diff mbox series

[bpf-next,06/16] bpf: Introduce bpf_dynptr_user

Message ID 20241008091501.8302-7-houtao@huaweicloud.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Support dynptr key for hash map | expand

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Commit Message

Hou Tao Oct. 8, 2024, 9:14 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

For bpf map with dynptr key support, the userspace application will use
bpf_dynptr_user to represent the bpf_dynptr in the map key and pass it
to bpf syscall. The bpf syscall will copy from bpf_dynptr_user to
construct a corresponding bpf_dynptr_kern object when the map key is an
input argument, and copy to bpf_dynptr_user from a bpf_dynptr_kern
object when the map key is an output argument.

For now the size of bpf_dynptr_user must be the same as bpf_dynptr, but
the last u32 field is not used, so make it a reserved field.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 include/uapi/linux/bpf.h       | 6 ++++++
 tools/include/uapi/linux/bpf.h | 6 ++++++
 2 files changed, 12 insertions(+)

Comments

Andrii Nakryiko Oct. 10, 2024, 9:50 p.m. UTC | #1 
On Tue, Oct 8, 2024 at 2:02 AM Hou Tao <houtao@huaweicloud.com> wrote:
>
> From: Hou Tao <houtao1@huawei.com>
>
> For bpf map with dynptr key support, the userspace application will use
> bpf_dynptr_user to represent the bpf_dynptr in the map key and pass it
> to bpf syscall. The bpf syscall will copy from bpf_dynptr_user to
> construct a corresponding bpf_dynptr_kern object when the map key is an
> input argument, and copy to bpf_dynptr_user from a bpf_dynptr_kern
> object when the map key is an output argument.
>
> For now the size of bpf_dynptr_user must be the same as bpf_dynptr, but
> the last u32 field is not used, so make it a reserved field.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
>  include/uapi/linux/bpf.h       | 6 ++++++
>  tools/include/uapi/linux/bpf.h | 6 ++++++
>  2 files changed, 12 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 07f7df308a01..72fe6a96b54c 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -7329,6 +7329,12 @@ struct bpf_dynptr {
>         __u64 __opaque[2];
>  } __attribute__((aligned(8)));
>
> +struct bpf_dynptr_user {

bikeshedding: maybe just bpf_udynptr?

> +       __u64 data;
> +       __u32 size;
> +       __u32 rsvd;
> +} __attribute__((aligned(8)));
> +
>  struct bpf_list_head {
>         __u64 __opaque[2];
>  } __attribute__((aligned(8)));
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 14f223282bfa..f12ce268e6be 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -7328,6 +7328,12 @@ struct bpf_dynptr {
>         __u64 __opaque[2];
>  } __attribute__((aligned(8)));
>
> +struct bpf_dynptr_user {
> +       __u64 data;

what if we use __bpf_md_ptr(void *, data), so users can just directly
use this struct (and then the next patch won't be necessary at all)

> +       __u32 size;
> +       __u32 rsvd;

please call it __reserved


> +} __attribute__((aligned(8)));
> +
>  struct bpf_list_head {
>         __u64 __opaque[2];
>  } __attribute__((aligned(8)));
> --
> 2.44.0
>
Alexei Starovoitov Oct. 10, 2024, 10:12 p.m. UTC | #2 
On Thu, Oct 10, 2024 at 2:50 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Tue, Oct 8, 2024 at 2:02 AM Hou Tao <houtao@huaweicloud.com> wrote:
> >
> > From: Hou Tao <houtao1@huawei.com>
> >
> > For bpf map with dynptr key support, the userspace application will use
> > bpf_dynptr_user to represent the bpf_dynptr in the map key and pass it
> > to bpf syscall. The bpf syscall will copy from bpf_dynptr_user to
> > construct a corresponding bpf_dynptr_kern object when the map key is an
> > input argument, and copy to bpf_dynptr_user from a bpf_dynptr_kern
> > object when the map key is an output argument.
> >
> > For now the size of bpf_dynptr_user must be the same as bpf_dynptr, but
> > the last u32 field is not used, so make it a reserved field.
> >
> > Signed-off-by: Hou Tao <houtao1@huawei.com>
> > ---
> >  include/uapi/linux/bpf.h       | 6 ++++++
> >  tools/include/uapi/linux/bpf.h | 6 ++++++
> >  2 files changed, 12 insertions(+)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index 07f7df308a01..72fe6a96b54c 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -7329,6 +7329,12 @@ struct bpf_dynptr {
> >         __u64 __opaque[2];
> >  } __attribute__((aligned(8)));
> >
> > +struct bpf_dynptr_user {
>
> bikeshedding: maybe just bpf_udynptr?

