From 41f67ccbe92b4fd09e1062b383e55e407ae5bfa1 Mon Sep 17 00:00:00 2001 From: Stefan Liebler Date: Thu, 2 Feb 2023 14:57:50 +0100 Subject: 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. --- sysdeps/s390/s390-32/dl-machine.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'sysdeps/s390/s390-32/dl-machine.h') diff --git a/sysdeps/s390/s390-32/dl-machine.h b/sysdeps/s390/s390-32/dl-machine.h index d09ab68..100a3e0 100644 --- a/sysdeps/s390/s390-32/dl-machine.h +++ b/sysdeps/s390/s390-32/dl-machine.h @@ -28,6 +28,9 @@ #include #include #include +#include + +#define ELF_MACHINE_IRELATIVE R_390_IRELATIVE /* This is an older, now obsolete value. */ #define EM_S390_OLD 0xA390 @@ -242,6 +245,12 @@ dl_platform_init (void) if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0') /* Avoid an empty string which would disturb us. */ GLRO(dl_platform) = NULL; + +#ifdef SHARED + /* init_cpu_features has been called early from __libc_start_main in + static executable. */ + init_cpu_features (&GLRO(dl_s390_cpu_features)); +#endif } static inline Elf32_Addr -- cgit v1.1