pkg/kconfig: store minimization results

Store config options identified using DebugTracer. Also change bisection
and configuration minimization code to use new DebugTracer.

2 files changed, 23 insertions, 19 deletions

diff --git a/pkg/kconfig/minimize.go b/pkg/kconfig/minimize.go
index bbcb95414..bbc66c4c1 100644
--- a/pkg/kconfig/minimize.go
+++ b/pkg/kconfig/minimize.go
@@ -4,9 +4,10 @@
 package kconfig
 
 import (
-	"fmt"
-	"io"
 	"sort"
+
+	"github.com/google/syzkaller/pkg/debugtracer"
+	"github.com/google/syzkaller/pkg/osutil"
 )
 
 // Minimize finds an equivalent with respect to the provided predicate, but smaller config.
@@ -15,15 +16,14 @@ import (
 // mostly by adding more configs. The minimization procedure thus consists of figuring out what set of configs that
 // are present in full and are not present in base affect the predicate.
 func (kconf *KConfig) Minimize(base, full *ConfigFile, pred func(*ConfigFile) (bool, error),
-	tw io.Writer) (*ConfigFile, error) {
-	trace := traceLogger{tw}
+	dt debugtracer.DebugTracer) (*ConfigFile, error) {
 	diff, other := kconf.missingConfigs(base, full)
-	trace.log("kconfig minimization: base=%v full=%v diff=%v", len(base.Configs), len(full.Configs), len(diff))
+	dt.Log("kconfig minimization: base=%v full=%v diff=%v", len(base.Configs), len(full.Configs), len(diff))
 	// First, check the base config as is, it is the smallest we can possibly get.
 	if res, err := pred(base); err != nil {
 		return nil, err
 	} else if res {
-		trace.log("base config crashes")
+		dt.Log("base config crashes")
 		return base, nil
 	}
 	// Since base does not crash, full config is our best bet for now.
@@ -45,7 +45,7 @@ top:
 	for len(diff) >= 2 {
 		half := len(diff) / 2
 		for _, part := range [][]string{diff[:half], diff[half:]} {
-			trace.log("trying half: %v", part)
+			dt.Log("trying half: %v", part)
 			closure := kconf.addDependencies(base, full, part)
 			candidate := base.clone()
 			// Always move all non-tristate configs from full to base as we don't minimize them.
@@ -60,20 +60,21 @@ top:
 				return nil, err
 			}
 			if res {
-				trace.log("half crashed")
+				dt.Log("half crashed")
 				diff = part
 				current = candidate
 				suspects = closure
 				continue top
 			}
 		}
-		trace.log("both halves did not crash")
+		dt.Log("both halves did not crash")
 		break
 	}
 	if suspects != nil {
-		trace.log("resulting configs: %v", suspects)
+		dt.Log("resulting configs: %v", suspects)
+		kconf.writeSuspects(dt, suspects)
 	} else {
-		trace.log("only full config crashes")
+		dt.Log("only full config crashes")
 	}
 	return current, nil
 }
@@ -110,10 +111,15 @@ func (kconf *KConfig) addDependencies(base, full *ConfigFile, configs []string)
 	return sorted
 }
 
-type traceLogger struct{ io.Writer }
+const CauseConfigFile = "cause.config"
+
+func (kconf *KConfig) writeSuspects(dt debugtracer.DebugTracer, suspects []string) {
+	cf := &ConfigFile{
+		Map: make(map[string]*Config),
+	}
 
-func (trace traceLogger) log(msg string, args ...interface{}) {
-	if trace.Writer != nil {
-		fmt.Fprintf(trace.Writer, msg+"\n", args...)
+	for _, cfg := range suspects {
+		cf.Set(cfg, Yes)
 	}
+	osutil.WriteFile(CauseConfigFile, cf.Serialize())
 }
diff --git a/pkg/kconfig/minimize_test.go b/pkg/kconfig/minimize_test.go
index 28dca33bd..1e1d2b0f2 100644
--- a/pkg/kconfig/minimize_test.go
+++ b/pkg/kconfig/minimize_test.go
@@ -4,10 +4,10 @@
 package kconfig
 
 import (
-	"bytes"
 	"fmt"
 	"testing"
 
+	"github.com/google/syzkaller/pkg/debugtracer"
 	"github.com/google/syzkaller/sys/targets"
 )
 
@@ -106,9 +106,7 @@ CONFIG_ROSE=y
 	}
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
-			trace := new(bytes.Buffer)
-			res, err := kconf.Minimize(base, full, test.pred, trace)
-			t.Log(trace.String())
+			res, err := kconf.Minimize(base, full, test.pred, &debugtracer.TestTracer{T: t})
 			if err != nil {
 				t.Fatal(err)
 			}