tools: bpftool: add simple perf event output reader

Users of BPF sooner or later discover perf_event_output() helpers
and BPF_MAP_TYPE_PERF_EVENT_ARRAY.  Dumping this array type is
not possible, however, we can add simple reading of perf events.
Create a new event_pipe subcommand for maps, this sub command
will only work with BPF_MAP_TYPE_PERF_EVENT_ARRAY maps.

Parts of the code from samples/bpf/trace_output_user.c.

Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Quentin Monnet <[email protected]>
Acked-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

1 files changed, 19 insertions, 0 deletions

diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 9c620770c6ed..32f9e397a6c0 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -331,6 +331,16 @@ char *get_fdinfo(int fd, const char *key)
 	return NULL;
 }
 
+void print_data_json(uint8_t *data, size_t len)
+{
+	unsigned int i;
+
+	jsonw_start_array(json_wtr);
+	for (i = 0; i < len; i++)
+		jsonw_printf(json_wtr, "%d", data[i]);
+	jsonw_end_array(json_wtr);
+}
+
 void print_hex_data_json(uint8_t *data, size_t len)
 {
 	unsigned int i;
@@ -421,6 +431,15 @@ void delete_pinned_obj_table(struct pinned_obj_table *tab)
 	}
 }
 
+unsigned int get_page_size(void)
+{
+	static int result;
+
+	if (!result)
+		result = getpagesize();
+	return result;
+}
+
 unsigned int get_possible_cpus(void)
 {
 	static unsigned int result;