From: Jakub Bogusz <qboosh@xxxxxxxxxxxxx>
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 <qboosh@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
tools/lib/bpf/hashmap.h | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h
index df59fd4fc95b..e0af36b0e5d8 100644
--- a/tools/lib/bpf/hashmap.h
+++ b/tools/lib/bpf/hashmap.h
@@ -11,14 +11,18 @@
#include <stdbool.h>
#include <stddef.h>
#include <limits.h>
-#ifndef __WORDSIZE
-#define __WORDSIZE (__SIZEOF_LONG__ * 8)
-#endif
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);
--
2.24.1
