1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* Copyright (c) 2022 Benjamin Tissoires 3 */ 4 5#ifndef __HID_BPF_HELPERS_H 6#define __HID_BPF_HELPERS_H 7 8#include "vmlinux.h" 9#include <bpf/bpf_helpers.h> 10#include <linux/errno.h> 11 12extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx, 13 unsigned int offset, 14 const size_t __sz) __ksym; 15extern struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id) __ksym; 16extern void hid_bpf_release_context(struct hid_bpf_ctx *ctx) __ksym; 17extern int hid_bpf_hw_request(struct hid_bpf_ctx *ctx, 18 __u8 *data, 19 size_t buf__sz, 20 enum hid_report_type type, 21 enum hid_class_request reqtype) __ksym; 22 23#define HID_MAX_DESCRIPTOR_SIZE 4096 24#define HID_IGNORE_EVENT -1 25 26/* extracted from <linux/input.h> */ 27#define BUS_ANY 0x00 28#define BUS_PCI 0x01 29#define BUS_ISAPNP 0x02 30#define BUS_USB 0x03 31#define BUS_HIL 0x04 32#define BUS_BLUETOOTH 0x05 33#define BUS_VIRTUAL 0x06 34#define BUS_ISA 0x10 35#define BUS_I8042 0x11 36#define BUS_XTKBD 0x12 37#define BUS_RS232 0x13 38#define BUS_GAMEPORT 0x14 39#define BUS_PARPORT 0x15 40#define BUS_AMIGA 0x16 41#define BUS_ADB 0x17 42#define BUS_I2C 0x18 43#define BUS_HOST 0x19 44#define BUS_GSC 0x1A 45#define BUS_ATARI 0x1B 46#define BUS_SPI 0x1C 47#define BUS_RMI 0x1D 48#define BUS_CEC 0x1E 49#define BUS_INTEL_ISHTP 0x1F 50#define BUS_AMD_SFH 0x20 51 52/* extracted from <linux/hid.h> */ 53#define HID_GROUP_ANY 0x0000 54#define HID_GROUP_GENERIC 0x0001 55#define HID_GROUP_MULTITOUCH 0x0002 56#define HID_GROUP_SENSOR_HUB 0x0003 57#define HID_GROUP_MULTITOUCH_WIN_8 0x0004 58#define HID_GROUP_RMI 0x0100 59#define HID_GROUP_WACOM 0x0101 60#define HID_GROUP_LOGITECH_DJ_DEVICE 0x0102 61#define HID_GROUP_STEAM 0x0103 62#define HID_GROUP_LOGITECH_27MHZ_DEVICE 0x0104 63#define HID_GROUP_VIVALDI 0x0105 64 65/* include/linux/mod_devicetable.h defines as (~0), but that gives us negative size arrays */ 66#define HID_VID_ANY 0x0000 67#define HID_PID_ANY 0x0000 68 69#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) 70 71/* Helper macro to convert (foo, __LINE__) into foo134 so we can use __LINE__ for 72 * field/variable names 73 */ 74#define COMBINE1(X, Y) X ## Y 75#define COMBINE(X, Y) COMBINE1(X, Y) 76 77/* Macro magic: 78 * __uint(foo, 123) creates a int (*foo)[1234] 79 * 80 * We use that macro to declare an anonymous struct with several 81 * fields, each is the declaration of an pointer to an array of size 82 * bus/group/vid/pid. (Because it's a pointer to such an array, actual storage 83 * would be sizeof(pointer) rather than sizeof(array). Not that we ever 84 * instantiate it anyway). 85 * 86 * This is only used for BTF introspection, we can later check "what size 87 * is the bus array" in the introspection data and thus extract the bus ID 88 * again. 89 * 90 * And we use the __LINE__ to give each of our structs a unique name so the 91 * BPF program writer doesn't have to. 92 * 93 * $ bpftool btf dump file target/bpf/HP_Elite_Presenter.bpf.o 94 * shows the inspection data, start by searching for .hid_bpf_config 95 * and working backwards from that (each entry references the type_id of the 96 * content). 97 */ 98 99#define HID_DEVICE(b, g, ven, prod) \ 100 struct { \ 101 __uint(name, 0); \ 102 __uint(bus, (b)); \ 103 __uint(group, (g)); \ 104 __uint(vid, (ven)); \ 105 __uint(pid, (prod)); \ 106 } COMBINE(_entry, __LINE__) 107 108/* Macro magic below is to make HID_BPF_CONFIG() look like a function call that 109 * we can pass multiple HID_DEVICE() invocations in. 110 * 111 * For up to 16 arguments, HID_BPF_CONFIG(one, two) resolves to 112 * 113 * union { 114 * HID_DEVICE(...); 115 * HID_DEVICE(...); 116 * } _device_ids SEC(".hid_bpf_config") 117 * 118 */ 119 120/* Returns the number of macro arguments, this expands 121 * NARGS(a, b, c) to NTH_ARG(a, b, c, 15, 14, 13, .... 4, 3, 2, 1). 122 * NTH_ARG always returns the 16th argument which in our case is 3. 123 * 124 * If we want more than 16 values _COUNTDOWN and _NTH_ARG both need to be 125 * updated. 126 */ 127#define _NARGS(...) _NARGS1(__VA_ARGS__, _COUNTDOWN) 128#define _NARGS1(...) _NTH_ARG(__VA_ARGS__) 129 130/* Add to this if we need more than 16 args */ 131#define _COUNTDOWN \ 132 15, 14, 13, 12, 11, 10, 9, 8, \ 133 7, 6, 5, 4, 3, 2, 1, 0 134 135/* Return the 16 argument passed in. See _NARGS above for usage. Note this is 136 * 1-indexed. 137 */ 138#define _NTH_ARG( \ 139 _1, _2, _3, _4, _5, _6, _7, _8, \ 140 _9, _10, _11, _12, _13, _14, _15,\ 141 N, ...) N 142 143/* Turns EXPAND(_ARG, a, b, c) into _ARG3(a, b, c) */ 144#define _EXPAND(func, ...) COMBINE(func, _NARGS(__VA_ARGS__)) (__VA_ARGS__) 145 146/* And now define all the ARG macros for each number of args we want to accept */ 147#define _ARG1(_1) _1; 148#define _ARG2(_1, _2) _1; _2; 149#define _ARG3(_1, _2, _3) _1; _2; _3; 150#define _ARG4(_1, _2, _3, _4) _1; _2; _3; _4; 151#define _ARG5(_1, _2, _3, _4, _5) _1; _2; _3; _4; _5; 152#define _ARG6(_1, _2, _3, _4, _5, _6) _1; _2; _3; _4; _5; _6; 153#define _ARG7(_1, _2, _3, _4, _5, _6, _7) _1; _2; _3; _4; _5; _6; _7; 154#define _ARG8(_1, _2, _3, _4, _5, _6, _7, _8) _1; _2; _3; _4; _5; _6; _7; _8; 155#define _ARG9(_1, _2, _3, _4, _5, _6, _7, _8, _9) _1; _2; _3; _4; _5; _6; _7; _8; _9; 156#define _ARG10(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; 157#define _ARG11(_1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b) _1; _2; _3; _4; _5; _6; _7; _8; _9; _a; _b; 158#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; 159#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; 160#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; 161#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; 162 163 164#define HID_BPF_CONFIG(...) union { \ 165 _EXPAND(_ARG, __VA_ARGS__) \ 166} _device_ids SEC(".hid_bpf_config") 167 168#endif /* __HID_BPF_HELPERS_H */ 169