diff mbox series

[v3,bpf-next,4/4] selftests/bpf: Add unit tests for pointers in global functions

Message ID 20210212205642.620788-5-me@ubique.spb.ru (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series Add support of pointer to struct in global functions | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 5 maintainers not CCed: shuah@kernel.org netdev@vger.kernel.org linux-kselftest@vger.kernel.org kpsingh@kernel.org yauheni.kaliuta@redhat.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 10 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch warning CHECK: Alignment should match open parenthesis CHECK: Blank lines aren't necessary after an open brace '{' CHECK: No space is necessary after a cast CHECK: Please use a blank line after function/struct/union/enum declarations WARNING: Prefer using '"%s...", __func__' to using 'test_global_func_args', this function's name, in a string WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? WARNING: line length of 85 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 94 exceeds 80 columns WARNING: line length of 96 exceeds 80 columns
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Dmitrii Banshchikov Feb. 12, 2021, 8:56 p.m. UTC
test_global_func9  - check valid pointer's scenarios
test_global_func10 - check that a smaller type cannot be passed as a
                     larger one
test_global_func11 - check that CTX pointer cannot be passed
test_global_func12 - check access to a null pointer
test_global_func13 - check access to an arbitrary pointer value
test_global_func14 - check that an opaque pointer cannot be passed
test_global_func15 - check that a variable has an unknown value after
		     it was passed to a global function by pointer
test_global_func16 - check access to uninitialized stack memory

test_global_func_args - check read and write operations through a pointer

Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
---
 .../bpf/prog_tests/global_func_args.c         |  60 ++++++++
 .../bpf/prog_tests/test_global_funcs.c        |   8 ++
 .../selftests/bpf/progs/test_global_func10.c  |  29 ++++
 .../selftests/bpf/progs/test_global_func11.c  |  19 +++
 .../selftests/bpf/progs/test_global_func12.c  |  21 +++
 .../selftests/bpf/progs/test_global_func13.c  |  24 ++++
 .../selftests/bpf/progs/test_global_func14.c  |  21 +++
 .../selftests/bpf/progs/test_global_func15.c  |  22 +++
 .../selftests/bpf/progs/test_global_func16.c  |  22 +++
 .../selftests/bpf/progs/test_global_func9.c   | 132 ++++++++++++++++++
 .../bpf/progs/test_global_func_args.c         |  91 ++++++++++++
 11 files changed, 449 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/global_func_args.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func10.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func11.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func12.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func13.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func14.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func15.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func16.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func9.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_global_func_args.c

Comments

Andrii Nakryiko Feb. 12, 2021, 9:15 p.m. UTC | #1
On Fri, Feb 12, 2021 at 12:57 PM Dmitrii Banshchikov <me@ubique.spb.ru> wrote:
>
> test_global_func9  - check valid pointer's scenarios
> test_global_func10 - check that a smaller type cannot be passed as a
>                      larger one
> test_global_func11 - check that CTX pointer cannot be passed
> test_global_func12 - check access to a null pointer
> test_global_func13 - check access to an arbitrary pointer value
> test_global_func14 - check that an opaque pointer cannot be passed
> test_global_func15 - check that a variable has an unknown value after
>                      it was passed to a global function by pointer
> test_global_func16 - check access to uninitialized stack memory
>
> test_global_func_args - check read and write operations through a pointer
>
> Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  .../bpf/prog_tests/global_func_args.c         |  60 ++++++++
>  .../bpf/prog_tests/test_global_funcs.c        |   8 ++
>  .../selftests/bpf/progs/test_global_func10.c  |  29 ++++
>  .../selftests/bpf/progs/test_global_func11.c  |  19 +++
>  .../selftests/bpf/progs/test_global_func12.c  |  21 +++
>  .../selftests/bpf/progs/test_global_func13.c  |  24 ++++
>  .../selftests/bpf/progs/test_global_func14.c  |  21 +++
>  .../selftests/bpf/progs/test_global_func15.c  |  22 +++
>  .../selftests/bpf/progs/test_global_func16.c  |  22 +++
>  .../selftests/bpf/progs/test_global_func9.c   | 132 ++++++++++++++++++
>  .../bpf/progs/test_global_func_args.c         |  91 ++++++++++++
>  11 files changed, 449 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/global_func_args.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func10.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func11.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func12.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func13.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func14.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func15.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func16.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func9.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func_args.c
>

