On Tue, Jun 23, 2020 at 12:40:02PM -0700, Andrii Nakryiko wrote: > On Tue, Jun 23, 2020 at 12:29 PM Jakub Bogusz wrote: > > > > On Mon, Jun 22, 2020 at 10:44:56PM -0700, Andrii Nakryiko wrote: > > > On Sun, Jun 21, 2020 at 7:34 AM Jakub Bogusz wrote: > > > > > > > > Hello, > > > > > > > > I noticed that _bpftool crashes when building kernel tools (5.7.x) for > > > > 32-bit targets because in libbpf hashmap implementation hash_bits() > > > > function returning numbers exceeding hashmap buckets capacity. > > > > > > > > Attached patch fixes this problem. > > > > > > > > > > Thanks! But this was already fixed by Arnaldo Carvalho de Melo > > > in 8ca8d4a84173 ("libbpf: Define __WORDSIZE if not available"). > > > > No, it's not: > > This change worked around __WORDSIZE not always being available. > > > > But the issue on (I)LP32 platforms is that 64-bit value is shifted by > > (32-bits) instead of (64-bits). > > > > (__SIZEOF_LONG__ * 8) is 32 on such architectures (i686, arm). > > I used __SIZEOF_LONG_LONG__ to get proper bit shift both on (I)LP32 and > > LP64 architectures. > > > > Ah, I see. I actually mentioned __SIZEOF_ constants on the original > fix patch. But I think in this case it has to use __SIZEOF_SIZE_T, > which on 32-bit should be 4, right? After changing constant to 32-bit, yes (to be precise, it should use maximum of __SIZEOF_SIZE_T__ and __SIZEOF_LONG__ if constant is specified with UL suffix; there is no constant suffix available for size_t). > > Should I provide an updated patch to apply on top of acme change? > > Yes, that would be good. But I think there is no need to penalize > 32-bit arches with use of 64-bit long longs, and instead it's better > to use #ifdef for 32-bit case vs 64-bit case. The multiplication > constant will change, of course, should be 2654435769. I'd appreciate > it if you can do the patch, thanks! OK, so now the patch provides two variants: - "long long" case for LP64 architectures - "long" case for (I)LP32 architectures (selected basing of __SIZEOF_ constants) matter) Regards, -- Jakub Bogusz http://qboosh.pl/