selftests/vDSO: Fix GNU hash table entry size for s390x

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 s390, this caused the GNU hash algorithm to access its 32-bit entries as if they
were 64-bit, triggering compiler warnings (assignment between "Elf64_Xword *" and
"Elf64_Word *") 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>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250217-selftests-vdso-s390-gnu-hash-v2-1-f6c2532ffe2a@linutronix.de
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 2fe5e983cb22f1ed066d0310a54f6aef2ed77ed8..f89d052c730eb43eea28d69ca27b56e897503e16 100644 (file)
--- 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];