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mirror of https://github.com/golang/go synced 2024-11-11 19:31:37 -07:00

cmd/compile, cmd/link: dynamically export writable static tmps

Static tmps are private to a package, but with plugins a package
can be shared among multiple DSOs. They need to have a consistent
view of the static tmps, especially for writable ones. So export
them. (Read-only static tmps have the same values anyway, so it
doesn't matter. Also Mach-O doesn't support dynamically exporting
read-only symbols anyway.)

Fixes #44956.

Change-Id: I921e25b7ab73cd5d5347800eccdb7931e3448779
Reviewed-on: https://go-review.googlesource.com/c/go/+/301793
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Zhang 2021-03-12 23:21:09 -05:00
parent dc1556eaef
commit 7a1e963058
8 changed files with 91 additions and 3 deletions

View File

@ -209,3 +209,10 @@ func TestMethod2(t *testing.T) {
goCmd(t, "build", "-o", "method2.exe", "./method2/main.go")
run(t, "./method2.exe")
}
func TestIssue44956(t *testing.T) {
goCmd(t, "build", "-buildmode=plugin", "-o", "issue44956p1.so", "./issue44956/plugin1.go")
goCmd(t, "build", "-buildmode=plugin", "-o", "issue44956p2.so", "./issue44956/plugin2.go")
goCmd(t, "build", "-o", "issue44956.exe", "./issue44956/main.go")
run(t, "./issue44956.exe")
}

View File

@ -0,0 +1,7 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package base
var X = &map[int]int{123: 456}

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@ -0,0 +1,47 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Issue 44956: writable static temp is not exported correctly.
// In the test below, package base is
//
// X = &map{...}
//
// which compiles to
//
// X = &stmp // static
// stmp = makemap(...) // in init function
//
// plugin1 and plugin2 both import base. plugin1 doesn't use
// base.X, so that symbol is deadcoded in plugin1.
//
// plugin1 is loaded first. base.init runs at that point, which
// initialize base.stmp.
//
// plugin2 is then loaded. base.init already ran, so it doesn't run
// again. When base.stmp is not exported, plugin2's base.X points to
// its own private base.stmp, which is not initialized, fail.
package main
import "plugin"
func main() {
_, err := plugin.Open("issue44956p1.so")
if err != nil {
panic("FAIL")
}
p2, err := plugin.Open("issue44956p2.so")
if err != nil {
panic("FAIL")
}
f, err := p2.Lookup("F")
if err != nil {
panic("FAIL")
}
x := f.(func() *map[int]int)()
if x == nil || (*x)[123] != 456 {
panic("FAIL")
}
}

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@ -0,0 +1,9 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import _ "testplugin/issue44956/base"
func main() {}

View File

@ -0,0 +1,11 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "testplugin/issue44956/base"
func F() *map[int]int { return base.X }
func main() {}

View File

@ -459,7 +459,6 @@ func StaticName(t *types.Type) *ir.Name {
statuniqgen++
typecheck.Declare(n, ir.PEXTERN)
n.SetType(t)
n.Linksym().Set(obj.AttrLocal, true)
return n
}

View File

@ -55,11 +55,12 @@ func (c initContext) String() string {
return "inNonInitFunction"
}
// readonlystaticname returns a name backed by a (writable) static data symbol.
// readonlystaticname returns a name backed by a read-only static data symbol.
func readonlystaticname(t *types.Type) *ir.Name {
n := staticinit.StaticName(t)
n.MarkReadonly()
n.Linksym().Set(obj.AttrContentAddressable, true)
n.Linksym().Set(obj.AttrLocal, true)
return n
}

View File

@ -31,6 +31,7 @@
package ld
import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
@ -140,7 +141,9 @@ func putelfsym(ctxt *Link, x loader.Sym, typ elf.SymType, curbind elf.SymBind) {
// One pass for each binding: elf.STB_LOCAL, elf.STB_GLOBAL,
// maybe one day elf.STB_WEAK.
bind := elf.STB_GLOBAL
if ldr.IsFileLocal(x) || ldr.AttrVisibilityHidden(x) || ldr.AttrLocal(x) {
if ldr.IsFileLocal(x) && !isStaticTmp(sname) || ldr.AttrVisibilityHidden(x) || ldr.AttrLocal(x) {
// Static tmp is package local, but a package can be shared among multiple DSOs.
// They need to have a single view of the static tmp that are writable.
bind = elf.STB_LOCAL
}
@ -856,3 +859,7 @@ func setCarrierSize(typ sym.SymKind, sz int64) {
}
CarrierSymByType[typ].Size = sz
}
func isStaticTmp(name string) bool {
return strings.Contains(name, "."+obj.StaticNamePref)
}