packages/golang
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
golang/0034-release-branch.go1.15-cmd-link-avoid-exporting-all-s.patch

189 lines
6.6 KiB
Diff
Raw Normal View History

batch synchronization
2021-06-18 15:46:44 +08:00
From 82f9c6cac1bcc6bc80f17d1415ac3f62c0afa6c5 Mon Sep 17 00:00:00 2001
From: Quim Muntal <quimmuntal@gmail.com>
Date: Thu, 22 Oct 2020 22:32:20 +0200
Subject: [PATCH 34/44] [release-branch.go1.15] cmd/link: avoid exporting all
symbols on windows buildmode=pie
Marking one functions with __declspec(dllexport) forces mingw to
create .reloc section without having to export all symbols.
See https://insights.sei.cmu.edu/cert/2018/08/when-aslr-is-not-really-aslr---the-case-of-incorrect-assumptions-and-bad-defaults.html for more info.
This change cuts 73kb of a "hello world" pie binary.
Updates #6853.
Updates #40795.
Fixes #43592.
Change-Id: I3cc57c3b64f61187550bc8751dfa085f106c8475
Reviewed-on: https://go-review.googlesource.com/c/go/+/264459
Trust: Alex Brainman <alex.brainman@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/300692
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Conflict:NA
Reference:https://github.com/golang/go/commit/82f9c6cac1bcc6bc80f17d1415ac3f62c0afa6c5
---
misc/cgo/testcshared/cshared_test.go | 9 ++++----
src/cmd/go/go_test.go | 33 ++++++++++++++++++++++++++++
src/cmd/link/internal/ld/lib.go | 3 ---
src/runtime/cgo/gcc_windows_386.c | 1 +
src/runtime/cgo/gcc_windows_amd64.c | 1 +
src/runtime/cgo/libcgo_windows.h | 12 ++++++++++
6 files changed, 52 insertions(+), 7 deletions(-)
create mode 100644 src/runtime/cgo/libcgo_windows.h
diff --git a/misc/cgo/testcshared/cshared_test.go b/misc/cgo/testcshared/cshared_test.go
index d717b4dfb3..dff2682e20 100644
--- a/misc/cgo/testcshared/cshared_test.go
+++ b/misc/cgo/testcshared/cshared_test.go
@@ -401,7 +401,7 @@ func main() {
defer f.Close()
section := f.Section(".edata")
if section == nil {
- t.Error(".edata section is not present")
+ t.Fatalf(".edata section is not present")
}
// TODO: deduplicate this struct from cmd/link/internal/ld/pe.go
@@ -418,7 +418,8 @@ func main() {
t.Fatalf("binary.Read failed: %v", err)
}
- expectedNumber := uint32(2)
+ // Only the two exported functions and _cgo_dummy_export should be exported
+ expectedNumber := uint32(3)
if exportAllSymbols {
if e.NumberOfFunctions <= expectedNumber {
@@ -429,10 +430,10 @@ func main() {
}
} else {
if e.NumberOfFunctions != expectedNumber {
- t.Fatalf("too many exported functions: %v", e.NumberOfFunctions)
+ t.Fatalf("got %d exported functions; want %d", e.NumberOfFunctions, expectedNumber)
}
if e.NumberOfNames != expectedNumber {
- t.Fatalf("too many exported names: %v", e.NumberOfNames)
+ t.Fatalf("got %d exported names; want %d", e.NumberOfNames, expectedNumber)
}
}
}
diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index 021930a8a8..3f790cdeab 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -9,6 +9,7 @@ import (
"debug/elf"
"debug/macho"
"debug/pe"
+ "encoding/binary"
"flag"
"fmt"
"go/format"
@@ -2166,6 +2167,38 @@ func testBuildmodePIE(t *testing.T, useCgo, setBuildmodeToPIE bool) {
if (dc & pe.IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE) == 0 {
t.Error("IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE flag is not set")
}
+ if useCgo {
+ // Test that only one symbol is exported (#40795).
+ // PIE binaries don´t require .edata section but unfortunately
+ // binutils doesn´t generate a .reloc section unless there is
+ // at least one symbol exported.
+ // See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
+ section := f.Section(".edata")
+ if section == nil {
+ t.Fatalf(".edata section is not present")
+ }
+ // TODO: deduplicate this struct from cmd/link/internal/ld/pe.go
+ type IMAGE_EXPORT_DIRECTORY struct {
+ _ [2]uint32
+ _ [2]uint16
+ _ [2]uint32
+ NumberOfFunctions uint32
+ NumberOfNames uint32
+ _ [3]uint32
+ }
+ var e IMAGE_EXPORT_DIRECTORY
+ if err := binary.Read(section.Open(), binary.LittleEndian, &e); err != nil {
+ t.Fatalf("binary.Read failed: %v", err)
+ }
+
+ // Only _cgo_dummy_export should be exported
+ if e.NumberOfFunctions != 1 {
+ t.Fatalf("got %d exported functions; want 1", e.NumberOfFunctions)
+ }
+ if e.NumberOfNames != 1 {
+ t.Fatalf("got %d exported names; want 1", e.NumberOfNames)
+ }
+ }
default:
panic("unreachable")
}
diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index fc89759997..d03fb6cf91 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -1423,9 +1423,6 @@ func (ctxt *Link) hostlink() {
if ctxt.Arch.PtrSize >= 8 {
argv = append(argv, "-Wl,--high-entropy-va")
}
- // Work around binutils limitation that strips relocation table for dynamicbase.
- // See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
- argv = append(argv, "-Wl,--export-all-symbols")
default:
// ELF.
if ctxt.UseRelro() {
diff --git a/src/runtime/cgo/gcc_windows_386.c b/src/runtime/cgo/gcc_windows_386.c
index 9184b91393..60cb011bf2 100644
--- a/src/runtime/cgo/gcc_windows_386.c
+++ b/src/runtime/cgo/gcc_windows_386.c
@@ -9,6 +9,7 @@
#include <stdio.h>
#include <errno.h>
#include "libcgo.h"
+#include "libcgo_windows.h"
static void threadentry(void*);
diff --git a/src/runtime/cgo/gcc_windows_amd64.c b/src/runtime/cgo/gcc_windows_amd64.c
index 7192a24631..0f8c817f0e 100644
--- a/src/runtime/cgo/gcc_windows_amd64.c
+++ b/src/runtime/cgo/gcc_windows_amd64.c
@@ -9,6 +9,7 @@
#include <stdio.h>
#include <errno.h>
#include "libcgo.h"
+#include "libcgo_windows.h"
static void threadentry(void*);
diff --git a/src/runtime/cgo/libcgo_windows.h b/src/runtime/cgo/libcgo_windows.h
new file mode 100644
index 0000000000..0013f06bae
--- /dev/null
+++ b/src/runtime/cgo/libcgo_windows.h
@@ -0,0 +1,12 @@
+// 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.
+
+// Ensure there's one symbol marked __declspec(dllexport).
+// If there are no exported symbols, the unfortunate behavior of
+// the binutils linker is to also strip the relocations table,
+// resulting in non-PIE binary. The other option is the
+// --export-all-symbols flag, but we don't need to export all symbols
+// and this may overflow the export table (#40795).
+// See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
+__declspec(dllexport) int _cgo_dummy_export;
--
2.27.0
Reference in New Issue Copy Permalink