all: add a DumpMemory feature

On Linux, verify that makedumpfile and the second kernel are present,
then set up a kernel to be used on panic.

9 files changed, 38 insertions, 4 deletions

diff --git a/pkg/flatrpc/flatrpc.fbs b/pkg/flatrpc/flatrpc.fbs
index 3876af965..b8542bf9e 100644
--- a/pkg/flatrpc/flatrpc.fbs
+++ b/pkg/flatrpc/flatrpc.fbs
@@ -34,6 +34,7 @@ enum Feature : uint64 (bit_flags) {
 	LRWPANEmulation,	// 802.15.4 standard
 	BinFmtMisc,
 	Swap,
+	MemoryDump,
 }
 
 table ConnectHelloRaw {
diff --git a/pkg/flatrpc/flatrpc.go b/pkg/flatrpc/flatrpc.go
index 439d06b67..9f86b077a 100644
--- a/pkg/flatrpc/flatrpc.go
+++ b/pkg/flatrpc/flatrpc.go
@@ -62,6 +62,7 @@ const (
 	FeatureLRWPANEmulation  Feature = 524288
 	FeatureBinFmtMisc       Feature = 1048576
 	FeatureSwap             Feature = 2097152
+	FeatureMemoryDump       Feature = 4194304
 )
 
 var EnumNamesFeature = map[Feature]string{
@@ -87,6 +88,7 @@ var EnumNamesFeature = map[Feature]string{
 	FeatureLRWPANEmulation:  "LRWPANEmulation",
 	FeatureBinFmtMisc:       "BinFmtMisc",
 	FeatureSwap:             "Swap",
+	FeatureMemoryDump:       "MemoryDump",
 }
 
 var EnumValuesFeature = map[string]Feature{
@@ -112,6 +114,7 @@ var EnumValuesFeature = map[string]Feature{
 	"LRWPANEmulation":  FeatureLRWPANEmulation,
 	"BinFmtMisc":       FeatureBinFmtMisc,
 	"Swap":             FeatureSwap,
+	"MemoryDump":       FeatureMemoryDump,
 }
 
 func (v Feature) String() string {
diff --git a/pkg/flatrpc/flatrpc.h b/pkg/flatrpc/flatrpc.h
index aa386f7dc..6807434e6 100644
--- a/pkg/flatrpc/flatrpc.h
+++ b/pkg/flatrpc/flatrpc.h
@@ -159,12 +159,13 @@ enum class Feature : uint64_t {
   LRWPANEmulation = 524288ULL,
   BinFmtMisc = 1048576ULL,
   Swap = 2097152ULL,
+  MemoryDump = 4194304ULL,
   NONE = 0,
-  ANY = 4194303ULL
+  ANY = 8388607ULL
 };
 FLATBUFFERS_DEFINE_BITMASK_OPERATORS(Feature, uint64_t)
 
-inline const Feature (&EnumValuesFeature())[22] {
+inline const Feature (&EnumValuesFeature())[23] {
   static const Feature values[] = {
     Feature::Coverage,
     Feature::Comparisons,
@@ -187,7 +188,8 @@ inline const Feature (&EnumValuesFeature())[22] {
     Feature::WifiEmulation,
     Feature::LRWPANEmulation,
     Feature::BinFmtMisc,
-    Feature::Swap
+    Feature::Swap,
+    Feature::MemoryDump
   };
   return values;
 }
@@ -216,6 +218,7 @@ inline const char *EnumNameFeature(Feature e) {
     case Feature::LRWPANEmulation: return "LRWPANEmulation";
     case Feature::BinFmtMisc: return "BinFmtMisc";
     case Feature::Swap: return "Swap";
+    case Feature::MemoryDump: return "MemoryDump";
     default: return "";
   }
 }
diff --git a/pkg/mgrconfig/config.go b/pkg/mgrconfig/config.go
index 45145243c..db6e10ba8 100644
--- a/pkg/mgrconfig/config.go
+++ b/pkg/mgrconfig/config.go
@@ -225,6 +225,9 @@ type Config struct {
 	// More details can be found in pkg/asset/config.go.
 	AssetStorage *asset.Config `json:"asset_storage"`
 
