netdev - [RFC PATCH v2 06/13] bpf: Add APIs to invoke tracing programs

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Message-Id: <20210929235910.1765396-7-jevburton.kernel@gmail.com>
Date:   Wed, 29 Sep 2021 23:59:03 +0000
From:   Joe Burton <jevburton.kernel@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>
Cc:     Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Petar Penkov <ppenkov@...gle.com>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Joe Burton <jevburton@...gle.com>
Subject: [RFC PATCH v2 06/13] bpf: Add APIs to invoke tracing programs

From: Joe Burton <jevburton@...gle.com>

The macros BPF_TRACE_MAP_{K,KV} provide a convenient way to invoke
tracing programs. Maps will register themselves with a late_initcall()
then use these macros to invoke tracing programs.

Signed-off-by: Joe Burton <jevburton@...gle.com>
---
 include/linux/bpf.h    | 13 +++++++++++++
 kernel/bpf/map_trace.c | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6f7aeeedca07..73f4524c1c29 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1532,6 +1532,16 @@ struct bpf_map_trace_progs {
 	struct mutex mutex; /* protects writes to progs, length */
 };
 
+struct bpf_map_trace_ctx__update_elem {
+	__bpf_md_ptr(void *, key);
+	__bpf_md_ptr(void *, value);
+	u64 flags;
+};
+
+struct bpf_map_trace_ctx__delete_elem {
+	__bpf_md_ptr(void *, key);
+};
+
 struct bpf_map_trace_reg {
 	const char *target;
 	enum bpf_map_trace_type trace_type;
@@ -1560,6 +1570,9 @@ int bpf_map_trace_reg_target(const struct bpf_map_trace_reg *reg_info);
 int bpf_map_trace_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
 			      struct bpf_prog *prog);
 int bpf_iter_link_attach(const union bpf_attr *attr, bpfptr_t uattr, struct bpf_prog *prog);
+void bpf_trace_map_update_elem(struct bpf_map *map, void *key, void *value,
+			       u64 flags);
+void bpf_trace_map_delete_elem(struct bpf_map *map, void *key);
 int bpf_iter_new_fd(struct bpf_link *link);
 bool bpf_link_is_iter(struct bpf_link *link);
 struct bpf_prog *bpf_iter_get_info(struct bpf_iter_meta *meta, bool in_stop);
diff --git a/kernel/bpf/map_trace.c b/kernel/bpf/map_trace.c
index ed0cbc941522..77a55f8cd119 100644
--- a/kernel/bpf/map_trace.c
+++ b/kernel/bpf/map_trace.c
@@ -295,3 +295,43 @@ int bpf_map_trace_link_attach(const union bpf_attr *attr, bpfptr_t uattr,
 	return err;
 }
 
+static void bpf_map_trace_run_progs(struct bpf_map *map,
+				    enum bpf_map_trace_type trace_type,
+				    void *ctx)
+{
+	struct bpf_map_trace_prog *prog;
+
+	if (!map->trace_progs)
+		return;
+
+	rcu_read_lock();
+	migrate_disable();
+	list_for_each_entry_rcu(prog,
+				&map->trace_progs->progs[trace_type].list,
+				list) {
+		bpf_prog_run(prog->prog, ctx);  /* return code is ignored */
+	}
+	migrate_enable();
+	rcu_read_unlock();
+}
+
+void bpf_trace_map_update_elem(struct bpf_map *map,
+			       void *key, void *value, u64 flags)
+{
+	struct bpf_map_trace_ctx__update_elem ctx;
+
+	ctx.key = key;
+	ctx.value = value;
+	ctx.flags = flags;
+	bpf_map_trace_run_progs(map, BPF_MAP_TRACE_UPDATE_ELEM, &ctx);
+}
+
+void bpf_trace_map_delete_elem(struct bpf_map *map,
+			       void *key)
+{
+	struct bpf_map_trace_ctx__delete_elem ctx;
+
+	ctx.key = key;
+	bpf_map_trace_run_progs(map, BPF_MAP_TRACE_DELETE_ELEM, &ctx);
+}
+
-- 
2.33.0.685.g46640cef36-goog