to gopark, from Go's src/runtime/trace.go. const ( TraceEvGoBlockSelect byte = 24 ) // Rand32 returns a non-cryptographically-secure random uint32. func Rand32() uint32 { return fastrand() } // Rand64 returns a non-cryptographically-secure random uint64. func Rand64() uint64 { return uint64(fastrand())<<32 | uint64(fastrand()) } //go:linkname fastrand runtime.fastrand func fastrand() uint32 // RandUintptr returns a non-cryptographically-secure random uintptr. func RandUintptr() uintptr { if unsafe.Sizeof(uintptr(0)) == 4 { return uintptr(Rand32()) } return uintptr(Rand64()) } // MapKeyHasher returns a hash function for pointers of m's key type. // // Preconditions: m must be a map. func MapKeyHasher(m interface{}) func(unsafe.Pointer, uintptr) uintptr { if rtyp := reflect.TypeOf(m); rtyp.Kind() != reflect.Map { panic(fmt.Sprintf("sync.MapKeyHasher: m is %v, not map", rtyp)) } mtyp := *(**maptype)(unsafe.Pointer(&m)) return mtyp.hasher } type maptype struct { size uintptr ptrdata uintptr hash uint32 tflag uint8 align uint8 fieldAlign uint8 kind uint8 equal func(unsafe.Pointer, unsafe.Pointer) bool gcdata *byte str int32 ptrToThis int32 key unsafe.Pointer elem unsafe.Pointer bucket unsafe.Pointer hasher func(unsafe.Pointer, uintptr) uintptr // more fields } // These functions are only used within the sync package. //go:linkname semacquire sync.runtime_Semacquire func semacquire(s *uint32) //go:linkname semrelease sync.runtime_Semrelease func semrelease(s *uint32, handoff bool, skipframes int) //go:linkname canSpin sync.runtime_canSpin func canSpin(i int) bool //go:linkname doSpin sync.runtime_doSpin func doSpin()