On Fri, 2023-09-08 at 22:22 +0000, Justin Stitt wrote:
> From: Benjamin Tissoires <bentiss@xxxxxxxxxx>
>
> For the hid-bpf tests to compile, we need to have the definition of
> struct hid_bpf_ctx. This definition is an internal one from the kernel
> and it is supposed to be defined in the generated vmlinux.h.
>
> This vmlinux.h header is generated based on the currently running kernel
> or if the kernel was already compiled in the tree. If you just compile
> the selftests without compiling the kernel beforehand and you are running
> on a 6.2 kernel, you'll end up with a vmlinux.h without the hid_bpf_ctx
> definition.
>
> Use the clever trick from tools/testing/selftests/bpf/progs/bpf_iter.h
> to force the definition of that symbol in case we don't find it in the
> BTF and also add __attribute__((preserve_access_index)) to further
> support CO-RE functionality for these tests.
>
> Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
> Signed-off-by: Benjamin Tissoires <bentiss@xxxxxxxxxx>
> ---
> tools/testing/selftests/hid/progs/hid.c | 3 --
> .../testing/selftests/hid/progs/hid_bpf_helpers.h | 49 ++++++++++++++++++++++
> 2 files changed, 49 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
> index 88c593f753b5..1e558826b809 100644
> --- a/tools/testing/selftests/hid/progs/hid.c
> +++ b/tools/testing/selftests/hid/progs/hid.c
> @@ -1,8 +1,5 @@
> // SPDX-License-Identifier: GPL-2.0
> /* Copyright (c) 2022 Red hat */
> -#include "vmlinux.h"
> -#include <bpf/bpf_helpers.h>
> -#include <bpf/bpf_tracing.h>
> #include "hid_bpf_helpers.h"
>
> char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
> index 4fff31dbe0e7..ab3b18ba48c4 100644
> --- a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
> +++ b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
> @@ -5,6 +5,55 @@
> #ifndef __HID_BPF_HELPERS_H
> #define __HID_BPF_HELPERS_H
>
> +/* "undefine" structs in vmlinux.h, because we "override" them below */
Hi Justin,
What you have here should work, however I still think that the trick
with "___local" suffix I refer to in [1] is a bit less hacky, e.g.:
enum hid_report_type___local { ... };
struct hid_bpf_ctx___local {
__u32 index;
const struct hid_device *hid; // this one should be in vmlinux.h with any config
__u32 allocated_size;
enum hid_report_type___local report_type;
union {
__s32 retval;
__s32 size;
};
} __attribute__((preserve_access_index));
enum hid_class_request___local { ... };
enum hid_bpf_attach_flags___local { ... };
...
extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx___local *ctx,
unsigned int offset,
(sorry for being a bore, won't bring this up anymore).
Thanks,
Eduard
[1] https://lore.kernel.org/bpf/e99b4226bd450fedfebd4eb5c37054f032432b4f.camel@xxxxxxxxx/
> +#define hid_bpf_ctx hid_bpf_ctx___not_used
> +#define hid_report_type hid_report_type___not_used
> +#define hid_class_request hid_class_request___not_used
> +#define hid_bpf_attach_flags hid_bpf_attach_flags___not_used
> +#include "vmlinux.h"
> +#undef hid_bpf_ctx
> +#undef hid_report_type
> +#undef hid_class_request
> +#undef hid_bpf_attach_flags
> +
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <linux/const.h>
> +
> +enum hid_report_type {
> + HID_INPUT_REPORT = 0,
> + HID_OUTPUT_REPORT = 1,
> + HID_FEATURE_REPORT = 2,
> +
> + HID_REPORT_TYPES,
> +};
> +
> +struct hid_bpf_ctx {
> + __u32 index;
> + const struct hid_device *hid;
> + __u32 allocated_size;
> + enum hid_report_type report_type;
> + union {
> + __s32 retval;
> + __s32 size;
> + };
> +} __attribute__((preserve_access_index));
> +
> +enum hid_class_request {
> + HID_REQ_GET_REPORT = 0x01,
> + HID_REQ_GET_IDLE = 0x02,
> + HID_REQ_GET_PROTOCOL = 0x03,
> + HID_REQ_SET_REPORT = 0x09,
> + HID_REQ_SET_IDLE = 0x0A,
> + 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,
> +};
> +
> /* following are kfuncs exported by HID for HID-BPF */
> extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
> unsigned int offset,
>
