170 lines
6.2 KiB
C
170 lines
6.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* Copyright (c) 2022 Benjamin Tissoires
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*/
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#ifndef __HID_BPF_HELPERS_H
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#define __HID_BPF_HELPERS_H
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include <linux/errno.h>
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extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
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unsigned int offset,
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const size_t __sz) __ksym;
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extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __ksym;
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extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __ksym;
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extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx,
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__u8 *data,
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size_t buf__sz,
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enum hid_report_type type,
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enum hid_class_request reqtype) __ksym;
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#define HID_MAX_DESCRIPTOR_SIZE 4096
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#define HID_IGNORE_EVENT -1
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/* extracted from <linux/input.h> */
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#define BUS_ANY 0x00
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#define BUS_PCI 0x01
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#define BUS_ISAPNP 0x02
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#define BUS_USB 0x03
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#define BUS_HIL 0x04
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#define BUS_BLUETOOTH 0x05
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#define BUS_VIRTUAL 0x06
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#define BUS_ISA 0x10
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#define BUS_I8042 0x11
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#define BUS_XTKBD 0x12
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#define BUS_RS232 0x13
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#define BUS_GAMEPORT 0x14
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#define BUS_PARPORT 0x15
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#define BUS_AMIGA 0x16
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#define BUS_ADB 0x17
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#define BUS_I2C 0x18
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#define BUS_HOST 0x19
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#define BUS_GSC 0x1A
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#define BUS_ATARI 0x1B
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#define BUS_SPI 0x1C
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#define BUS_RMI 0x1D
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#define BUS_CEC 0x1E
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#define BUS_INTEL_ISHTP 0x1F
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#define BUS_AMD_SFH 0x20
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/* extracted from <linux/hid.h> */
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#define HID_GROUP_ANY 0x0000
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#define HID_GROUP_GENERIC 0x0001
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#define HID_GROUP_MULTITOUCH 0x0002
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#define HID_GROUP_SENSOR_HUB 0x0003
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#define HID_GROUP_MULTITOUCH_WIN_8 0x0004
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#define HID_GROUP_RMI 0x0100
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#define HID_GROUP_WACOM 0x0101
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#define HID_GROUP_LOGITECH_DJ_DEVICE 0x0102
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#define HID_GROUP_STEAM 0x0103
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#define HID_GROUP_LOGITECH_27MHZ_DEVICE 0x0104
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#define HID_GROUP_VIVALDI 0x0105
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/* include/linux/mod_devicetable.h defines as (~0), but that gives us negative size arrays */
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#define HID_VID_ANY 0x0000
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#define HID_PID_ANY 0x0000
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#define BIT(n) (1UL << (n))
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
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/* Helper macro to convert (foo, __LINE__) into foo134 so we can use __LINE__ for
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* field/variable names
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*/
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#define COMBINE1(X, Y) X ## Y
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#define COMBINE(X, Y) COMBINE1(X, Y)
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/* Macro magic:
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* __uint(foo, 123) creates a int (*foo)[1234]
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*
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* We use that macro to declare an anonymous struct with several
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* fields, each is the declaration of an pointer to an array of size
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* bus/group/vid/pid. (Because it's a pointer to such an array, actual storage
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* would be sizeof(pointer) rather than sizeof(array). Not that we ever
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* instantiate it anyway).
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*
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* This is only used for BTF introspection, we can later check "what size
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* is the bus array" in the introspection data and thus extract the bus ID
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* again.
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*
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* And we use the __LINE__ to give each of our structs a unique name so the
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* BPF program writer doesn't have to.
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*
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* $ bpftool btf dump file target/bpf/HP_Elite_Presenter.bpf.o
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* shows the inspection data, start by searching for .hid_bpf_config
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* and working backwards from that (each entry references the type_id of the
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* content).
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*/
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#define HID_DEVICE(b, g, ven, prod) \
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struct { \
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__uint(name, 0); \
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__uint(bus, (b)); \
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__uint(group, (g)); \
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__uint(vid, (ven)); \
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__uint(pid, (prod)); \
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} COMBINE(_entry, __LINE__)
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/* Macro magic below is to make HID_BPF_CONFIG() look like a function call that
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* we can pass multiple HID_DEVICE() invocations in.
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*
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* For up to 16 arguments, HID_BPF_CONFIG(one, two) resolves to
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*
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* union {
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* HID_DEVICE(...);
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* HID_DEVICE(...);
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* } _device_ids SEC(".hid_bpf_config")
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*
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*/
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/* Returns the number of macro arguments, this expands
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* NARGS(a, b, c) to NTH_ARG(a, b, c, 15, 14, 13, .... 4, 3, 2, 1).
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* NTH_ARG always returns the 16th argument which in our case is 3.
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*
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* If we want more than 16 values _COUNTDOWN and _NTH_ARG both need to be
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* updated.
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*/
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#define _NARGS(...) _NARGS1(__VA_ARGS__, _COUNTDOWN)
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#define _NARGS1(...) _NTH_ARG(__VA_ARGS__)
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/* Add to this if we need more than 16 args */
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#define _COUNTDOWN \
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15, 14, 13, 12, 11, 10, 9, 8, \
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7, 6, 5, 4, 3, 2, 1, 0
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/* Return the 16 argument passed in. See _NARGS above for usage. Note this is
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* 1-indexed.
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*/
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#define _NTH_ARG( \
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_1, _2, _3, _4, _5, _6, _7, _8, \
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_9, _10, _11, _12, _13, _14, _15,\
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N, ...) N
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/* Turns EXPAND(_ARG, a, b, c) into _ARG3(a, b, c) */
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#define _EXPAND(func, ...) COMBINE(func, _NARGS(__VA_ARGS__)) (__VA_ARGS__)
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/* And now define all the ARG macros for each number of args we want to accept */
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#define _ARG1(_1) _1;
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#define _ARG2(_1, _2) _1; _2;
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#define _ARG3(_1, _2, _3) _1; _2; _3;
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#define _ARG4(_1, _2, _3, _4) _1; _2; _3; _4;
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#define _ARG5(_1, _2, _3, _4, _5) _1; _2; _3; _4; _5;
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#define _ARG6(_1, _2, _3, _4, _5, _6) _1; _2; _3; _4; _5; _6;
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#define _ARG7(_1, _2, _3, _4, _5, _6, _7) _1; _2; _3; _4; _5; _6; _7;
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#define _ARG8(_1, _2, _3, _4, _5, _6, _7, _8) _1; _2; _3; _4; _5; _6; _7; _8;
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#define _ARG9(_1, _2, _3, _4, _5, _6, _7, _8, _9) _1; _2; _3; _4; _5; _6; _7; _8; _9;
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#define _ARG10(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a;
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#define _ARG11(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b;
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#define _ARG12(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b; _c;
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#define _ARG13(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, _d) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b; _c; _d;
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#define _ARG14(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, _d, _e) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b; _c; _d; _e;
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#define _ARG15(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, _d, _e, _f) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b; _c; _d; _e; _f;
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#define HID_BPF_CONFIG(...) union { \
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_EXPAND(_ARG, __VA_ARGS__) \
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} _device_ids SEC(".hid_bpf_config")
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#endif /* __HID_BPF_HELPERS_H */
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