[PATCH bpf-next v2 0/4] Enable struct_ops programs to be sleepable

[PATCH bpf-next v2 0/4] Enable struct_ops programs to be sleepable

[David Vernet]

This is part 2 of https://lore.kernel.org/bpf/20230123232228.646563-1-void@manifault.com/

Changelog:
----------
v1 -> v2:
- Add support for specifying sleepable struct_ops programs with
  struct_ops.s in libbpf (Alexei).
- Move failure test case into new dummy_st_ops_fail.c prog file.
- Update test_dummy_sleepable() to use struct_ops.s instead of manually
  setting prog flags. Also remove open_load_skel() helper which is no
  longer needed.
- Fix verifier tests to expect new sleepable prog failure message.

David Vernet (4):
  bpf: Allow BPF_PROG_TYPE_STRUCT_OPS programs to be sleepable
  libbpf: Support sleepable struct_ops.s section
  bpf: Pass const struct bpf_prog * to .check_member
  bpf/selftests: Verify struct_ops prog sleepable behavior

 include/linux/bpf.h                           |  4 +-
 kernel/bpf/verifier.c                         |  7 ++-
 net/bpf/bpf_dummy_struct_ops.c                | 18 ++++++
 net/bpf/test_run.c                            |  6 ++
 net/ipv4/bpf_tcp_ca.c                         |  3 +-
 tools/lib/bpf/libbpf.c                        |  1 +
 .../selftests/bpf/prog_tests/dummy_st_ops.c   | 56 ++++++++++++++-----
 .../selftests/bpf/progs/dummy_st_ops_common.h | 20 +++++++
 .../selftests/bpf/progs/dummy_st_ops_fail.c   | 41 ++++++++++++++
 ...{dummy_st_ops.c => dummy_st_ops_success.c} | 18 +++---
 10 files changed, 145 insertions(+), 29 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c
 rename tools/testing/selftests/bpf/progs/{dummy_st_ops.c => dummy_st_ops_success.c} (75%)

-- 
2.39.0

[PATCH bpf-next v2 1/4] bpf: Allow BPF_PROG_TYPE_STRUCT_OPS programs to be sleepable

[David Vernet]

BPF struct_ops programs currently cannot be marked as sleepable. This
need not be the case -- struct_ops programs can be sleepable, and e.g.
invoke kfuncs that export the KF_SLEEPABLE flag. So as to allow future
struct_ops programs to invoke such kfuncs, this patch updates the
verifier to allow struct_ops programs to be sleepable. A follow-on patch
will add support to libbpf for specifying struct_ops.s as a sleepable
struct_ops program, and then another patch will add testcases to the
dummy_st_ops selftest suite which test sleepable struct_ops behavior.

Signed-off-by: David Vernet <void@manifault.com>
---
 kernel/bpf/verifier.c                            | 5 +++--
 tools/testing/selftests/bpf/verifier/sleepable.c | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 800488289297..2b8f0c0aa0cc 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -17054,7 +17054,8 @@ static bool can_be_sleepable(struct bpf_prog *prog)
 		}
 	}
 	return prog->type == BPF_PROG_TYPE_LSM ||
-	       prog->type == BPF_PROG_TYPE_KPROBE; /* only for uprobes */
+	       prog->type == BPF_PROG_TYPE_KPROBE /* only for uprobes */ ||
+	       prog->type == BPF_PROG_TYPE_STRUCT_OPS;
 }
 
 static int check_attach_btf_id(struct bpf_verifier_env *env)
@@ -17076,7 +17077,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
 	}
 
 	if (prog->aux->sleepable && !can_be_sleepable(prog)) {
-		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter and uprobe programs can be sleepable\n");
+		verbose(env, "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable\n");
 		return -EINVAL;
 	}
 
