[PATCH] AArch64: Remove zva_128 from memset

[Wilco Dijkstra]

Remove ZVA 128 support from memset - the new memset no longer
guarantees count >= 256, which can result in underflow and a
crash if ZVA size is 128 ([1]).  Since only one CPU uses a ZVA
size of 128 and its memcpy implementation was removed in commit
e162ab2bf1b82c40f29e1925986582fa07568ce8, remove this special
case too.

Passes regress, OK for commit?

[1] https://sourceware.org/pipermail/libc-alpha/2024-November/161626.html

---

diff --git a/sysdeps/aarch64/memset.S b/sysdeps/aarch64/memset.S
index b76dde1557ed8fb195c24a13a06f8d0d9ab126fa..8402219b1874b00a10ea460e278edbf54c6140f6 100644
--- a/sysdeps/aarch64/memset.S
+++ b/sysdeps/aarch64/memset.S
@@ -103,7 +103,7 @@ L(set_long):
 	mrs	zva_val, dczid_el0
 	and	zva_val, zva_val, 31
 	cmp	zva_val, 4		/* ZVA size is 64 bytes.  */
-	b.ne	L(zva_128)
+	b.ne	L(no_zva)
 #endif
 	stp	q0, q0, [dst, 32]
 	bic	dst, dstin, 63
@@ -136,28 +136,5 @@ L(no_zva_loop):
 	stp	q0, q0, [dstend, -32]
 	ret
 
-#ifndef ZVA64_ONLY
-	.p2align 4
-L(zva_128):
-	cmp	zva_val, 5		/* ZVA size is 128 bytes.  */
-	b.ne	L(no_zva)
-
-	stp	q0, q0, [dst, 32]
-	stp	q0, q0, [dst, 64]
-	stp	q0, q0, [dst, 96]
-	bic	dst, dst, 127
-	sub	count, dstend, dst	/* Count is now 128 too large.	*/
-	sub	count, count, 128 + 128	/* Adjust count and bias for loop.  */
-1:	add	dst, dst, 128
-	dc	zva, dst
-	subs	count, count, 128
-	b.hi	1b
-	stp	q0, q0, [dstend, -128]
-	stp	q0, q0, [dstend, -96]
-	stp	q0, q0, [dstend, -64]
-	stp	q0, q0, [dstend, -32]
-	ret
-#endif
-
 END (MEMSET)
 libc_hidden_builtin_def (MEMSET)