bpf: Introduce btf_tracing_ids

Similar to btf_sock_ids, btf_tracing_ids provides btf ID for task_struct,
file, and vm_area_struct via easy to understand format like
btf_tracing_ids[BTF_TRACING_TYPE_[TASK|file|VMA]].

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211112150243.1270987-3-songliubraving@fb.com
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1aafb43..d31a031 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6147,7 +6147,7 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env,
 	callee->regs[BPF_REG_2].type = PTR_TO_BTF_ID;
 	__mark_reg_known_zero(&callee->regs[BPF_REG_2]);
 	callee->regs[BPF_REG_2].btf =  btf_vmlinux;
-	callee->regs[BPF_REG_2].btf_id = btf_task_struct_ids[2];
+	callee->regs[BPF_REG_2].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA],
 
 	/* pointer to stack or null */
 	callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];