pkg/cover: fix prefix computation

* pkg/cover: Modify parsing logic
1. Remove prefix computation
2. Add a mgrconfig for kernel build directory

* pkg/report: shorten reports with kernelBuildSrc instead of kernelSrc

* pkg/report: Fix failing tests

* pkg/report: fix formating issues

* tools/syz-cover: Fix unintended redefinition

* make changes to fix failing ci build

* pkg/report: fix issues

14 files changed, 86 insertions, 116 deletions

diff --git a/pkg/cover/report.go b/pkg/cover/report.go
index a85b091d6..1b182b73a 100644
--- a/pkg/cover/report.go
+++ b/pkg/cover/report.go
@@ -23,6 +23,7 @@ import (
 type ReportGenerator struct {
 	vmlinux  string
 	srcDir   string
+	buildDir string
 	arch     string
 	symbols  []symbol
 	coverPCs []uint64
@@ -39,11 +40,12 @@ type coverage struct {
 	covered bool
 }
 
-func MakeReportGenerator(vmlinux, srcDir, arch string) (*ReportGenerator, error) {
+func MakeReportGenerator(vmlinux, srcDir, buildDir, arch string) (*ReportGenerator, error) {
 	rg := &ReportGenerator{
-		vmlinux: vmlinux,
-		srcDir:  srcDir,
-		arch:    arch,
+		vmlinux:  vmlinux,
+		srcDir:   srcDir,
+		buildDir: buildDir,
+		arch:     arch,
 	}
 	if err := rg.readSymbols(); err != nil {
 		return nil, err
@@ -61,7 +63,7 @@ func (rg *ReportGenerator) Do(w io.Writer, pcs []uint64) error {
 	for i, pc := range pcs {
 		pcs[i] = PreviousInstructionPC(rg.arch, pc)
 	}
-	covered, prefix, err := rg.symbolize(pcs)
+	covered, err := rg.symbolize(pcs)
 	if err != nil {
 		return err
 	}
@@ -69,23 +71,25 @@ func (rg *ReportGenerator) Do(w io.Writer, pcs []uint64) error {
 		return fmt.Errorf("'%s' does not have debug info (set CONFIG_DEBUG_INFO=y)", rg.vmlinux)
 	}
 	uncoveredPCs := rg.uncoveredPcsInFuncs(pcs)
-	uncovered, prefix2, err := rg.symbolize(uncoveredPCs)
+	uncovered, err := rg.symbolize(uncoveredPCs)
 	if err != nil {
 		return err
 	}
-	if len(uncoveredPCs) != 0 {
-		prefix = combinePrefix(prefix, prefix2)
-	}
-	return rg.generate(w, prefix, covered, uncovered)
+	return rg.generate(w, covered, uncovered)
 }
 
-func (rg *ReportGenerator) generate(w io.Writer, prefix string, covered, uncovered []symbolizer.Frame) error {
+func (rg *ReportGenerator) generate(w io.Writer, covered, uncovered []symbolizer.Frame) error {
 	var d templateData
 	for f, covered := range fileSet(covered, uncovered) {
-		remain := filepath.Clean(strings.TrimPrefix(f, prefix))
-		if rg.srcDir != "" && !strings.HasPrefix(remain, rg.srcDir) {
-			f = filepath.Join(rg.srcDir, remain)
+		if !strings.HasPrefix(f, rg.buildDir) {
+			return fmt.Errorf("path '%s' doesn't match build dir '%s'", f, rg.buildDir)
 		}
+
+		// Trim the existing build dir
+		remain := filepath.Clean(strings.TrimPrefix(f, rg.buildDir))
+
+		// Add the current kernel source dir
+		f = filepath.Join(rg.srcDir, remain)
 		lines, err := parseFile(f)
 		if err != nil {
 			return err
@@ -219,39 +223,20 @@ func (rg *ReportGenerator) uncoveredPcsInFuncs(pcs []uint64) []uint64 {
 	return uncoveredPCs
 }
 
-func (rg *ReportGenerator) symbolize(pcs []uint64) ([]symbolizer.Frame, string, error) {
+func (rg *ReportGenerator) symbolize(pcs []uint64) ([]symbolizer.Frame, error) {
 	symb := symbolizer.NewSymbolizer()
 	defer symb.Close()
 
 	frames, err := symb.SymbolizeArray(rg.vmlinux, pcs)
 	if err != nil {
-		return nil, "", err
+		return nil, err
 	}
 
