all: support swap feature on Linux

If the feature is supported on the device, allocate a 128MB swap file
after VM boot and activate it.

8 files changed, 92 insertions, 9 deletions

diff --git a/pkg/csource/common.go b/pkg/csource/common.go
index 6f3920126..3b30d85f4 100644
--- a/pkg/csource/common.go
+++ b/pkg/csource/common.go
@@ -127,6 +127,7 @@ func commonDefines(p *prog.Prog, opts Options) map[string]bool {
 		"SYZ_WIFI":                      opts.Wifi,
 		"SYZ_802154":                    opts.IEEE802154,
 		"SYZ_SYSCTL":                    opts.Sysctl,
+		"SYZ_SWAP":                      opts.Swap,
 		"SYZ_EXECUTOR_USES_SHMEM":       sysTarget.ExecutorUsesShmem,
 		"SYZ_EXECUTOR_USES_FORK_SERVER": sysTarget.ExecutorUsesForkServer,
 	}
diff --git a/pkg/csource/generated.go b/pkg/csource/generated.go
index 8c80cc363..bceb2dba4 100644
--- a/pkg/csource/generated.go
+++ b/pkg/csource/generated.go
@@ -3767,6 +3767,18 @@ static void initialize_wifi_devices(void)
 }
 #endif
 
+#if SYZ_EXECUTOR || (SYZ_NET_DEVICES && SYZ_NIC_VF) || SYZ_SWAP
+static int runcmdline(char* cmdline)
+{
+	debug("%s\n", cmdline);
+	int ret = system(cmdline);
+	if (ret) {
+		debug("FAIL: %s\n", cmdline);
+	}
+	return ret;
+}
+#endif
+
 #if SYZ_EXECUTOR || SYZ_NET_DEVICES
 #include <arpa/inet.h>
 #include <errno.h>
@@ -4028,15 +4040,6 @@ error:
 }
 
 #if SYZ_EXECUTOR || SYZ_NIC_VF
-static int runcmdline(char* cmdline)
-{
-	debug("%s\n", cmdline);
-	int ret = system(cmdline);
-	if (ret) {
-		debug("FAIL: %s\n", cmdline);
-	}
-	return ret;
-}
 
 static void netlink_nicvf_setup(void)
 {
@@ -11762,6 +11765,42 @@ static long syz_pkey_set(volatile long pkey, volatile long val)
 }
 #endif
 
+#if SYZ_EXECUTOR || SYZ_SWAP
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/swap.h>
+#include <sys/types.h>
+
+#define SWAP_FILE "./swap-file"
+#define SWAP_FILE_SIZE (128 * 1000 * 1000)
+
+static void setup_swap()
+{
+	swapoff(SWAP_FILE);
+	unlink(SWAP_FILE);
+	int fd = open(SWAP_FILE, O_CREAT | O_WRONLY | O_CLOEXEC, 0600);
+	if (fd == -1) {
+		failmsg("swap file open failed", "file: %s", SWAP_FILE);
+		return;
+	}
+	fallocate(fd, FALLOC_FL_ZERO_RANGE, 0, SWAP_FILE_SIZE);
+	close(fd);
+	char cmdline[64];
+	sprintf(cmdline, "mkswap %s", SWAP_FILE);
+	if (runcmdline(cmdline)) {
+		fail("mkswap failed");
+		return;
+	}
+	if (swapon(SWAP_FILE, SWAP_FLAG_PREFER) == 1) {
+		failmsg("swapon failed", "file: %s", SWAP_FILE);
+		return;
+	}
+}
+
+#endif
+
 #elif GOOS_test
 
