cmd/go: add -msan option

The -msan option compiles Go code to use the memory sanitizer.  This is
intended for use when linking with C/C++ code compiled with
-fsanitize=memory.  When memory blocks are passed back and forth between
C/C++ and Go, code in both languages will agree as to whether the memory
is correctly initialized or not, and will report errors for any use of
uninitialized memory.

Change-Id: I2dbdbd26951eacb7d84063cfc7297f88ffadd70c
Reviewed-on: https://go-review.googlesource.com/16169
Reviewed-by: David Crawshaw <crawshaw@golang.org>

misc/cgo/testsanitizers/msan.go

@@ -1,9 +1,6 @@
 package main
 
 /*
-#cgo CFLAGS: -fsanitize=memory
-#cgo LDFLAGS: -fsanitize=memory
-
 #include <stdint.h>
 
 void f(int32_t *p, int n) {

misc/cgo/testsanitizers/msan2.go

@@ -0,0 +1,31 @@
+package main
+
+/*
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void f(int32_t *p, int n) {
+  int32_t * volatile q = (int32_t *)malloc(sizeof(int32_t) * n);
+  memcpy(p, q, n * sizeof(*p));
+  free(q);
+}
+
+void g(int32_t *p, int n) {
+  if (p[4] != 1) {
+    abort();
+  }
+}
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+func main() {
+	a := make([]int32, 10)
+	C.f((*C.int32_t)(unsafe.Pointer(&a[0])), C.int(len(a)))
+	a[4] = 1
+	C.g((*C.int32_t)(unsafe.Pointer(&a[0])), C.int(len(a)))
+}

misc/cgo/testsanitizers/msan_fail.go

@@ -0,0 +1,31 @@
+package main
+
+/*
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void f(int32_t *p, int n) {
+  int32_t * volatile q = (int32_t *)malloc(sizeof(int32_t) * n);
+  memcpy(p, q, n * sizeof(*p));
+  free(q);
+}
+
+void g(int32_t *p, int n) {
+  if (p[4] != 1) {
+    abort();
+  }
+}
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+func main() {
+	a := make([]int32, 10)
+	C.f((*C.int32_t)(unsafe.Pointer(&a[0])), C.int(len(a)))
+	a[3] = 1
+	C.g((*C.int32_t)(unsafe.Pointer(&a[0])), C.int(len(a)))
+}

misc/cgo/testsanitizers/test.bash

@@ -31,4 +31,21 @@ if $CC --version | grep clang >& /dev/null; then
   fi
 fi
 
-go run msan.go
+status=0
+
+if ! go run -msan msan.go; then
+  echo "FAIL: msan"
+  status=1
+fi
+
+if ! go run -msan msan2.go; then
+  echo "FAIL: msan2"
+  status=1
+fi
+
+if go run -msan msan_fail.go 2>/dev/null; then
+  echo "FAIL: msan_fail"
+  status=1
+fi
+
+exit $status

src/cmd/go/alldocs.go

@@ -90,6 +90,9 @@ and test commands:
 	-race
 		enable data race detection.
 		Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
+	-msan
+		enable interoperation with memory sanitizer.
+		Supported only on linux/amd64.
 	-v
 		print the names of packages as they are compiled.
 	-work
@@ -112,8 +115,9 @@ and test commands:
 		a suffix to use in the name of the package installation directory,
 		in order to keep output separate from default builds.
 		If using the -race flag, the install suffix is automatically set to race
-		or, if set explicitly, has _race appended to it.  Using a -buildmode
-		option that requires non-default compile flags has a similar effect.
+		or, if set explicitly, has _race appended to it.  Likewise for the -msan
+		flag.  Using a -buildmode option that requires non-default compile flags
+		has a similar effect.
 	-ldflags 'flag list'
 		arguments to pass on each go tool link invocation.
 	-linkshared

