On Fri, May 6, 2022 at 7:22 AM Eugene Syromiatnikov <esyr@xxxxxxxxxx> wrote:
>
> Since bpf_kprobe_multi_link_attach doesn't support 32-bit kernels
> for whatever reason,
Jiri,
why did you add this restriction?
> having it enabled for compat processes on 64-bit
> kernels makes even less sense due to discrepances in the type sizes
> that it does not handle.
I don't follow this logic.
bpf progs are always 64-bit. Even when user space is 32-bit.
Jiri's check is for the kernel.
> Fixes: 0dcac272540613d4 ("bpf: Add multi kprobe link")
> Signed-off-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
> ---
> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index d8553f4..9560af6 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2410,7 +2410,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> int err;
>
> /* no support for 32bit archs yet */
> - if (sizeof(u64) != sizeof(void *))
> + if (sizeof(u64) != sizeof(void *) || in_compat_syscall())
> return -EOPNOTSUPP;
>
> if (prog->expected_attach_type != BPF_TRACE_KPROBE_MULTI)
> --
> 2.1.4
>
