arch/arm64/kernel/cpufeature.c

/*
 * Contains CPU feature definitions
 *
 * Copyright (C) 2015 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define pr_fmt(fmt) "CPU features: " fmt

#include <linux/bsearch.h>
#include <linux/cpumask.h>
#include <linux/crash_dump.h>
#include <linux/sort.h>
#include <linux/stop_machine.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <asm/cpu.h>
#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/fpsimd.h>
#include <asm/mmu_context.h>
#include <asm/processor.h>
#include <asm/sysreg.h>
#include <asm/traps.h>
#include <asm/virt.h>

unsigned long elf_hwcap __read_mostly;
EXPORT_SYMBOL_GPL(elf_hwcap);

#ifdef CONFIG_COMPAT
#define COMPAT_ELF_HWCAP_DEFAULT	\
				(COMPAT_HWCAP_HALF|COMPAT_HWCAP_THUMB|\
				 COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
				 COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\
				 COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\
				 COMPAT_HWCAP_LPAE)
unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
unsigned int compat_elf_hwcap2 __read_mostly;
#endif

DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
EXPORT_SYMBOL(cpu_hwcaps);
static struct arm64_cpu_capabilities const __ro_after_init *cpu_hwcaps_ptrs[ARM64_NCAPS];

/*
 * Flag to indicate if we have computed the system wide
 * capabilities based on the boot time active CPUs. This
 * will be used to determine if a new booting CPU should
 * go through the verification process to make sure that it
 * supports the system capabilities, without using a hotplug
 * notifier.
 */
static bool sys_caps_initialised;

static inline void set_sys_caps_initialised(void)
{
	sys_caps_initialised = true;
}

static int dump_cpu_hwcaps(struct notifier_block *self, unsigned long v, void *p)
{
	/* file-wide pr_fmt adds "CPU features: " prefix */
	pr_emerg("0x%*pb\n", ARM64_NCAPS, &cpu_hwcaps);
	return 0;
}

static struct notifier_block cpu_hwcaps_notifier = {
	.notifier_call = dump_cpu_hwcaps
};

static int __init register_cpu_hwcaps_dumper(void)
{
	atomic_notifier_chain_register(&panic_notifier_list,
				       &cpu_hwcaps_notifier);
	return 0;
}
__initcall(register_cpu_hwcaps_dumper);

DEFINE_STATIC_KEY_ARRAY_FALSE(cpu_hwcap_keys, ARM64_NCAPS);
EXPORT_SYMBOL(cpu_hwcap_keys);

#define __ARM64_FTR_BITS(SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
	{						\
		.sign = SIGNED,				\
		.visible = VISIBLE,			\
		.strict = STRICT,			\
		.type = TYPE,				\
		.shift = SHIFT,				\
		.width = WIDTH,				\
		.safe_val = SAFE_VAL,			\
	}

/* Define a feature with unsigned values */
#define ARM64_FTR_BITS(VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
	__ARM64_FTR_BITS(FTR_UNSIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL)

/* Define a feature with a signed value */
#define S_ARM64_FTR_BITS(VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
	__ARM64_FTR_BITS(FTR_SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL)

#define ARM64_FTR_END					\
	{						\
		.width = 0,				\
	}

/* meta feature for alternatives */
static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused);

static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap);

/*
 * NOTE: Any changes to the visibility of features should be kept in
 * sync with the documentation of the CPU feature register ABI.
 */
static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SM4_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SM3_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA3_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RDM_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_ATOMICS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_CRC32_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA2_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_SHA1_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_AES_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_SB_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPI_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_GPA_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_LRCPC_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_FCMA_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_JSCVT_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_API_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_APA_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR1_DPB_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV2_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_DIT_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
				   FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_RAS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
	S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI),
	S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_FP_SHIFT, 4, ID_AA64PFR0_FP_NI),
	/* Linux doesn't care about the EL3 */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL3_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL2_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL1_SHIFT, 4, ID_AA64PFR0_EL1_64BIT_ONLY),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_EL0_SHIFT, 4, ID_AA64PFR0_EL0_64BIT_ONLY),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = {
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_SSBS_SHIFT, 4, ID_AA64PFR1_SSBS_PSTATE_NI),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr0[] = {
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN4_SHIFT, 4, ID_AA64MMFR0_TGRAN4_NI),
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN64_SHIFT, 4, ID_AA64MMFR0_TGRAN64_NI),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_TGRAN16_SHIFT, 4, ID_AA64MMFR0_TGRAN16_NI),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_BIGENDEL0_SHIFT, 4, 0),
	/* Linux shouldn't care about secure memory */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_SNSMEM_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_BIGENDEL_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_ASID_SHIFT, 4, 0),
	/*
	 * Differing PARange is fine as long as all peripherals and memory are mapped
	 * within the minimum PARange of all CPUs
	 */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64MMFR0_PARANGE_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr1[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_PAN_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_LOR_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_HPD_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_VHE_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_VMIDBITS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR1_HADBS_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64mmfr2[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_FWB_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_AT_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LVA_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_IESB_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_LSM_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_UAO_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR2_CNP_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_ctr[] = {
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, 31, 1, 1), /* RES1 */
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_DIC_SHIFT, 1, 1),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_IDC_SHIFT, 1, 1),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_HIGHER_SAFE, CTR_CWG_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_HIGHER_SAFE, CTR_ERG_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_DMINLINE_SHIFT, 4, 1),
	/*
	 * Linux can handle differing I-cache policies. Userspace JITs will
	 * make use of *minLine.
	 * If we have differing I-cache policies, report it as the weakest - VIPT.
	 */
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_EXACT, 14, 2, ICACHE_POLICY_VIPT),	/* L1Ip */
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_IMINLINE_SHIFT, 4, 0),
	ARM64_FTR_END,
};

struct arm64_ftr_reg arm64_ftr_reg_ctrel0 = {
	.name		= "SYS_CTR_EL0",
	.ftr_bits	= ftr_ctr
};

static const struct arm64_ftr_bits ftr_id_mmfr0[] = {
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0xf),	/* InnerShr */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 24, 4, 0),	/* FCSE */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, 20, 4, 0),	/* AuxReg */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 0),	/* TCM */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),	/* ShareLvl */
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0xf),	/* OuterShr */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),	/* PMSA */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),	/* VMSA */
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_aa64dfr0[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, 36, 28, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64DFR0_PMSVER_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_CTX_CMPS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_WRPS_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64DFR0_BRPS_SHIFT, 4, 0),
	/*
	 * We can instantiate multiple PMU instances with different levels
	 * of support.
	 */
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_EXACT, ID_AA64DFR0_PMUVER_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_TRACEVER_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, ID_AA64DFR0_DEBUGVER_SHIFT, 4, 0x6),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_mvfr2[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),		/* FPMisc */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),		/* SIMDMisc */
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_dczid[] = {
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, 4, 1, 1),		/* DZP */
	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),	/* BS */
	ARM64_FTR_END,
};


static const struct arm64_ftr_bits ftr_id_isar5[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_RDM_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_CRC32_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SHA2_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SHA1_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_AES_SHIFT, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_ISAR5_SEVL_SHIFT, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_mmfr4[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),	/* ac2 */
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_pfr0[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),		/* State3 */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0),		/* State2 */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),		/* State1 */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),		/* State0 */
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_id_dfr0[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0),
	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 24, 4, 0xf),	/* PerfMon */
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 20, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_zcr[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE,
		ZCR_ELx_LEN_SHIFT, ZCR_ELx_LEN_SIZE, 0),	/* LEN */
	ARM64_FTR_END,
};

/*
 * Common ftr bits for a 32bit register with all hidden, strict
 * attributes, with 4bit feature fields and a default safe value of
 * 0. Covers the following 32bit registers:
 * id_isar[0-4], id_mmfr[1-3], id_pfr1, mvfr[0-1]
 */
static const struct arm64_ftr_bits ftr_generic_32bits[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 24, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 20, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 16, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 12, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 8, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 4, 4, 0),
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 0, 4, 0),
	ARM64_FTR_END,
};

/* Table for a single 32bit feature value */
static const struct arm64_ftr_bits ftr_single32[] = {
	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_EXACT, 0, 32, 0),
	ARM64_FTR_END,
};

static const struct arm64_ftr_bits ftr_raz[] = {
	ARM64_FTR_END,
};

