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authorJakub Bogusz <qboosh@pld-linux.org>2020-07-10 01:57:23 +0300
committerAlexei Starovoitov <ast@kernel.org>2020-07-10 05:38:55 +0300
commitb2f9f1535bb93ee5fa2ea30ac1c26fa0d676154c (patch)
tree2e875e49560069cea681049e70f0dc7ec38ca24c /tools
parentf43cb0d672aa8eb09bfdb779de5900c040487d1d (diff)
downloadlinux-b2f9f1535bb93ee5fa2ea30ac1c26fa0d676154c.tar.xz
libbpf: Fix libbpf hashmap on (I)LP32 architectures
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@pld-linux.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200709225723.1069937-1-andriin@fb.com
Diffstat (limited to 'tools')
-rw-r--r--tools/lib/bpf/hashmap.h12
1 files 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);