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/* Initialize CPU feature data. AArch64 version.
This file is part of the GNU C Library.
Copyright (C) 2017-2023 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
<https://www.gnu.org/licenses/>. */
#include <cpu-features.h>
#include <sys/auxv.h>
#include <elf/dl-hwcaps.h>
#include <sys/prctl.h>
#define DCZID_DZP_MASK (1 << 4)
#define DCZID_BS_MASK (0xf)
/* The maximal set of permitted tags that the MTE random tag generation
instruction may use. We exclude tag 0 because a) we want to reserve
that for the libc heap structures and b) because it makes it easier
to see when pointer have been correctly tagged. */
#define MTE_ALLOWED_TAGS (0xfffe << PR_MTE_TAG_SHIFT)
#if HAVE_TUNABLES
struct cpu_list
{
const char *name;
uint64_t midr;
};
static struct cpu_list cpu_list[] = {
{"thunderxt88", 0x430F0A10},
{"thunderx2t99", 0x431F0AF0},
{"thunderx2t99p1", 0x420F5160},
{"ares", 0x411FD0C0},
{"emag", 0x503F0001},
{"kunpeng920", 0x481FD010},
{"a64fx", 0x460F0010},
{"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)
{
register uint64_t midr = UINT64_MAX;
#if HAVE_TUNABLES
/* Get the tunable override. */
const char *mcpu = TUNABLE_GET (glibc, cpu, name, 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 (GLRO (dl_hwcap) & HWCAP_CPUID)
asm volatile ("mrs %0, midr_el1" : "=r"(midr));
else
midr = 0;
}
cpu_features->midr_el1 = midr;
/* Check if ZVA is enabled. */
unsigned dczid;
asm volatile ("mrs %0, dczid_el0" : "=r"(dczid));
if ((dczid & DCZID_DZP_MASK) == 0)
cpu_features->zva_size = 4 << (dczid & DCZID_BS_MASK);
/* Check if BTI is supported. */
cpu_features->bti = GLRO (dl_hwcap2) & HWCAP2_BTI;
/* Setup memory tagging support if the HW and kernel support it, and if
the user has requested it. */
cpu_features->mte_state = 0;
#ifdef USE_MTAG
# if HAVE_TUNABLES
int mte_state = TUNABLE_GET (glibc, mem, tagging, unsigned, 0);
cpu_features->mte_state = (GLRO (dl_hwcap2) & HWCAP2_MTE) ? mte_state : 0;
/* If we lack the MTE feature, disable the tunable, since it will
otherwise cause instructions that won't run on this CPU to be used. */
TUNABLE_SET (glibc, mem, tagging, cpu_features->mte_state);
# endif
if (cpu_features->mte_state & 4)
/* Enable choosing system-preferred faulting mode. */
__prctl (PR_SET_TAGGED_ADDR_CTRL,
(PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC
| MTE_ALLOWED_TAGS),
0, 0, 0);
else if (cpu_features->mte_state & 2)
__prctl (PR_SET_TAGGED_ADDR_CTRL,
(PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | MTE_ALLOWED_TAGS),
0, 0, 0);
else if (cpu_features->mte_state)
__prctl (PR_SET_TAGGED_ADDR_CTRL,
(PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_ASYNC | MTE_ALLOWED_TAGS),
0, 0, 0);
#endif
/* Check if SVE is supported. */
cpu_features->sve = GLRO (dl_hwcap) & HWCAP_SVE;
/* Check if MOPS is supported. */
cpu_features->mops = GLRO (dl_hwcap2) & HWCAP2_MOPS;
}
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