#define ARM64_FTR_REG(id, table) {		\
	.sys_id = id,				\
	.reg = 	&(struct arm64_ftr_reg){	\
		.name = #id,			\
		.ftr_bits = &((table)[0]),	\
	}}

static const struct __ftr_reg_entry {
	u32			sys_id;
	struct arm64_ftr_reg 	*reg;
} arm64_ftr_regs[] = {

	/* Op1 = 0, CRn = 0, CRm = 1 */
	ARM64_FTR_REG(SYS_ID_PFR0_EL1, ftr_id_pfr0),
	ARM64_FTR_REG(SYS_ID_PFR1_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_DFR0_EL1, ftr_id_dfr0),
	ARM64_FTR_REG(SYS_ID_MMFR0_EL1, ftr_id_mmfr0),
	ARM64_FTR_REG(SYS_ID_MMFR1_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_MMFR2_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_MMFR3_EL1, ftr_generic_32bits),

	/* Op1 = 0, CRn = 0, CRm = 2 */
	ARM64_FTR_REG(SYS_ID_ISAR0_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_ISAR1_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_ISAR2_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_ISAR3_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_ISAR4_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_ID_ISAR5_EL1, ftr_id_isar5),
	ARM64_FTR_REG(SYS_ID_MMFR4_EL1, ftr_id_mmfr4),

	/* Op1 = 0, CRn = 0, CRm = 3 */
	ARM64_FTR_REG(SYS_MVFR0_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_MVFR1_EL1, ftr_generic_32bits),
	ARM64_FTR_REG(SYS_MVFR2_EL1, ftr_mvfr2),

	/* Op1 = 0, CRn = 0, CRm = 4 */
	ARM64_FTR_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0),
	ARM64_FTR_REG(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1),
	ARM64_FTR_REG(SYS_ID_AA64ZFR0_EL1, ftr_raz),

	/* Op1 = 0, CRn = 0, CRm = 5 */
	ARM64_FTR_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0),
	ARM64_FTR_REG(SYS_ID_AA64DFR1_EL1, ftr_raz),

	/* Op1 = 0, CRn = 0, CRm = 6 */
	ARM64_FTR_REG(SYS_ID_AA64ISAR0_EL1, ftr_id_aa64isar0),
	ARM64_FTR_REG(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1),

	/* Op1 = 0, CRn = 0, CRm = 7 */
	ARM64_FTR_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0),
	ARM64_FTR_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1),
	ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),

	/* Op1 = 0, CRn = 1, CRm = 2 */
	ARM64_FTR_REG(SYS_ZCR_EL1, ftr_zcr),

	/* Op1 = 3, CRn = 0, CRm = 0 */
	{ SYS_CTR_EL0, &arm64_ftr_reg_ctrel0 },
	ARM64_FTR_REG(SYS_DCZID_EL0, ftr_dczid),

	/* Op1 = 3, CRn = 14, CRm = 0 */
	ARM64_FTR_REG(SYS_CNTFRQ_EL0, ftr_single32),
};

static int search_cmp_ftr_reg(const void *id, const void *regp)
{
	return (int)(unsigned long)id - (int)((const struct __ftr_reg_entry *)regp)->sys_id;
}

/*
 * get_arm64_ftr_reg - Lookup a feature register entry using its
 * sys_reg() encoding. With the array arm64_ftr_regs sorted in the
 * ascending order of sys_id , we use binary search to find a matching
 * entry.
 *
 * returns - Upon success,  matching ftr_reg entry for id.
 *         - NULL on failure. It is upto the caller to decide
 *	     the impact of a failure.
 */
static struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id)
{
	const struct __ftr_reg_entry *ret;

	ret = bsearch((const void *)(unsigned long)sys_id,
			arm64_ftr_regs,
			ARRAY_SIZE(arm64_ftr_regs),
			sizeof(arm64_ftr_regs[0]),
			search_cmp_ftr_reg);
	if (ret)
		return ret->reg;
	return NULL;
}

static u64 arm64_ftr_set_value(const struct arm64_ftr_bits *ftrp, s64 reg,
			       s64 ftr_val)
{
	u64 mask = arm64_ftr_mask(ftrp);

	reg &= ~mask;
	reg |= (ftr_val << ftrp->shift) & mask;
	return reg;
}

static s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new,
				s64 cur)
{
	s64 ret = 0;

	switch (ftrp->type) {
	case FTR_EXACT:
		ret = ftrp->safe_val;
		break;
	case FTR_LOWER_SAFE:
		ret = new < cur ? new : cur;
		break;
	case FTR_HIGHER_SAFE:
		ret = new > cur ? new : cur;
		break;
	default:
		BUG();
	}

	return ret;
}

static void __init sort_ftr_regs(void)
{
	int i;

	/* Check that the array is sorted so that we can do the binary search */
	for (i = 1; i < ARRAY_SIZE(arm64_ftr_regs); i++)
		BUG_ON(arm64_ftr_regs[i].sys_id < arm64_ftr_regs[i - 1].sys_id);
}

/*
 * Initialise the CPU feature register from Boot CPU values.
 * Also initiliases the strict_mask for the register.
 * Any bits that are not covered by an arm64_ftr_bits entry are considered
 * RES0 for the system-wide value, and must strictly match.
 */
static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new)
{
	u64 val = 0;
	u64 strict_mask = ~0x0ULL;
	u64 user_mask = 0;
	u64 valid_mask = 0;

	const struct arm64_ftr_bits *ftrp;
	struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg);

	BUG_ON(!reg);

	for (ftrp  = reg->ftr_bits; ftrp->width; ftrp++) {
		u64 ftr_mask = arm64_ftr_mask(ftrp);
		s64 ftr_new = arm64_ftr_value(ftrp, new);

		val = arm64_ftr_set_value(ftrp, val, ftr_new);

		valid_mask |= ftr_mask;
		if (!ftrp->strict)
			strict_mask &= ~ftr_mask;
		if (ftrp->visible)
			user_mask |= ftr_mask;
		else
			reg->user_val = arm64_ftr_set_value(ftrp,
							    reg->user_val,
							    ftrp->safe_val);
	}

	val &= valid_mask;

	reg->sys_val = val;
	reg->strict_mask = strict_mask;
	reg->user_mask = user_mask;
}

extern const struct arm64_cpu_capabilities arm64_errata[];
static const struct arm64_cpu_capabilities arm64_features[];

static void __init
init_cpu_hwcaps_indirect_list_from_array(const struct arm64_cpu_capabilities *caps)
{
	for (; caps->matches; caps++) {
		if (WARN(caps->capability >= ARM64_NCAPS,
			"Invalid capability %d\n", caps->capability))
			continue;
		if (WARN(cpu_hwcaps_ptrs[caps->capability],
			"Duplicate entry for capability %d\n",
			caps->capability))
			continue;
		cpu_hwcaps_ptrs[caps->capability] = caps;
	}
}

static void __init init_cpu_hwcaps_indirect_list(void)
{
	init_cpu_hwcaps_indirect_list_from_array(arm64_features);
	init_cpu_hwcaps_indirect_list_from_array(arm64_errata);
}

static void __init setup_boot_cpu_capabilities(void);

void __init init_cpu_features(struct cpuinfo_arm64 *info)
{
	/* Before we start using the tables, make sure it is sorted */
	sort_ftr_regs();

	init_cpu_ftr_reg(SYS_CTR_EL0, info->reg_ctr);
	init_cpu_ftr_reg(SYS_DCZID_EL0, info->reg_dczid);
	init_cpu_ftr_reg(SYS_CNTFRQ_EL0, info->reg_cntfrq);
	init_cpu_ftr_reg(SYS_ID_AA64DFR0_EL1, info->reg_id_aa64dfr0);
	init_cpu_ftr_reg(SYS_ID_AA64DFR1_EL1, info->reg_id_aa64dfr1);
	init_cpu_ftr_reg(SYS_ID_AA64ISAR0_EL1, info->reg_id_aa64isar0);
	init_cpu_ftr_reg(SYS_ID_AA64ISAR1_EL1, info->reg_id_aa64isar1);
	init_cpu_ftr_reg(SYS_ID_AA64MMFR0_EL1, info->reg_id_aa64mmfr0);
	init_cpu_ftr_reg(SYS_ID_AA64MMFR1_EL1, info->reg_id_aa64mmfr1);
	init_cpu_ftr_reg(SYS_ID_AA64MMFR2_EL1, info->reg_id_aa64mmfr2);
	init_cpu_ftr_reg(SYS_ID_AA64PFR0_EL1, info->reg_id_aa64pfr0);
	init_cpu_ftr_reg(SYS_ID_AA64PFR1_EL1, info->reg_id_aa64pfr1);
	init_cpu_ftr_reg(SYS_ID_AA64ZFR0_EL1, info->reg_id_aa64zfr0);

