[PATCH HID v2 04/16] selftests/hid: convert the hid_bpf selftests with struct_ops

Benjamin Tissoires
2024-06-07T15:28:41Z

We drop the need for the attach() bpf syscall, but we need to set up
the hid_id field before calling __load().

The .bpf.c part is mechanical: we create one struct_ops per HID-BPF
program, as all the tests are for one program at a time.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

---

changes in v2:
- use BPF_F_BEFORE
---
tools/testing/selftests/hid/hid_bpf.c | 59 +++++++++--------
tools/testing/selftests/hid/progs/hid.c | 76 +++++++++++++++-------
.../testing/selftests/hid/progs/hid_bpf_helpers.h | 19 ++----
3 files changed, 89 insertions(+), 65 deletions(-)

diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index f825623e3edc..967dfe6b58cb 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -460,7 +460,7 @@ FIXTURE(hid_bpf) {
int hid_id;
pthread_t tid;
struct hid *skel;
- int hid_links[3]; /* max number of programs loaded in a single test */
+ struct bpf_link *hid_links[3]; /* max number of programs loaded in a single test */
};
static void detach_bpf(FIXTURE_DATA(hid_bpf) * self)
{
@@ -472,7 +472,7 @@ static void detach_bpf(FIXTURE_DATA(hid_bpf) * self)

for (i = 0; i < ARRAY_SIZE(self->hid_links); i++) {
if (self->hid_links[i])
- close(self->hid_links[i]);
+ bpf_link__destroy(self->hid_links[i]);
}

hid__destroy(self->skel);
@@ -527,14 +527,7 @@ static void load_programs(const struct test_program programs[],
FIXTURE_DATA(hid_bpf) * self,
const FIXTURE_VARIANT(hid_bpf) * variant)
{
- int attach_fd, err = -EINVAL;
- struct attach_prog_args args = {
- .retval = -1,
- };
- DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
- .ctx_in = &args,
- .ctx_size_in = sizeof(args),
- );
+ int err = -EINVAL;

ASSERT_LE(progs_count, ARRAY_SIZE(self->hid_links))
TH_LOG("too many programs are to be loaded");
@@ -545,35 +538,41 @@ static void load_programs(const struct test_program programs[],

for (int i = 0; i < progs_count; i++) {
struct bpf_program *prog;
+ struct bpf_map *map;
+ int *ops_hid_id;

prog = bpf_object__find_program_by_name(*self->skel->skeleton->obj,
programs[i].name);
ASSERT_OK_PTR(prog) TH_LOG("can not find program by name '%s'", programs[i].name);

bpf_program__set_autoload(prog, true);
+
+ map = bpf_object__find_map_by_name(*self->skel->skeleton->obj,
+ programs[i].name + 4);
+ ASSERT_OK_PTR(map) TH_LOG("can not find struct_ops by name '%s'",
+ programs[i].name + 4);
+
+ /* hid_id is the first field of struct hid_bpf_ops */
+ ops_hid_id = bpf_map__initial_value(map, NULL);
+ ASSERT_OK_PTR(ops_hid_id) TH_LOG("unable to retrieve struct_ops data");
+
+ *ops_hid_id = self->hid_id;
}

err = hid__load(self->skel);
ASSERT_OK(err) TH_LOG("hid_skel_load failed: %d", err);

- attach_fd = bpf_program__fd(self->skel->progs.attach_prog);
- ASSERT_GE(attach_fd, 0) TH_LOG("locate attach_prog: %d", attach_fd);
-
for (int i = 0; i < progs_count; i++) {
- struct bpf_program *prog;
+ struct bpf_map *map;