-	prefix := ""
 	for i := range frames {
 		frame := &frames[i]
 		frame.PC--
-		if prefix == "" {
-			prefix = frame.File
-		} else {
-			prefix = combinePrefix(prefix, frame.File)
-			if prefix == "" {
-				break
-			}
-		}
-	}
-	return frames, prefix, nil
-}
-
-func combinePrefix(prefix, prefix2 string) string {
-	i := 0
-	for ; i < len(prefix) && i < len(prefix2); i++ {
-		if prefix[i] != prefix2[i] {
-			break
-		}
 	}
-	return prefix[:i]
+	return frames, nil
 }
 
 func parseFile(fn string) ([][]byte, error) {
diff --git a/pkg/mgrconfig/config.go b/pkg/mgrconfig/config.go
index 48609d5c4..a023803ef 100644
--- a/pkg/mgrconfig/config.go
+++ b/pkg/mgrconfig/config.go
@@ -24,6 +24,8 @@ type Config struct {
 	KernelObj string `json:"kernel_obj"`
 	// Kernel source directory (if not set defaults to KernelObj).
 	KernelSrc string `json:"kernel_src,omitempty"`
+	// Location of the driectory where the kernel was built (if not set defaults to KernelSrc)
+	KernelBuildSrc string `json:"kernel_build_src"`
 	// Arbitrary optional tag that is saved along with crash reports (e.g. branch/commit).
 	Tag string `json:"tag,omitempty"`
 	// Location of the disk image file.
diff --git a/pkg/mgrconfig/load.go b/pkg/mgrconfig/load.go
index 1fdcc0155..a4cbc8914 100644
--- a/pkg/mgrconfig/load.go
+++ b/pkg/mgrconfig/load.go
@@ -111,6 +111,9 @@ func Complete(cfg *Config) error {
 		cfg.KernelSrc = cfg.KernelObj // assume in-tree build by default
 	}
 	cfg.KernelSrc = osutil.Abs(cfg.KernelSrc)
+	if cfg.KernelBuildSrc == "" {
+		cfg.KernelBuildSrc = cfg.KernelSrc
+	}
 	if cfg.HubClient != "" && (cfg.Name == "" || cfg.HubAddr == "" || cfg.HubKey == "") {
 		return fmt.Errorf("hub_client is set, but name/hub_addr/hub_key is empty")
 	}
diff --git a/pkg/report/akaros.go b/pkg/report/akaros.go
index 1aec59cfc..602bdd829 100644
--- a/pkg/report/akaros.go
+++ b/pkg/report/akaros.go
@@ -21,7 +21,7 @@ type akaros struct {
 	objfile string
 }
 
-func ctorAkaros(target *targets.Target, kernelSrc, kernelObj string,
+func ctorAkaros(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	ctx := &akaros{
 		ignores: ignores,
diff --git a/pkg/report/freebsd.go b/pkg/report/freebsd.go
index b07e942db..1ca0b44be 100644
--- a/pkg/report/freebsd.go
+++ b/pkg/report/freebsd.go
@@ -11,17 +11,17 @@ import (
 )
 
 type freebsd struct {
-	kernelSrc string
-	kernelObj string
-	ignores   []*regexp.Regexp
+	kernelBuildSrc string
+	kernelObj      string
+	ignores        []*regexp.Regexp
 }
 
-func ctorFreebsd(target *targets.Target, kernelSrc, kernelObj string,
+func ctorFreebsd(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	ctx := &freebsd{
-		kernelSrc: kernelSrc,
-		kernelObj: kernelObj,
-		ignores:   ignores,
+		kernelBuildSrc: kernelBuildSrc,
+		kernelObj:      kernelObj,
+		ignores:        ignores,
 	}
 	return ctx, nil, nil
 }
diff --git a/pkg/report/fuchsia.go b/pkg/report/fuchsia.go
index b7399cc5c..b8467d5e1 100644
--- a/pkg/report/fuchsia.go
+++ b/pkg/report/fuchsia.go
@@ -39,7 +39,7 @@ var (
 	}
 )
 
