On Mon, Dec 16, 2024 at 03:24:01PM -0800, Andrii Nakryiko wrote: > On Fri, Dec 13, 2024 at 7:13 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote: > > > > On Fri, 2024-12-13 at 19:44 -0700, Daniel Xu wrote: > > > > [...] > > > > > > > + /* First handle precisely tracked STACK_ZERO, up to BPF_REG_SIZE */ > > > > > + stype = state->stack[spi].slot_type; > > > > > + for (i = 0; i < BPF_REG_SIZE && stype[i] == STACK_ZERO; i++) > > > > > > > > it's Friday and I'm lazy, but please double-check that this works for > > > > both big-endian and little-endian :) > > > > > > Any tips? Are the existing tests running thru s390x hosts in CI > > > sufficient or should I add some tests writen in C (and not BPF > > > assembler)? I can never think about endianness correctly... > > > > I think that if test operates on a key like: > > > > valid key 15 > > v > > 0000000f <-- written to stack as a single u64 value > > ^^^^^^^ > > stack zero marks > > > > and is executed (e.g. using __retval annotation), > > then CI passing for s390 should be enough. > > +1, something like that where for big-endian it will be all zero while > for little endian it would be 0xf (and then make sure that the test > should *fail* by making sure that 0xf is not a valid index, so NULL > check is necessary) How would it work for LE to be 0xF but BE to be 0x0? The prog passes a pointer to the beginning of the u32 to bpf_map_lookup_elem(). The kernel does a 4 byte read starting from that address. On both BE and LE all 4 bytes will be interpreted. So set bits cannot just go away. Am I missing something? Thanks, Daniel