diff --git a/tools/testing/selftests/bpf/verifier/sleepable.c b/tools/testing/selftests/bpf/verifier/sleepable.c
index bea0daef908a..1f0d2bdc673f 100644
--- a/tools/testing/selftests/bpf/verifier/sleepable.c
+++ b/tools/testing/selftests/bpf/verifier/sleepable.c
@@ -85,7 +85,7 @@
 	.expected_attach_type = BPF_TRACE_RAW_TP,
 	.kfunc = "sched_switch",
 	.result = REJECT,
-	.errstr = "Only fentry/fexit/fmod_ret, lsm, iter and uprobe programs can be sleepable",
+	.errstr = "Only fentry/fexit/fmod_ret, lsm, iter, uprobe, and struct_ops programs can be sleepable",
 	.flags = BPF_F_SLEEPABLE,
 	.runs = -1,
 },
-- 
2.39.0

[PATCH bpf-next v2 2/4] libbpf: Support sleepable struct_ops.s section

[David Vernet]

In a prior change, the verifier was updated to support sleepable
BPF_PROG_TYPE_STRUCT_OPS programs. A caller could set the program as
sleepable with bpf_program__set_flags(), but it would be more ergonomic
and more in-line with other sleepable program types if we supported
suffixing a struct_ops section name with .s to indicate that it's
sleepable.

Signed-off-by: David Vernet <void@manifault.com>
---
 tools/lib/bpf/libbpf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 27d9faa80471..eed5cec6f510 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8605,6 +8605,7 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("cgroup/setsockopt",	CGROUP_SOCKOPT, BPF_CGROUP_SETSOCKOPT, SEC_ATTACHABLE),
 	SEC_DEF("cgroup/dev",		CGROUP_DEVICE, BPF_CGROUP_DEVICE, SEC_ATTACHABLE_OPT),
 	SEC_DEF("struct_ops+",		STRUCT_OPS, 0, SEC_NONE),
+	SEC_DEF("struct_ops.s+",	STRUCT_OPS, 0, SEC_SLEEPABLE),
 	SEC_DEF("sk_lookup",		SK_LOOKUP, BPF_SK_LOOKUP, SEC_ATTACHABLE),
 };
 
-- 
2.39.0

[PATCH bpf-next v2 3/4] bpf: Pass const struct bpf_prog * to .check_member

[David Vernet]

The .check_member field of struct bpf_struct_ops is currently passed the
member's btf_type via const struct btf_type *t, and a const struct
btf_member *member. This allows the struct_ops implementation to check
whether e.g. an ops is supported, but it would be useful to also enforce
that the struct_ops prog being loaded for that member has other
qualities, like being sleepable (or not). This patch therefore updates
the .check_member() callback to also take a const struct bpf_prog *prog
argument.

Signed-off-by: David Vernet <void@manifault.com>
---
 include/linux/bpf.h   | 3 ++-
 kernel/bpf/verifier.c | 2 +-
 net/ipv4/bpf_tcp_ca.c | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index ad4bb36d4c10..50123afab9bf 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1422,7 +1422,8 @@ struct bpf_struct_ops {
 	const struct bpf_verifier_ops *verifier_ops;
 	int (*init)(struct btf *btf);
 	int (*check_member)(const struct btf_type *t,
-			    const struct btf_member *member);
+			    const struct btf_member *member,
+			    const struct bpf_prog *prog);
 	int (*init_member)(const struct btf_type *t,
 			   const struct btf_member *member,
 			   void *kdata, const void *udata);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2b8f0c0aa0cc..20dd03498e56 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -16732,7 +16732,7 @@ static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
 	}
 
 	if (st_ops->check_member) {
-		int err = st_ops->check_member(t, member);
+		int err = st_ops->check_member(t, member, prog);
 
 		if (err) {
 			verbose(env, "attach to unsupported member %s of struct %s\n",
diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c
index 4517d2bd186a..13fc0c185cd9 100644
--- a/net/ipv4/bpf_tcp_ca.c
+++ b/net/ipv4/bpf_tcp_ca.c
@@ -248,7 +248,8 @@ static int bpf_tcp_ca_init_member(const struct btf_type *t,
 }
 
 static int bpf_tcp_ca_check_member(const struct btf_type *t,
-				   const struct btf_member *member)
+				   const struct btf_member *member,
+				   const struct bpf_prog *prog)
 {
 	if (is_unsupported(__btf_member_bit_offset(t, member) / 8))
 		return -ENOTSUPP;
-- 
2.39.0

