Use common macro for Uprobe return flow

CHANGELOG.md

@@ -14,6 +14,9 @@ OpenTelemetry Go Automatic Instrumentation adheres to [Semantic Versioning](http
  It now has an additional flag indicating whether it'll build a dummy app for Go stdlib packages or not. ([#256]https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/256)
 - The function signature of `"go.opentelemetry.io/auto/offsets-tracker/target".New` has changed.
  It now accepts a flag to determine if the returned `Data` is from the Go stdlib or not. ([#256]https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/256)
+- Use UPROBE_RETURN to declare the common uprobe return logic (finding the corresponding context, setting up end time, and sending the event via perf buffer) ([#257]https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/257)
+- BASE_SPAN_PROPERTIES as common fields (start time, end time, SpanContext and ParentSpanContext) for all instrumentations events (consistent between C and Go structs). ([#257]https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/257)
+- Header guards in eBPF code. ([#257]https://github.com/open-telemetry/opentelemetry-go-instrumentation/pull/257)
 
 ### Fixed
 

include/alloc.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef _ALLOC_H_
+#define _ALLOC_H_
+
 #include "bpf_helpers.h"
 
 #define MAX_ENTRIES 50
@@ -119,3 +122,5 @@ static __always_inline void *write_target_data(void *data, s32 size)
  return NULL;
  }
 }
+
+#endif

include/arguments.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef _ARGUMENTS_H_
+#define _ARGUMENTS_H_
+
 #include "common.h"
 #include "bpf_tracing.h"
 #include "bpf_helpers.h"
@@ -80,4 +83,6 @@ static __always_inline void *get_consistent_key(struct pt_regs *ctx, void *conte
  void *ctx_ptr = 0;
  bpf_probe_read(&ctx_ptr, sizeof(ctx_ptr), contextContext);
  return ctx_ptr;
-}
+}
+
+#endif

include/go_context.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef _GO_CONTEXT_H_
+#define _GO_CONTEXT_H_
+
 #include "bpf_helpers.h"
 
 #define MAX_DISTANCE 10
@@ -83,4 +86,6 @@ static __always_inline void stop_tracking_span(struct span_context *sc) {
 
  bpf_map_delete_elem(&tracked_spans, &ctx);
  bpf_map_delete_elem(&tracked_spans_by_sc, sc);
-}
+}
+
+#endif

include/go_types.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef _GO_TYPES_H
+#define _GO_TYPES_H
+
 #include "alloc.h"
 #include "bpf_helpers.h"
 
@@ -121,4 +124,6 @@ static __always_inline void append_item_to_slice(struct go_slice *slice, void *n
  // Update len
  slice->len++;
  long success = bpf_probe_write_user(slice_user_ptr->len, &slice->len, sizeof(slice->len));
-}
+}
+
+#endif

include/span_context.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef _SPAN_CONTEXT_H_
+#define _SPAN_CONTEXT_H_
+
 #include "utils.h"
 
 #define SPAN_CONTEXT_STRING_SIZE 55
@@ -63,3 +66,5 @@ static __always_inline void w3c_string_to_span_context(char *str, struct span_co
  hex_string_to_bytes(str + trace_id_start_pos, TRACE_ID_STRING_SIZE, ctx->TraceID);
  hex_string_to_bytes(str + span_id_start_pod, SPAN_ID_STRING_SIZE, ctx->SpanID);
 }
+
+#endif