	if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0)) {
		init_cpu_ftr_reg(SYS_ID_DFR0_EL1, info->reg_id_dfr0);
		init_cpu_ftr_reg(SYS_ID_ISAR0_EL1, info->reg_id_isar0);
		init_cpu_ftr_reg(SYS_ID_ISAR1_EL1, info->reg_id_isar1);
		init_cpu_ftr_reg(SYS_ID_ISAR2_EL1, info->reg_id_isar2);
		init_cpu_ftr_reg(SYS_ID_ISAR3_EL1, info->reg_id_isar3);
		init_cpu_ftr_reg(SYS_ID_ISAR4_EL1, info->reg_id_isar4);
		init_cpu_ftr_reg(SYS_ID_ISAR5_EL1, info->reg_id_isar5);
		init_cpu_ftr_reg(SYS_ID_MMFR0_EL1, info->reg_id_mmfr0);
		init_cpu_ftr_reg(SYS_ID_MMFR1_EL1, info->reg_id_mmfr1);
		init_cpu_ftr_reg(SYS_ID_MMFR2_EL1, info->reg_id_mmfr2);
		init_cpu_ftr_reg(SYS_ID_MMFR3_EL1, info->reg_id_mmfr3);
		init_cpu_ftr_reg(SYS_ID_PFR0_EL1, info->reg_id_pfr0);
		init_cpu_ftr_reg(SYS_ID_PFR1_EL1, info->reg_id_pfr1);
		init_cpu_ftr_reg(SYS_MVFR0_EL1, info->reg_mvfr0);
		init_cpu_ftr_reg(SYS_MVFR1_EL1, info->reg_mvfr1);
		init_cpu_ftr_reg(SYS_MVFR2_EL1, info->reg_mvfr2);
	}

	if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
		init_cpu_ftr_reg(SYS_ZCR_EL1, info->reg_zcr);
		sve_init_vq_map();
	}

	/*
	 * Initialize the indirect array of CPU hwcaps capabilities pointers
	 * before we handle the boot CPU below.
	 */
	init_cpu_hwcaps_indirect_list();

	/*
	 * Detect and enable early CPU capabilities based on the boot CPU,
	 * after we have initialised the CPU feature infrastructure.
	 */
	setup_boot_cpu_capabilities();
}

static void update_cpu_ftr_reg(struct arm64_ftr_reg *reg, u64 new)
{
	const struct arm64_ftr_bits *ftrp;

	for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) {
		s64 ftr_cur = arm64_ftr_value(ftrp, reg->sys_val);
		s64 ftr_new = arm64_ftr_value(ftrp, new);

		if (ftr_cur == ftr_new)
			continue;
		/* Find a safe value */
		ftr_new = arm64_ftr_safe_value(ftrp, ftr_new, ftr_cur);
		reg->sys_val = arm64_ftr_set_value(ftrp, reg->sys_val, ftr_new);
	}

}

static int check_update_ftr_reg(u32 sys_id, int cpu, u64 val, u64 boot)
{
	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id);

	BUG_ON(!regp);
	update_cpu_ftr_reg(regp, val);
	if ((boot & regp->strict_mask) == (val & regp->strict_mask))
		return 0;
	pr_warn("SANITY CHECK: Unexpected variation in %s. Boot CPU: %#016llx, CPU%d: %#016llx\n",
			regp->name, boot, cpu, val);
	return 1;
}

/*
 * Update system wide CPU feature registers with the values from a
 * non-boot CPU. Also performs SANITY checks to make sure that there
 * aren't any insane variations from that of the boot CPU.
 */
void update_cpu_features(int cpu,
			 struct cpuinfo_arm64 *info,
			 struct cpuinfo_arm64 *boot)
{
	int taint = 0;

	/*
	 * The kernel can handle differing I-cache policies, but otherwise
	 * caches should look identical. Userspace JITs will make use of
	 * *minLine.
	 */
	taint |= check_update_ftr_reg(SYS_CTR_EL0, cpu,
				      info->reg_ctr, boot->reg_ctr);

	/*
	 * Userspace may perform DC ZVA instructions. Mismatched block sizes
	 * could result in too much or too little memory being zeroed if a
	 * process is preempted and migrated between CPUs.
	 */
	taint |= check_update_ftr_reg(SYS_DCZID_EL0, cpu,
				      info->reg_dczid, boot->reg_dczid);

	/* If different, timekeeping will be broken (especially with KVM) */
	taint |= check_update_ftr_reg(SYS_CNTFRQ_EL0, cpu,
				      info->reg_cntfrq, boot->reg_cntfrq);

	/*
	 * The kernel uses self-hosted debug features and expects CPUs to
	 * support identical debug features. We presently need CTX_CMPs, WRPs,
	 * and BRPs to be identical.
	 * ID_AA64DFR1 is currently RES0.
	 */
	taint |= check_update_ftr_reg(SYS_ID_AA64DFR0_EL1, cpu,
				      info->reg_id_aa64dfr0, boot->reg_id_aa64dfr0);
	taint |= check_update_ftr_reg(SYS_ID_AA64DFR1_EL1, cpu,
				      info->reg_id_aa64dfr1, boot->reg_id_aa64dfr1);
	/*
	 * Even in big.LITTLE, processors should be identical instruction-set
	 * wise.
	 */
	taint |= check_update_ftr_reg(SYS_ID_AA64ISAR0_EL1, cpu,
				      info->reg_id_aa64isar0, boot->reg_id_aa64isar0);
	taint |= check_update_ftr_reg(SYS_ID_AA64ISAR1_EL1, cpu,
				      info->reg_id_aa64isar1, boot->reg_id_aa64isar1);

	/*
	 * Differing PARange support is fine as long as all peripherals and
	 * memory are mapped within the minimum PARange of all CPUs.
	 * Linux should not care about secure memory.
	 */
	taint |= check_update_ftr_reg(SYS_ID_AA64MMFR0_EL1, cpu,
				      info->reg_id_aa64mmfr0, boot->reg_id_aa64mmfr0);
	taint |= check_update_ftr_reg(SYS_ID_AA64MMFR1_EL1, cpu,
				      info->reg_id_aa64mmfr1, boot->reg_id_aa64mmfr1);
	taint |= check_update_ftr_reg(SYS_ID_AA64MMFR2_EL1, cpu,
				      info->reg_id_aa64mmfr2, boot->reg_id_aa64mmfr2);

	/*
	 * EL3 is not our concern.
	 */
	taint |= check_update_ftr_reg(SYS_ID_AA64PFR0_EL1, cpu,
				      info->reg_id_aa64pfr0, boot->reg_id_aa64pfr0);
	taint |= check_update_ftr_reg(SYS_ID_AA64PFR1_EL1, cpu,
				      info->reg_id_aa64pfr1, boot->reg_id_aa64pfr1);

	taint |= check_update_ftr_reg(SYS_ID_AA64ZFR0_EL1, cpu,
				      info->reg_id_aa64zfr0, boot->reg_id_aa64zfr0);

	/*
	 * If we have AArch32, we care about 32-bit features for compat.
	 * If the system doesn't support AArch32, don't update them.
	 */
	if (id_aa64pfr0_32bit_el0(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1)) &&
		id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0)) {

		taint |= check_update_ftr_reg(SYS_ID_DFR0_EL1, cpu,
					info->reg_id_dfr0, boot->reg_id_dfr0);
		taint |= check_update_ftr_reg(SYS_ID_ISAR0_EL1, cpu,
					info->reg_id_isar0, boot->reg_id_isar0);
		taint |= check_update_ftr_reg(SYS_ID_ISAR1_EL1, cpu,
					info->reg_id_isar1, boot->reg_id_isar1);
		taint |= check_update_ftr_reg(SYS_ID_ISAR2_EL1, cpu,
					info->reg_id_isar2, boot->reg_id_isar2);
		taint |= check_update_ftr_reg(SYS_ID_ISAR3_EL1, cpu,
					info->reg_id_isar3, boot->reg_id_isar3);
		taint |= check_update_ftr_reg(SYS_ID_ISAR4_EL1, cpu,
					info->reg_id_isar4, boot->reg_id_isar4);
		taint |= check_update_ftr_reg(SYS_ID_ISAR5_EL1, cpu,
					info->reg_id_isar5, boot->reg_id_isar5);

