Re: [PATCH bpf-next v6 10/10] selftests/bpf: test case for register_bpf_struct_ops().

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On 10/26/23 21:55, Kui-Feng Lee wrote:


On 10/26/23 13:31, Eduard Zingerman wrote:
On Sat, 2023-10-21 at 22:03 -0700, thinker.li@xxxxxxxxx wrote:
From: Kui-Feng Lee <thinker.li@xxxxxxxxx>

Create a new struct_ops type called bpf_testmod_ops within the bpf_testmod module. When a struct_ops object is registered, the bpf_testmod module will
invoke test_2 from the module.

Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>

Hello,

Sorry for the late response, was moving through the patch-set very slowly. Please note that CI currently fails for this series [0], reported error is:

testing_helpers.c:13:10: fatal error: 'rcu_tasks_trace_gp.skel.h' file not found
    13 | #include "rcu_tasks_trace_gp.skel.h"
       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~

Thank! I will fix this dependency issue.


I get the same error when try to run tests locally (after full clean).
On the other hand it looks like `kern_sync_rcu_tasks_trace` changes
are not really necessary, when I undo these changes but keep changes in:

- .../selftests/bpf/bpf_testmod/bpf_testmod.c
- .../selftests/bpf/bpf_testmod/bpf_testmod.h
- .../bpf/prog_tests/test_struct_ops_module.c
- .../selftests/bpf/progs/struct_ops_module.c

struct_ops_module/regular_load test still passes.


The test will pass even without this change.
But, the test harness may complain by showing warnings.
You may see an additional warning message without this change.


One thing forgot to mentioned. The test harness may fail to unload
the bpf_testmod module.


Regarding assertion:

+    ASSERT_EQ(skel->bss->test_2_result, 7, "test_2_result");

Could you please leave a comment explaining why the value is 7?
I don't understand what invokes 'test_2' but changing it to 8
forces test to fail, so something does call 'test_2' :)

It is called by bpf_dummy_reg() in bpf_testmod.c.
I will add a comment here.


Also, when running test_maps I get the following error:

libbpf: bpf_map_create_opts has non-zero extra bytes
map_create_opts(317):FAIL:bpf_map_create() error:Invalid argument (name=hash_of_maps)

It looks like a padding issue. I will check it.


[0] https://patchwork.kernel.org/project/netdevbpf/patch/20231022050335.2579051-11-thinker.li@xxxxxxxxx/      (look for 'Logs for x86_64-gcc / build / build for x86_64 with gcc ')