src/cmd/go/build.go

@@ -69,6 +69,9 @@ and test commands:
 	-race
 		enable data race detection.
 		Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
+	-msan
+		enable interoperation with memory sanitizer.
+		Supported only on linux/amd64.
 	-v
 		print the names of packages as they are compiled.
 	-work
@@ -91,8 +94,9 @@ and test commands:
 		a suffix to use in the name of the package installation directory,
 		in order to keep output separate from default builds.
 		If using the -race flag, the install suffix is automatically set to race
-		or, if set explicitly, has _race appended to it.  Using a -buildmode
-		option that requires non-default compile flags has a similar effect.
+		or, if set explicitly, has _race appended to it.  Likewise for the -msan
+		flag.  Using a -buildmode option that requires non-default compile flags
+		has a similar effect.
 	-ldflags 'flag list'
 		arguments to pass on each go tool link invocation.
 	-linkshared
@@ -166,6 +170,7 @@ var buildGcflags []string    // -gcflags flag
 var buildLdflags []string    // -ldflags flag
 var buildGccgoflags []string // -gccgoflags flag
 var buildRace bool           // -race flag
+var buildMSan bool           // -msan flag
 var buildToolExec []string   // -toolexec flag
 var buildBuildmode string    // -buildmode flag
 var buildLinkshared bool     // -linkshared flag
@@ -225,6 +230,7 @@ func addBuildFlags(cmd *Command) {
 	cmd.Flag.BoolVar(&buildLinkshared, "linkshared", false, "")
 	cmd.Flag.StringVar(&buildPkgdir, "pkgdir", "", "")
 	cmd.Flag.BoolVar(&buildRace, "race", false, "")
+	cmd.Flag.BoolVar(&buildMSan, "msan", false, "")
 	cmd.Flag.Var((*stringsFlag)(&buildContext.BuildTags), "tags", "")
 	cmd.Flag.Var((*stringsFlag)(&buildToolExec), "toolexec", "")
 	cmd.Flag.BoolVar(&buildWork, "work", false, "")
@@ -422,7 +428,7 @@ func buildModeInit() {
 }
 
 func runBuild(cmd *Command, args []string) {
-	raceInit()
+	instrumentInit()
 	buildModeInit()
 	var b builder
 	b.init()
@@ -523,7 +529,7 @@ func runInstall(cmd *Command, args []string) {
 		fatalf("cannot install, GOBIN must be an absolute path")
 	}
 
-	raceInit()
+	instrumentInit()
 	buildModeInit()
 	pkgs := pkgsFilter(packagesForBuild(args))
 
@@ -877,7 +883,7 @@ func (b *builder) action1(mode buildMode, depMode buildMode, p *Package, looksha
 	// using cgo, to make sure we do not overwrite the binary while
 	// a package is using it.  If this is a cross-build, then the cgo we
 	// are writing is not the cgo we need to use.
-	if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace {
+	if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace && !buildMSan {
 		if (len(p.CgoFiles) > 0 || p.Standard && p.ImportPath == "runtime/cgo") && !buildLinkshared && buildBuildmode != "shared" {
 			var stk importStack
 			p1 := loadPackage("cmd/cgo", &stk)
@@ -2907,7 +2913,7 @@ func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofi
 	if p.Standard && p.ImportPath == "runtime/cgo" {
 		cgoflags = append(cgoflags, "-import_runtime_cgo=false")
 	}
-	if p.Standard && (p.ImportPath == "runtime/race" || p.ImportPath == "runtime/cgo") {
+	if p.Standard && (p.ImportPath == "runtime/race" || p.ImportPath == "runtime/msan" || p.ImportPath == "runtime/cgo") {
 		cgoflags = append(cgoflags, "-import_syscall=false")
 	}
 
@@ -3355,23 +3361,38 @@ func (q *actionQueue) pop() *action {
 	return heap.Pop(q).(*action)
 }
 
