Commit 14be4e6f3522 ("selftests: vDSO: fix ELF hash table entry size for s390x") changed the type of the ELF hash table entries to 64bit on s390x. However the *GNU* hash tables entries are always 32bit. The "bucket" pointer is shared between both hash algorithms. On s390x the GNU algorithm assigns and dereferences this pointer to a 64bit value as a pointer to a 32bit value, leading to compiler warnings and runtime crashes.

Introduce a new dedicated "gnu_bucket" pointer which is used by the GNU hash.

Fixes: e0746bde6f82 ("selftests/vDSO: support DT_GNU_HASH") Reviewed-by: Jens Remus jremus@linux.ibm.com Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de --- Changes in v2: - Fix wording around the width of pointers vs the pointed-to values - Link to v1: https://lore.kernel.org/r/20250213-selftests-vdso-s390-gnu-hash-v1-1-ace3bcc... --- tools/testing/selftests/vDSO/parse_vdso.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c index 2fe5e983cb22f1ed066d0310a54f6aef2ed77ed8..f89d052c730eb43eea28d69ca27b56e897503e16 100644 --- a/tools/testing/selftests/vDSO/parse_vdso.c +++ b/tools/testing/selftests/vDSO/parse_vdso.c @@ -53,7 +53,7 @@ static struct vdso_info /* Symbol table */ ELF(Sym) *symtab; const char *symstrings; - ELF(Word) *gnu_hash; + ELF(Word) *gnu_hash, *gnu_bucket; ELF_HASH_ENTRY *bucket, *chain; ELF_HASH_ENTRY nbucket, nchain;

@@ -185,8 +185,8 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) /* The bucket array is located after the header (4 uint32) and the bloom * filter (size_t array of gnu_hash[2] elements). */ - vdso_info.bucket = vdso_info.gnu_hash + 4 + - sizeof(size_t) / 4 * vdso_info.gnu_hash[2]; + vdso_info.gnu_bucket = vdso_info.gnu_hash + 4 + + sizeof(size_t) / 4 * vdso_info.gnu_hash[2]; } else { vdso_info.nbucket = hash[0]; vdso_info.nchain = hash[1]; @@ -268,11 +268,11 @@ void *vdso_sym(const char *version, const char *name) if (vdso_info.gnu_hash) { uint32_t h1 = gnu_hash(name), h2, *hashval;

- i = vdso_info.bucket[h1 % vdso_info.nbucket]; + i = vdso_info.gnu_bucket[h1 % vdso_info.nbucket]; if (i == 0) return 0; h1 |= 1; - hashval = vdso_info.bucket + vdso_info.nbucket + + hashval = vdso_info.gnu_bucket + vdso_info.nbucket + (i - vdso_info.gnu_hash[1]); for (;; i++) { ELF(Sym) *sym = &vdso_info.symtab[i];

--- base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b change-id: 20250213-selftests-vdso-s390-gnu-hash-7206671abc85

Best regards,