From 2d3a4d0232b1502ffb49010406916bca5fe693c5 Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa@kernel.org>
Date: Tue, 20 Aug 2024 07:48:20 +0000
Subject: [PATCH] tetragon: Remove install tail call machinery

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 pkg/sensors/program/loader.go  | 43 ----------------------------------
 pkg/sensors/program/program.go | 10 --------
 2 files changed, 53 deletions(-)

diff --git a/pkg/sensors/program/loader.go b/pkg/sensors/program/loader.go
index 36ef61c2c68..ac801aff32b 100644
--- a/pkg/sensors/program/loader.go
+++ b/pkg/sensors/program/loader.go
@@ -702,44 +702,6 @@ func slimVerifierError(errStr string) string {
 	return errStr[:headEnd] + "\n...\n" + errStr[tailStart:]
 }
 
-func installTailCalls(bpfDir string, spec *ebpf.CollectionSpec, coll *ebpf.Collection, load *Program) error {
-	// FIXME(JM): This should be replaced by using the cilium/ebpf prog array initialization.
-
-	secToProgName := make(map[string]string)
-	for name, prog := range spec.Programs {
-		secToProgName[prog.SectionName] = name
-	}
-
-	install := func(pinPath string, secPrefix string) error {
-		tailCallsMap, err := ebpf.LoadPinnedMap(filepath.Join(bpfDir, pinPath), nil)
-		if err != nil {
-			return nil
-		}
-		defer tailCallsMap.Close()
-
-		for i := 0; i < 13; i++ {
-			secName := fmt.Sprintf("%s/%d", secPrefix, i)
-			if progName, ok := secToProgName[secName]; ok {
-				if prog, ok := coll.Programs[progName]; ok {
-					err := tailCallsMap.Update(uint32(i), uint32(prog.FD()), ebpf.UpdateAny)
-					if err != nil {
-						return fmt.Errorf("update of tail-call map '%s' failed: %w", pinPath, err)
-					}
-				}
-			}
-		}
-		return nil
-	}
-
-	if load.TcMap != nil {
-		if err := install(load.TcMap.PinName, load.TcPrefix); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
 func doLoadProgram(
 	bpfDir string,
 	load *Program,
@@ -883,11 +845,6 @@ func doLoadProgram(
 		}
 	}
 
-	err = installTailCalls(bpfDir, spec, coll, load)
-	if err != nil {
-		return nil, fmt.Errorf("installing tail calls failed: %s", err)
-	}
-
 	for _, mapLoad := range load.MapLoad {
 		if m, ok := coll.Maps[mapLoad.Name]; ok {
 			if err := mapLoad.Load(m, mapLoad.Index); err != nil {
diff --git a/pkg/sensors/program/program.go b/pkg/sensors/program/program.go
index e52cc796761..5b84a7b5b22 100644
--- a/pkg/sensors/program/program.go
+++ b/pkg/sensors/program/program.go
@@ -121,10 +121,6 @@ type Program struct {
 	// Type information used for CO-RE relocations.
 	KernelTypes *btf.Spec
 
-	// Tail call prefix/map
-	TcPrefix string
-	TcMap    *Map
-
 	Link link.Link
 	Prog *ebpf.Program
 
@@ -147,12 +143,6 @@ func (p *Program) SetAttachData(d interface{}) *Program {
 	return p
 }
 
-func (p *Program) SetTailCall(prefix string, m *Map) *Program {
-	p.TcPrefix = prefix
-	p.TcMap = m
-	return p
-}
-
 func (p *Program) SetPolicy(policy string) *Program {
 	p.Policy = policy
 	return p