selftests/bpf: Add tests for arena spin lock

Add some basic selftests for qspinlock built over BPF arena using
cond_break_label macro.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250306035431.2186189-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
new file mode 100644 (file)
index 0000000..bc3616b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/arena_spin_lock.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <network_helpers.h>
+#include <sys/sysinfo.h>
+
+struct qspinlock { int val; };
+typedef struct qspinlock arena_spinlock_t;
+
+struct arena_qnode {
+       unsigned long next;
+       int count;
+       int locked;
+};
+
+#include "arena_spin_lock.skel.h"
+
+static long cpu;
+static int repeat;
+
+pthread_barrier_t barrier;
+
+static void *spin_lock_thread(void *arg)
+{
+       int err, prog_fd = *(u32 *)arg;
+       LIBBPF_OPTS(bpf_test_run_opts, topts,
+               .data_in = &pkt_v4,
+               .data_size_in = sizeof(pkt_v4),
+               .repeat = repeat,
+       );
+       cpu_set_t cpuset;
+
+       CPU_ZERO(&cpuset);
+       CPU_SET(__sync_fetch_and_add(&cpu, 1), &cpuset);
+       ASSERT_OK(pthread_setaffinity_np(pthread_self(), sizeof(cpuset), &cpuset), "cpu affinity");
+
+       err = pthread_barrier_wait(&barrier);
+       if (err != PTHREAD_BARRIER_SERIAL_THREAD && err != 0)
+               ASSERT_FALSE(true, "pthread_barrier");
+
+       err = bpf_prog_test_run_opts(prog_fd, &topts);
+       ASSERT_OK(err, "test_run err");
+       ASSERT_EQ((int)topts.retval, 0, "test_run retval");
+
+       pthread_exit(arg);
+}
+
+static void test_arena_spin_lock_size(int size)
+{
+       LIBBPF_OPTS(bpf_test_run_opts, topts);
+       struct arena_spin_lock *skel;
+       pthread_t thread_id[16];
+       int prog_fd, i, err;
+       void *ret;
+
+       if (get_nprocs() < 2) {
+               test__skip();
+               return;
+       }
+
+       skel = arena_spin_lock__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "arena_spin_lock__open_and_load"))
+               return;
+       if (skel->data->test_skip == 2) {
+               test__skip();
+               goto end;
+       }
+       skel->bss->cs_count = size;
+       skel->bss->limit = repeat * 16;
+
+       ASSERT_OK(pthread_barrier_init(&barrier, NULL, 16), "barrier init");
+
+       prog_fd = bpf_program__fd(skel->progs.prog);
+       for (i = 0; i < 16; i++) {
+               err = pthread_create(&thread_id[i], NULL, &spin_lock_thread, &prog_fd);
+               if (!ASSERT_OK(err, "pthread_create"))
+                       goto end_barrier;
+       }
+
+       for (i = 0; i < 16; i++) {
+               if (!ASSERT_OK(pthread_join(thread_id[i], &ret), "pthread_join"))
+                       goto end_barrier;
+               if (!ASSERT_EQ(ret, &prog_fd, "ret == prog_fd"))
+                       goto end_barrier;
+       }
+
+       ASSERT_EQ(skel->bss->counter, repeat * 16, "check counter value");
+
+end_barrier:
+       pthread_barrier_destroy(&barrier);
+end:
+       arena_spin_lock__destroy(skel);
+       return;
+}
+
+void test_arena_spin_lock(void)
+{
+       repeat = 1000;
+       if (test__start_subtest("arena_spin_lock_1"))
+               test_arena_spin_lock_size(1);
+       cpu = 0;
+       if (test__start_subtest("arena_spin_lock_1000"))
+               test_arena_spin_lock_size(1000);
+       cpu = 0;
+       repeat = 100;
+       if (test__start_subtest("arena_spin_lock_50000"))
+               test_arena_spin_lock_size(50000);
+}

diff --git a/tools/testing/selftests/bpf/progs/arena_spin_lock.c b/tools/testing/selftests/bpf/progs/arena_spin_lock.c
new file mode 100644 (file)
index 0000000..c4500c3
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/arena_spin_lock.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_arena_spin_lock.h"
+
+struct {
+       __uint(type, BPF_MAP_TYPE_ARENA);
+       __uint(map_flags, BPF_F_MMAPABLE);
+       __uint(max_entries, 100); /* number of pages */
+#ifdef __TARGET_ARCH_arm64
+       __ulong(map_extra, 0x1ull << 32); /* start of mmap() region */
+#else
+       __ulong(map_extra, 0x1ull << 44); /* start of mmap() region */
+#endif
+} arena SEC(".maps");
+
+int cs_count;
+
+#if defined(ENABLE_ATOMICS_TESTS) && defined(__BPF_FEATURE_ADDR_SPACE_CAST)
+arena_spinlock_t __arena lock;
+int test_skip = 1;
+#else
+int test_skip = 2;
+#endif
+
+int counter;
+int limit;
+
+SEC("tc")
+int prog(void *ctx)
+{
+       int ret = -2;
+
+#if defined(ENABLE_ATOMICS_TESTS) && defined(__BPF_FEATURE_ADDR_SPACE_CAST)
+       unsigned long flags;
+
+       if ((ret = arena_spin_lock_irqsave(&lock, flags)))
+               return ret;
+       if (counter != limit)
+               counter++;
+       bpf_repeat(cs_count);
+       ret = 0;
+       arena_spin_unlock_irqrestore(&lock, flags);
+#endif
+       return ret;
+}
+
+char _license[] SEC("license") = "GPL";