 #include <stdlib.h>
@@ -12645,6 +12684,9 @@ int main(void)
 #if SYZ_802154
 	setup_802154();
 #endif
+#if SYZ_SWAP
+	setup_swap();
+#endif
 #if SYZ_HANDLE_SEGV
 	install_segv_handler();
 #endif
diff --git a/pkg/csource/options.go b/pkg/csource/options.go
index 45cedb6a9..9a43c65fc 100644
--- a/pkg/csource/options.go
+++ b/pkg/csource/options.go
@@ -43,6 +43,7 @@ type Options struct {
 	Wifi          bool `json:"wifi,omitempty"`
 	IEEE802154    bool `json:"ieee802154,omitempty"`
 	Sysctl        bool `json:"sysctl,omitempty"`
+	Swap          bool `json:"swap,omitempty"`
 
 	UseTmpDir  bool `json:"tmpdir,omitempty"`
 	HandleSegv bool `json:"segv,omitempty"`
@@ -150,6 +151,7 @@ func (opts Options) checkLinuxOnly(OS string) error {
 		"Fault":         &opts.Fault,
 		"Leak":          &opts.Leak,
 		"Sysctl":        &opts.Sysctl,
+		"Swap":          &opts.Swap,
 	} {
 		if *opt {
 			return fmt.Errorf("option %v is not supported on %v", name, OS)
@@ -183,6 +185,7 @@ func DefaultOpts(cfg *mgrconfig.Config) Options {
 		opts.Wifi = true
 		opts.IEEE802154 = true
 		opts.Sysctl = true
+		opts.Swap = true
 	}
 	if cfg.Sandbox == "" || cfg.Sandbox == "setuid" {
 		opts.NetReset = false
@@ -316,6 +319,7 @@ func defaultFeatures(value bool) Features {
 		"wifi":        {"setup and use mac80211_hwsim for wifi emulation", value},
 		"ieee802154":  {"setup and use mac802154_hwsim for emulation", value},
 		"sysctl":      {"setup sysctl's for fuzzing", value},
+		"swap":        {"setup and use a swap file", value},
 	}
 }
 
diff --git a/pkg/csource/options_test.go b/pkg/csource/options_test.go
index 5edc56d02..5452f22ce 100644
--- a/pkg/csource/options_test.go
+++ b/pkg/csource/options_test.go
@@ -314,6 +314,7 @@ func TestParseFeaturesFlags(t *testing.T) {
 			"wifi":        true,
 			"ieee802154":  true,
 			"sysctl":      true,
+			"swap":        true,
 		}},
 		{"none", "none", false, map[string]bool{}},
 		{"all", "none", true, map[string]bool{
@@ -330,6 +331,7 @@ func TestParseFeaturesFlags(t *testing.T) {
 			"wifi":        true,
 			"ieee802154":  true,
 			"sysctl":      true,
+			"swap":        true,
 		}},
 		{"", "none", true, map[string]bool{}},
 		{"none", "all", true, map[string]bool{}},
@@ -347,6 +349,7 @@ func TestParseFeaturesFlags(t *testing.T) {
 			"wifi":        true,
 			"ieee802154":  true,
 			"sysctl":      true,
+			"swap":        true,
 		}},
 		{"tun,net_dev", "none", true, map[string]bool{
 			"tun":     true,
@@ -364,10 +367,14 @@ func TestParseFeaturesFlags(t *testing.T) {
 			"wifi":        true,
 			"ieee802154":  true,
 			"sysctl":      true,
+			"swap":        true,
 		}},
 		{"close_fds", "none", true, map[string]bool{
 			"close_fds": true,
 		}},
+		{"swap", "none", true, map[string]bool{
+			"swap": true,
+		}},
 	}
 	for i, test := range tests {
 		features, err := ParseFeaturesFlags(test.Enable, test.Disable, test.Default)
diff --git a/pkg/host/features.go b/pkg/host/features.go
index 343e76783..b8ec837f0 100644
--- a/pkg/host/features.go
+++ b/pkg/host/features.go
@@ -34,6 +34,7 @@ const (
 	FeatureVhciInjection
 	FeatureWifiEmulation
 	Feature802154Emulation
+	FeatureSwap
 	numFeatures
 )
 