-func ctorFuchsia(target *targets.Target, kernelSrc, kernelObj string,
+func ctorFuchsia(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	ctx := &fuchsia{
 		ignores: ignores,
diff --git a/pkg/report/gvisor.go b/pkg/report/gvisor.go
index aa5308f5d..8e24430c0 100644
--- a/pkg/report/gvisor.go
+++ b/pkg/report/gvisor.go
@@ -14,7 +14,7 @@ type gvisor struct {
 	ignores []*regexp.Regexp
 }
 
-func ctorGvisor(target *targets.Target, kernelSrc, kernelObj string,
+func ctorGvisor(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	ctx := &gvisor{
 		ignores: ignores,
diff --git a/pkg/report/linux.go b/pkg/report/linux.go
index fb12b5509..b9145566b 100644
--- a/pkg/report/linux.go
+++ b/pkg/report/linux.go
@@ -21,6 +21,7 @@ import (
 
 type linux struct {
 	kernelSrc             string
+	kernelBuildSrc        string
 	kernelObj             string
 	vmlinux               string
 	symbols               map[string][]symbolizer.Symbol
@@ -35,7 +36,7 @@ type linux struct {
 	eoi                   []byte
 }
 
-func ctorLinux(target *targets.Target, kernelSrc, kernelObj string, ignores []*regexp.Regexp) (Reporter, []string, error) {
+func ctorLinux(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string, ignores []*regexp.Regexp) (Reporter, []string, error) {
 	var symbols map[string][]symbolizer.Symbol
 	vmlinux := ""
 	if kernelObj != "" {
@@ -47,11 +48,12 @@ func ctorLinux(target *targets.Target, kernelSrc, kernelObj string, ignores []*r
 		}
 	}
 	ctx := &linux{
-		kernelSrc: kernelSrc,
-		kernelObj: kernelObj,
-		vmlinux:   vmlinux,
-		symbols:   symbols,
-		ignores:   ignores,
+		kernelSrc:      kernelSrc,
+		kernelBuildSrc: kernelBuildSrc,
+		kernelObj:      kernelObj,
+		vmlinux:        vmlinux,
+		symbols:        symbols,
+		ignores:        ignores,
 	}
 	ctx.consoleOutputRe = regexp.MustCompile(`^(?:\*\* [0-9]+ printk messages dropped \*\* )?(?:.* login: )?(?:\<[0-9]+\>)?\[ *[0-9]+\.[0-9]+\](\[ *(?:C|T)[0-9]+\])? `)
 	ctx.questionableRes = []*regexp.Regexp{
@@ -335,14 +337,13 @@ func (ctx *linux) Symbolize(rep *Report) error {
 func (ctx *linux) symbolize(rep *Report) error {
 	symb := symbolizer.NewSymbolizer()
 	defer symb.Close()
-	strip := ctx.stripPrefix(symb)
 	var symbolized []byte
 	s := bufio.NewScanner(bytes.NewReader(rep.Report))
 	prefix := rep.reportPrefixLen
 	for s.Scan() {
 		line := append([]byte{}, s.Bytes()...)
 		line = append(line, '\n')
-		newLine := symbolizeLine(symb.Symbolize, ctx.symbols, ctx.vmlinux, strip, line)
+		newLine := symbolizeLine(symb.Symbolize, ctx.symbols, ctx.vmlinux, ctx.kernelBuildSrc, line)
 		if prefix > len(symbolized) {
 			prefix += len(newLine) - len(line)
 		}
@@ -353,33 +354,6 @@ func (ctx *linux) symbolize(rep *Report) error {
 	return nil
 }
 
-func (ctx *linux) stripPrefix(symb *symbolizer.Symbolizer) string {
-	// Vmlinux may have been moved, so check if we can find debug info
-	// for some known functions and infer correct strip prefix from it.
-	knownSymbols := []struct {
-		symbol string
-		file   string
-	}{
-		{"__sanitizer_cov_trace_pc", "kernel/kcov.c"},
-		{"__asan_load1", "mm/kasan/kasan.c"},
-		{"start_kernel", "init/main.c"},
-	}
-	for _, s := range knownSymbols {
-		for _, covSymb := range ctx.symbols[s.symbol] {
-			frames, _ := symb.Symbolize(ctx.vmlinux, covSymb.Addr)
-			if len(frames) > 0 {
-				file := frames[len(frames)-1].File
-				if idx := strings.Index(file, s.file); idx != -1 {
-					return file[:idx]
-				}
-			}
-		}
-	}
-	// Strip vmlinux location from all paths.
-	strip, _ := filepath.Abs(ctx.vmlinux)
-	return filepath.Dir(strip) + string(filepath.Separator)
-}
-
 func symbolizeLine(symbFunc func(bin string, pc uint64) ([]symbolizer.Frame, error),
 	symbols map[string][]symbolizer.Symbol, vmlinux, strip string, line []byte) []byte {
 	match := linuxSymbolizeRe.FindSubmatchIndex(line)
diff --git a/pkg/report/netbsd.go b/pkg/report/netbsd.go
index 8a24b0eb1..c716d6df0 100644
--- a/pkg/report/netbsd.go
+++ b/pkg/report/netbsd.go
@@ -17,11 +17,12 @@ import (
 )
 