- prog = bpf_object__find_program_by_name(*self->skel->skeleton->obj,
- programs[i].name);
- ASSERT_OK_PTR(prog) TH_LOG("can not find program by name '%s'", programs[i].name);
-
- args.prog_fd = bpf_program__fd(prog);
- args.hid = self->hid_id;
- args.insert_head = programs[i].insert_head;
- err = bpf_prog_test_run_opts(attach_fd, &tattr);
- ASSERT_GE(args.retval, 0)
- TH_LOG("attach_hid(%s): %d", programs[i].name, args.retval);
+ map = bpf_object__find_map_by_name(*self->skel->skeleton->obj,
+ programs[i].name + 4);
+ ASSERT_OK_PTR(map) TH_LOG("can not find struct_ops by name '%s'",
+ programs[i].name + 4);

- self->hid_links[i] = args.retval;
+ self->hid_links[i] = bpf_map__attach_struct_ops(map);
+ ASSERT_OK_PTR(self->hid_links[i]) TH_LOG("failed to attach struct ops '%s'",
+ programs[i].name + 4);
}

self->hidraw_fd = open_hidraw(self->dev_id);
@@ -648,13 +647,17 @@ TEST_F(hid_bpf, test_attach_detach)
{ .name = "hid_first_event" },
{ .name = "hid_second_event" },
};
+ struct bpf_link *link;
__u8 buf[10] = {0};
- int err, link;
+ int err, link_fd;

LOAD_PROGRAMS(progs);

link = self->hid_links[0];
- ASSERT_GT(link, 0) TH_LOG("HID-BPF link not created");
+ ASSERT_OK_PTR(link) TH_LOG("HID-BPF link not created");
+
+ link_fd = bpf_link__fd(link);
+ ASSERT_GE(link_fd, 0) TH_LOG("HID-BPF link FD not valid");

/* inject one event */
buf[0] = 1;
@@ -673,7 +676,7 @@ TEST_F(hid_bpf, test_attach_detach)

/* pin the first program and immediately unpin it */
#define PIN_PATH "/sys/fs/bpf/hid_first_event"
- err = bpf_obj_pin(link, PIN_PATH);
+ err = bpf_obj_pin(link_fd, PIN_PATH);
ASSERT_OK(err) TH_LOG("error while calling bpf_obj_pin");
remove(PIN_PATH);
#undef PIN_PATH
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index f67d35def142..614f1aa32649 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -14,8 +14,8 @@ struct attach_prog_args {
__u64 callback_check = 52;
__u64 callback2_check = 52;

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx)
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);

@@ -29,8 +29,14 @@ int BPF_PROG(hid_first_event, struct hid_bpf_ctx *hid_ctx)
return hid_ctx->size;
}

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx)
+SEC(".struct_ops.link")
+struct hid_bpf_ops first_event = {
+ .hid_device_event = (void *)hid_first_event,
+ .hid_id = 2,
+};
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);

@@ -42,8 +48,13 @@ int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx)
return hid_ctx->size;
}

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx)
+SEC(".struct_ops.link")
+struct hid_bpf_ops second_event = {
+ .hid_device_event = (void *)hid_second_event,
+};
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);

@@ -55,15 +66,10 @@ int BPF_PROG(hid_change_report_id, struct hid_bpf_ctx *hid_ctx)
return 9;
}

-SEC("syscall")
-int attach_prog(struct attach_prog_args *ctx)
-{
- ctx->retval = hid_bpf_attach_prog(ctx->hid,
- ctx->prog_fd,
- ctx->insert_head ? HID_BPF_FLAG_INSERT_HEAD :
- HID_BPF_FLAG_NONE);
- return 0;
-}
+SEC(".struct_ops.link")
+struct hid_bpf_ops change_report_id = {
+ .hid_device_event = (void *)hid_change_report_id,
+};

struct hid_hw_request_syscall_args {
/* data needs to come at offset 0 so we can use it in calls */
@@ -181,7 +187,12 @@ static const __u8 rdesc[] = {
0xc0, /* END_COLLECTION */
};

