If the specified needle crosses a page-boundary, the s390-z15 ifunc variant of
strstr truncates the needle which results in invalid results.
This is fixed by loading the needle beyond the page boundary to v18 instead of v16.
The bug is sometimes observable in test-strstr.c in check1 and check2 as the
haystack and needle is stored on stack. Thus the needle can be on a page boundary.
check2 is now extended to test haystack / needles located on stack, at end of page
and on two pages.
This bug was introduced with commit 6f47401bd5
("S390: Add arch13 strstr ifunc variant.") and is already released in glibc 2.30.
This patch introduces the new arch13 ifunc variant for strstr.
For needles longer than 9 charachters it is relying on the common-code
implementation. For shorter needles it is using the new vstrs instruction
which is able to search a substring within a vector register.
ChangeLog:
* sysdeps/s390/Makefile (sysdep_routines): Add strstr-arch13.
* sysdeps/s390/ifunc-strstr.h (HAVE_STRSTR_ARCH13, STRSTR_ARCH13,
STRSTR_Z13_ONLY_USED_AS_FALLBACK, HAVE_STRSTR_IFUNC_AND_ARCH13_SUPPORT):
New defines.
* sysdeps/s390/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Add ifunc variant for arch13 strstr.
* sysdeps/s390/strstr-arch13.S: New file.
* sysdeps/s390/strstr-vx.c: Omit GI symbol for z13 strstr ifunc variant
if it is only used as fallback.
* sysdeps/s390/strstr.c (strstr): Add arch13 variant in ifunc selector.
