bpf/selftests: Verify struct_ops prog sleepable behavior

In a set of prior changes, we added the ability for struct_ops programs
to be sleepable. This patch enhances the dummy_st_ops selftest suite to
validate this behavior by adding a new sleepable struct_ops entry to
dummy_st_ops.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-5-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -1474,6 +1474,7 @@ struct bpf_dummy_ops {
 	int (*test_1)(struct bpf_dummy_ops_state *cb);
 	int (*test_2)(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
 		      char a3, unsigned long a4);
+	int (*test_sleepable)(struct bpf_dummy_ops_state *cb);
 };
 
 int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,

net/bpf/bpf_dummy_struct_ops.c

@@ -154,6 +154,23 @@ static bool bpf_dummy_ops_is_valid_access(int off, int size,
 	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
 }
 
+static int bpf_dummy_ops_check_member(const struct btf_type *t,
+				      const struct btf_member *member,
+				      const struct bpf_prog *prog)
+{
+	u32 moff = __btf_member_bit_offset(t, member) / 8;
+
+	switch (moff) {
+	case offsetof(struct bpf_dummy_ops, test_sleepable):
+		break;
+	default:
+		if (prog->aux->sleepable)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
 					   const struct bpf_reg_state *reg,
 					   int off, int size, enum bpf_access_type atype,
@@ -208,6 +225,7 @@ static void bpf_dummy_unreg(void *kdata)
 struct bpf_struct_ops bpf_bpf_dummy_ops = {
 	.verifier_ops = &bpf_dummy_verifier_ops,
 	.init = bpf_dummy_init,
+	.check_member = bpf_dummy_ops_check_member,
 	.init_member = bpf_dummy_init_member,
 	.reg = bpf_dummy_reg,
 	.unreg = bpf_dummy_unreg,

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

@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) 2021. Huawei Technologies Co., Ltd */
 #include <test_progs.h>
-#include "dummy_st_ops.skel.h"
+#include "dummy_st_ops_success.skel.h"
+#include "dummy_st_ops_fail.skel.h"
 #include "trace_dummy_st_ops.skel.h"
 
 /* Need to keep consistent with definition in include/linux/bpf.h */
@@ -11,17 +12,17 @@ struct bpf_dummy_ops_state {
 
 static void test_dummy_st_ops_attach(void)
 {
-	struct dummy_st_ops *skel;
+	struct dummy_st_ops_success *skel;
 	struct bpf_link *link;
 
-	skel = dummy_st_ops__open_and_load();
+	skel = dummy_st_ops_success__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
 		return;
 
 	link = bpf_map__attach_struct_ops(skel->maps.dummy_1);
 	ASSERT_EQ(libbpf_get_error(link), -EOPNOTSUPP, "dummy_st_ops_attach");
 
-	dummy_st_ops__destroy(skel);
+	dummy_st_ops_success__destroy(skel);
 }
 
 static void test_dummy_init_ret_value(void)
@@ -31,10 +32,10 @@ static void test_dummy_init_ret_value(void)
 		.ctx_in = args,
 		.ctx_size_in = sizeof(args),
 	);
-	struct dummy_st_ops *skel;
+	struct dummy_st_ops_success *skel;
 	int fd, err;
 
-	skel = dummy_st_ops__open_and_load();
+	skel = dummy_st_ops_success__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
 		return;
 
@@ -43,7 +44,7 @@ static void test_dummy_init_ret_value(void)
 	ASSERT_OK(err, "test_run");
 	ASSERT_EQ(attr.retval, 0xf2f3f4f5, "test_ret");
 
-	dummy_st_ops__destroy(skel);
+	dummy_st_ops_success__destroy(skel);
 }
 
 static void test_dummy_init_ptr_arg(void)
@@ -58,10 +59,10 @@ static void test_dummy_init_ptr_arg(void)
 		.ctx_size_in = sizeof(args),
 	);
 	struct trace_dummy_st_ops *trace_skel;
-	struct dummy_st_ops *skel;
+	struct dummy_st_ops_success *skel;
 	int fd, err;
 
-	skel = dummy_st_ops__open_and_load();
+	skel = dummy_st_ops_success__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
 		return;
 