		/*
		 * Regardless of the value of the AuxReg field, the AIFSR, ADFSR, and
		 * ACTLR formats could differ across CPUs and therefore would have to
		 * be trapped for virtualization anyway.
		 */
		taint |= check_update_ftr_reg(SYS_ID_MMFR0_EL1, cpu,
					info->reg_id_mmfr0, boot->reg_id_mmfr0);
		taint |= check_update_ftr_reg(SYS_ID_MMFR1_EL1, cpu,
					info->reg_id_mmfr1, boot->reg_id_mmfr1);
		taint |= check_update_ftr_reg(SYS_ID_MMFR2_EL1, cpu,
					info->reg_id_mmfr2, boot->reg_id_mmfr2);
		taint |= check_update_ftr_reg(SYS_ID_MMFR3_EL1, cpu,
					info->reg_id_mmfr3, boot->reg_id_mmfr3);
		taint |= check_update_ftr_reg(SYS_ID_PFR0_EL1, cpu,
					info->reg_id_pfr0, boot->reg_id_pfr0);
		taint |= check_update_ftr_reg(SYS_ID_PFR1_EL1, cpu,
					info->reg_id_pfr1, boot->reg_id_pfr1);
		taint |= check_update_ftr_reg(SYS_MVFR0_EL1, cpu,
					info->reg_mvfr0, boot->reg_mvfr0);
		taint |= check_update_ftr_reg(SYS_MVFR1_EL1, cpu,
					info->reg_mvfr1, boot->reg_mvfr1);
		taint |= check_update_ftr_reg(SYS_MVFR2_EL1, cpu,
					info->reg_mvfr2, boot->reg_mvfr2);
	}

	if (id_aa64pfr0_sve(info->reg_id_aa64pfr0)) {
		taint |= check_update_ftr_reg(SYS_ZCR_EL1, cpu,
					info->reg_zcr, boot->reg_zcr);

		/* Probe vector lengths, unless we already gave up on SVE */
		if (id_aa64pfr0_sve(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1)) &&
		    !sys_caps_initialised)
			sve_update_vq_map();
	}

	/*
	 * Mismatched CPU features are a recipe for disaster. Don't even
	 * pretend to support them.
	 */
	if (taint) {
		pr_warn_once("Unsupported CPU feature variation detected.\n");
		add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
	}
}

u64 read_sanitised_ftr_reg(u32 id)
{
	struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);

	/* We shouldn't get a request for an unsupported register */
	BUG_ON(!regp);
	return regp->sys_val;
}

#define read_sysreg_case(r)	\
	case r:		return read_sysreg_s(r)

/*
 * __read_sysreg_by_encoding() - Used by a STARTING cpu before cpuinfo is populated.
 * Read the system register on the current CPU
 */
static u64 __read_sysreg_by_encoding(u32 sys_id)
{
	switch (sys_id) {
	read_sysreg_case(SYS_ID_PFR0_EL1);
	read_sysreg_case(SYS_ID_PFR1_EL1);
	read_sysreg_case(SYS_ID_DFR0_EL1);
	read_sysreg_case(SYS_ID_MMFR0_EL1);
	read_sysreg_case(SYS_ID_MMFR1_EL1);
	read_sysreg_case(SYS_ID_MMFR2_EL1);
	read_sysreg_case(SYS_ID_MMFR3_EL1);
	read_sysreg_case(SYS_ID_ISAR0_EL1);
	read_sysreg_case(SYS_ID_ISAR1_EL1);
	read_sysreg_case(SYS_ID_ISAR2_EL1);
	read_sysreg_case(SYS_ID_ISAR3_EL1);
	read_sysreg_case(SYS_ID_ISAR4_EL1);
	read_sysreg_case(SYS_ID_ISAR5_EL1);
	read_sysreg_case(SYS_MVFR0_EL1);
	read_sysreg_case(SYS_MVFR1_EL1);
	read_sysreg_case(SYS_MVFR2_EL1);

	read_sysreg_case(SYS_ID_AA64PFR0_EL1);
	read_sysreg_case(SYS_ID_AA64PFR1_EL1);
	read_sysreg_case(SYS_ID_AA64DFR0_EL1);
	read_sysreg_case(SYS_ID_AA64DFR1_EL1);
	read_sysreg_case(SYS_ID_AA64MMFR0_EL1);
	read_sysreg_case(SYS_ID_AA64MMFR1_EL1);
	read_sysreg_case(SYS_ID_AA64MMFR2_EL1);
	read_sysreg_case(SYS_ID_AA64ISAR0_EL1);
	read_sysreg_case(SYS_ID_AA64ISAR1_EL1);

	read_sysreg_case(SYS_CNTFRQ_EL0);
	read_sysreg_case(SYS_CTR_EL0);
	read_sysreg_case(SYS_DCZID_EL0);

	default:
		BUG();
		return 0;
	}
}

#include <linux/irqchip/arm-gic-v3.h>

static bool
feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
{
	int val = cpuid_feature_extract_field(reg, entry->field_pos, entry->sign);

	return val >= entry->min_field_value;
}

static bool
has_cpuid_feature(const struct arm64_cpu_capabilities *entry, int scope)
{
	u64 val;

	WARN_ON(scope == SCOPE_LOCAL_CPU && preemptible());
	if (scope == SCOPE_SYSTEM)
		val = read_sanitised_ftr_reg(entry->sys_reg);
	else
		val = __read_sysreg_by_encoding(entry->sys_reg);

	return feature_matches(val, entry);
}

static bool has_useable_gicv3_cpuif(const struct arm64_cpu_capabilities *entry, int scope)
{
	bool has_sre;

	if (!has_cpuid_feature(entry, scope))
		return false;

	has_sre = gic_enable_sre();
	if (!has_sre)
		pr_warn_once("%s present but disabled by higher exception level\n",
			     entry->desc);

	return has_sre;
}

static bool has_no_hw_prefetch(const struct arm64_cpu_capabilities *entry, int __unused)
{
	u32 midr = read_cpuid_id();

	/* Cavium ThunderX pass 1.x and 2.x */
	return MIDR_IS_CPU_MODEL_RANGE(midr, MIDR_THUNDERX,
		MIDR_CPU_VAR_REV(0, 0),
		MIDR_CPU_VAR_REV(1, MIDR_REVISION_MASK));
}

static bool has_no_fpsimd(const struct arm64_cpu_capabilities *entry, int __unused)
{
	u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);

	return cpuid_feature_extract_signed_field(pfr0,
					ID_AA64PFR0_FP_SHIFT) < 0;
}

static bool has_cache_idc(const struct arm64_cpu_capabilities *entry,
			  int scope)
{
	u64 ctr;

	if (scope == SCOPE_SYSTEM)
		ctr = arm64_ftr_reg_ctrel0.sys_val;
	else
		ctr = read_cpuid_effective_cachetype();

	return ctr & BIT(CTR_IDC_SHIFT);
}

static void cpu_emulate_effective_ctr(const struct arm64_cpu_capabilities *__unused)
{
	/*
	 * If the CPU exposes raw CTR_EL0.IDC = 0, while effectively
	 * CTR_EL0.IDC = 1 (from CLIDR values), we need to trap accesses
	 * to the CTR_EL0 on this CPU and emulate it with the real/safe
	 * value.
	 */
	if (!(read_cpuid_cachetype() & BIT(CTR_IDC_SHIFT)))
		sysreg_clear_set(sctlr_el1, SCTLR_EL1_UCT, 0);
}

static bool has_cache_dic(const struct arm64_cpu_capabilities *entry,
			  int scope)
{
	u64 ctr;

	if (scope == SCOPE_SYSTEM)
		ctr = arm64_ftr_reg_ctrel0.sys_val;
	else
		ctr = read_cpuid_cachetype();

	return ctr & BIT(CTR_DIC_SHIFT);
}

static bool __maybe_unused
has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope)
{
	/*
	 * Kdump isn't guaranteed to power-off all secondary CPUs, CNP
	 * may share TLB entries with a CPU stuck in the crashed
	 * kernel.
	 */
	 if (is_kdump_kernel())
		return false;

	return has_cpuid_feature(entry, scope);
}

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */

static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
				int scope)
{
	/* List of CPUs that are not vulnerable and don't need KPTI */
	static const struct midr_range kpti_safe_list[] = {
		MIDR_ALL_VERSIONS(MIDR_CAVIUM_THUNDERX2),
		MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A35),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A53),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A57),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A72),
		MIDR_ALL_VERSIONS(MIDR_CORTEX_A73),
		{ /* sentinel */ }
	};
	char const *str = "command line option";

