pkg/kernel: add an option to provide full config for build

Normally config is applied on top of defconfig+kvmconfig.
This allows to provide full config that is used unmodified.

2 files changed, 24 insertions, 16 deletions

diff --git a/pkg/kernel/generated.go b/pkg/kernel/generated.go
index 08d08e474..0e6ba5b89 100644
--- a/pkg/kernel/generated.go
+++ b/pkg/kernel/generated.go
@@ -68,7 +68,7 @@ menuentry 'linux' --class gnu-linux --class gnu --class os {
 	insmod part_msdos
 	insmod ext2
 	set root='(hd0,1)'
-	linux /vmlinuz root=/dev/sda1 console=ttyS0 earlyprintk=serial vsyscall=native rodata=n ftrace_dump_on_oops=orig_cpu oops=panic panic_on_warn=1 panic=86400 kvm-intel.nested=1 kvm-intel.unrestricted_guest=1 kvm-intel.vmm_exclusive=1 kvm-intel.fasteoi=1 kvm-intel.ept=1 kvm-intel.flexpriority=1 kvm-intel.vpid=1 kvm-intel.emulate_invalid_guest_state=1 kvm-intel.eptad=1 kvm-intel.enable_shadow_vmcs=1 kvm-intel.pml=1 kvm-intel.enable_apicv=1
+	linux /vmlinuz root=/dev/sda1 console=ttyS0 earlyprintk=serial vsyscall=native rodata=n ftrace_dump_on_oops=orig_cpu oops=panic panic_on_warn=1 nmi_watchdog=panic panic=86400 kvm-intel.nested=1 kvm-intel.unrestricted_guest=1 kvm-intel.vmm_exclusive=1 kvm-intel.fasteoi=1 kvm-intel.ept=1 kvm-intel.flexpriority=1 kvm-intel.vpid=1 kvm-intel.emulate_invalid_guest_state=1 kvm-intel.eptad=1 kvm-intel.enable_shadow_vmcs=1 kvm-intel.pml=1 kvm-intel.enable_apicv=1
 }
 EOF
 sudo grub-install --boot-directory=disk.mnt/boot --no-floppy /dev/nbd0
diff --git a/pkg/kernel/kernel.go b/pkg/kernel/kernel.go
index d19d9c5e6..9e9b4b32d 100644
--- a/pkg/kernel/kernel.go
+++ b/pkg/kernel/kernel.go
@@ -24,27 +24,35 @@ import (
 	"github.com/google/syzkaller/pkg/osutil"
 )
 
-func Build(dir, compiler, config string) error {
+func Build(dir, compiler, config string, fullConfig bool) error {
 	const timeout = 10 * time.Minute // default timeout for command invocations
-	os.Remove(filepath.Join(dir, ".config"))
-	configFile := filepath.Join(dir, "syz.config")
-	if err := ioutil.WriteFile(configFile, []byte(config), 0600); err != nil {
-		return fmt.Errorf("failed to write config file: %v", err)
-	}
-	if _, err := osutil.RunCmd(timeout, dir, "make", "defconfig"); err != nil {
-		return err
-	}
-	if _, err := osutil.RunCmd(timeout, dir, "make", "kvmconfig"); err != nil {
-		return err
-	}
-	if _, err := osutil.RunCmd(timeout, dir, "scripts/kconfig/merge_config.sh", "-n", ".config", configFile); err != nil {
-		return err
+	if fullConfig {
+		if err := ioutil.WriteFile(filepath.Join(dir, ".config"), []byte(config), 0600); err != nil {
+			return fmt.Errorf("failed to write config file: %v", err)
+		}
+	} else {
+		os.Remove(filepath.Join(dir, ".config"))
+		configFile := filepath.Join(dir, "syz.config")
+		if err := ioutil.WriteFile(configFile, []byte(config), 0600); err != nil {
+			return fmt.Errorf("failed to write config file: %v", err)
+		}
+		defer os.Remove(configFile)
+		if _, err := osutil.RunCmd(timeout, dir, "make", "defconfig"); err != nil {
+			return err
+		}
+		if _, err := osutil.RunCmd(timeout, dir, "make", "kvmconfig"); err != nil {
+			return err
+		}
+		if _, err := osutil.RunCmd(timeout, dir, "scripts/kconfig/merge_config.sh", "-n", ".config", configFile); err != nil {
+			return err
+		}
 	}
 	if _, err := osutil.RunCmd(timeout, dir, "make", "olddefconfig"); err != nil {
 		return err
 	}
+	// We build only bzImage as we currently don't use modules.
 	// Build of a large kernel can take a while on a 1 CPU VM.
-	if _, err := osutil.RunCmd(3*time.Hour, dir, "make", "-j", strconv.Itoa(runtime.NumCPU()*2), "CC="+compiler); err != nil {
+	if _, err := osutil.RunCmd(3*time.Hour, dir, "make", "bzImage", "-j", strconv.Itoa(runtime.NumCPU()*2), "CC="+compiler); err != nil {
 		return err
 	}
 	return nil