[PATCH bpf-next v2 4/4] bpf/selftests: Verify struct_ops prog sleepable behavior

[David Vernet]

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 struct_ops entry to dummy_st_ops
which calls a KF_SLEEPABLE kfunc.

Signed-off-by: David Vernet <void@manifault.com>
---
 include/linux/bpf.h                           |  1 +
 net/bpf/bpf_dummy_struct_ops.c                | 18 ++++++
 net/bpf/test_run.c                            |  6 ++
 .../selftests/bpf/prog_tests/dummy_st_ops.c   | 56 ++++++++++++++-----
 .../selftests/bpf/progs/dummy_st_ops_common.h | 20 +++++++
 .../selftests/bpf/progs/dummy_st_ops_fail.c   | 41 ++++++++++++++
 ...{dummy_st_ops.c => dummy_st_ops_success.c} | 18 +++---
 7 files changed, 136 insertions(+), 24 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
 create mode 100644 tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c
 rename tools/testing/selftests/bpf/progs/{dummy_st_ops.c => dummy_st_ops_success.c} (75%)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 50123afab9bf..64034311c5f7 100644
--- a/include/linux/bpf.h
+++ b/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_3)(struct bpf_dummy_ops_state *cb);
 };
 
 int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
index 1ac4467928a9..46099737d1da 100644
--- a/net/bpf/bpf_dummy_struct_ops.c
+++ b/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_3):
+		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,
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 8da0d73b368e..33ea57d34c0b 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -730,6 +730,10 @@ noinline void bpf_kfunc_call_test_destructive(void)
 {
 }
 
+noinline void bpf_kfunc_call_test_sleepable(void)
+{
+}
+
 __diag_pop();
 
 BTF_SET8_START(bpf_test_modify_return_ids)
@@ -767,6 +771,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_sleepable, KF_SLEEPABLE)
 BTF_SET8_END(test_sk_check_kfunc_ids)
 
 static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
@@ -1680,6 +1685,7 @@ static int __init bpf_prog_test_run_init(void)
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_prog_test_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_prog_test_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_prog_test_kfunc_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_prog_test_kfunc_set);
 	return ret ?: register_btf_id_dtor_kfuncs(bpf_prog_test_dtor_kfunc,
 						  ARRAY_SIZE(bpf_prog_test_dtor_kfunc),
 						  THIS_MODULE);
diff --git a/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c b/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
index c11832657d2b..dbf568e0ade2 100644
--- a/tools/testing/selftests/bpf/prog_tests/dummy_st_ops.c
+++ b/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)
@@ -58,17 +59,17 @@ 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;
 
 	fd = bpf_program__fd(skel->progs.test_1);
 
 	trace_skel = trace_dummy_st_ops__open();
-	if (!ASSERT_OK_PTR(trace_skel, "trace_dummy_st_ops__open"))
+	if (!ASSERT_OK_PTR(trace_skel, "trace_dummy_st_ops_success__open"))
 		goto done;
 
 	err = bpf_program__set_attach_target(trace_skel->progs.fentry_test_1,
@@ -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;
 
