selftests/bpf: Add test verifying bpf_ringbuf_reserve retval use in map ops

Add a test_ringbuf_map_key test prog, borrowing heavily from extant
test_ringbuf.c. The program tries to use the result of
bpf_ringbuf_reserve as map_key, which was not possible before previouis
commits in this series. The test runner added to prog_tests/ringbuf.c
verifies that the program loads and does basic sanity checks to confirm
that it runs as expected.

Also, refactor test_ringbuf such that runners for existing test_ringbuf
and newly-added test_ringbuf_map_key are subtests of 'ringbuf' top-level
test.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221020160721.4030492-3-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index e6cf21f..79edef1 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -359,9 +359,11 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h              \
                test_subskeleton.skel.h test_subskeleton_lib.skel.h     \
                test_usdt.skel.h
 
-LSKELS := fentry_test.c fexit_test.c fexit_sleep.c \
-       test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
-       map_ptr_kern.c core_kern.c core_kern_overflow.c
+LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c           \
+       trace_printk.c trace_vprintk.c map_ptr_kern.c                   \
+       core_kern.c core_kern_overflow.c test_ringbuf.c                 \
+       test_ringbuf_map_key.c
+
 # Generate both light skeleton and libbpf skeleton for these
 LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
        kfunc_call_test_subprog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
index 9a80fe8..ac104dc 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
@@ -13,6 +13,7 @@
 #include <linux/perf_event.h>
 #include <linux/ring_buffer.h>
 #include "test_ringbuf.lskel.h"
+#include "test_ringbuf_map_key.lskel.h"
 
 #define EDONE 7777
 
@@ -58,6 +59,7 @@ static int process_sample(void *ctx, void *data, size_t len)
        }
 }
 
+static struct test_ringbuf_map_key_lskel *skel_map_key;
 static struct test_ringbuf_lskel *skel;
 static struct ring_buffer *ringbuf;
 
@@ -81,7 +83,7 @@ static void *poll_thread(void *input)
        return (void *)(long)ring_buffer__poll(ringbuf, timeout);
 }
 
-void test_ringbuf(void)
+static void ringbuf_subtest(void)
 {
        const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample);
        pthread_t thread;
@@ -297,3 +299,65 @@ cleanup:
        ring_buffer__free(ringbuf);
        test_ringbuf_lskel__destroy(skel);
 }
+
+static int process_map_key_sample(void *ctx, void *data, size_t len)
+{
+       struct sample *s;
+       int err, val;
+
+       s = data;
+       switch (s->seq) {
+       case 1:
+               ASSERT_EQ(s->value, 42, "sample_value");
+               err = bpf_map_lookup_elem(skel_map_key->maps.hash_map.map_fd,
+                                         s, &val);
+               ASSERT_OK(err, "hash_map bpf_map_lookup_elem");
+               ASSERT_EQ(val, 1, "hash_map val");
+               return -EDONE;
+       default:
+               return 0;
+       }
+}
+
+static void ringbuf_map_key_subtest(void)
+{
+       int err;
+
+       skel_map_key = test_ringbuf_map_key_lskel__open();
+       if (!ASSERT_OK_PTR(skel_map_key, "test_ringbuf_map_key_lskel__open"))
+               return;
+
+       skel_map_key->maps.ringbuf.max_entries = getpagesize();
+       skel_map_key->bss->pid = getpid();
+
+       err = test_ringbuf_map_key_lskel__load(skel_map_key);
+       if (!ASSERT_OK(err, "test_ringbuf_map_key_lskel__load"))
+               goto cleanup;
+
+       ringbuf = ring_buffer__new(skel_map_key->maps.ringbuf.map_fd,
+                                  process_map_key_sample, NULL, NULL);
+       if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
+               goto cleanup;
+
+       err = test_ringbuf_map_key_lskel__attach(skel_map_key);
+       if (!ASSERT_OK(err, "test_ringbuf_map_key_lskel__attach"))
+               goto cleanup_ringbuf;
+
+       syscall(__NR_getpgid);
+       ASSERT_EQ(skel_map_key->bss->seq, 1, "skel_map_key->bss->seq");
+       err = ring_buffer__poll(ringbuf, -1);
+       ASSERT_EQ(err, -EDONE, "ring_buffer__poll");
+
+cleanup_ringbuf:
+       ring_buffer__free(ringbuf);
+cleanup:
+       test_ringbuf_map_key_lskel__destroy(skel_map_key);
+}
+
+void test_ringbuf(void)
+{
+       if (test__start_subtest("ringbuf"))
+               ringbuf_subtest();
+       if (test__start_subtest("ringbuf_map_key"))
+               ringbuf_map_key_subtest();
+}

diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c b/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c
new file mode 100644 (file)
index 0000000..2760bf6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf_map_key.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct sample {
+       int pid;
+       int seq;
+       long value;
+       char comm[16];
+};
+
+struct {
+       __uint(type, BPF_MAP_TYPE_RINGBUF);
+} ringbuf SEC(".maps");
+
+struct {
+       __uint(type, BPF_MAP_TYPE_HASH);
+       __uint(max_entries, 1000);
+       __type(key, struct sample);
+       __type(value, int);
+} hash_map SEC(".maps");
+
+/* inputs */
+int pid = 0;
+
+/* inner state */
+long seq = 0;
+
+SEC("fentry/" SYS_PREFIX "sys_getpgid")
+int test_ringbuf_mem_map_key(void *ctx)
+{
+       int cur_pid = bpf_get_current_pid_tgid() >> 32;
+       struct sample *sample, sample_copy;
+       int *lookup_val;
+
+       if (cur_pid != pid)
+               return 0;
+
+       sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
+       if (!sample)
+               return 0;
+
+       sample->pid = pid;
+       bpf_get_current_comm(sample->comm, sizeof(sample->comm));
+       sample->seq = ++seq;
+       sample->value = 42;
+
+       /* test using 'sample' (PTR_TO_MEM | MEM_ALLOC) as map key arg
+        */
+       lookup_val = (int *)bpf_map_lookup_elem(&hash_map, sample);
+
+       /* workaround - memcpy is necessary so that verifier doesn't
+        * complain with:
+        *   verifier internal error: more than one arg with ref_obj_id R3
+        * when trying to do bpf_map_update_elem(&hash_map, sample, &sample->seq, BPF_ANY);
+        *
+        * Since bpf_map_lookup_elem above uses 'sample' as key, test using
+        * sample field as value below
+        */
+       __builtin_memcpy(&sample_copy, sample, sizeof(struct sample));
+       bpf_map_update_elem(&hash_map, &sample_copy, &sample->seq, BPF_ANY);
+
+       bpf_ringbuf_submit(sample, 0);
+       return 0;
+}