	/*
	 * For reasons that aren't entirely clear, enabling KPTI on Cavium
	 * ThunderX leads to apparent I-cache corruption of kernel text, which
	 * ends as well as you might imagine. Don't even try.
	 */
	if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456)) {
		str = "ARM64_WORKAROUND_CAVIUM_27456";
		__kpti_forced = -1;
	}

	/* Forced? */
	if (__kpti_forced) {
		pr_info_once("kernel page table isolation forced %s by %s\n",
			     __kpti_forced > 0 ? "ON" : "OFF", str);
		return __kpti_forced > 0;
	}

	/* Useful for KASLR robustness */
	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE))
		return true;

	/* Don't force KPTI for CPUs that are not vulnerable */
	if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list))
		return false;

	/* Defer to CPU feature registers */
	return !has_cpuid_feature(entry, scope);
}

static void
kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
{
	typedef void (kpti_remap_fn)(int, int, phys_addr_t);
	extern kpti_remap_fn idmap_kpti_install_ng_mappings;
	kpti_remap_fn *remap_fn;

	static bool kpti_applied = false;
	int cpu = smp_processor_id();

	if (kpti_applied)
		return;

	remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);

	cpu_install_idmap();
	remap_fn(cpu, num_online_cpus(), __pa_symbol(swapper_pg_dir));
	cpu_uninstall_idmap();

	if (!cpu)
		kpti_applied = true;

	return;
}

static int __init parse_kpti(char *str)
{
	bool enabled;
	int ret = strtobool(str, &enabled);

	if (ret)
		return ret;

	__kpti_forced = enabled ? 1 : -1;
	return 0;
}
early_param("kpti", parse_kpti);
#endif	/* CONFIG_UNMAP_KERNEL_AT_EL0 */

#ifdef CONFIG_ARM64_HW_AFDBM
static inline void __cpu_enable_hw_dbm(void)
{
	u64 tcr = read_sysreg(tcr_el1) | TCR_HD;

	write_sysreg(tcr, tcr_el1);
	isb();
}

static bool cpu_has_broken_dbm(void)
{
	/* List of CPUs which have broken DBM support. */
	static const struct midr_range cpus[] = {
#ifdef CONFIG_ARM64_ERRATUM_1024718
		MIDR_RANGE(MIDR_CORTEX_A55, 0, 0, 1, 0),  // A55 r0p0 -r1p0
#endif
		{},
	};

	return is_midr_in_range_list(read_cpuid_id(), cpus);
}

static bool cpu_can_use_dbm(const struct arm64_cpu_capabilities *cap)
{
	return has_cpuid_feature(cap, SCOPE_LOCAL_CPU) &&
	       !cpu_has_broken_dbm();
}

static void cpu_enable_hw_dbm(struct arm64_cpu_capabilities const *cap)
{
	if (cpu_can_use_dbm(cap))
		__cpu_enable_hw_dbm();
}

static bool has_hw_dbm(const struct arm64_cpu_capabilities *cap,
		       int __unused)
{
	static bool detected = false;
	/*
	 * DBM is a non-conflicting feature. i.e, the kernel can safely
	 * run a mix of CPUs with and without the feature. So, we
	 * unconditionally enable the capability to allow any late CPU
	 * to use the feature. We only enable the control bits on the
	 * CPU, if it actually supports.
	 *
	 * We have to make sure we print the "feature" detection only
	 * when at least one CPU actually uses it. So check if this CPU
	 * can actually use it and print the message exactly once.
	 *
	 * This is safe as all CPUs (including secondary CPUs - due to the
	 * LOCAL_CPU scope - and the hotplugged CPUs - via verification)
	 * goes through the "matches" check exactly once. Also if a CPU
	 * matches the criteria, it is guaranteed that the CPU will turn
	 * the DBM on, as the capability is unconditionally enabled.
	 */
	if (!detected && cpu_can_use_dbm(cap)) {
		detected = true;
		pr_info("detected: Hardware dirty bit management\n");
	}

	return true;
}

#endif

#ifdef CONFIG_ARM64_VHE
static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused)
{
	return is_kernel_in_hyp_mode();
}

static void cpu_copy_el2regs(const struct arm64_cpu_capabilities *__unused)
{
	/*
	 * Copy register values that aren't redirected by hardware.
	 *
	 * Before code patching, we only set tpidr_el1, all CPUs need to copy
	 * this value to tpidr_el2 before we patch the code. Once we've done
	 * that, freshly-onlined CPUs will set tpidr_el2, so we don't need to
	 * do anything here.
	 */
	if (!alternatives_applied)
		write_sysreg(read_sysreg(tpidr_el1), tpidr_el2);
}
#endif

static void cpu_has_fwb(const struct arm64_cpu_capabilities *__unused)
{
	u64 val = read_sysreg_s(SYS_CLIDR_EL1);

	/* Check that CLIDR_EL1.LOU{U,IS} are both 0 */
	WARN_ON(val & (7 << 27 | 7 << 21));
}

#ifdef CONFIG_ARM64_SSBD
static int ssbs_emulation_handler(struct pt_regs *regs, u32 instr)
{
	if (user_mode(regs))
		return 1;

	if (instr & BIT(PSTATE_Imm_shift))
		regs->pstate |= PSR_SSBS_BIT;
	else
		regs->pstate &= ~PSR_SSBS_BIT;

	arm64_skip_faulting_instruction(regs, 4);
	return 0;
}

static struct undef_hook ssbs_emulation_hook = {
	.instr_mask	= ~(1U << PSTATE_Imm_shift),
	.instr_val	= 0xd500401f | PSTATE_SSBS,
	.fn		= ssbs_emulation_handler,
};

static void cpu_enable_ssbs(const struct arm64_cpu_capabilities *__unused)
{
	static bool undef_hook_registered = false;
	static DEFINE_SPINLOCK(hook_lock);

	spin_lock(&hook_lock);
	if (!undef_hook_registered) {
		register_undef_hook(&ssbs_emulation_hook);
		undef_hook_registered = true;
	}
	spin_unlock(&hook_lock);

	if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) {
		sysreg_clear_set(sctlr_el1, 0, SCTLR_ELx_DSSBS);
		arm64_set_ssbd_mitigation(false);
	} else {
		arm64_set_ssbd_mitigation(true);
	}
}
#endif /* CONFIG_ARM64_SSBD */

#ifdef CONFIG_ARM64_PAN
static void cpu_enable_pan(const struct arm64_cpu_capabilities *__unused)
{
	/*
	 * We modify PSTATE. This won't work from irq context as the PSTATE
	 * is discarded once we return from the exception.
	 */
	WARN_ON_ONCE(in_interrupt());

	sysreg_clear_set(sctlr_el1, SCTLR_EL1_SPAN, 0);
	asm(SET_PSTATE_PAN(1));
}
#endif /* CONFIG_ARM64_PAN */

#ifdef CONFIG_ARM64_RAS_EXTN
static void cpu_clear_disr(const struct arm64_cpu_capabilities *__unused)
{
	/* Firmware may have left a deferred SError in this register. */
	write_sysreg_s(0, SYS_DISR_EL1);
}
#endif /* CONFIG_ARM64_RAS_EXTN */

#ifdef CONFIG_ARM64_PTR_AUTH
static bool has_address_auth(const struct arm64_cpu_capabilities *entry,
			     int __unused)
{
	u64 isar1 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
	bool api, apa;

	apa = cpuid_feature_extract_unsigned_field(isar1,
					ID_AA64ISAR1_APA_SHIFT) > 0;
	api = cpuid_feature_extract_unsigned_field(isar1,
					ID_AA64ISAR1_API_SHIFT) > 0;

	return apa || api;
}

static bool has_generic_auth(const struct arm64_cpu_capabilities *entry,
			     int __unused)
{
	u64 isar1 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
	bool gpi, gpa;

	gpa = cpuid_feature_extract_unsigned_field(isar1,
					ID_AA64ISAR1_GPA_SHIFT) > 0;
	gpi = cpuid_feature_extract_unsigned_field(isar1,
					ID_AA64ISAR1_GPI_SHIFT) > 0;