@@ -119,10 +120,31 @@ 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);
 }
 
-void test_dummy_st_ops(void)
+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_3);
+	err = bpf_prog_test_run_opts(fd, &attr);
+	ASSERT_OK(err, "test_run");
+
+	dummy_st_ops_success__destroy(skel);
+}
+
+void test_dummy_st_ops_success(void)
 {
 	if (test__start_subtest("dummy_st_ops_attach"))
 		test_dummy_st_ops_attach();
@@ -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);
 }
diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
new file mode 100644
index 000000000000..7d0761594b69
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#ifndef _DUMMY_ST_OPS_COMMON_H
+#define _DUMMY_ST_OPS_COMMON_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);
+	int (*test_3)(struct bpf_dummy_ops_state *state);
+};
+
+void bpf_kfunc_call_test_sleepable(void) __ksym;
+
+#endif /* _DUMMY_ST_OPS_COMMON_H */
diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c b/tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c
new file mode 100644
index 000000000000..e3f6c5445e0d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_fail.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#include "bpf_misc.h"
+#include "dummy_st_ops_common.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/test_3")
+__failure __msg("program must be sleepable to call sleepable kfunc bpf_kfunc_call_test_sleepable")
+int BPF_PROG(test_supported_field_not_in_sleepable_section, struct bpf_dummy_ops_state *state)
+{
+	/*
+	 * Calls a sleepable kfunc, but doesn't mark self as sleepable, even
+	 * though test_3 is allowed to be a sleepable field in struct
+	 * bpf_ops_dummy.
+	 */
+	bpf_kfunc_call_test_sleepable();
+	return 0;
+}
+
+SEC(".struct_ops")
+struct bpf_dummy_ops dummy_1 = {
+	.test_1 = NULL,
+	.test_2 = (void *)test_unsupported_field_sleepable,
+	.test_3 = (void *)test_supported_field_not_in_sleepable_section,
+};
diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops.c b/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
similarity index 75%
rename from tools/testing/selftests/bpf/progs/dummy_st_ops.c
rename to tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
index ead87edb75e2..1e9fab99ac0d 100644
--- a/tools/testing/selftests/bpf/progs/dummy_st_ops.c
+++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_success.c
@@ -4,15 +4,7 @@
 #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);
-};
+#include "dummy_st_ops_common.h"
 
 char _license[] SEC("license") = "GPL";
 
@@ -43,8 +35,16 @@ int BPF_PROG(test_2, struct bpf_dummy_ops_state *state, int a1, unsigned short a
 	return 0;
 }
 
+SEC("struct_ops.s/test_3")
+int BPF_PROG(test_3, struct bpf_dummy_ops_state *state)
+{
+	bpf_kfunc_call_test_sleepable();
+	return 0;
+}
+
 SEC(".struct_ops")
 struct bpf_dummy_ops dummy_1 = {
 	.test_1 = (void *)test_1,
 	.test_2 = (void *)test_2,
+	.test_3 = (void *)test_3,
 };
-- 
2.39.0

Re: [PATCH bpf-next v2 4/4] bpf/selftests: Verify struct_ops prog sleepable behavior

[Martin KaFai Lau]

On 1/24/23 8:08 AM, David Vernet wrote:
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 50123afab9bf..64034311c5f7 100644
> --- a/include/linux/bpf.h
> +++ b/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_3)(struct bpf_dummy_ops_state *cb);

nit. May be a self describe name like test_sleepable().

>   };
>   
>   int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
> diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
> index 1ac4467928a9..46099737d1da 100644
> --- a/net/bpf/bpf_dummy_struct_ops.c
> +++ b/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_3):
> +		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,
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index 8da0d73b368e..33ea57d34c0b 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -730,6 +730,10 @@ noinline void bpf_kfunc_call_test_destructive(void)
>   {
>   }
>   
> +noinline void bpf_kfunc_call_test_sleepable(void)
> +{
> +}
> +
>   __diag_pop();
>   
>   BTF_SET8_START(bpf_test_modify_return_ids)
> @@ -767,6 +771,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
>   BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
>   BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS)
>   BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE)
> +BTF_ID_FLAGS(func, bpf_kfunc_call_test_sleepable, KF_SLEEPABLE)

KF_SLEEPABLE kfunc is not specific to the struct_ops prog. I hope a test has 
already covered that KF_SLEEPABLE kfunc can only be called from sleepable prog. 
eg. there is bpf_fentry_test1.

