HID: bpf: add support for new workqueue triggering BPF call

Add new bpf_hid_schedule_work() API to trigger execution of a BPF program
in a workqueue. A new BPF identifier is also added for the workqueue
program called hid/work.

Signed-off-by: Tero Kristo <tero.kristo@linux.intel.com>

drivers/hid/hid-bpf.c

@@ -89,6 +89,8 @@ static int hid_bpf_prog_attach(struct hid_device *hdev, const union bpf_attr *at
 			return ret;
 
 		return hid_reconnect(hdev);
+	case BPF_HID_WORK:
+		return __hid_bpf_prog_attach(hdev, &hdev->bpf.work_prog, prog);
 	}
 
 	return -EINVAL;
@@ -163,6 +165,11 @@ int hid_bpf_prog_detach(struct hid_device *hdev, struct bpf_prog *prog)
 			return ret;
 
 		return hid_reconnect(hdev);
+	case BPF_HID_WORK:
+		if (prog != hdev->bpf.work_prog)
+			return -EINVAL;
+
+		return __hid_bpf_prog_detach(hdev, &hdev->bpf.work_prog);
 	default:
 		return -EINVAL;
 	}
@@ -577,6 +584,24 @@ static const struct bpf_func_proto bpf_hid_set_data_proto = {
 	.arg4_type = ARG_ANYTHING,
 };
 
+BPF_CALL_2(bpf_hid_schedule_work, void*, ctx, u64, timeout)
+{
+	struct hid_bpf_ctx *bpf_ctx = ctx;
+
+	if (!delayed_work_pending(&bpf_ctx->work))
+		schedule_delayed_work(&bpf_ctx->work, timeout);
+
+	return 0;
+}
+
+static const struct bpf_func_proto bpf_hid_schedule_work_proto = {
+	.func      = bpf_hid_schedule_work,
+	.gpl_only  = true,
+	.ret_type  = RET_INTEGER,
+	.arg1_type = ARG_PTR_TO_CTX,
+	.arg2_type = ARG_ANYTHING,
+};
+
 static const struct bpf_func_proto *
 hid_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {
@@ -593,6 +618,8 @@ hid_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_hid_raw_request_proto;
 	case BPF_FUNC_hid_set_data:
 		return &bpf_hid_set_data_proto;
+	case BPF_FUNC_hid_schedule_work:
+		return &bpf_hid_schedule_work_proto;
 	default:
 		return bpf_base_func_proto(func_id);
 	}
@@ -659,6 +686,18 @@ static struct hid_device *__hid_bpf_fd_to_hdev(int fd)
 	return hdev;
 }
 
+static void hid_bpf_work(struct work_struct *work)
+{
+	struct hid_bpf_ctx *ctx =
+		container_of(work, struct hid_bpf_ctx, work.work);
+
+	migrate_disable();
+
+	bpf_prog_run(ctx->hdev->bpf.work_prog, ctx);
+
+	migrate_enable();
+}
+
 static struct hid_bpf_ctx *hid_bpf_allocate(struct hid_device *hdev)
 {
 	struct hid_bpf_ctx *ctx;
@@ -669,6 +708,8 @@ static struct hid_bpf_ctx *hid_bpf_allocate(struct hid_device *hdev)
 
 	ctx->hdev = hdev;
 
+	INIT_DELAYED_WORK(&ctx->work, hid_bpf_work);
+
 	return ctx;
 }
 

include/linux/hid.h

@@ -371,6 +371,7 @@ struct hid_device {							/* device report descriptor */
 	struct {
 		struct mutex lock;
 		struct bpf_prog __rcu *rdesc_fixup_prog;
+		struct bpf_prog __rcu *work_prog;
 		struct bpf_prog_array __rcu *event_progs;
 		struct bpf_prog_array __rcu *kevent_progs;
 		struct hid_bpf_ctx *ctx;

include/uapi/linux/bpf.h

@@ -999,6 +999,7 @@ enum bpf_attach_type {
 	BPF_HID_RAW_EVENT,
 	BPF_HID_RDESC_FIXUP,
 	BPF_HID_KERNEL_EVENT,
+	BPF_HID_WORK,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -4981,6 +4982,12 @@ union bpf_attr {
  *	Return
  *		The number of traversed items for success, **-EINVAL** for
  *		invalid **flags**.
+ *
+ * u32 bpf_hid_schedule_work(void *ctx, u64 timeout)
+ *	Description
+ *		Schedules a delayed work after the specified timeout.
+ *	Return
+ *		0 on success, a negative error on failure.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5169,6 +5176,7 @@ union bpf_attr {
 	FN(hid_set_data),		\
 	FN(hid_get_data),		\
 	FN(hid_foreach_rdesc_item),	\
+	FN(hid_schedule_work),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper

include/uapi/linux/bpf_hid.h

@@ -10,6 +10,7 @@
 #define _UAPI__LINUX_BPF_HID_H__
 
 #include <linux/types.h>
+#include <linux/workqueue.h>
 
 #define HID_BPF_MAX_BUFFER_SIZE		16384		/* 16kb */
 
@@ -36,6 +37,7 @@ struct hid_bpf_ctx {
 		unsigned char request;
 		int retval;
 	} event;
+	struct delayed_work work;
 };
 
 /* in sync with struct hid_item */

kernel/bpf/syscall.c

@@ -3184,6 +3184,7 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
 	case BPF_HID_KERNEL_EVENT:
 	case BPF_HID_RAW_EVENT:
 	case BPF_HID_RDESC_FIXUP:
+	case BPF_HID_WORK:
 		return BPF_PROG_TYPE_HID;
 	default:
 		return BPF_PROG_TYPE_UNSPEC;

tools/include/uapi/linux/bpf.h

@@ -999,6 +999,7 @@ enum bpf_attach_type {
 	BPF_HID_RAW_EVENT,
 	BPF_HID_RDESC_FIXUP,
 	BPF_HID_KERNEL_EVENT,
+	BPF_HID_WORK,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -4981,6 +4982,12 @@ union bpf_attr {
  *	Return
  *		The number of traversed items for success, **-EINVAL** for
  *		invalid **flags**.
+ *
+ * u32 bpf_hid_schedule_work(void *ctx, u64 timeout)
+ *	Description
+ *		Schedules a delayed work after the specified timeout.
+ *	Return
+ *		0 on success, a negative error on failure.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5169,6 +5176,7 @@ union bpf_attr {
 	FN(hid_set_data),		\
 	FN(hid_get_data),		\
 	FN(hid_foreach_rdesc_item),	\
+	FN(hid_schedule_work),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper

tools/lib/bpf/libbpf.c

@@ -8370,6 +8370,7 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("hid/event",		HID, BPF_HID_KERNEL_EVENT, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX),
 	SEC_DEF("hid/raw_event",	HID, BPF_HID_RAW_EVENT, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX),
 	SEC_DEF("hid/rdesc_fixup",	HID, BPF_HID_RDESC_FIXUP, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX),
+	SEC_DEF("hid/work",		HID, BPF_HID_WORK, SEC_ATTACHABLE_OPT | SEC_SLOPPY_PFX),
 };
 
 #define MAX_TYPE_NAME_SIZE 32