selftests/bpf: convert get_current_cgroup_id_user to test_progs

get_current_cgroup_id_user allows testing for bpf_get_current_cgroup_id()
bpf API but is not integrated into test_progs, and so is not tested
automatically in CI.

Convert it to the test_progs framework to allow running it automatically.
The most notable differences with the old test are the following:
- the new test relies on autoattach instead of manually hooking/enabling
  the targeted tracepoint through perf_event, which reduces quite a lot the
  test code size
- it also accesses bpf prog data through global variables instead of maps
- sleep duration passed to nanosleep syscall has been reduced to its
  minimum to not impact overall CI duration (we only care about the syscall
  being properly triggered, not about the passed duration)

Signed-off-by: Alexis Lothoré (eBPF Foundation) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin KaFai Lau <[email protected]>

Author: Tropicao

tools/testing/selftests/bpf/.gitignore

@@ -19,7 +19,6 @@ test_sock
 urandom_read
 test_sockmap
 test_lirc_mode2_user
-get_cgroup_id_user
 test_skb_cgroup_id_user
 test_cgroup_storage
 test_flow_dissector

tools/testing/selftests/bpf/Makefile

@@ -67,7 +67,7 @@ endif
 
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
-	test_sock test_sockmap get_cgroup_id_user \
+	test_sock test_sockmap \
 	test_cgroup_storage \
 	test_tcpnotify_user test_sysctl \
 	test_progs-no_alu32
@@ -295,7 +295,6 @@ $(OUTPUT)/test_skb_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_sock: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_sockmap: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_tcpnotify_user: $(CGROUP_HELPERS) $(TESTING_HELPERS) $(TRACE_HELPERS)
-$(OUTPUT)/get_cgroup_id_user: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_cgroup_storage: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_sock_fields: $(CGROUP_HELPERS) $(TESTING_HELPERS)
 $(OUTPUT)/test_sysctl: $(CGROUP_HELPERS) $(TESTING_HELPERS)

tools/testing/selftests/bpf/get_cgroup_id_user.c

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include "test_progs.h"
+#include "cgroup_helpers.h"
+#include "get_cgroup_id_kern.skel.h"
+
+#define TEST_CGROUP "/test-bpf-get-cgroup-id/"
+
+void test_cgroup_get_current_cgroup_id(void)
+{
+	struct get_cgroup_id_kern *skel;
+	const struct timespec req = {
+		.tv_sec = 0,
+		.tv_nsec = 1,
+	};
+	int cgroup_fd;
+	__u64 ucgid;
+
+	cgroup_fd = cgroup_setup_and_join(TEST_CGROUP);
+	if (!ASSERT_OK_FD(cgroup_fd, "cgroup switch"))
+		return;
+
+	skel = get_cgroup_id_kern__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "load program"))
+		goto cleanup_cgroup;
+
+	if (!ASSERT_OK(get_cgroup_id_kern__attach(skel), "attach bpf program"))
+		goto cleanup_progs;
+
+	skel->bss->expected_pid = getpid();
+	/* trigger the syscall on which is attached the tested prog */
+	if (!ASSERT_OK(syscall(__NR_nanosleep, &req, NULL), "nanosleep"))
+		goto cleanup_progs;
+
+	ucgid = get_cgroup_id(TEST_CGROUP);
+
+	ASSERT_EQ(skel->bss->cg_id, ucgid, "compare cgroup ids");
+
+cleanup_progs:
+	get_cgroup_id_kern__destroy(skel);
+cleanup_cgroup:
+	close(cgroup_fd);
+	cleanup_cgroup_environment();
+}

tools/testing/selftests/bpf/prog_tests/cgroup_get_current_cgroup_id.c

@@ -4,34 +4,16 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 
-struct {
-	__uint(type, BPF_MAP_TYPE_ARRAY);
-	__uint(max_entries, 1);
-	__type(key, __u32);
-	__type(value, __u64);
-} cg_ids SEC(".maps");
-
-struct {
-	__uint(type, BPF_MAP_TYPE_ARRAY);
-	__uint(max_entries, 1);
-	__type(key, __u32);
-	__type(value, __u32);
-} pidmap SEC(".maps");
+__u64 cg_id;
+__u64 expected_pid;
 
 SEC("tracepoint/syscalls/sys_enter_nanosleep")
 int trace(void *ctx)
 {
 	__u32 pid = bpf_get_current_pid_tgid();
-	__u32 key = 0, *expected_pid;
-	__u64 *val;
-
-	expected_pid = bpf_map_lookup_elem(&pidmap, &key);
-	if (!expected_pid || *expected_pid != pid)
-		return 0;
 
-	val = bpf_map_lookup_elem(&cg_ids, &key);
-	if (val)
-		*val = bpf_get_current_cgroup_id();
+	if (expected_pid == pid)
+		cg_id = bpf_get_current_cgroup_id();
 
 	return 0;
 }