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/* Initialize CPU feature data. AArch64 version.
This file is part of the GNU C Library.
Copyright (C) 2017 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
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
<http://www.gnu.org/licenses/>. */
#include <cpu-features.h>
#include <sys/auxv.h>
#include <elf/dl-hwcaps.h>
#if HAVE_TUNABLES
struct cpu_list
{
const char *name;
uint64_t midr;
};
static struct cpu_list cpu_list[] = {
{"falkor", 0x510FC000},
{"thunderxt88", 0x430F0A10},
{"generic", 0x0}
};
static uint64_t
get_midr_from_mcpu (const char *mcpu)
{
for (int i = 0; i < sizeof (cpu_list) / sizeof (struct cpu_list); i++)
if (strcmp (mcpu, cpu_list[i].name) == 0)
return cpu_list[i].midr;
return UINT64_MAX;
}
#endif
static inline void
init_cpu_features (struct cpu_features *cpu_features)
{
uint64_t hwcap_mask = GET_HWCAP_MASK();
uint64_t hwcap = GLRO (dl_hwcap) & hwcap_mask;
register uint64_t midr = UINT64_MAX;
#if HAVE_TUNABLES
/* Get the tunable override. */
const char *mcpu = TUNABLE_GET (glibc, tune, cpu, const char *, NULL);
if (mcpu != NULL)
midr = get_midr_from_mcpu (mcpu);
#endif
/* If there was no useful tunable override, query the MIDR if the kernel
allows it. */
if (midr == UINT64_MAX)
{
if (hwcap & HWCAP_CPUID)
asm volatile ("mrs %0, midr_el1" : "=r"(midr));
else
midr = 0;
}
cpu_features->midr_el1 = midr;
}
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