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/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 390176a..25ea521 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -764,7 +764,7 @@ const struct bpf_func_proto bpf_get_current_task_btf_proto = {
 	.func		= bpf_get_current_task_btf,
 	.gpl_only	= true,
 	.ret_type	= RET_PTR_TO_BTF_ID,
-	.ret_btf_id	= &btf_task_struct_ids[0],
+	.ret_btf_id	= &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
 };
 
 BPF_CALL_1(bpf_task_pt_regs, struct task_struct *, task)
@@ -779,7 +779,7 @@ const struct bpf_func_proto bpf_task_pt_regs_proto = {
 	.func		= bpf_task_pt_regs,
 	.gpl_only	= true,
 	.arg1_type	= ARG_PTR_TO_BTF_ID,
-	.arg1_btf_id	= &btf_task_struct_ids[0],
+	.arg1_btf_id	= &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
 	.ret_type	= RET_PTR_TO_BTF_ID,
 	.ret_btf_id	= &bpf_task_pt_regs_ids[0],
 };