From f27fa68807007b0f6c0c5bab67d218588e1ec71f Mon Sep 17 00:00:00 2001
From: Florian Lehner <florian.lehner@elastic.co>
Date: Tue, 29 Oct 2024 10:45:53 +0100
Subject: [PATCH] fixup: dynamic symbol prefix lookup for kprobe

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>
---
 libpf/symbol.go  | 12 ++++++++++++
 tracer/tracer.go |  7 ++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/libpf/symbol.go b/libpf/symbol.go
index d71a5f8f..bb33af2f 100644
--- a/libpf/symbol.go
+++ b/libpf/symbol.go
@@ -6,6 +6,7 @@ package libpf // import "go.opentelemetry.io/ebpf-profiler/libpf"
 import (
 	"fmt"
 	"sort"
+	"strings"
 )
 
 // SymbolValue represents the value associated with a symbol, e.g. either an
@@ -81,6 +82,17 @@ func (symmap *SymbolMap) LookupSymbol(symbolName SymbolName) (*Symbol, error) {
 	return nil, fmt.Errorf("symbol %v not present in map", symbolName)
 }
 
+// LookupSymbolByPrefix loops over all known symbols and returns the first symbol
+// that starts with the given prefix.
+func (symmap *SymbolMap) LookupSymbolByPrefix(prefix string) (*Symbol, error) {
+	for name, sym := range symmap.nameToSymbol {
+		if strings.HasPrefix(string(name), prefix) {
+			return sym, nil
+		}
+	}
+	return nil, fmt.Errorf("no symbol not present that starts with '%s' in map", prefix)
+}
+
 // LookupSymbolAddress returns the address of a symbol.
 // Returns SymbolValueInvalid and error if not found.
 func (symmap *SymbolMap) LookupSymbolAddress(symbolName SymbolName) (SymbolValue, error) {
diff --git a/tracer/tracer.go b/tracer/tracer.go
index 34ba1819..9c8d317b 100644
--- a/tracer/tracer.go
+++ b/tracer/tracer.go
@@ -1277,7 +1277,12 @@ func (t *Tracer) StartOffCPUProfiling() error {
 		return errors.New("off-cpu program finish_task_switch is not available")
 	}
 
-	kprobeLink, err := link.Kprobe("finish_task_switch.isra.0", kprobeProg, nil)
+	kprobeSymbol, err := t.kernelSymbols.LookupSymbolByPrefix("finish_task_switch")
+	if err != nil {
+		return errors.New("failed to find kernel symbol for finish_task_switch")
+	}
+
+	kprobeLink, err := link.Kprobe(string(kprobeSymbol.Name), kprobeProg, nil)
 	if err != nil {
 		return err
 	}