[...]
Andrii Nakryiko Feb. 23, 2021, 6:43 a.m. UTC | #2
On Fri, Feb 12, 2021 at 12:57 PM Dmitrii Banshchikov <me@ubique.spb.ru> wrote:
>
> test_global_func9  - check valid pointer's scenarios
> test_global_func10 - check that a smaller type cannot be passed as a
>                      larger one
> test_global_func11 - check that CTX pointer cannot be passed
> test_global_func12 - check access to a null pointer
> test_global_func13 - check access to an arbitrary pointer value
> test_global_func14 - check that an opaque pointer cannot be passed
> test_global_func15 - check that a variable has an unknown value after
>                      it was passed to a global function by pointer
> test_global_func16 - check access to uninitialized stack memory
>
> test_global_func_args - check read and write operations through a pointer
>
> Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
> ---
>  .../bpf/prog_tests/global_func_args.c         |  60 ++++++++
>  .../bpf/prog_tests/test_global_funcs.c        |   8 ++
>  .../selftests/bpf/progs/test_global_func10.c  |  29 ++++
>  .../selftests/bpf/progs/test_global_func11.c  |  19 +++
>  .../selftests/bpf/progs/test_global_func12.c  |  21 +++
>  .../selftests/bpf/progs/test_global_func13.c  |  24 ++++
>  .../selftests/bpf/progs/test_global_func14.c  |  21 +++
>  .../selftests/bpf/progs/test_global_func15.c  |  22 +++
>  .../selftests/bpf/progs/test_global_func16.c  |  22 +++
>  .../selftests/bpf/progs/test_global_func9.c   | 132 ++++++++++++++++++
>  .../bpf/progs/test_global_func_args.c         |  91 ++++++++++++
>  11 files changed, 449 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/global_func_args.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func10.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func11.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func12.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func13.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func14.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func15.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func16.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func9.c
>  create mode 100644 tools/testing/selftests/bpf/progs/test_global_func_args.c
>

[...]

> diff --git a/tools/testing/selftests/bpf/progs/test_global_func11.c b/tools/testing/selftests/bpf/progs/test_global_func11.c
> new file mode 100644
> index 000000000000..28488047c849
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_global_func11.c
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <stddef.h>
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +
> +struct S {
> +       int x;
> +};
> +
> +__noinline int foo(const struct S *s)
> +{
> +       return s ? bpf_get_prandom_u32() < s->x : 0;
> +}
> +
> +SEC("cgroup_skb/ingress")
> +int test_cls(struct __sk_buff *skb)
> +{
> +       return foo(skb);

This needs (void *) cast. It currently generates compilation warning:

progs/test_global_func11.c:18:13: warning: incompatible pointer types
passing 'struct __sk_buff *' to parameter of type 'const struct S *'
[-Wincompatible-pointer-types]
        return foo(skb);
                   ^~~
progs/test_global_func11.c:10:36: note: passing argument to parameter 's' here
__noinline int foo(const struct S *s)
                                   ^

Please send a follow-up patch.

