wip: try to resolve symbols

Signed-off-by: Massimiliano Giovagnoli <me@maxgio.it>

README.md

@@ -0,0 +1,8 @@
+## Quickstart
+
+```shell
+$ go build ./toy_app/toy.go -o ./toy_app/toy
+./toy_app/toy &
+[1] 591488
+$ sudo go run ./main.go --pid 591488 --duration 10
+```

go.mod

@@ -1,11 +1,10 @@
 module github.com/maxgio92/perf-profiler-go
 
-go 1.20
+go 1.21.1
 
 require (
-	github.com/iovisor/gobpf v0.2.1-0.20221005153822-16120a1bf4d4
+	github.com/maxgio92/gobpf v0.0.0-20231021162119-ff4afec32fd2
 	github.com/pkg/errors v0.9.1
-	github.com/tklauser/numcpus v0.6.1
-	golang.org/x/sys v0.8.0
-	modernc.org/libc v1.22.6
+	golang.org/x/sys v0.13.0
+	modernc.org/libc v1.27.0
 )

go.sum

@@ -1,10 +1,8 @@
-github.com/iovisor/gobpf v0.2.1-0.20221005153822-16120a1bf4d4 h1:WpizD4VUT5V+VcaQSvW5BlvFpQYrd2974H9KbiGa5/0=
-github.com/iovisor/gobpf v0.2.1-0.20221005153822-16120a1bf4d4/go.mod h1:WSY9Jj5RhdgC3ci1QaacvbFdQ8cbrEjrpiZbLHLt2s4=
+github.com/maxgio92/gobpf v0.0.0-20231021162119-ff4afec32fd2 h1:ykUIr/kZLiGMlQFYZQBiJLtQYB7cMfvUaADuwPP1J5M=
+github.com/maxgio92/gobpf v0.0.0-20231021162119-ff4afec32fd2/go.mod h1:4LyFQGAyzW0qdThO5Chz+Ay9mbITSh5WVUUYw6x3uk8=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
-github.com/tklauser/numcpus v0.6.1 h1:ng9scYS7az0Bk4OZLvrNXNSAO2Pxr1XXRAPyjhIx+Fk=
-github.com/tklauser/numcpus v0.6.1/go.mod h1:1XfjsgE2zo8GVw7POkMbHENHzVg3GzmoZ9fESEdAacY=
-golang.org/x/sys v0.8.0 h1:EBmGv8NaZBZTWvrbjNoL6HVt+IVy3QDQpJs7VRIw3tU=
-golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-modernc.org/libc v1.22.6 h1:cbXU8R+A6aOjRuhsFh3nbDWXO/Hs4ClJRXYB11KmPDo=
-modernc.org/libc v1.22.6/go.mod h1:jj+Z7dTNX8fBScMVNRAYZ/jF91K8fdT2hYMThc3YjBY=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+modernc.org/libc v1.27.0 h1:Z35IJO5v46n+d1RWRzCD3CiMYYc9TotabBDl75kRmdo=
+modernc.org/libc v1.27.0/go.mod h1:DaG/4Q3LRRdqpiLyP0C2m1B8ZMGkQ+cCgOIjEtQlYhQ=

kernel/perf_profiler.bpf.c

@@ -26,7 +26,8 @@ const int kNumMapEntries = 65536;
 BPF_STACK_TRACE(stack_traces, kNumMapEntries);
 
 /*
-// libbpf way
+ * libbpf way
+ *
 struct {
   __uint(type, BPF_MAP_TYPE_STACK_TRACE);
   __uint(max_entries, kNumMapEntries);
@@ -39,7 +40,8 @@ struct {
 BPF_HASH(histogram, struct stack_trace_key_t, uint64_t, kNumMapEntries);
 
 /*
-// libbpf way
+ * libbpf way
+ *
 struct {
   __uint(type, BPF_MAP_TYPE_HASH);
   __uint(max_entries, kNumMapEntries);
@@ -62,33 +64,47 @@ int sample_stack_trace(struct bpf_perf_event_data* ctx) {
   key.user_stack_id = user_stack_id;
   key.kernel_stack_id = kernel_stack_id;
 