include/uprobe.h

@@ -0,0 +1,50 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef _UPROBE_H_
+#define _UPROBE_H_
+
+#include "common.h"
+#include "span_context.h"
+#include "go_context.h"
+
+#define BASE_SPAN_PROPERTIES \
+ u64 start_time; \
+ u64 end_time; \
+ struct span_context sc; \
+ struct span_context psc; 
+
+// Common flow for uprobe return:
+// 1. Find consistend key for the current uprobe context
+// 2. Use the key to lookup for the uprobe context in the uprobe_context_map
+// 3. Update the end time of the found span
+// 4. Submit the constructed event to the agent code using perf buffer events_map
+// 5. Delete the span from the uprobe_context_map
+// 6. Delete the span from the global active spans map
+#define UPROBE_RETURN(name, event_type, ctx_struct_pos, ctx_struct_offset, uprobe_context_map, events_map) \
+SEC("uprobe/##name##") \
+int uprobe_##name##_Returns(struct pt_regs *ctx) { \
+ void *req_ptr = get_argument(ctx, ctx_struct_pos); \
+ void *key = get_consistent_key(ctx, (void *)(req_ptr + ctx_struct_offset)); \
+ void *req_ptr_map = bpf_map_lookup_elem(&uprobe_context_map, &key); \
+ event_type tmpReq = {}; \
+ bpf_probe_read(&tmpReq, sizeof(tmpReq), req_ptr_map); \
+ tmpReq.end_time = bpf_ktime_get_ns(); \
+ bpf_perf_event_output(ctx, &events_map, BPF_F_CURRENT_CPU, &tmpReq, sizeof(tmpReq)); \
+ bpf_map_delete_elem(&uprobe_context_map, &key); \
+ stop_tracking_span(&tmpReq.sc); \
+ return 0; \
+}
+
+#endif

pkg/instrumentors/bpf/github.com/gin-gonic/gin/bpf/probe.bpf.c

@@ -15,6 +15,7 @@
 #include "arguments.h"
 #include "span_context.h"
 #include "go_context.h"
+#include "uprobe.h"
 
 char __license[] SEC("license") = "Dual MIT/GPL";
 
@@ -23,11 +24,9 @@ char __license[] SEC("license") = "Dual MIT/GPL";
 #define MAX_CONCURRENT 50
 
 struct http_request_t {
- u64 start_time;
- u64 end_time;
+ BASE_SPAN_PROPERTIES
  char method[METHOD_MAX_LEN];
  char path[PATH_MAX_LEN];
- struct span_context sc;
 };
 
 struct {
@@ -90,20 +89,4 @@ int uprobe_GinEngine_ServeHTTP(struct pt_regs *ctx) {
  return 0;
 }
 
-SEC("uprobe/GinEngine_ServeHTTP")
-int uprobe_GinEngine_ServeHTTP_Returns(struct pt_regs *ctx) {
- u64 request_pos = 4;
- void *req_ptr = get_argument(ctx, request_pos);
-
- // Get key
- void *key = get_consistent_key(ctx, (void *)(req_ptr + ctx_ptr_pos));
-
- void *httpReq_ptr = bpf_map_lookup_elem(&http_events, &key);
- struct http_request_t httpReq = {};
- bpf_probe_read(&httpReq, sizeof(httpReq), httpReq_ptr);
- httpReq.end_time = bpf_ktime_get_ns();
- bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &httpReq, sizeof(httpReq));
- bpf_map_delete_elem(&http_events, &key);
- stop_tracking_span(&httpReq.sc);
- return 0;
-}
+UPROBE_RETURN(GinEngine_ServeHTTP, struct http_request_t, 4, ctx_ptr_pos, http_events, events)

pkg/instrumentors/bpf/github.com/gin-gonic/gin/probe.go

@@ -45,11 +45,9 @@ const instrumentedPkg = "github.com/gin-gonic/gin"
 // Event represents an event in the gin-gonic/gin server during an HTTP
 // request-response.
 type Event struct {
- StartTime uint64
- EndTime uint64
- Method [7]byte
- Path [100]byte
- SpanContext context.EBPFSpanContext
+ context.BaseSpanProperties
+ Method [7]byte
+ Path [100]byte
 }
 
 // Instrumentor is the gin-gonic/gin instrumentor.

pkg/instrumentors/bpf/github.com/gin-gonic/gin/probe_test.go

@@ -36,13 +36,15 @@ func TestInstrumentorConvertEvent(t *testing.T) {
 
  i := New()
  got := i.convertEvent(&Event{
- StartTime: uint64(start.UnixNano()),
- EndTime: uint64(end.UnixNano()),
+ BaseSpanProperties: context.BaseSpanProperties{
+ StartTime: uint64(start.UnixNano()),
+ EndTime: uint64(end.UnixNano()),
+ SpanContext: context.EBPFSpanContext{TraceID: traceID, SpanID: spanID},
+ },
  // "GET"
  Method: [7]byte{0x47, 0x45, 0x54},
  // "/foo/bar"
- Path: [100]byte{0x2f, 0x66, 0x6f, 0x6f, 0x2f, 0x62, 0x61, 0x72},
- SpanContext: context.EBPFSpanContext{TraceID: traceID, SpanID: spanID},
+ Path: [100]byte{0x2f, 0x66, 0x6f, 0x6f, 0x2f, 0x62, 0x61, 0x72},
  })
 