> +}

[...]
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/global_func_args.c b/tools/testing/selftests/bpf/prog_tests/global_func_args.c
new file mode 100644
index 000000000000..8bcc2869102f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/global_func_args.c
@@ -0,0 +1,60 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include "test_progs.h"
+#include "network_helpers.h"
+
+static __u32 duration;
+
+static void test_global_func_args0(struct bpf_object *obj)
+{
+	int err, i, map_fd, actual_value;
+	const char *map_name = "values";
+
+	map_fd = bpf_find_map(__func__, obj, map_name);
+	if (CHECK(map_fd < 0, "bpf_find_map", "cannot find BPF map %s: %s\n",
+		map_name, strerror(errno)))
+		return;
+
+	struct {
+		const char *descr;
+		int expected_value;
+	} tests[] = {
+		{"passing NULL pointer", 0},
+		{"returning value", 1},
+		{"reading local variable", 100 },
+		{"writing local variable", 101 },
+		{"reading global variable", 42 },
+		{"writing global variable", 43 },
+		{"writing to pointer-to-pointer", 1 },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i) {
+		const int expected_value = tests[i].expected_value;
+
+		err = bpf_map_lookup_elem(map_fd, &i, &actual_value);
+
+		CHECK(err || actual_value != expected_value, tests[i].descr,
+			 "err %d result %d expected %d\n", err, actual_value, expected_value);
+	}
+}
+
+void test_global_func_args(void)
+{
+	const char *file = "./test_global_func_args.o";
+	__u32 retval;
+	struct bpf_object *obj;
+	int err, prog_fd;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd);
+	if (CHECK(err, "load program", "error %d loading %s\n", err, file))
+		return;
+
+	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+				NULL, NULL, &retval, &duration);
+	CHECK(err || retval, "pass global func args run",
+	      "err %d errno %d retval %d duration %d\n",
+	      err, errno, retval, duration);
+
+	test_global_func_args0(obj);
+
+	bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
index 32e4348b714b..7e13129f593a 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_global_funcs.c
@@ -61,6 +61,14 @@  void test_test_global_funcs(void)
 		{ "test_global_func6.o" , "modified ctx ptr R2" },
 		{ "test_global_func7.o" , "foo() doesn't return scalar" },
 		{ "test_global_func8.o" },
+		{ "test_global_func9.o" },
+		{ "test_global_func10.o", "invalid indirect read from stack" },
+		{ "test_global_func11.o", "Caller passes invalid args into func#1" },
+		{ "test_global_func12.o", "invalid mem access 'mem_or_null'" },
+		{ "test_global_func13.o", "Caller passes invalid args into func#1" },
+		{ "test_global_func14.o", "reference type('FWD S') size cannot be determined" },
+		{ "test_global_func15.o", "At program exit the register R0 has value" },
+		{ "test_global_func16.o", "invalid indirect read from stack" },
 	};
 	libbpf_print_fn_t old_print_fn = NULL;
 	int err, i, duration = 0;
diff --git a/tools/testing/selftests/bpf/progs/test_global_func10.c b/tools/testing/selftests/bpf/progs/test_global_func10.c
new file mode 100644
index 000000000000..61c2ae92ce41
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func10.c
@@ -0,0 +1,29 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct Small {
+	int x;
+};
+
+struct Big {
+	int x;
+	int y;
+};
+
+__noinline int foo(const struct Big *big)
+{
+	if (big == 0)
+		return 0;
+
+	return bpf_get_prandom_u32() < big->y;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	const struct Small small = {.x = skb->len };
+
+	return foo((struct Big *)&small) ? 1 : 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func11.c b/tools/testing/selftests/bpf/progs/test_global_func11.c
new file mode 100644
index 000000000000..28488047c849
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func11.c
@@ -0,0 +1,19 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct S {
+	int x;
+};
+
+__noinline int foo(const struct S *s)
+{
+	return s ? bpf_get_prandom_u32() < s->x : 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	return foo(skb);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func12.c b/tools/testing/selftests/bpf/progs/test_global_func12.c
new file mode 100644
index 000000000000..62343527cc59
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func12.c
@@ -0,0 +1,21 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct S {
+	int x;
+};
+
+__noinline int foo(const struct S *s)
+{
+	return bpf_get_prandom_u32() < s->x;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	const struct S s = {.x = skb->len };
+
+	return foo(&s);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func13.c b/tools/testing/selftests/bpf/progs/test_global_func13.c
new file mode 100644
index 000000000000..ff8897c1ac22
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func13.c
@@ -0,0 +1,24 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct S {
+	int x;
+};
+
+__noinline int foo(const struct S *s)
+{
+	if (s)