-  // BCC way
-  //u64 zero = 0;
-  //histogram.lookup_or_try_init(&key, &zero);
+  /*
+   * BCC way
+   *
+  u64 zero = 0;
+  histogram.lookup_or_try_init(&key, &zero);
+  */
   histogram.atomic_increment(key);
 
-  //// libbpf wa*y
-  //u64* count = bpf_map_lookup_elem(&histogram, &key);
-  //if(count){
-  //   u64 c = *count;
-  //   c++;
-  //   bpf_map_update_elem(&histogram, &key, &c, BPF_EXIST);
-  //}else{
-  //   u64 one = 1;
-  //   bpf_map_update_elem(&histogram, &key, &one, BPF_NOEXIST);
-  //}
-
-  // DEBUG
-  //bpf_trace_printk("Stack trace id: tgid %d\n", sizeof("Stack trace id: tgid %d\n"), key.pid);
-  //bpf_trace_printk("Stack trace id: user stack id %d - kernel stack id %d \n", sizeof("Stack trace id: user stack id %d - kernel stack id %d \n"), key.user_stack_id);
+  /*
+   * libbpf way
+   *
+  u64* count = bpf_map_lookup_elem(&histogram, &key);
+  if(count){
+     u64 c = *count;
+     c++;
+     bpf_map_update_elem(&histogram, &key, &c, BPF_EXIST);
+  }else{
+     u64 one = 1;
+     bpf_map_update_elem(&histogram, &key, &one, BPF_NOEXIST);
+  }
+  */
+
+  /*
+   * DEBUG
+   *
+  bpf_trace_printk("Stack trace id: tgid %d\n", sizeof("Stack trace id: tgid %d\n"), key.pid);
+  bpf_trace_printk("Stack trace id: user stack id %d - kernel stack id %d \n", sizeof("Stack trace id: user stack id %d - kernel stack id %d \n"), key.user_stack_id);
   bpf_trace_printk("Key: Current tgid %d;", (u64)pid);
   bpf_trace_printk("Key: User stack id is %d;", (u64)user_stack_id);
   bpf_trace_printk("Key: Kernel stack id is %d;", (u64)kernel_stack_id);
+  */
 
   u64 *count = histogram.lookup(&key);
+
+  /*
+   * DEBUG
+   *
   if (count) {
     bpf_trace_printk("Stack trace count is %llu\n", (u64*)*count);
   }
+  */
 
   return 0;
 }

main.go

@@ -6,13 +6,13 @@ import (
 	"encoding/binary"
 	"flag"
 	"fmt"
-	"github.com/iovisor/gobpf/bcc"
-	"github.com/iovisor/gobpf/pkg/ksym"
+	"os"
+	"time"
+
+	"github.com/maxgio92/gobpf/bcc"
 	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 	libc "modernc.org/libc/sys/types"
-	"os"
-	"time"
 
 	. "github.com/maxgio92/perf-profiler-go/internal/utils"
 )
@@ -23,18 +23,18 @@ type Options struct {
 }
 
 type HistogramKey struct {
-	Pid libc.Pid_t
+	Pid int32
 
 	// UserStackId, an index into the stack-traces map.
-	UserStackId libc.U_int32_t
+	UserStackId uint32
 
 	// KernelStackId, an index into the stack-traces map.
-	KernelStackId libc.U_int32_t
+	KernelStackId uint32
 }
 
 // StackTrace is an array of instruction pointers (IP).
 // 127 is the size of the trace, as for the default PERF_MAX_STACK_DEPTH.
-type StackTrace [127]libc.Ulong
+type StackTrace [127]uint64
 
 const (
 	probeFile = "kernel/perf_profiler.bpf.c"
@@ -45,8 +45,7 @@ const (
 
 	samplingPeriodMillis = 11
 
-	userSymUnknown   = "[USER_UNKNOWN]"
-	kernelSymUnknown = "[KERN_UNKNOWN]"
+	symUnknown = "[UNKNOWN]"
 )
 
 func main() {
@@ -127,7 +126,8 @@ func main() {
 
 	time.Sleep(time.Duration(o.duration) * time.Second)
 
