Re: [PATCH bpf] bpf: fix UML x86_64 compile failure

[Alexei Starovoitov]

On Thu, Jun 13, 2024 at 8:30 AM Shung-Hsi Yu <shung-hsi.yu@xxxxxxxx> wrote:
>
> On Thu, Jun 13, 2024 at 04:25:20AM GMT, Maciej Żenczykowski wrote:
> > Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
> > Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> > Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> > Fixes: 1ae6921009e5 ("bpf: inline bpf_get_smp_processor_id() helper")
> > Signed-off-by: Maciej Żenczykowski <maze@xxxxxxxxxx>
> > ---
> >  kernel/bpf/verifier.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index 36ef8e96787e..7a354b1e6197 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -20313,7 +20313,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
> >                       goto next_insn;
> >               }
> >
> > -#ifdef CONFIG_X86_64
> > +#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
> >               /* Implement bpf_get_smp_processor_id() inline. */
> >               if (insn->imm == BPF_FUNC_get_smp_processor_id &&
> >                   prog->jit_requested && bpf_jit_supports_percpu_insn()) {
>
> The patch needs a change description[1].
>
> Maybe something along the line of why pcpu_hot.cpu_number not accessible
> in User-mode Linux? (I don't know bpf_get_smp_processor_id() or UML that
> well, just suggesting possible change description)

+1


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