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Revert "cmd/link: fix GC data reading from shared library"

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This reverts CL 240462.

Reason for revert: test fails on PPC64LE.

Updates #39927.

Change-Id: I4f14fd0c36e604a80ae9f2f86d1e643e28945e93
Reviewed-on: https://go-review.googlesource.com/c/go/+/240616
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Cherry Zhang 2020-06-30 19:09:38 +00:00 committed by Austin Clements
parent 5779bb4e92
commit 96e8366437
5 changed files with 9 additions and 82 deletions
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16
misc/cgo/testshared/shared_test.go
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@ -38,15 +38,7 @@ var testWork = flag.Bool("testwork", false, "if true, log and do not delete the
// run runs a command and calls t.Errorf if it fails.
func run(t *testing.T, msg string, args ...string) {
runWithEnv(t, msg, nil, args...)
}
// runWithEnv runs a command under the given environment and calls t.Errorf if it fails.
func runWithEnv(t *testing.T, msg string, env []string, args ...string) {
c := exec.Command(args[0], args[1:]...)
if len(env) != 0 {
c.Env = append(os.Environ(), env...)
}
if output, err := c.CombinedOutput(); err != nil {
t.Errorf("executing %s (%s) failed %s:\n%s", strings.Join(args, " "), msg, err, output)
}
@ -1042,11 +1034,3 @@ func TestGeneratedHash(t *testing.T) {
func TestPackageOrder(t *testing.T) {
goCmd(t, "install", "-buildmode=shared", "-linkshared", "./issue39777/a", "./issue39777/b")
}
// Test that GC data are generated correctly by the linker when it needs a type defined in
// a shared library. See issue 39927.
func TestGCData(t *testing.T) {
goCmd(t, "install", "-buildmode=shared", "-linkshared", "./gcdata/p")
goCmd(t, "build", "-linkshared", "./gcdata/main")
runWithEnv(t, "running gcdata/main", []string{"GODEBUG=clobberfree=1"}, "./main")
}

37
misc/cgo/testshared/testdata/gcdata/main/main.go vendored
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@ -1,37 +0,0 @@
// Copyright 2020 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.
// Test that GC data is generated correctly for global
// variables with types defined in a shared library.
// See issue 39927.
// This test run under GODEBUG=clobberfree=1. The check
// *x[i] == 12345 depends on this debug mode to clobber
// the value if the object is freed prematurely.
package main
import (
"fmt"
"runtime"
"testshared/gcdata/p"
)
var x p.T
func main() {
for i := range x {
x[i] = new(int)
*x[i] = 12345
}
runtime.GC()
runtime.GC()
runtime.GC()
for i := range x {
if *x[i] != 12345 {
fmt.Printf("x[%d] == %d, want 12345\n", i, *x[i])
panic("FAIL")
}
}
}

7
misc/cgo/testshared/testdata/gcdata/p/p.go vendored
View File

@ -1,7 +0,0 @@
// Copyright 2020 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 p
type T [10]*int

27
src/cmd/link/internal/ld/decodesym.go
View File

@ -10,7 +10,6 @@ import (
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"debug/elf"
"log"
)
// Decoding the type.* symbols. This has to be in sync with
@ -230,15 +229,8 @@ func decodetypeGcmask(ctxt *Link, s loader.Sym) []byte {
ptrdata := decodetypePtrdata(ctxt.Arch, symData)
sect := findShlibSection(ctxt, ctxt.loader.SymPkg(s), addr)
if sect != nil {
bits := ptrdata / int64(ctxt.Arch.PtrSize)
r := make([]byte, (bits+7)/8)
// ldshlibsyms avoids closing the ELF file so sect.ReadAt works.
// If we remove this read (and the ones in decodetypeGcprog), we
// can close the file.
_, err := sect.ReadAt(r, int64(addr-sect.Addr))
if err != nil {
log.Fatal(err)
}
r := make([]byte, ptrdata/int64(ctxt.Arch.PtrSize))
sect.ReadAt(r, int64(addr-sect.Addr))
return r
}
Exitf("cannot find gcmask for %s", ctxt.loader.SymName(s))
@ -259,15 +251,9 @@ func decodetypeGcprog(ctxt *Link, s loader.Sym) []byte {
// A gcprog is a 4-byte uint32 indicating length, followed by
// the actual program.
progsize := make([]byte, 4)
_, err := sect.ReadAt(progsize, int64(addr-sect.Addr))
if err != nil {
log.Fatal(err)
}
sect.ReadAt(progsize, int64(addr-sect.Addr))
progbytes := make([]byte, ctxt.Arch.ByteOrder.Uint32(progsize))
_, err = sect.ReadAt(progbytes, int64(addr-sect.Addr+4))
if err != nil {
log.Fatal(err)
}
sect.ReadAt(progbytes, int64(addr-sect.Addr+4))
return append(progsize, progbytes...)
}
Exitf("cannot find gcmask for %s", ctxt.loader.SymName(s))
@ -282,7 +268,7 @@ func decodetypeGcprog(ctxt *Link, s loader.Sym) []byte {
func findShlibSection(ctxt *Link, path string, addr uint64) *elf.Section {
for _, shlib := range ctxt.Shlibs {
if shlib.Path == path {
for _, sect := range shlib.File.Sections[1:] { // skip the NULL section
for _, sect := range shlib.File.Sections {
if sect.Addr <= addr && addr <= sect.Addr+sect.Size {
return sect
}
@ -293,5 +279,8 @@ func findShlibSection(ctxt *Link, path string, addr uint64) *elf.Section {
}
func decodetypeGcprogShlib(ctxt *Link, data []byte) uint64 {
if ctxt.Arch.Family == sys.ARM64 {
return 0
}
return decodeInuxi(ctxt.Arch, data[2*int32(ctxt.Arch.PtrSize)+8+1*int32(ctxt.Arch.PtrSize):], ctxt.Arch.PtrSize)
}

4
src/cmd/link/internal/ld/lib.go
View File

@ -2124,9 +2124,7 @@ func ldshlibsyms(ctxt *Link, shlib string) {
Errorf(nil, "cannot open shared library: %s", libpath)
return
}
// Keep the file open as decodetypeGcprog needs to read from it.
// TODO: fix. Maybe mmap the file.
//defer f.Close()
defer f.Close()
hash, err := readnote(f, ELF_NOTE_GO_NAME, ELF_NOTE_GOABIHASH_TAG)
if err != nil {