-	fmt.Println("Stack trace histogram map")
+	fmt.Printf("PID\t\tTIMES\tKERNEL STACK ID\tKERNEL STACK TRACE\tUSER STACK ID\tUSER STACK TRACE\n")
+
 	for it := histogram.Iter(); it.Next(); {
 		histogramKeyBin := it.Key()
 		count := it.Leaf()
@@ -142,27 +142,27 @@ func main() {
 
 		var symbolsStr string
 
-		fmt.Printf("\tmatched stack trace executed %d times\n\t\tpid: %v\n",
-			binary.LittleEndian.Uint64(count), histogramKey.Pid)
+		fmt.Printf("%v\t%v\t\t", histogramKey.Pid, binary.LittleEndian.Uint64(count))
 
-		fmt.Printf("\t\tkernel stack id: %v\n", histogramKey.KernelStackId)
+		fmt.Printf("%v\t\t", histogramKey.KernelStackId)
 
-		// Check if the trace is of kernel or user stack.
 		if histogramKey.KernelStackId != 0 {
 			stackTrace, err := getStackTrace(stackTraces, histogramKey.KernelStackId)
 			if err == nil && stackTrace != nil {
-				symbolsStr += getStackTraceSyms(stackTrace, kernelSymUnknown)
+				symbolsStr += getStackTraceSyms(bpfModule, int(histogramKey.Pid), stackTrace, false)
 			}
 		}
-		fmt.Printf("\t\tuser stack id: %v\n", histogramKey.UserStackId)
+		fmt.Printf("%v\t\t\t", histogramKey.UserStackId)
 
 		if histogramKey.UserStackId != 0 {
 			stackTrace, err := getStackTrace(stackTraces, histogramKey.UserStackId)
 			if err == nil && stackTrace != nil {
-				symbolsStr += getStackTraceSyms(stackTrace, userSymUnknown)
+				symbolsStr += getStackTraceSyms(bpfModule, int(histogramKey.Pid), stackTrace, true)
 			}
 		}
 
+		fmt.Printf("\n")
+
 		// Increment the result map value for the histogramKey stack symbol string (e.g. "main;subfunc;")
 		result[symbolsStr]++
 	}
@@ -186,18 +186,26 @@ func getStackTrace(stackTracesMap *bcc.Table, id libc.U_int32_t) (*StackTrace, e
 	return &stackTrace, nil
 }
 
-func getStackTraceSyms(stackTrace *StackTrace, unknown string) string {
+func getStackTraceSyms(module *bcc.Module, pid int, stackTrace *StackTrace, user bool) string {
 	var symbolsStr string
+	if !user {
+		pid = -1
+	}
 	for _, ip := range stackTrace {
 		if ip != 0 {
-			sym, err := ksym.Ksym(fmt.Sprintf("%016x", ip))
-			if err != nil {
-				sym = unknown
+			sym := module.GetSymbolByAddr(ip, pid)
+			if sym == "" {
+				sym = symUnknown
+				fmt.Printf("%#016x %s; ", ip, sym)
+			} else {
+				fmt.Printf("%s; ", sym)
 			}
-			fmt.Printf("\t\t\t%#016x\t%s\n", ip, sym)
 			symbolsStr += sym
 			symbolsStr += ";"
 		}
 	}
+
+	fmt.Printf("\t")
+
 	return symbolsStr
 }

toy_app/README.md

@@ -0,0 +1,8 @@
+## Stack walking
+
+```
+dlv debug ./toy.go
+(dlv) source stackannotate.star
+(dlv) continue toy.go:60
+(dlv) stackannotate
+```