+		return bpf_get_prandom_u32() < s->x;
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	const struct S *s = (const struct S *)(0xbedabeda);
+
+	return foo(s);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func14.c b/tools/testing/selftests/bpf/progs/test_global_func14.c
new file mode 100644
index 000000000000..698c77199ebf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func14.c
@@ -0,0 +1,21 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct S;
+
+__noinline int foo(const struct S *s)
+{
+	if (s)
+		return bpf_get_prandom_u32() < *(const int *) s;
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+
+	return foo(NULL);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func15.c b/tools/testing/selftests/bpf/progs/test_global_func15.c
new file mode 100644
index 000000000000..c19c435988d5
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func15.c
@@ -0,0 +1,22 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+__noinline int foo(unsigned int *v)
+{
+	if (v)
+		*v = bpf_get_prandom_u32();
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	unsigned int v = 1;
+
+	foo(&v);
+
+	return v;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func16.c b/tools/testing/selftests/bpf/progs/test_global_func16.c
new file mode 100644
index 000000000000..0312d1e8d8c0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func16.c
@@ -0,0 +1,22 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+__noinline int foo(int (*arr)[10])
+{
+	if (arr)
+		return (*arr)[9];
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	int array[10];
+
+	const int rv = foo(&array);
+
+	return rv ? 1 : 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func9.c b/tools/testing/selftests/bpf/progs/test_global_func9.c
new file mode 100644
index 000000000000..bd233ddede98
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func9.c
@@ -0,0 +1,132 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct S {
+	int x;
+};
+
+struct C {
+	int x;
+	int y;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, struct S);
+} map SEC(".maps");
+
+enum E {
+	E_ITEM
+};
+
+static int global_data_x = 100;
+static int volatile global_data_y = 500;
+
+__noinline int foo(const struct S *s)
+{
+	if (s)
+		return bpf_get_prandom_u32() < s->x;
+
+	return 0;
+}
+
+__noinline int bar(int *x)
+{
+	if (x)
+		*x &= bpf_get_prandom_u32();
+
+	return 0;
+}
+__noinline int baz(volatile int *x)
+{
+	if (x)
+		*x &= bpf_get_prandom_u32();
+
+	return 0;
+}
+
+__noinline int qux(enum E *e)
+{
+	if (e)
+		return *e;
+
+	return 0;
+}
+
+__noinline int quux(int (*arr)[10])
+{
+	if (arr)
+		return (*arr)[9];
+
+	return 0;
+}
+
+__noinline int quuz(int **p)
+{
+	if (p)
+		*p = NULL;
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	int result = 0;
+
+	{
+		const struct S s = {.x = skb->len };
+
+		result |= foo(&s);
+	}
+
+	{
+		const __u32 key = 1;
+		const struct S *s = bpf_map_lookup_elem(&map, &key);
+
+		result |= foo(s);
+	}
+
+	{
+		const struct C c = {.x = skb->len, .y = skb->family };
+
+		result |= foo((const struct S *)&c);
+	}
+
+	{
+		result |= foo(NULL);
+	}
+
+	{
+		bar(&result);
+		bar(&global_data_x);
+	}
+
+	{
+		result |= baz(&global_data_y);
+	}
+
+	{
+		enum E e = E_ITEM;
+
+		result |= qux(&e);
+	}
+
+	{
+		int array[10] = {0};
+
+		result |= quux(&array);
+	}
+
+	{
+		int *p;
+
+		result |= quuz(&p);
+	}
+
+	return result ? 1 : 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func_args.c b/tools/testing/selftests/bpf/progs/test_global_func_args.c
new file mode 100644
index 000000000000..cae309538a9e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_global_func_args.c
@@ -0,0 +1,91 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+
+#include <bpf/bpf_helpers.h>
+
+struct S {
+	int v;
+};
+
+static volatile struct S global_variable;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 7);
+	__type(key, __u32);
+	__type(value, int);
+} values SEC(".maps");
+
+static void save_value(__u32 index, int value)
+{
+	bpf_map_update_elem(&values, &index, &value, 0);
+}
+
+__noinline int foo(__u32 index, struct S *s)
+{
+	if (s) {
+		save_value(index, s->v);
+		return ++s->v;
+	}
+
+	save_value(index, 0);
+
+	return 1;
+}
+
+__noinline int bar(__u32 index, volatile struct S *s)
+{
+	if (s) {
+		save_value(index, s->v);
+		return ++s->v;
+	}
+
+	save_value(index, 0);
+
+	return 1;
+}
+
+__noinline int baz(struct S **s)
+{
+	if (s)
+		*s = 0;
+
+	return 0;
+}
+
+SEC("cgroup_skb/ingress")
+int test_cls(struct __sk_buff *skb)
+{
+	__u32 index = 0;
+
+	{
+		const int v = foo(index++, 0);
+
+		save_value(index++, v);
+	}
+
+	{
+		struct S s = { .v = 100 };
+
+		foo(index++, &s);
+		save_value(index++, s.v);
+	}
+
+	{
+		global_variable.v = 42;
+		bar(index++, &global_variable);
+		save_value(index++, global_variable.v);
+	}
+
+	{
+		struct S v, *p = &v;
+
+		baz(&p);
+		save_value(index++, !p);
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";