113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "hid_bpf_helpers.h"
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SEC("fmod_ret/hid_bpf_device_event")
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int BPF_PROG(hid_y_event, struct hid_bpf_ctx *hctx)
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{
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s16 y;
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__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
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if (!data)
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return 0; /* EPERM check */
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bpf_printk("event: size: %d", hctx->size);
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bpf_printk("incoming event: %02x %02x %02x",
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data[0],
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data[1],
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data[2]);
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bpf_printk(" %02x %02x %02x",
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data[3],
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data[4],
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data[5]);
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bpf_printk(" %02x %02x %02x",
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data[6],
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data[7],
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data[8]);
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y = data[3] | (data[4] << 8);
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y = -y;
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data[3] = y & 0xFF;
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data[4] = (y >> 8) & 0xFF;
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bpf_printk("modified event: %02x %02x %02x",
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data[0],
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data[1],
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data[2]);
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bpf_printk(" %02x %02x %02x",
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data[3],
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data[4],
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data[5]);
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bpf_printk(" %02x %02x %02x",
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data[6],
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data[7],
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data[8]);
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return 0;
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}
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SEC("fmod_ret/hid_bpf_device_event")
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int BPF_PROG(hid_x_event, struct hid_bpf_ctx *hctx)
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{
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s16 x;
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__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
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if (!data)
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return 0; /* EPERM check */
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x = data[1] | (data[2] << 8);
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x = -x;
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data[1] = x & 0xFF;
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data[2] = (x >> 8) & 0xFF;
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return 0;
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}
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SEC("fmod_ret/hid_bpf_rdesc_fixup")
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int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
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{
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__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
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if (!data)
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return 0; /* EPERM check */
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bpf_printk("rdesc: %02x %02x %02x",
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data[0],
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data[1],
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data[2]);
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bpf_printk(" %02x %02x %02x",
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data[3],
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data[4],
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data[5]);
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bpf_printk(" %02x %02x %02x ...",
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data[6],
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data[7],
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data[8]);
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/*
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* The original report descriptor contains:
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*
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* 0x05, 0x01, // Usage Page (Generic Desktop) 30
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* 0x16, 0x01, 0x80, // Logical Minimum (-32767) 32
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* 0x26, 0xff, 0x7f, // Logical Maximum (32767) 35
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* 0x09, 0x30, // Usage (X) 38
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* 0x09, 0x31, // Usage (Y) 40
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*
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* So byte 39 contains Usage X and byte 41 Usage Y.
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*
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* We simply swap the axes here.
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*/
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data[39] = 0x31;
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data[41] = 0x30;
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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