 type netbsd struct {
-	kernelSrc    string
-	kernelObj    string
-	kernelObject string
-	symbols      map[string][]symbolizer.Symbol
-	ignores      []*regexp.Regexp
+	kernelSrc      string
+	kernelBuildSrc string
+	kernelObj      string
+	kernelObject   string
+	symbols        map[string][]symbolizer.Symbol
+	ignores        []*regexp.Regexp
 }
 
 var (
@@ -33,7 +34,7 @@ var (
 	}
 )
 
-func ctorNetbsd(target *targets.Target, kernelSrc, kernelObj string,
+func ctorNetbsd(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	var symbols map[string][]symbolizer.Symbol
 	ignores = append(ignores, regexp.MustCompile("event_init: unable to initialize")) // postfix output
@@ -47,11 +48,12 @@ func ctorNetbsd(target *targets.Target, kernelSrc, kernelObj string,
 		}
 	}
 	ctx := &netbsd{
-		kernelSrc:    kernelSrc,
-		kernelObj:    kernelObj,
-		kernelObject: kernelObject,
-		symbols:      symbols,
-		ignores:      ignores,
+		kernelSrc:      kernelSrc,
+		kernelBuildSrc: kernelBuildSrc,
+		kernelObj:      kernelObj,
+		kernelObject:   kernelObject,
+		symbols:        symbols,
+		ignores:        ignores,
 	}
 	return ctx, nil, nil
 }
@@ -134,7 +136,7 @@ func (ctx *netbsd) symbolizeLine(symbFunc func(bin string, pc uint64) ([]symboli
 	// and line numbers.
 	for _, frame := range frames {
 		file := frame.File
-		file = strings.TrimPrefix(file, ctx.kernelSrc)
+		file = strings.TrimPrefix(file, ctx.kernelBuildSrc)
 		file = strings.TrimPrefix(file, "/")
 		info := fmt.Sprintf(" %v:%v", file, frame.Line)
 		modified := append([]byte{}, line...)
diff --git a/pkg/report/netbsd_test.go b/pkg/report/netbsd_test.go
index 1fec41ab0..be5e69130 100644
--- a/pkg/report/netbsd_test.go
+++ b/pkg/report/netbsd_test.go
@@ -82,10 +82,11 @@ func TestNetbsdSymbolizeLine(t *testing.T) {
 		}
 	}
 	nbsd := netbsd{
-		kernelSrc:    "netbsd/src",
-		kernelObj:    "/netbsd/src/obj/sys/arch/amd64/compile/GENERIC",
-		kernelObject: "netbsd.gdb",
-		symbols:      symbols,
+		kernelSrc:      "netbsd/src",
+		kernelBuildSrc: "netbsd/src",
+		kernelObj:      "/netbsd/src/obj/sys/arch/amd64/compile/GENERIC",
+		kernelObject:   "netbsd.gdb",
+		symbols:        symbols,
 	}
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
diff --git a/pkg/report/openbsd.go b/pkg/report/openbsd.go
index 4bd47f865..7a0c318a5 100644
--- a/pkg/report/openbsd.go
+++ b/pkg/report/openbsd.go
@@ -17,11 +17,12 @@ import (
 )
 
 type openbsd struct {
-	kernelSrc    string
-	kernelObj    string
-	kernelObject string
-	symbols      map[string][]symbolizer.Symbol
-	ignores      []*regexp.Regexp
+	kernelSrc      string
+	kernelBuildSrc string
+	kernelObj      string
+	kernelObject   string
+	symbols        map[string][]symbolizer.Symbol
+	ignores        []*regexp.Regexp
 }
 
 var (
@@ -33,7 +34,7 @@ var (
 	}
 )
 
