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Message-ID: <CAO-hwJL4UMQMOC-CQKXZ_Np2b7H2rSnAji=Yypc62k_+GejwcA@mail.gmail.com>
Date: Wed, 24 Jan 2024 10:58:53 +0100
From: Benjamin Tissoires <benjamin.tissoires@...hat.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Benjamin Tissoires <bentiss@...nel.org>, Jiri Kosina <jikos@...nel.org>,
Dan Carpenter <dan.carpenter@...aro.org>, Daniel Borkmann <daniel@...earbox.net>,
linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH 2/2] HID: bpf: use __bpf_kfunc instead of noinline
On Tue, Jan 23, 2024 at 8:57 PM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
>
> On Tue, Jan 23, 2024 at 8:46 AM Benjamin Tissoires <bentiss@...nel.org> wrote:
> >
> > Follow the docs at Documentation/bpf/kfuncs.rst:
> > - declare the function with `__bpf_kfunc`
> > - disables missing prototype warnings, which allows to remove them from
> > include/linux/hid-bpf.h
> >
> > Removing the prototypes is not an issue because we currently have to
> > redeclare them when writing the BPF program. They will eventually be
> > generated by bpftool directly AFAIU.
> >
> > Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>
> > ---
> > drivers/hid/bpf/hid_bpf_dispatch.c | 22 +++++++++++++++++-----
> > include/linux/hid_bpf.h | 11 -----------
> > 2 files changed, 17 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c
> > index 5111d1fef0d3..119e4f03df55 100644
> > --- a/drivers/hid/bpf/hid_bpf_dispatch.c
> > +++ b/drivers/hid/bpf/hid_bpf_dispatch.c
> > @@ -143,6 +143,11 @@ u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *s
> > }
> > EXPORT_SYMBOL_GPL(call_hid_bpf_rdesc_fixup);
> >
> > +/* Disables missing prototype warnings */
> > +__diag_push();
> > +__diag_ignore_all("-Wmissing-prototypes",
> > + "Global kfuncs as their definitions will be in BTF");
> > +
>
> would it be possible to use __bpf_kfunc_start_defs() and
> __bpf_kfunc_end_defs() macros instead of explicit __diag push/pop
> pairs? It's defined in include/linux/btf.h
Sure, I'll use them in v2.
I also realized that I had some memory leaks because I never called
put_device() after bus_find_device(), so I need to add another fix to
this series.
Cheers,
Benjamin
>
> > /**
> > * hid_bpf_get_data - Get the kernel memory pointer associated with the context @ctx
> > *
> > @@ -152,7 +157,7 @@ EXPORT_SYMBOL_GPL(call_hid_bpf_rdesc_fixup);
> > *
> > * @returns %NULL on error, an %__u8 memory pointer on success
> > */
> > -noinline __u8 *
> > +__bpf_kfunc __u8 *
> > hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t rdwr_buf_size)
> > {
> > struct hid_bpf_ctx_kern *ctx_kern;
> > @@ -167,6 +172,7 @@ hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t rdwr
> >
> > return ctx_kern->data + offset;
> > }
> > +__diag_pop(); /* missing prototype warnings */
> >
> > /*
> > * The following set contains all functions we agree BPF programs
> > @@ -274,6 +280,11 @@ static int do_hid_bpf_attach_prog(struct hid_device *hdev, int prog_fd, struct b
> > return fd;
> > }
> >
> > +/* Disables missing prototype warnings */
> > +__diag_push();
> > +__diag_ignore_all("-Wmissing-prototypes",
> > + "Global kfuncs as their definitions will be in BTF");
> > +
> > /**
> > * hid_bpf_attach_prog - Attach the given @prog_fd to the given HID device
> > *
> > @@ -286,7 +297,7 @@ static int do_hid_bpf_attach_prog(struct hid_device *hdev, int prog_fd, struct b
> > * is pinned to the BPF file system).
> > */
> > /* called from syscall */
> > -noinline int
> > +__bpf_kfunc int
> > hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags)
> > {
> > struct hid_device *hdev;
> > @@ -328,7 +339,7 @@ hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags)
> > *
> > * @returns A pointer to &struct hid_bpf_ctx on success, %NULL on error.
> > */
> > -noinline struct hid_bpf_ctx *
> > +__bpf_kfunc struct hid_bpf_ctx *
> > hid_bpf_allocate_context(unsigned int hid_id)
> > {
> > struct hid_device *hdev;
> > @@ -359,7 +370,7 @@ hid_bpf_allocate_context(unsigned int hid_id)
> > * @ctx: the HID-BPF context to release
> > *
> > */
> > -noinline void
> > +__bpf_kfunc void
> > hid_bpf_release_context(struct hid_bpf_ctx *ctx)
> > {
> > struct hid_bpf_ctx_kern *ctx_kern;
> > @@ -380,7 +391,7 @@ hid_bpf_release_context(struct hid_bpf_ctx *ctx)
> > *
> > * @returns %0 on success, a negative error code otherwise.
> > */
> > -noinline int
> > +__bpf_kfunc int
> > hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz,
> > enum hid_report_type rtype, enum hid_class_request reqtype)
> > {
> > @@ -448,6 +459,7 @@ hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz,
> > kfree(dma_data);
> > return ret;
> > }
> > +__diag_pop(); /* missing prototype warnings */
> >
> > /* our HID-BPF entrypoints */
> > BTF_SET8_START(hid_bpf_fmodret_ids)
> > diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
> > index 840cd254172d..7118ac28d468 100644
> > --- a/include/linux/hid_bpf.h
> > +++ b/include/linux/hid_bpf.h
> > @@ -77,17 +77,6 @@ enum hid_bpf_attach_flags {
> > int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
> > int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx);
> >
> > -/* Following functions are kfunc that we export to BPF programs */
> > -/* available everywhere in HID-BPF */
> > -__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);
> > -int hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz,
> > - enum hid_report_type rtype, enum hid_class_request reqtype);
> > -struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id);
> > -void hid_bpf_release_context(struct hid_bpf_ctx *ctx);
> > -
> > /*
> > * Below is HID internal
> > */
> >
> > --
> > 2.43.0
> >
> >
>
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