pkg/cover: refactor module discovery interface

Make module discovery convert host.KernelModule to backend.Module.

Also error if we have modules on non-Linux
and make it possible to return errors from module discovery.

5 files changed, 62 insertions, 44 deletions

diff --git a/pkg/cover/backend/backend.go b/pkg/cover/backend/backend.go
index afc8b1958..afdea950a 100644
--- a/pkg/cover/backend/backend.go
+++ b/pkg/cover/backend/backend.go
@@ -4,6 +4,9 @@
 package backend
 
 import (
+	"fmt"
+
+	"github.com/google/syzkaller/pkg/host"
 	"github.com/google/syzkaller/sys/targets"
 )
 
@@ -59,10 +62,13 @@ type Range struct {
 
 const LineEnd = 1 << 30
 
-func Make(target *targets.Target, vm, srcDir, buildDir string,
-	moduleObj []string, modules []*Module) (*Impl, error) {
+func Make(target *targets.Target, vm, objDir, srcDir, buildDir string,
+	moduleObj []string, modules []host.KernelModule) (*Impl, error) {
+	if objDir == "" {
+		return nil, fmt.Errorf("kernel obj directory is not specified")
+	}
 	if vm == "gvisor" {
-		return makeGvisor(target, srcDir, buildDir, modules)
+		return makeGvisor(target, objDir, srcDir, buildDir, modules)
 	}
-	return makeELF(target, srcDir, buildDir, moduleObj, modules)
+	return makeELF(target, objDir, srcDir, buildDir, moduleObj, modules)
 }
diff --git a/pkg/cover/backend/elf.go b/pkg/cover/backend/elf.go
index 8d24542c2..604ea8031 100644
--- a/pkg/cover/backend/elf.go
+++ b/pkg/cover/backend/elf.go
@@ -18,23 +18,25 @@ import (
 	"strings"
 	"unsafe"
 
+	"github.com/google/syzkaller/pkg/host"
 	"github.com/google/syzkaller/pkg/log"
 	"github.com/google/syzkaller/pkg/osutil"
 	"github.com/google/syzkaller/pkg/symbolizer"
 	"github.com/google/syzkaller/sys/targets"
 )
 
-func makeELF(target *targets.Target, srcDir, buildDir string,
-	moduleObj []string, modules []*Module) (*Impl, error) {
+func makeELF(target *targets.Target, objDir, srcDir, buildDir string,
+	moduleObj []string, hostModules []host.KernelModule) (*Impl, error) {
+	modules, err := discoverModules(target, objDir, moduleObj, hostModules)
+	if err != nil {
+		return nil, err
+	}
 	// Here and below index 0 refers to coverage callbacks (__sanitizer_cov_trace_pc)
 	// and index 1 refers to comparison callbacks (__sanitizer_cov_trace_cmp*).
 	var allCoverPoints [2][]uint64
 	var allSymbols []*Symbol
 	var allRanges []pcRange
 	var allUnits []*CompileUnit
-	if target.OS == targets.Linux {
-		getModules(moduleObj, modules)
-	}
 	var pcBase uint64
 	for _, module := range modules {
 		if module.Path == "" {
@@ -108,7 +110,7 @@ func makeELF(target *targets.Target, srcDir, buildDir string,
 		if len(unit.PCs) == 0 {
 			continue // drop the unit
 		}
-		objDir := filepath.Dir(modules[0].Path) // TODO: won't work for out-of-tree modules
+		// TODO: objDir won't work for out-of-tree modules.
 		unit.Name, unit.Path = cleanPath(unit.Name, objDir, srcDir, buildDir)
 		allUnits[nunit] = unit
 		nunit++
diff --git a/pkg/cover/backend/gvisor.go b/pkg/cover/backend/gvisor.go
index 22f07a88b..3bb8e67ef 100644
--- a/pkg/cover/backend/gvisor.go
+++ b/pkg/cover/backend/gvisor.go
@@ -10,15 +10,16 @@ import (
 	"regexp"
 	"strconv"
 
+	"github.com/google/syzkaller/pkg/host"
 	"github.com/google/syzkaller/pkg/osutil"
 	"github.com/google/syzkaller/sys/targets"
 )
 
