ProgramInfo.Instructions fails on parsing BTF line info

[aibor]

Describe the bug

With version 0.12.0 calling ProgramInfo.Instructions returns:

parse line info: parsing BTF line info: offset 1 is not aligned with instruction size

With 0.11.0 the method returns the Instructions as expected.

To Reproduce

Given a simple XDP program in src/src.c, that doesn't do much, but more than just returning:

__attribute__((section("xdp"), used))
int test(void *ctx) {
  return ctx == 0;
}

And a simple go test program:

package main

import (
	"testing"
)

//go:generate ./gobin/bpf2go -target bpfel test src/src.c

func TestInstructions(t *testing.T) {
	var objs testObjects
	err := loadTestObjects(&objs, nil)
	if err != nil {
		t.Fatalf("load: %v", err)
	}

	info, err := objs.Test.Info()
	if err != nil {
		t.Fatalf("info: %v", err)
	}

	ins, err := info.Instructions()
	if err != nil {
		t.Fatalf("instructions: %v", err)
	}

	t.Log(ins)
}

The test fails with:

=== RUN   TestInstructions
    main_test.go:29: instructions: parse line info: parsing BTF line info: offset 1 is not aligned with instruction size
--- FAIL: TestInstructions (0.00s)

Expected behavior

With version 0.11.0 the method does not fail and produces the output:

=== RUN   TestInstructions
    main_test.go:32: test:
        	0: MovImm dst: r0 imm: 1
        	1: JEqImm dst: r1 off: 1 imm: 0
        	2: MovImm dst: r0 imm: 0
        	3: Exit

--- PASS: TestInstructions (0.00s)

[lmb]

cc @dylandreimerink can you take a look?

[dylandreimerink]

Thanks for the report! I have it locally reproduced.

When we parse the offsets from ELF we divide the instruction offset of the line info to go from a byte offset to an instruction offset here

However, when we use the same logic to parse from the kernel we should do the reverse. Same goes for the parse functions of funcInfo and CORERelo as well