prog_test: remove map from TestProgramInstructions

Kernels up until 4.16 return kernel pointers in the constant field of map load
instructions and don't set the source register to pseudo values correctly. This
results in an incorrect Tag value calculation on the userspace side.

Remove the use of a map fd in TestProgramInstructions to fix the test between
kernel versions 4.13 and 4.16.

Signed-off-by: Timo Beckers <timo@isovalent.com>

info.go

@@ -214,7 +214,10 @@ func (pi *ProgramInfo) Runtime() (time.Duration, bool) {
 // inspecting loaded programs for troubleshooting, dumping, etc.
 //
 // For example, map accesses are made to reference their kernel map IDs,
-// not the FDs they had when the program was inserted.
+// not the FDs they had when the program was inserted. Note that before
+// the introduction of bpf_insn_prepare_dump in kernel 4.16, xlated
+// instructions were not sanitized, making the output even less reusable
+// and less likely to round-trip or evaluate to the same program Tag.
 //
 // The first instruction is marked as a symbol using the Program's name.
 //

prog_test.go

@@ -687,17 +687,12 @@ func TestProgramBindMap(t *testing.T) {
 }
 
 func TestProgramInstructions(t *testing.T) {
-	arr := createArray(t)
-	defer arr.Close()
-
 	name := "test_prog"
 	spec := &ProgramSpec{
 		Type: SocketFilter,
 		Name: name,
 		Instructions: asm.Instructions{
 			asm.LoadImm(asm.R0, -1, asm.DWord).WithSymbol(name),
-			asm.LoadMapPtr(asm.R1, arr.FD()),
-			asm.Mov.Imm32(asm.R0, 0),
 			asm.Return(),
 		},
 		License: "MIT",