	return gpa || gpi;
}
#endif /* CONFIG_ARM64_PTR_AUTH */

static const struct arm64_cpu_capabilities arm64_features[] = {
	{
		.desc = "GIC system register CPU interface",
		.capability = ARM64_HAS_SYSREG_GIC_CPUIF,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_useable_gicv3_cpuif,
		.sys_reg = SYS_ID_AA64PFR0_EL1,
		.field_pos = ID_AA64PFR0_GIC_SHIFT,
		.sign = FTR_UNSIGNED,
		.min_field_value = 1,
	},
#ifdef CONFIG_ARM64_PAN
	{
		.desc = "Privileged Access Never",
		.capability = ARM64_HAS_PAN,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64MMFR1_EL1,
		.field_pos = ID_AA64MMFR1_PAN_SHIFT,
		.sign = FTR_UNSIGNED,
		.min_field_value = 1,
		.cpu_enable = cpu_enable_pan,
	},
#endif /* CONFIG_ARM64_PAN */
#if defined(CONFIG_AS_LSE) && defined(CONFIG_ARM64_LSE_ATOMICS)
	{
		.desc = "LSE atomic instructions",
		.capability = ARM64_HAS_LSE_ATOMICS,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64ISAR0_EL1,
		.field_pos = ID_AA64ISAR0_ATOMICS_SHIFT,
		.sign = FTR_UNSIGNED,
		.min_field_value = 2,
	},
#endif /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
	{
		.desc = "Software prefetching using PRFM",
		.capability = ARM64_HAS_NO_HW_PREFETCH,
		.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
		.matches = has_no_hw_prefetch,
	},
#ifdef CONFIG_ARM64_UAO
	{
		.desc = "User Access Override",
		.capability = ARM64_HAS_UAO,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64MMFR2_EL1,
		.field_pos = ID_AA64MMFR2_UAO_SHIFT,
		.min_field_value = 1,
		/*
		 * We rely on stop_machine() calling uao_thread_switch() to set
		 * UAO immediately after patching.
		 */
	},
#endif /* CONFIG_ARM64_UAO */
#ifdef CONFIG_ARM64_PAN
	{
		.capability = ARM64_ALT_PAN_NOT_UAO,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = cpufeature_pan_not_uao,
	},
#endif /* CONFIG_ARM64_PAN */
#ifdef CONFIG_ARM64_VHE
	{
		.desc = "Virtualization Host Extensions",
		.capability = ARM64_HAS_VIRT_HOST_EXTN,
		.type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
		.matches = runs_at_el2,
		.cpu_enable = cpu_copy_el2regs,
	},
#endif	/* CONFIG_ARM64_VHE */
	{
		.desc = "32-bit EL0 Support",
		.capability = ARM64_HAS_32BIT_EL0,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64PFR0_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64PFR0_EL0_SHIFT,
		.min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
	},
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
	{
		.desc = "Kernel page table isolation (KPTI)",
		.capability = ARM64_UNMAP_KERNEL_AT_EL0,
		.type = ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE,
		/*
		 * The ID feature fields below are used to indicate that
		 * the CPU doesn't need KPTI. See unmap_kernel_at_el0 for
		 * more details.
		 */
		.sys_reg = SYS_ID_AA64PFR0_EL1,
		.field_pos = ID_AA64PFR0_CSV3_SHIFT,
		.min_field_value = 1,
		.matches = unmap_kernel_at_el0,
		.cpu_enable = kpti_install_ng_mappings,
	},
#endif
	{
		/* FP/SIMD is not implemented */
		.capability = ARM64_HAS_NO_FPSIMD,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.min_field_value = 0,
		.matches = has_no_fpsimd,
	},
#ifdef CONFIG_ARM64_PMEM
	{
		.desc = "Data cache clean to Point of Persistence",
		.capability = ARM64_HAS_DCPOP,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.field_pos = ID_AA64ISAR1_DPB_SHIFT,
		.min_field_value = 1,
	},
#endif
#ifdef CONFIG_ARM64_SVE
	{
		.desc = "Scalable Vector Extension",
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.capability = ARM64_SVE,
		.sys_reg = SYS_ID_AA64PFR0_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64PFR0_SVE_SHIFT,
		.min_field_value = ID_AA64PFR0_SVE,
		.matches = has_cpuid_feature,
		.cpu_enable = sve_kernel_enable,
	},
#endif /* CONFIG_ARM64_SVE */
#ifdef CONFIG_ARM64_RAS_EXTN
	{
		.desc = "RAS Extension Support",
		.capability = ARM64_HAS_RAS_EXTN,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64PFR0_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64PFR0_RAS_SHIFT,
		.min_field_value = ID_AA64PFR0_RAS_V1,
		.cpu_enable = cpu_clear_disr,
	},
#endif /* CONFIG_ARM64_RAS_EXTN */
	{
		.desc = "Data cache clean to the PoU not required for I/D coherence",
		.capability = ARM64_HAS_CACHE_IDC,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cache_idc,
		.cpu_enable = cpu_emulate_effective_ctr,
	},
	{
		.desc = "Instruction cache invalidation not required for I/D coherence",
		.capability = ARM64_HAS_CACHE_DIC,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cache_dic,
	},
	{
		.desc = "Stage-2 Force Write-Back",
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.capability = ARM64_HAS_STAGE2_FWB,
		.sys_reg = SYS_ID_AA64MMFR2_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64MMFR2_FWB_SHIFT,
		.min_field_value = 1,
		.matches = has_cpuid_feature,
		.cpu_enable = cpu_has_fwb,
	},
#ifdef CONFIG_ARM64_HW_AFDBM
	{
		/*
		 * Since we turn this on always, we don't want the user to
		 * think that the feature is available when it may not be.
		 * So hide the description.
		 *
		 * .desc = "Hardware pagetable Dirty Bit Management",
		 *
		 */
		.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
		.capability = ARM64_HW_DBM,
		.sys_reg = SYS_ID_AA64MMFR1_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64MMFR1_HADBS_SHIFT,
		.min_field_value = 2,
		.matches = has_hw_dbm,
		.cpu_enable = cpu_enable_hw_dbm,
	},
#endif
#ifdef CONFIG_ARM64_SSBD
	{
		.desc = "CRC32 instructions",
		.capability = ARM64_HAS_CRC32,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64ISAR0_EL1,
		.field_pos = ID_AA64ISAR0_CRC32_SHIFT,
		.min_field_value = 1,
	},
	{
		.desc = "Speculative Store Bypassing Safe (SSBS)",
		.capability = ARM64_SSBS,
		.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64PFR1_EL1,
		.field_pos = ID_AA64PFR1_SSBS_SHIFT,
		.sign = FTR_UNSIGNED,
		.min_field_value = ID_AA64PFR1_SSBS_PSTATE_ONLY,
		.cpu_enable = cpu_enable_ssbs,
	},
#endif
#ifdef CONFIG_ARM64_CNP
	{
		.desc = "Common not Private translations",
		.capability = ARM64_HAS_CNP,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_useable_cnp,
		.sys_reg = SYS_ID_AA64MMFR2_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64MMFR2_CNP_SHIFT,
		.min_field_value = 1,
		.cpu_enable = cpu_enable_cnp,
	},
#endif
	{
		.desc = "Speculation barrier (SB)",
		.capability = ARM64_HAS_SB,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_cpuid_feature,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.field_pos = ID_AA64ISAR1_SB_SHIFT,
		.sign = FTR_UNSIGNED,
		.min_field_value = 1,
	},
#ifdef CONFIG_ARM64_PTR_AUTH
	{
		.desc = "Address authentication (architected algorithm)",
		.capability = ARM64_HAS_ADDRESS_AUTH_ARCH,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64ISAR1_APA_SHIFT,
		.min_field_value = ID_AA64ISAR1_APA_ARCHITECTED,
		.matches = has_cpuid_feature,
	},
	{
		.desc = "Address authentication (IMP DEF algorithm)",
		.capability = ARM64_HAS_ADDRESS_AUTH_IMP_DEF,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64ISAR1_API_SHIFT,
		.min_field_value = ID_AA64ISAR1_API_IMP_DEF,
		.matches = has_cpuid_feature,
	},
	{
		.capability = ARM64_HAS_ADDRESS_AUTH,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_address_auth,
	},
	{
		.desc = "Generic authentication (architected algorithm)",
		.capability = ARM64_HAS_GENERIC_AUTH_ARCH,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64ISAR1_GPA_SHIFT,
		.min_field_value = ID_AA64ISAR1_GPA_ARCHITECTED,
		.matches = has_cpuid_feature,
	},
	{
		.desc = "Generic authentication (IMP DEF algorithm)",
		.capability = ARM64_HAS_GENERIC_AUTH_IMP_DEF,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.sys_reg = SYS_ID_AA64ISAR1_EL1,
		.sign = FTR_UNSIGNED,
		.field_pos = ID_AA64ISAR1_GPI_SHIFT,
		.min_field_value = ID_AA64ISAR1_GPI_IMP_DEF,
		.matches = has_cpuid_feature,
	},
	{
		.capability = ARM64_HAS_GENERIC_AUTH,
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
		.matches = has_generic_auth,
	},
#endif /* CONFIG_ARM64_PTR_AUTH */
	{},
};

