On Fri, Feb 26, 2021 at 07:20:14PM +0100, Ilya Leoshkevich wrote: > test_snprintf_btf fails on s390, because NULL points to a readable > struct lowcore there. Fix by using _REGION1_SIZE instead. > > Error message example: > > printing 0000000000000000 should generate error, got (361) > > Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> > --- > > v1: https://lore.kernel.org/bpf/20210226135923.114211-1-iii@xxxxxxxxxxxxx/ > v1 -> v2: Yonghong suggested to add the pointer value to the error > message. > I've noticed that I've been passing BADPTR as flags, therefore > the fix worked only by accident. Put it into p.ptr where it > belongs. > > .../testing/selftests/bpf/progs/netif_receive_skb.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/bpf/progs/netif_receive_skb.c b/tools/testing/selftests/bpf/progs/netif_receive_skb.c > index 6b670039ea67..4d158de73c2d 100644 > --- a/tools/testing/selftests/bpf/progs/netif_receive_skb.c > +++ b/tools/testing/selftests/bpf/progs/netif_receive_skb.c > @@ -16,6 +16,13 @@ bool skip = false; > #define STRSIZE 2048 > #define EXPECTED_STRSIZE 256 > > +#if defined(bpf_target_s390) > +/* NULL points to a readable struct lowcore on s390, so take _REGION1_SIZE */ > +#define BADPTR ((void *)(1ULL << 53)) > +#else > +#define BADPTR 0 > +#endif > + > #ifndef ARRAY_SIZE > #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) > #endif > @@ -113,11 +120,11 @@ int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb) > } > > /* Check invalid ptr value */ > - p.ptr = 0; > + p.ptr = BADPTR; > __ret = bpf_snprintf_btf(str, STRSIZE, &p, sizeof(p), 0); > if (__ret >= 0) { > - bpf_printk("printing NULL should generate error, got (%d)", > - __ret); > + bpf_printk("printing %p should generate error, got (%d)", > + BADPTR, __ret); > ret = -ERANGE; This will work for now on s390, since _right now_ we don't map anything that high, but there is no guarantee that it will stay this way. I'd rather skip this test for s390.