+	// MemoryDump enables feature to dump memory of the target VM on crash.
+	MemoryDump bool `json:"memory_dump"`
+
 	// Experimental options.
 	Experimental Experimental
 
diff --git a/pkg/rpcserver/rpcserver.go b/pkg/rpcserver/rpcserver.go
index 04c5d877f..385c0350d 100644
--- a/pkg/rpcserver/rpcserver.go
+++ b/pkg/rpcserver/rpcserver.go
@@ -162,6 +162,9 @@ func New(cfg *RemoteConfig) (Server, error) {
 	if !cfg.Experimental.RemoteCover {
 		features &= ^flatrpc.FeatureExtraCoverage
 	}
+	if !cfg.MemoryDump {
+		features &= ^flatrpc.FeatureMemoryDump
+	}
 	return newImpl(&Config{
 		Config: vminfo.Config{
 			Target:     cfg.Target,
@@ -170,6 +173,7 @@ func New(cfg *RemoteConfig) (Server, error) {
 			Syscalls:   cfg.Syscalls,
 			Debug:      cfg.Debug,
 			Cover:      cfg.Cover,
+			MemoryDump: cfg.MemoryDump,
 			Sandbox:    sandbox,
 			SandboxArg: cfg.SandboxArg,
 		},
diff --git a/pkg/rpcserver/rpcserver_test.go b/pkg/rpcserver/rpcserver_test.go
index 429b275ac..86dddcf76 100644
--- a/pkg/rpcserver/rpcserver_test.go
+++ b/pkg/rpcserver/rpcserver_test.go
@@ -72,6 +72,20 @@ func TestNew(t *testing.T) {
 			},
 			expectedServCheck: func(srv Server) {
 				s := srv.(*server)
+				assert.Equal(t, s.cfg.Config.Features,
+					flatrpc.AllFeatures&(^flatrpc.FeatureExtraCoverage)&(^flatrpc.FeatureMemoryDump))
+				assert.Nil(t, s.serv)
+			},
+		},
+		{
+			name: "memory dump enabled",
+			modifyCfg: func() *mgrconfig.Config {
+				cfg := defaultCfg
+				cfg.MemoryDump = true
+				return &cfg
+			},
+			expectedServCheck: func(srv Server) {
+				s := srv.(*server)
 				assert.Equal(t, s.cfg.Config.Features, flatrpc.AllFeatures&(^flatrpc.FeatureExtraCoverage))
 				assert.Nil(t, s.serv)
 			},
diff --git a/pkg/runtest/run_test.go b/pkg/runtest/run_test.go
index 97c31d6f9..14c643bba 100644
--- a/pkg/runtest/run_test.go
+++ b/pkg/runtest/run_test.go
@@ -106,7 +106,8 @@ func test(t *testing.T, sysTarget *targets.Target) {
 				flatrpc.FeatureWifiEmulation |
 				flatrpc.FeatureLRWPANEmulation |
 				flatrpc.FeatureBinFmtMisc |
-				flatrpc.FeatureSwap
+				flatrpc.FeatureSwap |
+				flatrpc.FeatureMemoryDump
 			for feat, name := range flatrpc.EnumNamesFeature {
 				if features&feat != want&feat {
 					t.Errorf("expect feature %v to be %v, but it is %v",
diff --git a/pkg/vminfo/features.go b/pkg/vminfo/features.go
index 6c4d6ae6d..34cf995ae 100644
--- a/pkg/vminfo/features.go
+++ b/pkg/vminfo/features.go
@@ -115,6 +115,9 @@ func (ctx *checkContext) finishFeatures(featureInfos []*flatrpc.FeatureInfo) (Fe
 	if feat := features[flatrpc.FeatureCoverage]; ctx.cfg.Cover && !feat.Enabled {
 		return features, fmt.Errorf("coverage is not supported: %v", feat.Reason)
 	}
+	if feat := features[flatrpc.FeatureMemoryDump]; ctx.cfg.MemoryDump && !feat.Enabled {
+		return features, fmt.Errorf("memory dump is not supported: %v", feat.Reason)
+	}
 	return features, nil
 }
 
@@ -171,6 +174,7 @@ func (ctx *checkContext) featureToFlags(feat flatrpc.Feature) (flatrpc.ExecEnv,
 	case flatrpc.FeatureLRWPANEmulation:
 	case flatrpc.FeatureBinFmtMisc:
 	case flatrpc.FeatureSwap:
+	case flatrpc.FeatureMemoryDump:
 	default:
 		panic(fmt.Sprintf("unknown feature %v", flatrpc.EnumNamesFeature[feat]))
 	}
diff --git a/pkg/vminfo/vminfo.go b/pkg/vminfo/vminfo.go
index 41fadf59a..f807ec9a0 100644
--- a/pkg/vminfo/vminfo.go
+++ b/pkg/vminfo/vminfo.go
@@ -51,6 +51,7 @@ type Config struct {
 	Syscalls   []int
 	Debug      bool
 	Cover      bool
+	MemoryDump bool
 	Sandbox    flatrpc.ExecEnv
 	SandboxArg int64
 }