From: Jakub Bogusz Date: Thu, 9 Jul 2020 15:57:23 -0700 Subject: libbpf: Fix libbpf hashmap on (I)LP32 architectures Git-commit: b2f9f1535bb93ee5fa2ea30ac1c26fa0d676154c Patch-mainline: 5.8-rc5 References: x86_32 crashes fix On ILP32, 64-bit result was shifted by value calculated for 32-bit long type and returned value was much outside hashmap capacity. As advised by Andrii Nakryiko, this patch uses different hashing variant for architectures with size_t shorter than long long. Fixes: e3b924224028 ("libbpf: add resizable non-thread safe internal hashmap") Signed-off-by: Jakub Bogusz Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200709225723.1069937-1-andriin@fb.com Signed-off-by: Jiri Slaby --- lib/bpf/src/hashmap.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/lib/bpf/src/hashmap.h +++ b/lib/bpf/src/hashmap.h @@ -16,11 +16,19 @@ #include #endif #include "libbpf_internal.h" +#include static inline size_t hash_bits(size_t h, int bits) { /* shuffle bits and return requested number of upper bits */ - return (h * 11400714819323198485llu) >> (__WORDSIZE - bits); +#if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__) + /* LP64 case */ + return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits); +#elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__) + return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits); +#else +# error "Unsupported size_t size" +#endif } typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);