@@ -77,6 +78,7 @@ func Check(target *prog.Target) (*Features, error) {
 		FeatureVhciInjection:    {Name: "hci packet injection", Reason: unsupported},
 		FeatureWifiEmulation:    {Name: "wifi device emulation", Reason: unsupported},
 		Feature802154Emulation:  {Name: "802.15.4 emulation", Reason: unsupported},
+		FeatureSwap:             {Name: "swap file", Reason: unsupported},
 	}
 	if noHostChecks(target) {
 		return res, nil
@@ -125,6 +127,9 @@ func Setup(target *prog.Target, features *Features, featureFlags csource.Feature
 	if featureFlags["ieee802154"].Enabled && features[Feature802154Emulation].Enabled {
 		args = append(args, "802154")
 	}
+	if features[FeatureSwap].Enabled {
+		args = append(args, "swap")
+	}
 	output, err := osutil.RunCmd(5*time.Minute, "", executor, args...)
 	log.Logf(1, "executor %v\n%s", args, output)
 	return err
diff --git a/pkg/host/features_linux.go b/pkg/host/features_linux.go
index 142e58e3b..408e219eb 100644
--- a/pkg/host/features_linux.go
+++ b/pkg/host/features_linux.go
@@ -5,6 +5,7 @@ package host
 
 import (
 	"fmt"
+	"os/exec"
 	"regexp"
 	"runtime"
 	"runtime/debug"
@@ -37,6 +38,7 @@ func init() {
 	checkFeature[FeatureVhciInjection] = checkVhciInjection
 	checkFeature[FeatureWifiEmulation] = checkWifiEmulation
 	checkFeature[Feature802154Emulation] = check802154Emulation
+	checkFeature[FeatureSwap] = checkSwap
 }
 
 func checkCoverage() string {
@@ -287,6 +289,16 @@ func check802154Emulation() string {
 	return ""
 }
 
+func checkSwap() string {
+	if err := osutil.IsAccessible("/proc/swaps"); err != nil {
+		return err.Error()
+	}
+	if _, err := exec.LookPath("mkswap"); err != nil {
+		return "mkswap is not available"
+	}
+	return ""
+}
+
 func requireKernel(x, y int) string {
 	info := new(unix.Utsname)
 	if err := unix.Uname(info); err != nil {
diff --git a/pkg/repro/repro.go b/pkg/repro/repro.go
index 87b9eaa4c..9cfb28dd8 100644
--- a/pkg/repro/repro.go
+++ b/pkg/repro/repro.go
@@ -201,6 +201,9 @@ func createStartOptions(cfg *mgrconfig.Config, features *host.Features, crashTyp
 		if !features[host.Feature802154Emulation].Enabled {
 			opts.IEEE802154 = false
 		}
+		if !features[host.FeatureSwap].Enabled {
+			opts.Swap = false
+		}
 	}
 	return opts
 }
@@ -817,6 +820,7 @@ var cSimplifies = append(progSimplifies, []Simplify{
 		opts.USB = false
 		opts.VhciInjection = false
 		opts.Wifi = false
+		opts.Swap = false
 		return true
 	},
 	func(opts *csource.Options) bool {
@@ -926,4 +930,11 @@ var cSimplifies = append(progSimplifies, []Simplify{
 		opts.Sysctl = false
 		return true
 	},
+	func(opts *csource.Options) bool {
+		if !opts.Swap {
+			return false
+		}
+		opts.Swap = false
+		return true
+	},
 }...)
diff --git a/pkg/runtest/run.go b/pkg/runtest/run.go
index 1952a9f98..3e4543fab 100644
--- a/pkg/runtest/run.go
+++ b/pkg/runtest/run.go
@@ -467,6 +467,7 @@ func (ctx *Context) createCTest(p *prog.Prog, sandbox string, threaded bool, tim
 		HandleSegv:  true,
 		Cgroups:     p.Target.OS == targets.Linux && sandbox != "",
 		Trace:       true,
+		Swap:        ctx.Features[host.FeatureSwap].Enabled,
 	}
 	if sandbox != "" {
 		if ctx.Features[host.FeatureNetInjection].Enabled {