#define HWCAP_CAP(reg, field, s, min_value, cap_type, cap)	\
	{							\
		.desc = #cap,					\
		.type = ARM64_CPUCAP_SYSTEM_FEATURE,		\
		.matches = has_cpuid_feature,			\
		.sys_reg = reg,					\
		.field_pos = field,				\
		.sign = s,					\
		.min_field_value = min_value,			\
		.hwcap_type = cap_type,				\
		.hwcap = cap,					\
	}

static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_PMULL),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_AES),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA1_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SHA1),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA2_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SHA2),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA2_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_SHA512),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_CRC32_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_CRC32),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_ATOMICS_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_ATOMICS),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_RDM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_ASIMDRDM),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA3_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SHA3),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SM3_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SM3),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SM4_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SM4),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_DP_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_ASIMDDP),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_FHM_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_ASIMDFHM),
	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_TS_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_FLAGM),
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, HWCAP_FP),
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_FPHP),
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, HWCAP_ASIMD),
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_ASIMDHP),
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_DIT_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_DIT),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_DPB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_DCPOP),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_JSCVT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_JSCVT),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_FCMA_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_FCMA),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_LRCPC),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_LRCPC_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_ILRCPC),
	HWCAP_CAP(SYS_ID_AA64ISAR1_EL1, ID_AA64ISAR1_SB_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SB),
	HWCAP_CAP(SYS_ID_AA64MMFR2_EL1, ID_AA64MMFR2_AT_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_USCAT),
#ifdef CONFIG_ARM64_SVE
	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_SVE_SHIFT, FTR_UNSIGNED, ID_AA64PFR0_SVE, CAP_HWCAP, HWCAP_SVE),
#endif
	HWCAP_CAP(SYS_ID_AA64PFR1_EL1, ID_AA64PFR1_SSBS_SHIFT, FTR_UNSIGNED, ID_AA64PFR1_SSBS_PSTATE_INSNS, CAP_HWCAP, HWCAP_SSBS),
	{},
};

static const struct arm64_cpu_capabilities compat_elf_hwcaps[] = {
#ifdef CONFIG_COMPAT
	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 2, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_PMULL),
	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_AES),
	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_SHA1_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SHA1),
	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_SHA2_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_SHA2),
	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_CRC32_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_CRC32),
#endif
	{},
};

static void __init cap_set_elf_hwcap(const struct arm64_cpu_capabilities *cap)
{
	switch (cap->hwcap_type) {
	case CAP_HWCAP:
		elf_hwcap |= cap->hwcap;
		break;
#ifdef CONFIG_COMPAT
	case CAP_COMPAT_HWCAP:
		compat_elf_hwcap |= (u32)cap->hwcap;
		break;
	case CAP_COMPAT_HWCAP2:
		compat_elf_hwcap2 |= (u32)cap->hwcap;
		break;
#endif
	default:
		WARN_ON(1);
		break;
	}
}

/* Check if we have a particular HWCAP enabled */
static bool cpus_have_elf_hwcap(const struct arm64_cpu_capabilities *cap)
{
	bool rc;

	switch (cap->hwcap_type) {
	case CAP_HWCAP:
		rc = (elf_hwcap & cap->hwcap) != 0;
		break;
#ifdef CONFIG_COMPAT
	case CAP_COMPAT_HWCAP:
		rc = (compat_elf_hwcap & (u32)cap->hwcap) != 0;
		break;
	case CAP_COMPAT_HWCAP2:
		rc = (compat_elf_hwcap2 & (u32)cap->hwcap) != 0;
		break;
#endif
	default:
		WARN_ON(1);
		rc = false;
	}

	return rc;
}

static void __init setup_elf_hwcaps(const struct arm64_cpu_capabilities *hwcaps)
{
	/* We support emulation of accesses to CPU ID feature registers */
	elf_hwcap |= HWCAP_CPUID;
	for (; hwcaps->matches; hwcaps++)
		if (hwcaps->matches(hwcaps, cpucap_default_scope(hwcaps)))
			cap_set_elf_hwcap(hwcaps);
}

static void update_cpu_capabilities(u16 scope_mask)
{
	int i;
	const struct arm64_cpu_capabilities *caps;

	scope_mask &= ARM64_CPUCAP_SCOPE_MASK;
	for (i = 0; i < ARM64_NCAPS; i++) {
		caps = cpu_hwcaps_ptrs[i];
		if (!caps || !(caps->type & scope_mask) ||
		    cpus_have_cap(caps->capability) ||
		    !caps->matches(caps, cpucap_default_scope(caps)))
			continue;

		if (caps->desc)
			pr_info("detected: %s\n", caps->desc);
		cpus_set_cap(caps->capability);
	}
}

/*
 * Enable all the available capabilities on this CPU. The capabilities
 * with BOOT_CPU scope are handled separately and hence skipped here.
 */
static int cpu_enable_non_boot_scope_capabilities(void *__unused)
{
	int i;
	u16 non_boot_scope = SCOPE_ALL & ~SCOPE_BOOT_CPU;

	for_each_available_cap(i) {
		const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[i];

		if (WARN_ON(!cap))
			continue;

		if (!(cap->type & non_boot_scope))
			continue;

		if (cap->cpu_enable)
			cap->cpu_enable(cap);
	}
	return 0;
}

/*
 * Run through the enabled capabilities and enable() it on all active
 * CPUs
 */
static void __init enable_cpu_capabilities(u16 scope_mask)
{
	int i;
	const struct arm64_cpu_capabilities *caps;
	bool boot_scope;

	scope_mask &= ARM64_CPUCAP_SCOPE_MASK;
	boot_scope = !!(scope_mask & SCOPE_BOOT_CPU);

	for (i = 0; i < ARM64_NCAPS; i++) {
		unsigned int num;

		caps = cpu_hwcaps_ptrs[i];
		if (!caps || !(caps->type & scope_mask))
			continue;
		num = caps->capability;
		if (!cpus_have_cap(num))
			continue;

		/* Ensure cpus_have_const_cap(num) works */
		static_branch_enable(&cpu_hwcap_keys[num]);

		if (boot_scope && caps->cpu_enable)
			/*
			 * Capabilities with SCOPE_BOOT_CPU scope are finalised
			 * before any secondary CPU boots. Thus, each secondary
			 * will enable the capability as appropriate via
			 * check_local_cpu_capabilities(). The only exception is
			 * the boot CPU, for which the capability must be
			 * enabled here. This approach avoids costly
			 * stop_machine() calls for this case.
			 */
			caps->cpu_enable(caps);
	}

	/*
	 * For all non-boot scope capabilities, use stop_machine()
	 * as it schedules the work allowing us to modify PSTATE,
	 * instead of on_each_cpu() which uses an IPI, giving us a
	 * PSTATE that disappears when we return.
	 */
	if (!boot_scope)
		stop_machine(cpu_enable_non_boot_scope_capabilities,
			     NULL, cpu_online_mask);
}

/*
 * Run through the list of capabilities to check for conflicts.
 * If the system has already detected a capability, take necessary
 * action on this CPU.
 *
 * Returns "false" on conflicts.
 */
static bool verify_local_cpu_caps(u16 scope_mask)
{
	int i;
	bool cpu_has_cap, system_has_cap;
	const struct arm64_cpu_capabilities *caps;

	scope_mask &= ARM64_CPUCAP_SCOPE_MASK;

	for (i = 0; i < ARM64_NCAPS; i++) {
		caps = cpu_hwcaps_ptrs[i];
		if (!caps || !(caps->type & scope_mask))
			continue;

		cpu_has_cap = caps->matches(caps, SCOPE_LOCAL_CPU);
		system_has_cap = cpus_have_cap(caps->capability);

		if (system_has_cap) {
			/*
			 * Check if the new CPU misses an advertised feature,
			 * which is not safe to miss.
			 */
			if (!cpu_has_cap && !cpucap_late_cpu_optional(caps))
				break;
			/*
			 * We have to issue cpu_enable() irrespective of
			 * whether the CPU has it or not, as it is enabeld
			 * system wide. It is upto the call back to take
			 * appropriate action on this CPU.
			 */
			if (caps->cpu_enable)
				caps->cpu_enable(caps);
		} else {
			/*
			 * Check if the CPU has this capability if it isn't
			 * safe to have when the system doesn't.
			 */
			if (cpu_has_cap && !cpucap_late_cpu_permitted(caps))
				break;
		}
	}

