Check if tracer.delegate is set at tracer.Start to avoid tracking it (#…

…569) Co-authored-by: Eden Federman <[email protected]>
open-telemetry · Dec 31, 2023 · da00d2e · da00d2e
1 parent 4e962c0
commit da00d2e
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Showing 7 changed files with 137 additions and 2 deletions.
diff --git a/internal/pkg/inject/offset_results.json b/internal/pkg/inject/offset_results.json
@@ -1,4 +1,95 @@
 [
+  {
+    "module": "go.opentelemetry.io/otel",
+    "packages": [
+      {
+        "package": "go.opentelemetry.io/otel/internal/global",
+        "structs": [
+          {
+            "struct": "tracer",
+            "fields": [
+              {
+                "field": "delegate",
+                "offsets": [
+                  {
+                    "offset": 40,
+                    "versions": [
+                      "0.19.0",
+                      "0.20.0"
+                    ]
+                  },
+                  {
+                    "offset": 48,
+                    "versions": [
+                      "1.0.0-RC1",
+                      "1.0.0-RC2",
+                      "1.0.0-RC3",
+                      "1.0.0",
+                      "1.0.1",
+                      "1.1.0",
+                      "1.2.0",
+                      "1.3.0",
+                      "1.4.0",
+                      "1.4.1",
+                      "1.5.0",
+                      "1.6.0",
+                      "1.6.1",
+                      "1.6.2",
+                      "1.6.3",
+                      "1.7.0",
+                      "1.8.0",
+                      "1.9.0",
+                      "1.10.0",
+                      "1.11.0",
+                      "1.11.1",
+                      "1.11.2",
+                      "1.12.0",
+                      "1.13.0",
+                      "1.14.0",
+                      "1.15.0-rc.1",
+                      "1.15.0-rc.2",
+                      "1.15.0",
+                      "1.15.1",
+                      "1.16.0-rc.1",
+                      "1.16.0",
+                      "1.17.0",
+                      "1.18.0",
+                      "1.19.0-rc.1",
+                      "1.19.0"
+                    ]
+                  },
+                  {
+                    "offset": 56,
+                    "versions": [
+                      "0.14.0",
+                      "0.15.0",
+                      "0.16.0",
+                      "0.17.0",
+                      "0.18.0"
+                    ]
+                  },
+                  {
+                    "offset": 64,
+                    "versions": [
+                      "0.2.2",
+                      "0.2.3",
+                      "0.3.0",
+                      "0.4.0",
+                      "0.4.1",
+                      "0.4.2",
+                      "0.4.3",
+                      "1.20.0",
+                      "1.21.0"
+                    ]
+                  }
+                ]
+              }
+            ]
+          }
+        ]
+      }
+    ]
+  },
   {
     "module": "golang.org/x/net",
     "packages": [

diff --git a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/bpf/probe.bpf.c b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/bpf/probe.bpf.c
@@ -62,14 +62,20 @@ struct {
 } events SEC(".maps");
 
 // Injected in init
-volatile const u64 span_name_pos;
-volatile const u64 span_attributes_pos;
+volatile const u64 tracer_delegate_pos;
 
 // This instrumentation attaches uprobe to the following function:
 // func (t *tracer) Start(ctx context.Context, name string, opts ...trace.SpanStartOption) (context.Context, trace.Span)
 // https://github.com/open-telemetry/opentelemetry-go/blob/98b32a6c3a87fbee5d34c063b9096f416b250897/internal/global/trace.go#L149
 SEC("uprobe/Start")
 int uprobe_Start(struct pt_regs *ctx) {
+    void *tracer_ptr = get_argument(ctx, 1);
+    void *delegate_ptr = NULL;
+    bpf_probe_read(&delegate_ptr, sizeof(delegate_ptr), (void*)(tracer_ptr + tracer_delegate_pos));
+    if (delegate_ptr != NULL) {
+        // Delegate is set, so we should not instrument this call
+        return 0;
+    }
     struct span_name_t span_name = {0};
 
