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.
Regards,
--
Jakub Bogusz http://qboosh.pl/
Ensure that hash_bits returns value fits in given bits (for bits > 0):
multiplier is long long (which is the same or wider than size_t), so shift bits
must be based on long long size, not __WORDSIZE.
Signed-off-by: Jakub Bogusz <qboosh@xxxxxxxxxxxxx>
--- linux-5.7/tools/lib/bpf/hashmap.h.orig 2020-06-01 01:49:15.000000000 +0200
+++ linux-5.7/tools/lib/bpf/hashmap.h 2020-06-21 15:22:07.298466419 +0200
@@ -10,17 +10,12 @@
#include <stdbool.h>
#include <stddef.h>
-#ifdef __GLIBC__
-#include <bits/wordsize.h>
-#else
-#include <bits/reg.h>
-#endif
#include "libbpf_internal.h"
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);
+ return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits);
}
typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
