Hi Baruch,
On Tue, Jun 4, 2019 at 1:40 PM Baruch Siach <baruch@xxxxxxxxxx> wrote:
> Merge commit 1c8c5a9d38f60 ("Merge
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next") undid the
> fix from commit 36f9814a494 ("bpf: fix uapi hole for 32 bit compat
> applications") by taking the gpl_compatible 1-bit field definition from
> commit b85fab0e67b162 ("bpf: Add gpl_compatible flag to struct
> bpf_prog_info") as is. That breaks architectures with 16-bit alignment
> like m68k. Widen gpl_compatible to 32-bit to restore alignment of the
> following fields.
>
> Thanks to Dmitry V. Levin his analysis of this bug history.
>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
Thanks for your patch!
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3140,7 +3140,7 @@ struct bpf_prog_info {
> __aligned_u64 map_ids;
> char name[BPF_OBJ_NAME_LEN];
> __u32 ifindex;
> - __u32 gpl_compatible:1;
> + __u32 gpl_compatible;
> __u64 netns_dev;
> __u64 netns_ino;
Wouldn't it be better to change the types of the fields that require
8-byte alignment from __u64 to __aligned_u64, like is already used
for the map_ids fields?
Without that, some day people will need to add a new flag, and will
convert the 32-bit flag to a bitfield again to make space, reintroducing
the issue.
> __u32 nr_jited_ksyms;
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 63e0cf66f01a..fe73829b5b1c 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -3140,7 +3140,7 @@ struct bpf_prog_info {
> __aligned_u64 map_ids;
> char name[BPF_OBJ_NAME_LEN];
> __u32 ifindex;
> - __u32 gpl_compatible:1;
> + __u32 gpl_compatible;
> __u64 netns_dev;
> __u64 netns_ino;
Same here.
> __u32 nr_jited_ksyms;
> --
> 2.20.1
>
--
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