-func ctorOpenbsd(target *targets.Target, kernelSrc, kernelObj string,
+func ctorOpenbsd(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	var symbols map[string][]symbolizer.Symbol
 	kernelObject := ""
@@ -46,11 +47,12 @@ func ctorOpenbsd(target *targets.Target, kernelSrc, kernelObj string,
 		}
 	}
 	ctx := &openbsd{
-		kernelSrc:    kernelSrc,
-		kernelObj:    kernelObj,
-		kernelObject: kernelObject,
-		symbols:      symbols,
-		ignores:      ignores,
+		kernelSrc:      kernelSrc,
+		kernelBuildSrc: kernelBuildSrc,
+		kernelObj:      kernelObj,
+		kernelObject:   kernelObject,
+		symbols:        symbols,
+		ignores:        ignores,
 	}
 	return ctx, nil, nil
 }
@@ -124,7 +126,7 @@ func (ctx *openbsd) symbolizeLine(symbFunc func(bin string, pc uint64) ([]symbol
 	var symbolized []byte
 	for _, frame := range frames {
 		file := frame.File
-		file = strings.TrimPrefix(file, ctx.kernelSrc)
+		file = strings.TrimPrefix(file, ctx.kernelBuildSrc)
 		file = strings.TrimPrefix(file, "/")
 		info := fmt.Sprintf(" %v:%v", file, frame.Line)
 		modified := append([]byte{}, line...)
diff --git a/pkg/report/openbsd_test.go b/pkg/report/openbsd_test.go
index e8fc7dfe3..a4b3acfb1 100644
--- a/pkg/report/openbsd_test.go
+++ b/pkg/report/openbsd_test.go
@@ -82,10 +82,11 @@ func TestOpenbsdSymbolizeLine(t *testing.T) {
 		}
 	}
 	obsd := openbsd{
-		kernelSrc:    "/usr/src",
-		kernelObj:    "/usr/src/sys/arch/amd64/compile/SYZKALLER/obj",
-		kernelObject: "bsd.gdb",
-		symbols:      symbols,
+		kernelSrc:      "/usr/src",
+		kernelBuildSrc: "/usr/src",
+		kernelObj:      "/usr/src/sys/arch/amd64/compile/SYZKALLER/obj",
+		kernelObject:   "bsd.gdb",
+		symbols:        symbols,
 	}
 	for i, test := range tests {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
diff --git a/pkg/report/report.go b/pkg/report/report.go
index ffed1578e..69b604e2b 100644
--- a/pkg/report/report.go
+++ b/pkg/report/report.go
@@ -98,7 +98,7 @@ func NewReporter(cfg *mgrconfig.Config) (Reporter, error) {
 	if target == nil && typ != "gvisor" {
 		return nil, fmt.Errorf("unknown target %v/%v", cfg.TargetOS, cfg.TargetArch)
 	}
-	rep, suppressions, err := ctor(target, cfg.KernelSrc, cfg.KernelObj, ignores)
+	rep, suppressions, err := ctor(target, cfg.KernelSrc, cfg.KernelBuildSrc, cfg.KernelObj, ignores)
 	if err != nil {
 		return nil, err
 	}
@@ -125,7 +125,7 @@ var ctors = map[string]fn{
 	"windows": ctorStub,
 }
 
-type fn func(*targets.Target, string, string, []*regexp.Regexp) (Reporter, []string, error)
+type fn func(*targets.Target, string, string, string, []*regexp.Regexp) (Reporter, []string, error)
 
 func compileRegexps(list []string) ([]*regexp.Regexp, error) {
 	compiled := make([]*regexp.Regexp, len(list))
diff --git a/pkg/report/stub.go b/pkg/report/stub.go
index e7f581c08..ba6d20c2e 100644
--- a/pkg/report/stub.go
+++ b/pkg/report/stub.go
@@ -15,7 +15,7 @@ type stub struct {
 	ignores   []*regexp.Regexp
 }
 
-func ctorStub(target *targets.Target, kernelSrc, kernelObj string,
+func ctorStub(target *targets.Target, kernelSrc, kernelBuildSrc, kernelObj string,
 	ignores []*regexp.Regexp) (Reporter, []string, error) {
 	ctx := &stub{
 		kernelSrc: kernelSrc,