---
  tools/testing/selftests/bpf/Makefile          |  2 +
  .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 59 +++++++++++++++++++
  .../selftests/bpf/bpf_testmod/bpf_testmod.h   |  5 ++
  .../bpf/prog_tests/test_struct_ops_module.c   | 38 ++++++++++++
  .../selftests/bpf/progs/struct_ops_module.c   | 30 ++++++++++
  tools/testing/selftests/bpf/testing_helpers.c | 35 +++++++++++
  6 files changed, 169 insertions(+)
  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c   create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_module.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index caede9b574cb..dd7ff14e1fdf 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -706,6 +706,8 @@ $(OUTPUT)/uprobe_multi: uprobe_multi.c
      $(call msg,BINARY,,$@)
      $(Q)$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@
+$(OUTPUT)/testing_helpers.o: $(OUTPUT)/rcu_tasks_trace_gp.skel.h
+
  EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)    \
      prog_tests/tests.h map_tests/tests.h verifier/tests.h        \
      feature bpftool                            \
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index cefc5dd72573..f1a20669d884 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -1,5 +1,6 @@
  // SPDX-License-Identifier: GPL-2.0
  /* Copyright (c) 2020 Facebook */
+#include <linux/bpf.h>
  #include <linux/btf.h>
  #include <linux/btf_ids.h>
  #include <linux/error-injection.h>
@@ -517,11 +518,66 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_static_unused_arg)
  BTF_ID_FLAGS(func, bpf_kfunc_call_test_offset)
  BTF_SET8_END(bpf_testmod_check_kfunc_ids)
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+
+DEFINE_STRUCT_OPS_VALUE_TYPE(bpf_testmod_ops);
+
+static int bpf_testmod_ops_init(struct btf *btf)
+{
+    return 0;
+}
+
+static bool bpf_testmod_ops_is_valid_access(int off, int size,
+                        enum bpf_access_type type,
+                        const struct bpf_prog *prog,
+                        struct bpf_insn_access_aux *info)
+{
+    return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
+}
+
+static int bpf_testmod_ops_init_member(const struct btf_type *t,
+                       const struct btf_member *member,
+                       void *kdata, const void *udata)
+{
+    return 0;
+}
+
  static const struct btf_kfunc_id_set bpf_testmod_kfunc_set = {
      .owner = THIS_MODULE,
      .set   = &bpf_testmod_check_kfunc_ids,
  };
+static const struct bpf_verifier_ops bpf_testmod_verifier_ops = {
+    .is_valid_access = bpf_testmod_ops_is_valid_access,
+};
+
+static int bpf_dummy_reg(void *kdata)
+{
+    struct bpf_testmod_ops *ops = kdata;
+    int r;
+
+    BTF_STRUCT_OPS_TYPE_EMIT(bpf_testmod_ops);
+    r = ops->test_2(4, 3);
+
+    return 0;
+}
+
+static void bpf_dummy_unreg(void *kdata)
+{
+}
+
+struct bpf_struct_ops bpf_bpf_testmod_ops = {
+    .verifier_ops = &bpf_testmod_verifier_ops,
+    .init = bpf_testmod_ops_init,
+    .init_member = bpf_testmod_ops_init_member,
+    .reg = bpf_dummy_reg,
+    .unreg = bpf_dummy_unreg,
+    .name = "bpf_testmod_ops",
+    .owner = THIS_MODULE,
+};
+
+#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
+
  extern int bpf_fentry_test1(int a);
  static int bpf_testmod_init(void)
@@ -532,6 +588,9 @@ static int bpf_testmod_init(void)
      ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_testmod_kfunc_set);       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_testmod_kfunc_set);       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_testmod_kfunc_set);
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+    ret = ret ?: register_bpf_struct_ops(&bpf_bpf_testmod_ops);
+#endif
      if (ret < 0)
          return ret;
      if (bpf_fentry_test1(0) < 0)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index f32793efe095..ca5435751c79 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -28,4 +28,9 @@ struct bpf_iter_testmod_seq {
      int cnt;
  };
+struct bpf_testmod_ops {
+    int (*test_1)(void);
+    int (*test_2)(int a, int b);
+};
+
  #endif /* _BPF_TESTMOD_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
new file mode 100644
index 000000000000..7261fc6c377a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_module.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <time.h>
+
+#include "rcu_tasks_trace_gp.skel.h"
+#include "struct_ops_module.skel.h"
+
+static void test_regular_load(void)
+{
+    struct struct_ops_module *skel;
+    struct bpf_link *link;
+    DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
+    int err;
+
+    skel = struct_ops_module__open_opts(&opts);
+    if (!ASSERT_OK_PTR(skel, "struct_ops_module_open"))
+        return;
+    err = struct_ops_module__load(skel);
+    if (!ASSERT_OK(err, "struct_ops_module_load"))
+        return;
+
+    link = bpf_map__attach_struct_ops(skel->maps.testmod_1);
+    ASSERT_OK_PTR(link, "attach_test_mod_1");
+
+    ASSERT_EQ(skel->bss->test_2_result, 7, "test_2_result");
+
+    bpf_link__destroy(link);
+
+    struct_ops_module__destroy(skel);
+}
+
+void serial_test_struct_ops_module(void)
+{
+    if (test__start_subtest("regular_load"))
+        test_regular_load();
+}
+
diff --git a/tools/testing/selftests/bpf/progs/struct_ops_module.c b/tools/testing/selftests/bpf/progs/struct_ops_module.c
new file mode 100644
index 000000000000..cb305d04342f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/struct_ops_module.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "../bpf_testmod/bpf_testmod.h"
+
+char _license[] SEC("license") = "GPL";
+
+int test_2_result = 0;
+
+SEC("struct_ops/test_1")
+int BPF_PROG(test_1)
+{
+    return 0xdeadbeef;
+}
+
+SEC("struct_ops/test_2")
+int BPF_PROG(test_2, int a, int b)
+{
+    test_2_result = a + b;
+    return a + b;
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_ops testmod_1 = {
+    .test_1 = (void *)test_1,
+    .test_2 = (void *)test_2,
+};
+
diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
index 8d994884c7b4..05870cd62458 100644
--- a/tools/testing/selftests/bpf/testing_helpers.c
+++ b/tools/testing/selftests/bpf/testing_helpers.c
@@ -10,6 +10,7 @@
  #include "test_progs.h"
  #include "testing_helpers.h"
  #include <linux/membarrier.h>
+#include "rcu_tasks_trace_gp.skel.h"
  int parse_num_list(const char *s, bool **num_set, int *num_set_len)
  {
@@ -380,10 +381,44 @@ int load_bpf_testmod(bool verbose)
      return 0;
  }
+/* This function will trigger call_rcu_tasks_trace() in the kernel */
+static int kern_sync_rcu_tasks_trace(void)
+{
+    struct rcu_tasks_trace_gp *rcu;
+    time_t start;
+    long gp_seq;
+    LIBBPF_OPTS(bpf_test_run_opts, opts);
+
+    rcu = rcu_tasks_trace_gp__open_and_load();
+    if (IS_ERR(rcu))
+        return -EFAULT;
+    if (rcu_tasks_trace_gp__attach(rcu))
+        return -EFAULT;
+
+    gp_seq = READ_ONCE(rcu->bss->gp_seq);
+
+    if (bpf_prog_test_run_opts(bpf_program__fd(rcu->progs.do_call_rcu_tasks_trace),
+                   &opts))
+        return -EFAULT;
+    if (opts.retval != 0)
+        return -EFAULT;
+
+    start = time(NULL);
+    while ((start + 2) > time(NULL) &&
+           gp_seq == READ_ONCE(rcu->bss->gp_seq))
+        sched_yield();
+
+    rcu_tasks_trace_gp__destroy(rcu);
+
+    return 0;
+}
+
  /*
   * Trigger synchronize_rcu() in kernel.
   */
  int kern_sync_rcu(void)
  {
+    if (kern_sync_rcu_tasks_trace())
+        return -EFAULT;
      return syscall(__NR_membarrier, MEMBARRIER_CMD_SHARED, 0, 0);
  }





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