@@ -91,7 +92,7 @@ static void test_dummy_init_ptr_arg(void)
 	ASSERT_EQ(trace_skel->bss->val, exp_retval, "fentry_val");
 
 done:
-	dummy_st_ops__destroy(skel);
+	dummy_st_ops_success__destroy(skel);
 	trace_dummy_st_ops__destroy(trace_skel);
 }
 
@@ -102,12 +103,12 @@ static void test_dummy_multiple_args(void)
 		.ctx_in = args,
 		.ctx_size_in = sizeof(args),
 	);
-	struct dummy_st_ops *skel;
+	struct dummy_st_ops_success *skel;
 	int fd, err;
 	size_t i;
 	char name[8];
 
-	skel = dummy_st_ops__open_and_load();
+	skel = dummy_st_ops_success__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
 		return;
 
@@ -119,7 +120,28 @@ static void test_dummy_multiple_args(void)
 		ASSERT_EQ(skel->bss->test_2_args[i], args[i], name);
 	}
 
-	dummy_st_ops__destroy(skel);
+	dummy_st_ops_success__destroy(skel);
+}
+
+static void test_dummy_sleepable(void)
+{
+	__u64 args[1] = {0};
+	LIBBPF_OPTS(bpf_test_run_opts, attr,
+		.ctx_in = args,
+		.ctx_size_in = sizeof(args),
+	);
+	struct dummy_st_ops_success *skel;
+	int fd, err;
+
+	skel = dummy_st_ops_success__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "dummy_st_ops_load"))
+		return;
+
+	fd = bpf_program__fd(skel->progs.test_sleepable);
+	err = bpf_prog_test_run_opts(fd, &attr);
+	ASSERT_OK(err, "test_run");
+
+	dummy_st_ops_success__destroy(skel);
 }
 
 void test_dummy_st_ops(void)
@@ -132,4 +154,8 @@ void test_dummy_st_ops(void)
 		test_dummy_init_ptr_arg();
 	if (test__start_subtest("dummy_multiple_args"))
 		test_dummy_multiple_args();
+	if (test__start_subtest("dummy_sleepable"))
+		test_dummy_sleepable();
+
+	RUN_TESTS(dummy_st_ops_fail);
 }

tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c

@@ -0,0 +1,27 @@
+// 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_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops.s/test_2")
+__failure __msg("attach to unsupported member test_2 of struct bpf_dummy_ops")
+int BPF_PROG(test_unsupported_field_sleepable,
+	     struct bpf_dummy_ops_state *state, int a1, unsigned short a2,
+	     char a3, unsigned long a4)
+{
+	/* Tries to mark an unsleepable field in struct bpf_dummy_ops as sleepable. */
+	return 0;
+}
+
+SEC(".struct_ops")
+struct bpf_dummy_ops dummy_1 = {
+	.test_1 = NULL,
+	.test_2 = (void *)test_unsupported_field_sleepable,
+	.test_sleepable = (void *)NULL,
+};

tools/testing/selftests/bpf/progs/dummy_st_ops_success.c

@@ -1,19 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) 2021. Huawei Technologies Co., Ltd */
-#include <linux/bpf.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
-struct bpf_dummy_ops_state {
-	int val;
-} __attribute__((preserve_access_index));
-
-struct bpf_dummy_ops {
-	int (*test_1)(struct bpf_dummy_ops_state *state);
-	int (*test_2)(struct bpf_dummy_ops_state *state, int a1, unsigned short a2,
-		      char a3, unsigned long a4);
-};
-
 char _license[] SEC("license") = "GPL";
 
 SEC("struct_ops/test_1")
@@ -43,8 +33,15 @@ int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a
 	return 0;
 }
 
+SEC("struct_ops.s/test_sleepable")
+int BPF_PROG(test_sleepable, struct bpf_dummy_ops_state *state)
+{
+	return 0;
+}
+
 SEC(".struct_ops")
 struct bpf_dummy_ops dummy_1 = {
 	.test_1 = (void *)test_1,
 	.test_2 = (void *)test_2,
+	.test_sleepable = (void *)test_sleepable,
 };