-func makeGvisor(target *targets.Target, srcDir, buildDir string, modules []*Module) (*Impl, error) {
-	if len(modules) != 1 {
+func makeGvisor(target *targets.Target, objDir, srcDir, buildDir string, modules []host.KernelModule) (*Impl, error) {
+	if len(modules) != 0 {
 		return nil, fmt.Errorf("gvisor coverage does not support modules")
 	}
-	bin := modules[0].Path
+	bin := filepath.Join(objDir, target.KernelObject)
 	// pkg/build stores runsc as 'vmlinux' (we pretent to be linux), but a local build will have it as 'runsc'.
 	if !osutil.IsExist(bin) {
 		bin = filepath.Join(filepath.Dir(bin), "runsc")
diff --git a/pkg/cover/backend/modules.go b/pkg/cover/backend/modules.go
index c7a75ed22..41b61de23 100644
--- a/pkg/cover/backend/modules.go
+++ b/pkg/cover/backend/modules.go
@@ -11,22 +11,44 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/google/syzkaller/pkg/host"
 	"github.com/google/syzkaller/pkg/log"
+	"github.com/google/syzkaller/sys/targets"
 )
 
-func getModules(dirs []string, modules []*Module) {
-	byName := make(map[string]*Module)
-	for _, mod := range modules {
+func discoverModules(target *targets.Target, objDir string, moduleObj []string, hostModules []host.KernelModule) (
+	[]*Module, error) {
+	modules := []*Module{
+		{Path: filepath.Join(objDir, target.KernelObject)},
+	}
+	if target.OS == targets.Linux {
+		modules1, err := discoverModulesLinux(append([]string{objDir}, moduleObj...), hostModules)
+		if err != nil {
+			return nil, err
+		}
+		modules = append(modules, modules1...)
+	} else if len(hostModules) != 0 {
+		return nil, fmt.Errorf("%v coverage does not support modules", target.OS)
+	}
+	return modules, nil
+}
+
+func discoverModulesLinux(dirs []string, hostModules []host.KernelModule) ([]*Module, error) {
+	byName := make(map[string]host.KernelModule)
+	for _, mod := range hostModules {
 		byName[mod.Name] = mod
 	}
+	var modules []*Module
 	files := findModulePaths(dirs)
 	for _, path := range files {
 		name := strings.TrimSuffix(filepath.Base(path), ".ko")
-		if module := byName[name]; module != nil {
-			if module.Path != "" {
-				continue
-			}
-			module.Path = path
+		if mod, ok := byName[name]; ok {
+			delete(byName, name)
+			modules = append(modules, &Module{
+				Name: mod.Name,
+				Addr: mod.Addr,
+				Path: path,
+			})
 			continue
 		}
 		name, err := getModuleName(path)
@@ -37,14 +59,17 @@ func getModules(dirs []string, modules []*Module) {
 		if name == "" {
 			continue
 		}
-		if module := byName[name]; module != nil {
-			if module.Path != "" {
-				continue
-			}
-			module.Path = path
+		if mod, ok := byName[name]; ok {
+			delete(byName, name)
+			modules = append(modules, &Module{
+				Name: mod.Name,
+				Addr: mod.Addr,
+				Path: path,
+			})
 		}
 	}
 	log.Logf(0, "kernel modules: %v", modules)
+	return modules, nil
 }
 
 func findModulePaths(dirs []string) []string {
diff --git a/pkg/cover/report.go b/pkg/cover/report.go
index b622af4a4..8f805fe10 100644
--- a/pkg/cover/report.go
+++ b/pkg/cover/report.go
@@ -5,7 +5,6 @@ package cover
 
 import (
 	"fmt"
-	"path/filepath"
 	"sort"
 
 	"github.com/google/syzkaller/pkg/cover/backend"
@@ -30,23 +29,8 @@ type Prog struct {
 var RestorePC = backend.RestorePC
 
 func MakeReportGenerator(target *targets.Target, vm, objDir, srcDir, buildDir string, subsystem []mgrconfig.Subsystem,
-	moduleObj []string, hostModules []host.KernelModule) (*ReportGenerator, error) {
-	if objDir == "" {
-		return nil, fmt.Errorf("kernel obj directory is not specified")
-	}
-	moduleObj = append([]string{objDir}, moduleObj...)
-	modules := []*backend.Module{
-		{
-			Path: filepath.Join(objDir, target.KernelObject),
-		},
-	}
-	for _, mod := range hostModules {
-		modules = append(modules, &backend.Module{
-			Name: mod.Name,
-			Addr: mod.Addr,
-		})
-	}
-	impl, err := backend.Make(target, vm, srcDir, buildDir, moduleObj, modules)
+	moduleObj []string, modules []host.KernelModule) (*ReportGenerator, error) {
+	impl, err := backend.Make(target, vm, objDir, srcDir, buildDir, moduleObj, modules)
 	if err != nil {
 		return nil, err
 	}