diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/powerpc/cpu-features.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/powerpc/cpu-features.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/powerpc/cpu-features.c b/sysdeps/unix/sysv/linux/powerpc/cpu-features.c new file mode 100644 index 0000000000..7c6e20e702 --- /dev/null +++ b/sysdeps/unix/sysv/linux/powerpc/cpu-features.c @@ -0,0 +1,124 @@ +/* Initialize cpu feature data. PowerPC version. + Copyright (C) 2017-2023 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 <array_length.h> +#include <stdint.h> +#include <cpu-features.h> +#include <elf/dl-tunables.h> +#include <unistd.h> +#include <string.h> + +static void +TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp) +{ + /* The current IFUNC selection is always using the most recent + features which are available via AT_HWCAP or AT_HWCAP2. But in + some scenarios it is useful to adjust this selection. + + The environment variable: + + GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,.... + + Can be used to enable HWCAP/HWCAP2 feature yyy, disable HWCAP/HWCAP2 + feature xxx, where the feature name is case-sensitive and has to match + the ones mentioned in the file{sysdeps/powerpc/dl-procinfo.c}. */ + + /* Copy the features from dl_powerpc_cpu_features, which contains the + features provided by AT_HWCAP and AT_HWCAP2. */ + struct cpu_features *cpu_features = &GLRO(dl_powerpc_cpu_features); + unsigned long int tcbv_hwcap = cpu_features->hwcap; + unsigned long int tcbv_hwcap2 = cpu_features->hwcap2; + const char *token = valp->strval; + do + { + const char *token_end, *feature; + bool disable; + size_t token_len, i, feature_len, offset = 0; + /* Find token separator or end of string. */ + for (token_end = token; *token_end != ','; token_end++) + if (*token_end == '\0') + break; + + /* Determine feature. */ + token_len = token_end - token; + if (*token == '-') + { + disable = true; + feature = token + 1; + feature_len = token_len - 1; + } + else + { + disable = false; + feature = token; + feature_len = token_len; + } + for (i = 0; i < array_length (hwcap_tunables); ++i) + { + const char *hwcap_name = hwcap_names + offset; + size_t hwcap_name_len = strlen (hwcap_name); + /* Check the tunable name on the supported list. */ + if (hwcap_name_len == feature_len + && memcmp (feature, hwcap_name, feature_len) == 0) + { + /* Update the hwcap and hwcap2 bits. */ + if (disable) + { + /* Id is 1 for hwcap2 tunable. */ + if (hwcap_tunables[i].id) + cpu_features->hwcap2 &= ~(hwcap_tunables[i].mask); + else + cpu_features->hwcap &= ~(hwcap_tunables[i].mask); + } + else + { + /* Enable the features and also check that no unsupported + features were enabled by user. */ + if (hwcap_tunables[i].id) + cpu_features->hwcap2 |= (tcbv_hwcap2 & hwcap_tunables[i].mask); + else + cpu_features->hwcap |= (tcbv_hwcap & hwcap_tunables[i].mask); + } + break; + } + offset += hwcap_name_len + 1; + } + token += token_len; + /* ... and skip token separator for next round. */ + if (*token == ',') + token++; + } + while (*token != '\0'); +} + +static inline void +init_cpu_features (struct cpu_features *cpu_features, uint64_t hwcaps[]) +{ + /* Fill the cpu_features with the supported hwcaps + which are set by __tcb_parse_hwcap_and_convert_at_platform. */ + cpu_features->hwcap = hwcaps[0]; + cpu_features->hwcap2 = hwcaps[1]; + /* Default is to use aligned memory access on optimized function unless + tunables is enable, since for this case user can explicit disable + unaligned optimizations. */ + int32_t cached_memfunc = TUNABLE_GET (glibc, cpu, cached_memopt, int32_t, + NULL); + cpu_features->use_cached_memopt = (cached_memfunc > 0); + TUNABLE_GET (glibc, cpu, hwcaps, tunable_val_t *, + TUNABLE_CALLBACK (set_hwcaps)); +} |