pkg/build: support cross-compilation for linux

We currently only support native build in pkg/build (does not even pass ARCH).
Move the existing cross-compilation logic from sys/syz-extract/linux.go
and reuse it in both places.

1 files changed, 3 insertions, 24 deletions

diff --git a/sys/syz-extract/linux.go b/sys/syz-extract/linux.go
index 47e5d20e6..53dd8b09a 100644
--- a/sys/syz-extract/linux.go
+++ b/sys/syz-extract/linux.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/syzkaller/pkg/build"
 	"github.com/google/syzkaller/pkg/compiler"
 	"github.com/google/syzkaller/pkg/osutil"
 	"github.com/google/syzkaller/sys/targets"
@@ -79,35 +80,13 @@ func (*linux) prepareArch(arch *Arch) error {
 	if !arch.build {
 		return nil
 	}
-	target := arch.target
-	var cflags []string
-	for _, flag := range target.CFlags {
-		if !strings.HasPrefix(flag, "-W") {
-			cflags = append(cflags, flag)
-		}
-	}
 	kernelDir := arch.sourceDir
-	buildDir := arch.buildDir
-	makeArgs := []string{
-		"ARCH=" + target.KernelArch,
-		"CFLAGS=" + strings.Join(cflags, " "),
-		"O=" + buildDir,
-		"-j", fmt.Sprint(runtime.NumCPU()),
-	}
-	if target.Triple != "" {
-		makeArgs = append(makeArgs, "CROSS_COMPILE="+target.Triple+"-")
-	}
-	if target.KernelCompiler != "" {
-		makeArgs = append(makeArgs, "CC="+target.KernelCompiler)
-	}
-	if target.KernelLinker != "" {
-		makeArgs = append(makeArgs, "LD="+target.KernelLinker)
-	}
+	makeArgs := build.LinuxMakeArgs(arch.target, "", "", arch.buildDir)
 	out, err := osutil.RunCmd(time.Hour, kernelDir, "make", append(makeArgs, "defconfig")...)
 	if err != nil {
 		return fmt.Errorf("make defconfig failed: %v\n%s", err, out)
 	}
-	_, err = osutil.RunCmd(time.Minute, buildDir, filepath.Join(kernelDir, "scripts", "config"),
+	_, err = osutil.RunCmd(time.Minute, arch.buildDir, filepath.Join(kernelDir, "scripts", "config"),
 		// powerpc arch is configured to be big-endian by default, but we want little-endian powerpc.
 		// Since all of our archs are little-endian for now, we just blindly switch it.
 		"-d", "CPU_BIG_ENDIAN", "-e", "CPU_LITTLE_ENDIAN",