The ctx position in return probe might be incorrect

[minimAluminiumalism]

This issue has already been mentioned in Slack, and it is posted here to track progress.

In the database/sql instrumentation, I found two pieces of code:
https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/e6f3f3cab8[…]2/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c

get_Go_context(ctx, 2, 0, true, &go_context);

https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/e6f3f3cab8[…]2/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c

UPROBE_RETURN(queryDC, struct sql_request_t, sql_events, events, 3, 0, true)

In the entry probe, the context_pos is 2, but in the return probe the context_pos is 3? I suppose the position in the return probe is also 2?

Although I believe there is an error of ctx pos, currently the functionality is still working properly.

[MrAlias]

This is working for versions of Go > 1.17 where the context is not used to get a consistent eBPF map key.

[MrAlias]

Verified this is incorrect.

Test

Update the database end-to-end test to use Go < 1.17 (see #1771 also)

diff --git a/internal/test/e2e/databasesql/Dockerfile b/internal/test/e2e/databasesql/Dockerfile
index a50dfc75..48551411 100644
--- a/internal/test/e2e/databasesql/Dockerfile
+++ b/internal/test/e2e/databasesql/Dockerfile
@@ -1,4 +1,4 @@
-FROM golang:1.23.6@sha256:927112936d6b496ed95f55f362cc09da6e3e624ef868814c56d55bd7323e0959
+FROM golang:1.16

 # pre-copy/cache go.mod for pre-downloading dependencies and only redownloading
 # them in subsequent builds if they change
diff --git a/internal/test/e2e/databasesql/go.mod b/internal/test/e2e/databasesql/go.mod
index bb73bb66..ca339c81 100644
--- a/internal/test/e2e/databasesql/go.mod
+++ b/internal/test/e2e/databasesql/go.mod
@@ -1,5 +1,5 @@
 module go.opentelemetry.io/auto/internal/test/e2e/databasesql

-go 1.22.0
+go 1.16

-require github.com/mattn/go-sqlite3 v1.14.24
+require github.com/mattn/go-sqlite3 v1.14.1
diff --git a/internal/test/e2e/databasesql/go.sum b/internal/test/e2e/databasesql/go.sum
index 9dcdc9b6..49dee20a 100644
--- a/internal/test/e2e/databasesql/go.sum
+++ b/internal/test/e2e/databasesql/go.sum
@@ -1,2 +1,11 @@
-github.com/mattn/go-sqlite3 v1.14.24 h1:tpSp2G2KyMnnQu99ngJ47EIkWVmliIizyZBfPrBWDRM=
-github.com/mattn/go-sqlite3 v1.14.24/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
+github.com/PuerkitoBio/goquery v1.5.1/go.mod h1:GsLWisAFVj4WgDibEWF4pvYnkVQBpKBKeU+7zCJoLcc=
+github.com/andybalholm/cascadia v1.1.0/go.mod h1:GsXiBklL0woXo1j/WYWtSYYC4ouU9PqHO0sqidkEA4Y=
+github.com/mattn/go-sqlite3 v1.14.1 h1:AHx9Ra40wIzl+GelgX2X6AWxmT5tfxhI1PL0523HcSw=
+github.com/mattn/go-sqlite3 v1.14.1/go.mod h1:JIl7NbARA7phWnGvh0LKTyg7S9BA+6gx71ShQilpsus=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20180218175443-cbe0f9307d01/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20200202094626-16171245cfb2/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/internal/test/e2e/databasesql/main.go b/internal/test/e2e/databasesql/main.go
index 67d83655..29471066 100644
--- a/internal/test/e2e/databasesql/main.go
+++ b/internal/test/e2e/databasesql/main.go
@@ -7,7 +7,7 @@ import (
        "database/sql"
        "fmt"
        "io"
-       "log/slog"
+       "log"
        "net/http"
        "os"
        "time"
@@ -80,11 +80,11 @@ func (s *Server) query(w http.ResponseWriter, req *http.Request, query string) {

        rows, err := conn.QueryContext(req.Context(), query)
        if err != nil {
-               slog.Error("query failed", "query", query, "error", err)
+               log.Println("query failed", "query", query, "error", err)
                return
        }

