all: determine patched symbols for focused fuzzing

Hash the code section of the individual symbols from vmlinux.o and use
it to determine the functions that changed their bodies between the base
and the patched build.

If the number of affected symbols is reasonable (<5%), fuzz it with the
highest priority.

1 files changed, 44 insertions, 3 deletions

diff --git a/pkg/manager/diff_test.go b/pkg/manager/diff_test.go
index f2408f13b..9e27dc288 100644
--- a/pkg/manager/diff_test.go
+++ b/pkg/manager/diff_test.go
@@ -4,6 +4,7 @@
 package manager
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/google/syzkaller/pkg/mgrconfig"
@@ -24,6 +25,10 @@ int main(void) { }`,
 		"c.c": `int main(void) { }`,
 	}))
 
+	baseHashes, patchedHashes := dummySymbolHashes(), dummySymbolHashes()
+	baseHashes["function"] = "hash1"
+	patchedHashes["function"] = "hash2"
+
 	PatchFocusAreas(cfg, [][]byte{
 		[]byte(`diff --git a/b.c b/b.c
 index 103167d..fbf7a68 100644
@@ -34,7 +39,7 @@ index 103167d..fbf7a68 100644
 \ No newline at end of file
 +int main(void) { return 1; }
 \ No newline at end of file`),
-		// Also, emulate an update to te header.h.
+		// Also, emulate an update to header.h.
 		[]byte(`diff --git a/header.h b/header.h
 index 103167d..fbf7a68 100644
 --- a/header.h
@@ -44,11 +49,18 @@ index 103167d..fbf7a68 100644
 \ No newline at end of file
 +Test2
 \ No newline at end of file`),
-	})
+	}, baseHashes, patchedHashes)
 
 	assert.Equal(t, []mgrconfig.FocusArea{
 		{
-			Name: modifiedArea,
+			Name: symbolsArea,
+			Filter: mgrconfig.CovFilterCfg{
+				Functions: []string{"function"},
+			},
+			Weight: 6.0,
+		},
+		{
+			Name: filesArea,
 			Filter: mgrconfig.CovFilterCfg{
 				Files: []string{"b.c", "header.h"},
 			},
@@ -66,3 +78,32 @@ index 103167d..fbf7a68 100644
 		},
 	}, cfg.Experimental.FocusAreas)
 }
+
+func dummySymbolHashes() map[string]string {
+	ret := map[string]string{}
+	for i := 0; i < 100; i++ {
+		ret[fmt.Sprint(i)] = fmt.Sprint(i)
+	}
+	return ret
+}
+
+func TestModifiedSymbols(t *testing.T) {
+	t.Run("too many changed", func(t *testing.T) {
+		ret := modifiedSymbols(map[string]string{
+			"functionA": "hash1",
+			"functionB": "hash2",
+		}, map[string]string{
+			"functionA": "hash1",
+			"functionB": "hash is not hash2",
+		})
+		assert.Empty(t, ret)
+	})
+	t.Run("less than threshold", func(t *testing.T) {
+		base, patched := dummySymbolHashes(), dummySymbolHashes()
+		base["function"] = "hash1"
+		patched["function"] = "hash2"
+		base["function2"] = "hash1"
+		patched["function2"] = "hash2"
+		assert.Equal(t, []string{"function", "function2"}, modifiedSymbols(base, patched))
+	})
+}