Re: [PATCH 12/18] bpf: Add trampolines to kallsyms

On Wed, Feb 26, 2020 at 10:26:40PM -0800, Martin KaFai Lau wrote:

SNIP

quoted

+	ksym->start = (unsigned long) data;
+	ksym->end = ksym->start + BPF_IMAGE_SIZE;
+	bpf_ksym_add(ksym);
+	perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start,
+			   BPF_IMAGE_SIZE, false, ksym->name);
+}
+
+void bpf_image_ksym_del(struct bpf_ksym *ksym)
+{
+	bpf_ksym_del(ksym);
+	perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start,
+			   BPF_IMAGE_SIZE, true, ksym->name);
+}
+
 struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 {
 	struct bpf_trampoline *tr;

@@ -131,6 +148,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
 	for (i = 0; i < BPF_TRAMP_MAX; i++)
 		INIT_HLIST_HEAD(&tr->progs_hlist[i]);
 	tr->image = image;
+	INIT_LIST_HEAD_RCU(&tr->ksym.lnode);
 out:
 	mutex_unlock(&trampoline_mutex);
 	return tr;

@@ -267,6 +285,14 @@ static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(enum bpf_attach_type t)
 	}
 }
 
+static void bpf_trampoline_ksym_add(struct bpf_trampoline *tr)
+{
+	struct bpf_ksym *ksym = &tr->ksym;
+
+	snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", tr->key);

Do you have plan to support struct_ops which is also using
trampoline (in bpf_struct_ops_map_update_elem())?
Any idea on the name? bpf_struct_ops_<map_id>? 

right, I was wondering we should also do that,
I'll check on it

jirka