Commit a22ee38d authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Vasily Gorbik
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selftests/vDSO: Fix GNU hash table entry size for s390x 



Commit 14be4e6f ("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: e0746bde ("selftests/vDSO: support DT_GNU_HASH")
Reviewed-by: default avatarJens Remus <jremus@linux.ibm.com>
Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: default avatarShuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250217-selftests-vdso-s390-gnu-hash-v2-1-f6c2532ffe2a@linutronix.de


Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 5623bc23

tools/testing/selftests/vDSO/parse_vdso.c

+5 −5
Original line number Diff line number Diff line
@@ -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;
@@ -185,7 +185,7 @@ 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 +

		vdso_info.gnu_bucket = vdso_info.gnu_hash + 4 +

				       sizeof(size_t) / 4 * vdso_info.gnu_hash[2];

	} else {

		vdso_info.nbucket = hash[0];
@@ -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];