Makefile: don't compile all targets into target binaries

Currently target binaries contain support for all OS/arch combinations.
However, obviously a fuchsia target binary won't test windows.
For target binaries we need support only for a single target
(with the exception of 386/arm target in amd64/arm64 binaries).
So compile in only _the_ target into target binaries.
This reduces akaros/amd64 fuzzer binary from 33 to 7 MB
and execprog from 28 to 2 MB.

1 files changed, 22 insertions, 5 deletions

diff --git a/sys/syz-sysgen/sysgen.go b/sys/syz-sysgen/sysgen.go
index 65242910b..467987c45 100644
--- a/sys/syz-sysgen/sysgen.go
+++ b/sys/syz-sysgen/sysgen.go
@@ -114,6 +114,7 @@ func main() {
 				job.OK = true
 			}()
 		}
+		writeEmpty(OS)
 		wg.Wait()
 
 		var syscallArchs []ArchData
@@ -160,15 +161,23 @@ func main() {
 }
 
 func generate(target *targets.Target, prg *compiler.Prog, consts map[string]uint64, out io.Writer) {
-	fmt.Fprintf(out, "// AUTOGENERATED FILE\n\n")
+	tag := fmt.Sprintf("syz_target,syz_os_%v,syz_arch_%v", target.OS, target.Arch)
+	if target.VMArch != "" {
+		tag += fmt.Sprintf(" syz_target,syz_os_%v,syz_arch_%v", target.OS, target.VMArch)
+	}
+	fmt.Fprintf(out, "// AUTOGENERATED FILE\n")
+	fmt.Fprintf(out, "// +build !syz_target %v\n\n", tag)
 	fmt.Fprintf(out, "package gen\n\n")
-	fmt.Fprintf(out, "import . \"github.com/google/syzkaller/prog\"\n\n")
+	fmt.Fprintf(out, "import . \"github.com/google/syzkaller/prog\"\n")
+	fmt.Fprintf(out, "import . \"github.com/google/syzkaller/sys/%v\"\n\n", target.OS)
 
-	fmt.Fprintf(out, "var Target_%v = &Target{"+
+	fmt.Fprintf(out, "func init() {\n")
+	fmt.Fprintf(out, "\tRegisterTarget(&Target{"+
 		"OS: %q, Arch: %q, Revision: revision_%v, PtrSize: %v, "+
 		"PageSize: %v, NumPages: %v, DataOffset: %v, Syscalls: syscalls_%v, "+
-		"Resources: resources_%v, Structs: structDescs_%v, Consts: consts_%v}\n\n",
-		target.Arch, target.OS, target.Arch, target.Arch, target.PtrSize,
+		"Resources: resources_%v, Structs: structDescs_%v, Consts: consts_%v}, "+
+		"InitTarget)\n}\n\n",
+		target.OS, target.Arch, target.Arch, target.PtrSize,
 		target.PageSize, target.NumPages, target.DataOffset,
 		target.Arch, target.Arch, target.Arch, target.Arch)
 
@@ -196,6 +205,14 @@ func generate(target *targets.Target, prg *compiler.Prog, consts map[string]uint
 	fmt.Fprintf(out, "\n\n")
 }
 
+func writeEmpty(OS string) {
+	const data = `// AUTOGENERATED FILE
+// This file is needed if OS is completely excluded by build tags.
+package gen
+`
+	writeSource(filepath.Join("sys", OS, "gen", "empty.go"), []byte(data))
+}
+
 func generateExecutorSyscalls(target *targets.Target, syscalls []*prog.Syscall, rev string) ArchData {
 	data := ArchData{
 		Revision:   rev,