-       slog.Info("queryDB called", "query", query)
+       log.Println("queryDB called", "query", query)
        for rows.Next() {
                var id int
                var firstName string
@@ -125,7 +125,7 @@ func (s *Server) invalid(w http.ResponseWriter, req *http.Request) {

 func main() {
        port := fmt.Sprintf(":%d", 8080)
-       slog.Info("starting http server", "port", port)
+       log.Println("starting http server", "port", port)

        s := NewServer()

@@ -156,14 +156,14 @@ func main() {
        for _, t := range tests {
                resp, err := http.Get(t.url)
                if err != nil {
-                       slog.Error("failed GET", "error", err)
+                       log.Println("failed GET", "error", err)
                }
                if resp != nil {
                        body, err := io.ReadAll(resp.Body)
                        if err != nil {
-                               slog.Error("failed to read HTTP body", "error", err)
+                               log.Println("failed to read HTTP body", "error", err)
                        }
-                       slog.Info("request successful", "body", string(body[:]))
+                       log.Println("request successful", "body", string(body[:]))
                        _ = resp.Body.Close()
                }
        }

Run the test: make fixture-databasesql.

The output will be missing the database spans:

   @@ -49,165 +49,6 @@
          },
          "schemaUrl": "https://opentelemetry.io/schemas/1.26.0",
          "scopeSpans": [
   -        {
   -          "schemaUrl": "https://opentelemetry.io/schemas/1.26.0",
   -          "scope": {
   -            "name": "go.opentelemetry.io/auto/database/sql",
   -            "version": "v0.20.0"
   -          },
   -          "spans": [
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "SELECT * FROM contacts"
   -                  }
   -                },
   -                {
   -                  "key": "db.operation.name",
   -                  "value": {
   -                    "stringValue": "SELECT"
   -                  }
   -                },
   -                {
   -                  "key": "db.collection.name",
   -                  "value": {
   -                    "stringValue": "contacts"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "SELECT contacts",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            },
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "INSERT INTO contacts (first_name) VALUES ('Mike')"
   -                  }
   -                },
   -                {
   -                  "key": "db.operation.name",
   -                  "value": {
   -                    "stringValue": "INSERT"
   -                  }
   -                },
   -                {
   -                  "key": "db.collection.name",
   -                  "value": {
   -                    "stringValue": "contacts"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "INSERT contacts",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            },
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "UPDATE contacts SET last_name = 'Santa' WHERE first_name = 'Mike'"
   -                  }
   -                },
   -                {
   -                  "key": "db.operation.name",
   -                  "value": {
   -                    "stringValue": "UPDATE"
   -                  }
   -                },
   -                {
   -                  "key": "db.collection.name",
   -                  "value": {
   -                    "stringValue": "contacts"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "UPDATE contacts",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            },
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "DELETE FROM contacts WHERE first_name = 'Mike'"
   -                  }
   -                },
   -                {
   -                  "key": "db.operation.name",
   -                  "value": {
   -                    "stringValue": "DELETE"
   -                  }
   -                },
   -                {
   -                  "key": "db.collection.name",
   -                  "value": {
   -                    "stringValue": "contacts"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "DELETE contacts",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            },
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "DROP TABLE contacts"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "DB",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            },
   -            {
   -              "attributes": [
   -                {
   -                  "key": "db.query.text",
   -                  "value": {
   -                    "stringValue": "syntax error"
   -                  }
   -                }
   -              ],
   -              "flags": 256,
   -              "kind": 3,
   -              "name": "DB",
   -              "parentSpanId": "xxxxx",
   -              "spanId": "xxxxx",
   -              "status": {},
   -              "traceId": "xxxxx"
   -            }
   -          ]
   -        },

Change the arg position:

diff --git a/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c b/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c
index 9ef6086d..a814e1d4 100644
--- a/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c
+++ b/internal/pkg/instrumentation/bpf/database/sql/bpf/probe.bpf.c
@@ -69,7 +69,7 @@ int uprobe_queryDC(struct pt_regs *ctx) {

 // This instrumentation attaches uprobe to the following function:
 // func (db *DB) queryDC(ctx, txctx context.Context, dc *driverConn, releaseConn func(error), query string, args []any)
-UPROBE_RETURN(queryDC, struct sql_request_t, sql_events, events, 3, 0, true)
+UPROBE_RETURN(queryDC, struct sql_request_t, sql_events, events, 2, 0, true)

 // This instrumentation attaches uprobe to the following function:
 // func (db *DB) execDC(ctx context.Context, dc *driverConn, release func(error), query string, args []any)

Re-run the end-to-end test and the expected spans are now exported.