Re: [PATCH bpf] selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep

[Daniel Borkmann]

On 7/12/24 6:07 PM, Alexei Starovoitov wrote:
> On Fri, Jul 12, 2024 at 6:50 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
> > On 7/11/24 4:00 PM, Puranjay Mohan wrote:
> > [...]
> > > I was able find the root cause of this bug and will send a fix soon!
> > >
> > > > Unable to handle kernel paging request at virtual address ffff0000c2a80e68
> > >
> > > We are running this test on Qemu with '-cpu max', this means 52-bit
> > > virtual addresses are being used.
> > >
> > > The trampolines generation code has the following two lines:
> > >
> > >                emit_addr_mov_i64(A64_R(0), (const u64)im, ctx);
> > >                emit_call((const u64)__bpf_tramp_enter, ctx);
> > >
> > > here the address of struct bpf_tramp_image is moved to R0 and passed as
> > > an argument to __bpf_tramp_enter().
> > >
> > > emit_addr_mov_i64() assumes that the address passed to it is in the
> > > vmalloc space and uses at most 48 bits. It sets all the remaining bits
> > > to 1.
> > >
> > > but struct bpf_tramp_image is allocated using kzalloc() and when 52-bit
> > > VAs are used, its address is not guaranteed to be 48-bit, therefore we
> > > see this bug, where  0xfff[0]0000c2a80e68 is converted to
> > > 0xfff[f]0000c2a80e68 when the trampoline is generated.
> > >
> > > The fix would be use emit_a64_mov_i64() for moving this address into R0.
> >
> > It looks like there is still an issue left. A recent CI run on bpf-next is
> > still hitting the same on arm64:
> >
> > Base:
> >
> >     https://github.com/kernel-patches/bpf/commits/series/870746%3D%3Ebpf-next/
> >
> > CI:
> >
> >     https://github.com/kernel-patches/bpf/actions/runs/9905842936/job/27366435436
> >
> >     [...]
> >     #89/11   fexit_bpf2bpf/func_replace_global_func:OK
> >     #89/12   fexit_bpf2bpf/fentry_to_cgroup_bpf:OK
> >     #89/13   fexit_bpf2bpf/func_replace_progmap:OK
> >     #89      fexit_bpf2bpf:OK
> >     Error: The operation was canceled.
>
> Let's denylist that test again for now?

Agree, done/pushed now.