     // Getting span name

diff --git a/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go b/internal/pkg/instrumentation/bpf/go.opentelemetry.io/otel/traceglobal/probe.go
@@ -20,6 +20,7 @@ import (
 	"os"
 
 	"go.opentelemetry.io/auto/internal/pkg/instrumentation/probe"
+	"go.opentelemetry.io/auto/internal/pkg/structfield"
 
 	"github.com/cilium/ebpf/link"
 	"github.com/cilium/ebpf/perf"
@@ -87,6 +88,10 @@ func New(logger logr.Logger) probe.Probe {
 				Key: "attr_type_stringslice",
 				Val: uint64(attribute.STRINGSLICE),
 			},
+			probe.StructFieldConst{
+				Key: "tracer_delegate_pos",
+				Val: structfield.NewID("go.opentelemetry.io/otel", "go.opentelemetry.io/otel/internal/global", "tracer", "delegate"),
+			},
 		},
 		Uprobes: []probe.Uprobe[bpfObjects]{
 			{

diff --git a/internal/tools/inspect/cmd/offsetgen/main.go b/internal/tools/inspect/cmd/offsetgen/main.go
@@ -80,6 +80,11 @@ func manifests() ([]inspect.Manifest, error) {
 		return nil, fmt.Errorf("failed to get \"golang.org/x/net\" versions: %w", err)
 	}
 
+	goOtelVers, err := PkgVersions("go.opentelemetry.io/otel")
+	if err != nil {
+		return nil, fmt.Errorf("failed to get \"go.opentelemetry.io/otel\" versions: %w", err)
+	}
+
 	ren := func(src string) inspect.Renderer {
 		return inspect.NewRenderer(logger, src, inspect.DefaultFS)
 	}
@@ -140,6 +145,15 @@ func manifests() ([]inspect.Manifest, error) {
 				structfield.NewID("golang.org/x/net", "golang.org/x/net/http2", "FrameHeader", "StreamID"),
 			},
 		},
+		{
+			Application: inspect.Application{
+				Renderer: ren("templates/go.opentelemetry.io/otel/traceglobal/*.tmpl"),
+				Versions: goOtelVers,
+			},
+			StructFields: []structfield.ID{
+				structfield.NewID("go.opentelemetry.io/otel", "go.opentelemetry.io/otel/internal/global", "tracer", "delegate"),
+			},
+		},
 	}, nil
 }
 

diff --git a/internal/tools/inspect/render.go b/internal/tools/inspect/render.go
@@ -29,6 +29,7 @@ import (
 //go:embed templates/google.golang.org/grpc/*.tmpl
 //go:embed templates/net/http/*.tmpl
 //go:embed templates/runtime/*.tmpl
+//go:embed templates/go.opentelemetry.io/otel/traceglobal/*.tmpl
 var DefaultFS embed.FS
 
 // Renderer renders templates from an fs.FS.

diff --git a/internal/tools/inspect/templates/go.opentelemetry.io/otel/traceglobal/go.mod.tmpl b/internal/tools/inspect/templates/go.opentelemetry.io/otel/traceglobal/go.mod.tmpl
@@ -0,0 +1,5 @@
+module otelapp
+
+go 1.12
+
+require go.opentelemetry.io/otel {{ .Version }}
diff --git a/internal/tools/inspect/templates/go.opentelemetry.io/otel/traceglobal/main.go.tmpl b/internal/tools/inspect/templates/go.opentelemetry.io/otel/traceglobal/main.go.tmpl
@@ -0,0 +1,13 @@
+package main
+
+import (
+	"context"
+	"go.opentelemetry.io/otel"
+)
+
+var tracer = otel.Tracer("trace-example")
+
+func main() {
+	_, span := tracer.Start(context.Background(), "some name")
+	defer span.End()
+}