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S390: Influence hwcaps/stfle via GLIBC_TUNABLES.

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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.
This commit is contained in:
Stefan Liebler
2023-02-02 14:57:50 +01:00
parent 0b9d2d4a76
commit 41f67ccbe9
12 changed files with 423 additions and 64 deletions
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41
sysdeps/s390/multiarch/ifunc-resolve.h
View File

@@ -19,42 +19,17 @@
#include <unistd.h>
#include <dl-procinfo.h>
#include <cpu-features.h>
#define S390_STFLE_BITS_Z10 34 /* General instructions extension */
#define S390_STFLE_BITS_Z196 45 /* Distinct operands, pop ... */
#define S390_STFLE_BITS_ARCH13_MIE3 61 /* Miscellaneous-Instruction-Extensions
Facility 3, e.g. mvcrl. */
#define S390_IS_ARCH13_MIE3(STFLE_BITS) \
((STFLE_BITS & (1ULL << (63 - S390_STFLE_BITS_ARCH13_MIE3))) != 0)
#define S390_IS_Z196(STFLE_BITS) \
((STFLE_BITS & (1ULL << (63 - S390_STFLE_BITS_Z196))) != 0)
#define S390_IS_Z10(STFLE_BITS) \
((STFLE_BITS & (1ULL << (63 - S390_STFLE_BITS_Z10))) != 0)
#define S390_STORE_STFLE(STFLE_BITS) \
/* We want just 1 double word to be returned. */ \
register unsigned long reg0 __asm__("0") = 0; \
\
__asm__ __volatile__(".machine push" "\n\t" \
".machine \"z9-109\"" "\n\t" \
".machinemode \"zarch_nohighgprs\"\n\t" \
"stfle %0" "\n\t" \
".machine pop" "\n" \
: "=QS" (STFLE_BITS), "+d" (reg0) \
: : "cc");
#define s390_libc_ifunc_expr_stfle_init() \
unsigned long long stfle_bits = 0ULL; \
if (__glibc_likely ((hwcap & HWCAP_S390_STFLE) \
&& (hwcap & HWCAP_S390_ZARCH) \
&& (hwcap & HWCAP_S390_HIGH_GPRS))) \
{ \
S390_STORE_STFLE (stfle_bits); \
}
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_init()
#define s390_libc_ifunc_expr(TYPE_FUNC, FUNC, EXPR) \
__ifunc (TYPE_FUNC, FUNC, EXPR, unsigned long int hwcap, \
s390_libc_ifunc_expr_init);