Messages in this thread | | | Date | Wed, 24 Aug 2022 11:48:49 +0200 | Subject | Re: [PATCH bpf-next v7 13/24] HID: initial BPF implementation | From | Benjamin Tissoires <> |
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On 7/28/22 16:19, Greg KH wrote: > On Thu, Jul 21, 2022 at 05:36:14PM +0200, Benjamin Tissoires wrote: >> --- /dev/null >> +++ b/include/linux/hid_bpf.h >> @@ -0,0 +1,102 @@ >> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ > > This is not a uapi .h file, so the "WITH Linux-syscall-note" should not > be here, right?
thanks, dropping this syscall note from the series.
> > >> + >> +#ifndef __HID_BPF_H >> +#define __HID_BPF_H >> + >> +#include <linux/spinlock.h> >> +#include <uapi/linux/hid.h> >> +#include <uapi/linux/hid_bpf.h> >> + >> +struct hid_device; >> + >> +/* >> + * The following is the HID BPF API. >> + * >> + * It should be treated as UAPI, so extra care is required >> + * when making change to this file. > > So is this uapi? If so, shouldn't it go into a uapi include directory > so we know this and properly track it and maintain it that way?
IMO it's a grey area. It is not "uapi" because it doesn't export anything that userspace can use. A userspace program can not include that and use it in other words.
So strictly speaking, it's a normal part of a kernel header file, because it's a description of what other kernel users (though here, eBPF programs) can use.
But I really want that part of the API to be considered as "stable" and give some guarantees to the users that I won't change it at every release. Thus the "uapi-like".
> >> + */ >> + >> +/** >> + * struct hid_bpf_ctx - User accessible data for all HID programs >> + * >> + * ``data`` is not directly accessible from the context. We need to issue >> + * a call to ``hid_bpf_get_data()`` in order to get a pointer to that field. >> + * >> + * All of these fields are currently read-only. >> + * >> + * @index: program index in the jump table. No special meaning (a smaller index >> + * doesn't mean the program will be executed before another program with >> + * a bigger index). >> + * @hid: the ``struct hid_device`` representing the device itself >> + * @report_type: used for ``hid_bpf_device_event()`` >> + * @size: Valid data in the data field. >> + * >> + * Programs can get the available valid size in data by fetching this field. >> + */ >> +struct hid_bpf_ctx { >> + __u32 index; >> + const struct hid_device *hid; >> + enum hid_report_type report_type; >> + __s32 size; >> +}; >> + >> +/* Following functions are tracepoints that BPF programs can attach to */ >> +int hid_bpf_device_event(struct hid_bpf_ctx *ctx); >> + >> +/* Following functions are kfunc that we export to BPF programs */ >> +/* only available in tracing */ >> +__u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t __sz); >> + >> +/* only available in syscall */ >> +int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags); >> + >> +/* >> + * Below is HID internal >> + */ >> + >> +/* internal function to call eBPF programs, not to be used by anybody */ >> +int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx); >> + >> +#define HID_BPF_MAX_PROGS_PER_DEV 64 >> +#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1) >> + >> +/* types of HID programs to attach to */ >> +enum hid_bpf_prog_type { >> + HID_BPF_PROG_TYPE_UNDEF = -1, >> + HID_BPF_PROG_TYPE_DEVICE_EVENT, /* an event is emitted from the device */ >> + HID_BPF_PROG_TYPE_MAX, >> +}; >> + >> +struct hid_bpf_ops { >> + struct module *owner; >> + struct bus_type *bus_type; >> +}; >> + >> +extern struct hid_bpf_ops *hid_bpf_ops; >> + >> +struct hid_bpf_prog_list { >> + u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV]; >> + u8 prog_cnt; >> +}; >> + >> +/* stored in each device */ >> +struct hid_bpf { >> + struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */ >> + bool destroyed; /* prevents the assignment of any progs */ >> + >> + spinlock_t progs_lock; /* protects RCU update of progs */ >> +}; >> + >> +#ifdef CONFIG_HID_BPF >> +int dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data, >> + u32 size, int interrupt); >> +void hid_bpf_destroy_device(struct hid_device *hid); >> +void hid_bpf_device_init(struct hid_device *hid); >> +#else /* CONFIG_HID_BPF */ >> +static inline int dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data, >> + u32 size, int interrupt) { return 0; } >> +static inline void hid_bpf_destroy_device(struct hid_device *hid) {} >> +static inline void hid_bpf_device_init(struct hid_device *hid) {} >> +#endif /* CONFIG_HID_BPF */ >> + >> +#endif /* __HID_BPF_H */ >> diff --git a/include/uapi/linux/hid_bpf.h b/include/uapi/linux/hid_bpf.h >> new file mode 100644 >> index 000000000000..ba8caf9b60ee >> --- /dev/null >> +++ b/include/uapi/linux/hid_bpf.h >> @@ -0,0 +1,25 @@ >> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ > > This is fine, it is in include/uapi/ > > Other than those minor comments, this all looks good to me! > > Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >
Great! And thanks a lot for the other reviews.
I finally managed to get some time to work on it after some time off and urgent sh**t happening, so I'll send a new version of the series today.
Cheers, Benjamin
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