This new kfunc could then be omitted and make the test simpler. There is no need 
to add the test to the DENYLIST.s390x: 
https://github.com/kernel-patches/bpf/actions/runs/3998188872/jobs/6861920516

> diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
> new file mode 100644
> index 000000000000..7d0761594b69
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
> +
> +#ifndef _DUMMY_ST_OPS_COMMON_H
> +#define _DUMMY_ST_OPS_COMMON_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);
> +	int (*test_3)(struct bpf_dummy_ops_state *state);
> +};

Instead of adding a new dummy_st_ops_common.h header, try to directly include 
vmlinux.h in the dummy_st_ops_{success,fail}.c.

> +
> +void bpf_kfunc_call_test_sleepable(void) __ksym;

Re: [PATCH bpf-next v2 4/4] bpf/selftests: Verify struct_ops prog sleepable behavior

[David Vernet]

On Tue, Jan 24, 2023 at 11:52:17AM -0800, Martin KaFai Lau wrote:
> On 1/24/23 8:08 AM, David Vernet wrote:
> > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > index 50123afab9bf..64034311c5f7 100644
> > --- a/include/linux/bpf.h
> > +++ b/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_3)(struct bpf_dummy_ops_state *cb);
> 
> nit. May be a self describe name like test_sleepable().

Will do. I agree that's better, but was just following the existing
contours of the file. Happy to have an excuse to improve it.

> 
> >   };
> >   int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
> > diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
> > index 1ac4467928a9..46099737d1da 100644
> > --- a/net/bpf/bpf_dummy_struct_ops.c
> > +++ b/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_3):
> > +		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,
> > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> > index 8da0d73b368e..33ea57d34c0b 100644
> > --- a/net/bpf/test_run.c
> > +++ b/net/bpf/test_run.c
> > @@ -730,6 +730,10 @@ noinline void bpf_kfunc_call_test_destructive(void)
> >   {
> >   }
> > +noinline void bpf_kfunc_call_test_sleepable(void)
> > +{
> > +}
> > +
> >   __diag_pop();
> >   BTF_SET8_START(bpf_test_modify_return_ids)
> > @@ -767,6 +771,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
> >   BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
> >   BTF_ID_FLAGS(func, bpf_kfunc_call_test_ref, KF_TRUSTED_ARGS)
> >   BTF_ID_FLAGS(func, bpf_kfunc_call_test_destructive, KF_DESTRUCTIVE)
> > +BTF_ID_FLAGS(func, bpf_kfunc_call_test_sleepable, KF_SLEEPABLE)
> 
> KF_SLEEPABLE kfunc is not specific to the struct_ops prog. I hope a test has
> already covered that KF_SLEEPABLE kfunc can only be called from sleepable
> prog. eg. there is bpf_fentry_test1.
> 
> This new kfunc could then be omitted and make the test simpler. There is no
> need to add the test to the DENYLIST.s390x:
> https://github.com/kernel-patches/bpf/actions/runs/3998188872/jobs/6861920516

Ah, good point. Totally forgot about s390x. Will send out a v3 that
doesn't bother with also including the KF_SLEEPABLE invocation, and
instead just validates that .check_member() is called.

> 
> > diff --git a/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
> > new file mode 100644
> > index 000000000000..7d0761594b69
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/dummy_st_ops_common.h
> > @@ -0,0 +1,20 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
> > +
> > +#ifndef _DUMMY_ST_OPS_COMMON_H
> > +#define _DUMMY_ST_OPS_COMMON_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);
> > +	int (*test_3)(struct bpf_dummy_ops_state *state);
> > +};
> 
> Instead of adding a new dummy_st_ops_common.h header, try to directly
> include vmlinux.h in the dummy_st_ops_{success,fail}.c.

Ack, I'll give it a shot. Should be fine to include once we get rid of
the test logic that includes the KF_SLEEPABLE kfunc.

> 
> > +
> > +void bpf_kfunc_call_test_sleepable(void) __ksym;
>