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

Adding trampolines to kallsyms. It's displayed as
  bpf_trampoline_<ID> [bpf]

where ID is the BTF id of the trampoline function.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf.h     |  3 +++
 kernel/bpf/trampoline.c | 38 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 76934893bccf..c216af89254f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h

@@ -502,6 +502,7 @@ struct bpf_trampoline {
 	/* Executable image of trampoline */
 	void *image;
 	u64 selector;
+	struct bpf_ksym ksym;
 };
 
 #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */

@@ -573,6 +574,8 @@ struct bpf_image {
 #define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image))
 bool is_bpf_image_address(unsigned long address);
 void *bpf_image_alloc(void);
+void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym);
+void bpf_image_ksym_del(struct bpf_ksym *ksym);
 /* Called only from code, so there's no need for stubs. */
 void bpf_ksym_add(struct bpf_ksym *ksym);
 void bpf_ksym_del(struct bpf_ksym *ksym);

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 6b264a92064b..4b0ae976a6eb 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c

@@ -5,6 +5,7 @@
 #include <linux/filter.h>
 #include <linux/ftrace.h>
 #include <linux/rbtree_latch.h>
+#include <linux/perf_event.h>
 
 /* dummy _ops. The verifier will operate on target program's ops. */
 const struct bpf_verifier_ops bpf_extension_verifier_ops = {

@@ -96,6 +97,22 @@ bool is_bpf_image_address(unsigned long addr)
 	return ret;
 }
 
+void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym)
+{
+	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);