glibc/sysdeps/s390/multiarch/ifunc-resolve.h
Stefan Liebler 41f67ccbe9 S390: Influence hwcaps/stfle via GLIBC_TUNABLES.
This patch enables the option to influence hwcaps and stfle bits used
by the s390 specific ifunc-resolvers.  The currently x86-specific
tunable glibc.cpu.hwcaps is also used on s390x to achieve the task. In
addition the user can also set a CPU arch-level like z13 instead of
single HWCAP and STFLE features.

Note that the tunable only handles the features which are really used
in the IFUNC-resolvers.  All others are ignored as the values are only
used inside glibc.  Thus we can influence:
- HWCAP_S390_VXRS (z13)
- HWCAP_S390_VXRS_EXT (z14)
- HWCAP_S390_VXRS_EXT2 (z15)
- STFLE_MIE3 (z15)

The influenced hwcap/stfle-bits are stored in the s390-specific
cpu_features struct which also contains reserved fields for future
usage.

The ifunc-resolvers and users of stfle bits are adjusted to use the
information from cpu_features struct.

On 31bit, the ELF_MACHINE_IRELATIVE macro is now also defined.
Otherwise the new ifunc-resolvers segfaults as they depend on
the not yet processed_rtld_global_ro@GLIBC_PRIVATE relocation.
2023-02-07 09:19:27 +01:00

36 lines
1.4 KiB
C

/* IFUNC resolver function for CPU specific functions.
32/64 bit S/390 version.
Copyright (C) 2015-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <unistd.h>
#include <dl-procinfo.h>
#include <cpu-features.h>
#define s390_libc_ifunc_expr_stfle_init() \
const unsigned long long *stfle_bits = features->stfle_bits;
#define s390_libc_ifunc_expr_init() \
const struct cpu_features *features = &GLRO(dl_s390_cpu_features); \
/* The hwcap from kernel is passed as argument, but we \
explicitly use the hwcaps from cpu-features struct. */ \
hwcap = features->hwcap;
#define s390_libc_ifunc_expr(TYPE_FUNC, FUNC, EXPR) \
__ifunc (TYPE_FUNC, FUNC, EXPR, unsigned long int hwcap, \
s390_libc_ifunc_expr_init);