switch from assembly stubs to go:linkname comment

The go:linkname way works with Go 1.17 (with regabi), too.

Upstream did this in 2015 in
0b8d583320

See also https://sitano.github.io/2016/04/28/golang-private/ for more background
about both techniques.
geesefs-0-30-9
Michael Stapelberg 2021-08-02 09:34:49 +02:00
parent 8edaf5989f
commit 0630024b2b
5 changed files with 12 additions and 72 deletions

View File

@ -70,7 +70,7 @@ func (m *OutMessage) OutHeader() *fusekernel.OutHeader {
func (m *OutMessage) Grow(n int) unsafe.Pointer {
p := m.GrowNoZero(n)
if p != nil {
memclr(p, uintptr(n))
jacobsa_fuse_memclr(p, uintptr(n))
}
return p
@ -113,7 +113,7 @@ func (m *OutMessage) Append(src []byte) {
}
sh := (*reflect.SliceHeader)(unsafe.Pointer(&src))
memmove(p, unsafe.Pointer(sh.Data), uintptr(sh.Len))
jacobsa_fuse_memmove(p, unsafe.Pointer(sh.Data), uintptr(sh.Len))
return
}
@ -126,7 +126,7 @@ func (m *OutMessage) AppendString(src string) {
}
sh := (*reflect.StringHeader)(unsafe.Pointer(&src))
memmove(p, unsafe.Pointer(sh.Data), uintptr(sh.Len))
jacobsa_fuse_memmove(p, unsafe.Pointer(sh.Data), uintptr(sh.Len))
return
}

View File

@ -80,7 +80,7 @@ func TestMemclr(t *testing.T) {
p = unsafe.Pointer(&b[0])
}
memclr(p, uintptr(len(b)))
jacobsa_fuse_memclr(p, uintptr(len(b)))
// Check
if i := findNonZero(p, len(b)); i != len(b) {

View File

@ -21,9 +21,11 @@ import "unsafe"
// Zero the n bytes starting at p.
//
// REQUIRES: the region does not contain any Go pointers.
func memclr(p unsafe.Pointer, n uintptr)
//go:linkname jacobsa_fuse_memclr runtime.memclrNoHeapPointers
func jacobsa_fuse_memclr(p unsafe.Pointer, n uintptr)
//go:noescape
// Copy from src to dst, allowing overlap.
func memmove(dst unsafe.Pointer, src unsafe.Pointer, n uintptr)
//go:linkname jacobsa_fuse_memmove runtime.memmove
func jacobsa_fuse_memmove(dst unsafe.Pointer, src unsafe.Pointer, n uintptr)

View File

@ -1,40 +0,0 @@
// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build amd64 arm64 ppc64 ppc64le arm
// +build go1.8
// Assembly code isn't subject to visibility restrictions, so we can jump
// directly into package runtime.
//
// Technique copied from here:
// https://github.com/golang/go/blob/d8c6dac/src/os/signal/sig.s
#include "textflag.h"
#ifdef GOARCH_arm
#define JMP B
#endif
#ifdef GOARCH_ppc64
#define JMP BR
#endif
#ifdef GOARCH_ppc64le
#define JMP BR
#endif
TEXT ·memclr(SB),NOSPLIT,$0-16
JMP runtime·memclrNoHeapPointers(SB)
TEXT ·memmove(SB),NOSPLIT,$0-24
JMP runtime·memmove(SB)

View File

@ -12,29 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.
// +build amd64 arm64 ppc64 ppc64le arm
// +build !go1.8
// Assembly code isn't subject to visibility restrictions, so we can jump
// directly into package runtime.
//
// Technique copied from here:
// https://github.com/golang/go/blob/d8c6dac/src/os/signal/sig.s
#include "textflag.h"
#ifdef GOARCH_arm
#define JMP B
#endif
#ifdef GOARCH_ppc64
#define JMP BR
#endif
#ifdef GOARCH_ppc64le
#define JMP BR
#endif
TEXT ·memclr(SB),NOSPLIT,$0-16
JMP runtime·memclr(SB)
TEXT ·memmove(SB),NOSPLIT,$0-24
JMP runtime·memmove(SB)
// The buffer package uses //go:linkname to push a few functions into this
// package but we still need a .s file so the Go tool does not pass -complete
// to the go tool compile so the latter does not complain about Go functions
// with no bodies.