diff options
Diffstat (limited to 'sysdeps/unix/sysv')
| -rw-r--r-- | sysdeps/unix/sysv/linux/aarch64/cpu-features.c | 48 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/aarch64/cpu-features.h | 3 |
2 files changed, 50 insertions, 1 deletions
diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c index 12146ddf71..5b0a2814d1 100644 --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c @@ -20,6 +20,7 @@ #include <sys/auxv.h> #include <elf/dl-hwcaps.h> #include <sys/prctl.h> +#include <sys/utsname.h> #define DCZID_DZP_MASK (1 << 4) #define DCZID_BS_MASK (0xf) @@ -59,6 +60,46 @@ get_midr_from_mcpu (const char *mcpu) } #endif +#if __LINUX_KERNEL_VERSION < 0x060200 + +/* Return true if we prefer using SVE in string ifuncs. Old kernels disable + SVE after every system call which results in unnecessary traps if memcpy + uses SVE. This is true for kernels between 4.15.0 and before 6.2.0, except + for 5.14.0 which was patched. For these versions return false to avoid using + SVE ifuncs. + Parse the kernel version into a 24-bit kernel.major.minor value without + calling any library functions. If uname() is not supported or if the version + format is not recognized, assume the kernel is modern and return true. */ + +static inline bool +prefer_sve_ifuncs (void) +{ + struct utsname buf; + const char *p = &buf.release[0]; + int kernel = 0; + int val; + + if (__uname (&buf) < 0) + return true; + + for (int shift = 16; shift >= 0; shift -= 8) + { + for (val = 0; *p >= '0' && *p <= '9'; p++) + val = val * 10 + *p - '0'; + kernel |= (val & 255) << shift; + if (*p++ != '.') + break; + } + + if (kernel >= 0x060200 || kernel == 0x050e00) + return true; + if (kernel >= 0x040f00) + return false; + return true; +} + +#endif + static inline void init_cpu_features (struct cpu_features *cpu_features) { @@ -119,6 +160,13 @@ init_cpu_features (struct cpu_features *cpu_features) /* Check if SVE is supported. */ cpu_features->sve = GLRO (dl_hwcap) & HWCAP_SVE; + cpu_features->prefer_sve_ifuncs = cpu_features->sve; + +#if __LINUX_KERNEL_VERSION < 0x060200 + if (cpu_features->sve) + cpu_features->prefer_sve_ifuncs = prefer_sve_ifuncs (); +#endif + /* Check if MOPS is supported. */ cpu_features->mops = GLRO (dl_hwcap2) & HWCAP2_MOPS; } diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h index d3bfc1b318..5f2da91ebb 100644 --- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.h +++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.h @@ -1,6 +1,6 @@ /* Initialize CPU feature data. AArch64 version. This file is part of the GNU C Library. - Copyright (C) 2017-2021 Free Software Foundation, Inc. + Copyright (C) 2017-2024 Free Software Foundation, Inc. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public @@ -71,6 +71,7 @@ struct cpu_features /* Currently, the GLIBC memory tagging tunable only defines 8 bits. */ uint8_t mte_state; bool sve; + bool prefer_sve_ifuncs; bool mops; }; |