-SEC("?fmod_ret/hid_bpf_rdesc_fixup")
+/*
+ * the following program is marked as sleepable (struct_ops.s).
+ * This is not strictly mandatory but is a nice test for
+ * sleepable struct_ops
+ */
+SEC("?struct_ops.s/hid_rdesc_fixup")
int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4096 /* size */);
@@ -200,8 +211,13 @@ int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hid_ctx)
return sizeof(rdesc) + 73;
}

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_test_insert1, struct hid_bpf_ctx *hid_ctx)
+SEC(".struct_ops.link")
+struct hid_bpf_ops rdesc_fixup = {
+ .hid_rdesc_fixup = (void *)hid_rdesc_fixup,
+};
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_test_insert1, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);

@@ -217,8 +233,14 @@ int BPF_PROG(hid_test_insert1, struct hid_bpf_ctx *hid_ctx)
return 0;
}

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_test_insert2, struct hid_bpf_ctx *hid_ctx)
+SEC(".struct_ops.link")
+struct hid_bpf_ops test_insert1 = {
+ .hid_device_event = (void *)hid_test_insert1,
+ .flags = BPF_F_BEFORE,
+};
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_test_insert2, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);

@@ -234,8 +256,13 @@ int BPF_PROG(hid_test_insert2, struct hid_bpf_ctx *hid_ctx)
return 0;
}

-SEC("?fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_test_insert3, struct hid_bpf_ctx *hid_ctx)
+SEC(".struct_ops.link")
+struct hid_bpf_ops test_insert2 = {
+ .hid_device_event = (void *)hid_test_insert2,
+};
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_test_insert3, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 4 /* size */);

@@ -250,3 +277,8 @@ int BPF_PROG(hid_test_insert3, struct hid_bpf_ctx *hid_ctx)

return 0;
}
+
+SEC(".struct_ops.link")
+struct hid_bpf_ops test_insert3 = {
+ .hid_device_event = (void *)hid_test_insert3,
+};
diff --git a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
index 9cd56821d0f1..e02e24e3eab3 100644
--- a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
+++ b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
@@ -20,9 +20,6 @@
#define HID_REQ_SET_REPORT HID_REQ_SET_REPORT___not_used
#define HID_REQ_SET_IDLE HID_REQ_SET_IDLE___not_used
#define HID_REQ_SET_PROTOCOL HID_REQ_SET_PROTOCOL___not_used
-#define HID_BPF_FLAG_NONE HID_BPF_FLAG_NONE___not_used
-#define HID_BPF_FLAG_INSERT_HEAD HID_BPF_FLAG_INSERT_HEAD___not_used
-#define HID_BPF_FLAG_MAX HID_BPF_FLAG_MAX___not_used

#include "vmlinux.h"

@@ -40,9 +37,6 @@
#undef HID_REQ_SET_REPORT
#undef HID_REQ_SET_IDLE
#undef HID_REQ_SET_PROTOCOL
-#undef HID_BPF_FLAG_NONE
-#undef HID_BPF_FLAG_INSERT_HEAD
-#undef HID_BPF_FLAG_MAX

#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
@@ -57,10 +51,8 @@ enum hid_report_type {
};

struct hid_bpf_ctx {
- __u32 index;
- const struct hid_device *hid;
+ struct hid_device *hid;
__u32 allocated_size;
- enum hid_report_type report_type;
union {
__s32 retval;
__s32 size;
@@ -76,17 +68,14 @@ enum hid_class_request {
HID_REQ_SET_PROTOCOL = 0x0B,
};

-enum hid_bpf_attach_flags {
- HID_BPF_FLAG_NONE = 0,
- HID_BPF_FLAG_INSERT_HEAD = _BITUL(0),
- HID_BPF_FLAG_MAX,
-};
+#ifndef BPF_F_BEFORE
+#define BPF_F_BEFORE (1U << 3)
+#endif

/* following are kfuncs exported by HID for HID-BPF */
extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
unsigned int offset,
const size_t __sz) __ksym;
-extern int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, u32 flags) __ksym;
extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __ksym;
extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __ksym;
extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,

--
2.44.0