-func raceInit() {
-	if !buildRace {
+func instrumentInit() {
+	if !buildRace && !buildMSan {
 		return
 	}
+	if buildRace && buildMSan {
+		fmt.Fprintf(os.Stderr, "go %s: may not use -race and -msan simultaneously", flag.Args()[0])
+		os.Exit(2)
+	}
 	if goarch != "amd64" || goos != "linux" && goos != "freebsd" && goos != "darwin" && goos != "windows" {
-		fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
+		fmt.Fprintf(os.Stderr, "go %s: -race and -msan are only supported on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
 		os.Exit(2)
 	}
 	if !buildContext.CgoEnabled {
 		fmt.Fprintf(os.Stderr, "go %s: -race requires cgo; enable cgo by setting CGO_ENABLED=1\n", flag.Args()[0])
 		os.Exit(2)
 	}
-	buildGcflags = append(buildGcflags, "-race")
-	buildLdflags = append(buildLdflags, "-race")
+	if buildRace {
+		buildGcflags = append(buildGcflags, "-race")
+		buildLdflags = append(buildLdflags, "-race")
+	} else {
+		buildGcflags = append(buildGcflags, "-msan")
+		buildLdflags = append(buildLdflags, "-msan")
+	}
 	if buildContext.InstallSuffix != "" {
 		buildContext.InstallSuffix += "_"
 	}
-	buildContext.InstallSuffix += "race"
-	buildContext.BuildTags = append(buildContext.BuildTags, "race")
+
+	if buildRace {
+		buildContext.InstallSuffix += "race"
+		buildContext.BuildTags = append(buildContext.BuildTags, "race")
+	} else {
+		buildContext.InstallSuffix += "msan"
+		buildContext.BuildTags = append(buildContext.BuildTags, "msan")
+	}
 }

src/cmd/go/pkg.go

@@ -710,6 +710,7 @@ func expandScanner(err error) error {
 
 var raceExclude = map[string]bool{
 	"runtime/race": true,
+	"runtime/msan": true,
 	"runtime/cgo":  true,
 	"cmd/cgo":      true,
 	"syscall":      true,
@@ -723,6 +724,7 @@ var cgoExclude = map[string]bool{
 var cgoSyscallExclude = map[string]bool{
 	"runtime/cgo":  true,
 	"runtime/race": true,
+	"runtime/msan": true,
 }
 
 // load populates p using information from bp, err, which should
@@ -838,6 +840,10 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 		if buildRace && (!p.Standard || !raceExclude[p.ImportPath]) {
 			importPaths = append(importPaths, "runtime/race")
 		}
+		// MSan uses runtime/msan.
+		if buildMSan && (!p.Standard || !raceExclude[p.ImportPath]) {
+			importPaths = append(importPaths, "runtime/msan")
+		}
 		// On ARM with GOARM=5, everything depends on math for the link.
 		if p.Name == "main" && goarch == "arm" {
 			importPaths = append(importPaths, "math")

src/cmd/go/run.go

@@ -64,7 +64,7 @@ func printStderr(args ...interface{}) (int, error) {
 }
 
 func runRun(cmd *Command, args []string) {
-	raceInit()
+	instrumentInit()
 	buildModeInit()
 	var b builder
 	b.init()

src/cmd/go/test.go

@@ -327,7 +327,7 @@ func runTest(cmd *Command, args []string) {
 
 	findExecCmd() // initialize cached result
 
-	raceInit()
+	instrumentInit()
 	buildModeInit()
 	pkgs := packagesForBuild(pkgArgs)
 	if len(pkgs) == 0 {
@@ -395,7 +395,7 @@ func runTest(cmd *Command, args []string) {
 		if deps["C"] {
 			delete(deps, "C")
 			deps["runtime/cgo"] = true
-			if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace {
+			if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace && !buildMSan {
 				deps["cmd/cgo"] = true
 			}
 		}
@@ -543,6 +543,9 @@ func runTest(cmd *Command, args []string) {
 		if buildRace {
 			extraOpts = "-race "
 		}
+		if buildMSan {
+			extraOpts = "-msan "
+		}
 		fmt.Fprintf(os.Stderr, "installing these packages with 'go test %s-i%s' will speed future tests.\n\n", extraOpts, args)
 	}