  sc := trace.NewSpanContext(trace.SpanContextConfig{

pkg/instrumentors/bpf/github.com/gorilla/mux/bpf/probe.bpf.c

@@ -15,6 +15,7 @@
 #include "arguments.h"
 #include "span_context.h"
 #include "go_context.h"
+#include "uprobe.h"
 
 char __license[] SEC("license") = "Dual MIT/GPL";
 
@@ -23,11 +24,9 @@ char __license[] SEC("license") = "Dual MIT/GPL";
 #define MAX_CONCURRENT 50
 
 struct http_request_t {
- u64 start_time;
- u64 end_time;
+ BASE_SPAN_PROPERTIES
  char method[METHOD_MAX_LEN];
  char path[PATH_MAX_LEN];
- struct span_context sc;
 };
 
 struct {
@@ -90,20 +89,4 @@ int uprobe_GorillaMux_ServeHTTP(struct pt_regs *ctx) {
  return 0;
 }
 
-SEC("uprobe/GorillaMux_ServeHTTP")
-int uprobe_GorillaMux_ServeHTTP_Returns(struct pt_regs *ctx) {
- u64 request_pos = 4;
- void* req_ptr = get_argument(ctx, request_pos);
-
- // Get key
- void *key = get_consistent_key(ctx, (void *)(req_ptr + ctx_ptr_pos));
-
- void *httpReq_ptr = bpf_map_lookup_elem(&http_events, &key);
- struct http_request_t httpReq = {};
- bpf_probe_read(&httpReq, sizeof(httpReq), httpReq_ptr);
- httpReq.end_time = bpf_ktime_get_ns();
- bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, &httpReq, sizeof(httpReq));
- bpf_map_delete_elem(&http_events, &key);
- stop_tracking_span(&httpReq.sc);
- return 0;
-}
+UPROBE_RETURN(GorillaMux_ServeHTTP, struct http_request_t, 4, ctx_ptr_pos, http_events, events)

pkg/instrumentors/bpf/github.com/gorilla/mux/probe.go

@@ -44,11 +44,9 @@ const instrumentedPkg = "github.com/gorilla/mux"
 // Event represents an event in the gorilla/mux server during an HTTP
 // request-response.
 type Event struct {
- StartTime uint64
- EndTime uint64
- Method [7]byte
- Path [100]byte
- SpanContext context.EBPFSpanContext
+ context.BaseSpanProperties
+ Method [7]byte
+ Path [100]byte
 }
 
 // Instrumentor is the gorilla/mux instrumentor.

pkg/instrumentors/bpf/github.com/gorilla/mux/probe_test.go

@@ -36,13 +36,15 @@ func TestInstrumentorConvertEvent(t *testing.T) {
 
  i := New()
  got := i.convertEvent(&Event{
- StartTime: uint64(start.UnixNano()),
- EndTime: uint64(end.UnixNano()),
+ BaseSpanProperties: context.BaseSpanProperties{
+ StartTime: uint64(start.UnixNano()),
+ EndTime: uint64(end.UnixNano()),
+ SpanContext: context.EBPFSpanContext{TraceID: traceID, SpanID: spanID},
+ },
  // "GET"
  Method: [7]byte{0x47, 0x45, 0x54},
  // "/foo/bar"
- Path: [100]byte{0x2f, 0x66, 0x6f, 0x6f, 0x2f, 0x62, 0x61, 0x72},
- SpanContext: context.EBPFSpanContext{TraceID: traceID, SpanID: spanID},
+ Path: [100]byte{0x2f, 0x66, 0x6f, 0x6f, 0x2f, 0x62, 0x61, 0x72},
  })
 
  sc := trace.NewSpanContext(trace.SpanContextConfig{