all: support coverage of kernel modules

The PCs returned for dynamic loaded module (DLKM) is not
parsed in coverage page, these PCs are dropped.

The commit is to use DLKM modules' load address and symbol file
to restore the PC and show coverage data of DLKM.

Introduced new config module_obj to specify module directories.

Example of config:
 "module_obj": [
   "module_path1"
   "module_path2"
 ]

For linux target, before Manager.Connect run, load addresses are
getting from /proc/modules in order to group PCs into modules.
And so, if modules are under kernel_obj or module_obj dir,
their addresses and paths can be generated automatically.
kernel_obj is searched before module_obj dir and the first found
ko object is always used.

Also note that kaslr needs to be disabled.

3 files changed, 38 insertions, 0 deletions

diff --git a/pkg/host/machine_info.go b/pkg/host/machine_info.go
index 7a7cd2612..8bd706a15 100644
--- a/pkg/host/machine_info.go
+++ b/pkg/host/machine_info.go
@@ -26,9 +26,19 @@ func CollectMachineInfo() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
+func CollectModulesInfo() ([]KernelModule, error) {
+	return machineModulesInfo()
+}
+
 var machineInfoFuncs []machineInfoFunc
+var machineModulesInfo func() ([]KernelModule, error)
 
 type machineInfoFunc struct {
 	name string
 	fn   func(*bytes.Buffer) error
 }
+
+type KernelModule struct {
+	Name string
+	Addr uint64
+}
diff --git a/pkg/host/machine_info_linux.go b/pkg/host/machine_info_linux.go
index da1ee481a..eab2a1810 100644
--- a/pkg/host/machine_info_linux.go
+++ b/pkg/host/machine_info_linux.go
@@ -10,6 +10,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 )
 
@@ -18,6 +19,7 @@ func init() {
 		{"CPU Info", readCPUInfo},
 		{"KVM", readKVMInfo},
 	}
+	machineModulesInfo = getModulesInfo
 }
 
 func readCPUInfo(buffer *bytes.Buffer) error {
@@ -120,3 +122,21 @@ func readKVMInfo(buffer *bytes.Buffer) error {
 	}
 	return nil
 }
+
+func getModulesInfo() ([]KernelModule, error) {
+	var addr uint64
+	var modules []KernelModule
+	modulesText, _ := ioutil.ReadFile("/proc/modules")
+	re := regexp.MustCompile(`(\w+) .*(0[x|X][a-fA-F0-9]+)[^\n]*`)
+	matches := re.FindAllSubmatch(modulesText, -1)
+	for _, m := range matches {
+		if _, err := fmt.Sscanf(strings.TrimPrefix(strings.ToLower(string(m[2])), "0x"), "%x", &addr); err != nil {
+			return nil, fmt.Errorf("address parsing error in /proc/modules")
+		}
+		modules = append(modules, KernelModule{
+			Name: string(m[1]),
+			Addr: addr,
+		})
+	}
+	return modules, nil
+}
diff --git a/pkg/host/machine_info_linux_test.go b/pkg/host/machine_info_linux_test.go
index 5075751d5..87ebbf025 100644
--- a/pkg/host/machine_info_linux_test.go
+++ b/pkg/host/machine_info_linux_test.go
@@ -143,6 +143,14 @@ D:	d
 	}
 }
 
+func TestGetModulesInfo(t *testing.T) {
+	modules, err := getModulesInfo()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("modules:\n%v", modules)
+}
+
 type cannedTest struct {
 	arch string
 	data string