I don't like it. Looks too similar and easy to misread.
I think bpf_dynptr_user is better.
Hou Tao Oct. 21, 2024, 1:51 p.m. UTC | #3 
HI,

On 10/11/2024 5:50 AM, Andrii Nakryiko wrote:
> On Tue, Oct 8, 2024 at 2:02 AM Hou Tao <houtao@huaweicloud.com> wrote:
>> From: Hou Tao <houtao1@huawei.com>
>>
>> For bpf map with dynptr key support, the userspace application will use
>> bpf_dynptr_user to represent the bpf_dynptr in the map key and pass it
>> to bpf syscall. The bpf syscall will copy from bpf_dynptr_user to
>> construct a corresponding bpf_dynptr_kern object when the map key is an
>> input argument, and copy to bpf_dynptr_user from a bpf_dynptr_kern
>> object when the map key is an output argument.
>>
>> For now the size of bpf_dynptr_user must be the same as bpf_dynptr, but
>> the last u32 field is not used, so make it a reserved field.
>>
>> Signed-off-by: Hou Tao <houtao1@huawei.com>
>> ---
>>  include/uapi/linux/bpf.h       | 6 ++++++
>>  tools/include/uapi/linux/bpf.h | 6 ++++++
>>  2 files changed, 12 insertions(+)
>>
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index 07f7df308a01..72fe6a96b54c 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -7329,6 +7329,12 @@ struct bpf_dynptr {
>>         __u64 __opaque[2];
>>  } __attribute__((aligned(8)));
>>
>> +struct bpf_dynptr_user {
> bikeshedding: maybe just bpf_udynptr?
>
>> +       __u64 data;
>> +       __u32 size;
>> +       __u32 rsvd;
>> +} __attribute__((aligned(8)));
>> +
>>  struct bpf_list_head {
>>         __u64 __opaque[2];
>>  } __attribute__((aligned(8)));
>> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
>> index 14f223282bfa..f12ce268e6be 100644
>> --- a/tools/include/uapi/linux/bpf.h
>> +++ b/tools/include/uapi/linux/bpf.h
>> @@ -7328,6 +7328,12 @@ struct bpf_dynptr {
>>         __u64 __opaque[2];
>>  } __attribute__((aligned(8)));
>>
>> +struct bpf_dynptr_user {
>> +       __u64 data;
> what if we use __bpf_md_ptr(void *, data), so users can just directly
> use this struct (and then the next patch won't be necessary at all)

Thanks for the suggestion. Will do in v2.
>> +       __u32 size;
>> +       __u32 rsvd;
> please call it __reserved

Got it.
>
>
>> +} __attribute__((aligned(8)));
>> +
>>  struct bpf_list_head {
>>         __u64 __opaque[2];
>>  } __attribute__((aligned(8)));
>> --
>> 2.44.0
>>
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 07f7df308a01..72fe6a96b54c 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7329,6 +7329,12 @@  struct bpf_dynptr {
 	__u64 __opaque[2];
 } __attribute__((aligned(8)));
 
+struct bpf_dynptr_user {
+	__u64 data;
+	__u32 size;
+	__u32 rsvd;
+} __attribute__((aligned(8)));
+
 struct bpf_list_head {
 	__u64 __opaque[2];
 } __attribute__((aligned(8)));
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 14f223282bfa..f12ce268e6be 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7328,6 +7328,12 @@  struct bpf_dynptr {
 	__u64 __opaque[2];
 } __attribute__((aligned(8)));
 
+struct bpf_dynptr_user {
+	__u64 data;
+	__u32 size;
+	__u32 rsvd;
+} __attribute__((aligned(8)));
+
 struct bpf_list_head {
 	__u64 __opaque[2];
 } __attribute__((aligned(8)));