libc: ARM64: fix memset for non-standard ZVA sizes
372f19e9e27c ("libc: ARM64: update memset/strlen/memcpy/memmove to
newlib/cortex-strings") introduced a bug in memset, only occurring
on the [set_long + zero + non-standard ZVA size] path, more
specifically when DCZID_EL0 reports a size different to 64 or 128.
On platforms with such sizes reported by DCZID_EL0, various string*
unit tests fail due to memset zeroing memory before and/or after the
area it is supposed to set.
Bug: 38342450
Test: bionic-unit-tests --gtest_filter=string*
Change-Id: Idb80c0269226e40e343645a58608e3f324378468
(cherry picked from commit f19eeb8446de27e6b43c77642b03729e10facb2c)
diff --git a/libc/arch-arm64/generic/bionic/memset.S b/libc/arch-arm64/generic/bionic/memset.S
index 3416cfb..12fc09d 100644
--- a/libc/arch-arm64/generic/bionic/memset.S
+++ b/libc/arch-arm64/generic/bionic/memset.S
@@ -80,7 +80,7 @@
#define tmp1w w5
#define tmp2 x6
#define tmp2w w6
-#define zva_len x5
+#define zva_len x7
#define zva_lenw w7
#define L(l) .L ## l