On Fri, Jul 17, 2020 at 06:53:23PM +0200, Ilya Leoshkevich wrote:
> Both signed and unsigned variants of BPF_JMP | BPF_K require
> sign-extending the immediate. JIT emits cgfi for the signed case,
> which is correct, and clgfi for the unsigned case, which is not
> correct: clgfi zero-extends the immediate.
>
> s390 does not provide an instruction that does sign-extension and
> unsigned comparison at the same time. Therefore, fix by first loading
> the sign-extended immediate into work register REG_1 and proceeding
> as if it's BPF_X.
>
> Fixes: 4e9b4a6883dd ("s390/bpf: Use relative long branches")
> Reported-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
> Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
This fixes the failing tests I was seeing. Thanks!
Tested-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