	if (i < ARM64_NCAPS) {
		pr_crit("CPU%d: Detected conflict for capability %d (%s), System: %d, CPU: %d\n",
			smp_processor_id(), caps->capability,
			caps->desc, system_has_cap, cpu_has_cap);
		return false;
	}

	return true;
}

/*
 * Check for CPU features that are used in early boot
 * based on the Boot CPU value.
 */
static void check_early_cpu_features(void)
{
	verify_cpu_asid_bits();
	/*
	 * Early features are used by the kernel already. If there
	 * is a conflict, we cannot proceed further.
	 */
	if (!verify_local_cpu_caps(SCOPE_BOOT_CPU))
		cpu_panic_kernel();
}

static void
verify_local_elf_hwcaps(const struct arm64_cpu_capabilities *caps)
{

	for (; caps->matches; caps++)
		if (cpus_have_elf_hwcap(caps) && !caps->matches(caps, SCOPE_LOCAL_CPU)) {
			pr_crit("CPU%d: missing HWCAP: %s\n",
					smp_processor_id(), caps->desc);
			cpu_die_early();
		}
}

static void verify_sve_features(void)
{
	u64 safe_zcr = read_sanitised_ftr_reg(SYS_ZCR_EL1);
	u64 zcr = read_zcr_features();

	unsigned int safe_len = safe_zcr & ZCR_ELx_LEN_MASK;
	unsigned int len = zcr & ZCR_ELx_LEN_MASK;

	if (len < safe_len || sve_verify_vq_map()) {
		pr_crit("CPU%d: SVE: required vector length(s) missing\n",
			smp_processor_id());
		cpu_die_early();
	}

	/* Add checks on other ZCR bits here if necessary */
}


/*
 * Run through the enabled system capabilities and enable() it on this CPU.
 * The capabilities were decided based on the available CPUs at the boot time.
 * Any new CPU should match the system wide status of the capability. If the
 * new CPU doesn't have a capability which the system now has enabled, we
 * cannot do anything to fix it up and could cause unexpected failures. So
 * we park the CPU.
 */
static void verify_local_cpu_capabilities(void)
{
	/*
	 * The capabilities with SCOPE_BOOT_CPU are checked from
	 * check_early_cpu_features(), as they need to be verified
	 * on all secondary CPUs.
	 */
	if (!verify_local_cpu_caps(SCOPE_ALL & ~SCOPE_BOOT_CPU))
		cpu_die_early();

	verify_local_elf_hwcaps(arm64_elf_hwcaps);

	if (system_supports_32bit_el0())
		verify_local_elf_hwcaps(compat_elf_hwcaps);

	if (system_supports_sve())
		verify_sve_features();
}

void check_local_cpu_capabilities(void)
{
	/*
	 * All secondary CPUs should conform to the early CPU features
	 * in use by the kernel based on boot CPU.
	 */
	check_early_cpu_features();

	/*
	 * If we haven't finalised the system capabilities, this CPU gets
	 * a chance to update the errata work arounds and local features.
	 * Otherwise, this CPU should verify that it has all the system
	 * advertised capabilities.
	 */
	if (!sys_caps_initialised)
		update_cpu_capabilities(SCOPE_LOCAL_CPU);
	else
		verify_local_cpu_capabilities();
}

static void __init setup_boot_cpu_capabilities(void)
{
	/* Detect capabilities with either SCOPE_BOOT_CPU or SCOPE_LOCAL_CPU */
	update_cpu_capabilities(SCOPE_BOOT_CPU | SCOPE_LOCAL_CPU);
	/* Enable the SCOPE_BOOT_CPU capabilities alone right away */
	enable_cpu_capabilities(SCOPE_BOOT_CPU);
}

DEFINE_STATIC_KEY_FALSE(arm64_const_caps_ready);
EXPORT_SYMBOL(arm64_const_caps_ready);

static void __init mark_const_caps_ready(void)
{
	static_branch_enable(&arm64_const_caps_ready);
}

bool this_cpu_has_cap(unsigned int n)
{
	if (!WARN_ON(preemptible()) && n < ARM64_NCAPS) {
		const struct arm64_cpu_capabilities *cap = cpu_hwcaps_ptrs[n];

		if (cap)
			return cap->matches(cap, SCOPE_LOCAL_CPU);
	}

	return false;
}

static void __init setup_system_capabilities(void)
{
	/*
	 * We have finalised the system-wide safe feature
	 * registers, finalise the capabilities that depend
	 * on it. Also enable all the available capabilities,
	 * that are not enabled already.
	 */
	update_cpu_capabilities(SCOPE_SYSTEM);
	enable_cpu_capabilities(SCOPE_ALL & ~SCOPE_BOOT_CPU);
}

void __init setup_cpu_features(void)
{
	u32 cwg;

	setup_system_capabilities();
	mark_const_caps_ready();
	setup_elf_hwcaps(arm64_elf_hwcaps);

	if (system_supports_32bit_el0())
		setup_elf_hwcaps(compat_elf_hwcaps);

	if (system_uses_ttbr0_pan())
		pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");

	sve_setup();
	minsigstksz_setup();

	/* Advertise that we have computed the system capabilities */
	set_sys_caps_initialised();

	/*
	 * Check for sane CTR_EL0.CWG value.
	 */
	cwg = cache_type_cwg();
	if (!cwg)
		pr_warn("No Cache Writeback Granule information, assuming %d\n",
			ARCH_DMA_MINALIGN);
}

static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused)
{
	return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO));
}

static void __maybe_unused cpu_enable_cnp(struct arm64_cpu_capabilities const *cap)
{
	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
}

/*
 * We emulate only the following system register space.
 * Op0 = 0x3, CRn = 0x0, Op1 = 0x0, CRm = [0, 4 - 7]
 * See Table C5-6 System instruction encodings for System register accesses,
 * ARMv8 ARM(ARM DDI 0487A.f) for more details.
 */
static inline bool __attribute_const__ is_emulated(u32 id)
{
	return (sys_reg_Op0(id) == 0x3 &&
		sys_reg_CRn(id) == 0x0 &&
		sys_reg_Op1(id) == 0x0 &&
		(sys_reg_CRm(id) == 0 ||
		 ((sys_reg_CRm(id) >= 4) && (sys_reg_CRm(id) <= 7))));
}

/*
 * With CRm == 0, reg should be one of :
 * MIDR_EL1, MPIDR_EL1 or REVIDR_EL1.
 */
static inline int emulate_id_reg(u32 id, u64 *valp)
{
	switch (id) {
	case SYS_MIDR_EL1:
		*valp = read_cpuid_id();
		break;
	case SYS_MPIDR_EL1:
		*valp = SYS_MPIDR_SAFE_VAL;
		break;
	case SYS_REVIDR_EL1:
		/* IMPLEMENTATION DEFINED values are emulated with 0 */
		*valp = 0;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static int emulate_sys_reg(u32 id, u64 *valp)
{
	struct arm64_ftr_reg *regp;

	if (!is_emulated(id))
		return -EINVAL;

	if (sys_reg_CRm(id) == 0)
		return emulate_id_reg(id, valp);

	regp = get_arm64_ftr_reg(id);
	if (regp)
		*valp = arm64_ftr_reg_user_value(regp);
	else
		/*
		 * The untracked registers are either IMPLEMENTATION DEFINED
		 * (e.g, ID_AFR0_EL1) or reserved RAZ.
		 */
		*valp = 0;
	return 0;
}

int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt)
{
	int rc;
	u64 val;

	rc = emulate_sys_reg(sys_reg, &val);
	if (!rc) {
		pt_regs_write_reg(regs, rt, val);
		arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
	}
	return rc;
}

static int emulate_mrs(struct pt_regs *regs, u32 insn)
{
	u32 sys_reg, rt;

	/*
	 * sys_reg values are defined as used in mrs/msr instruction.
	 * shift the imm value to get the encoding.
	 */
	sys_reg = (u32)aarch64_insn_decode_immediate(AARCH64_INSN_IMM_16, insn) << 5;
	rt = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RT, insn);
	return do_emulate_mrs(regs, sys_reg, rt);
}

static struct undef_hook mrs_hook = {
	.instr_mask = 0xfff00000,
	.instr_val  = 0xd5300000,
	.pstate_mask = PSR_AA32_MODE_MASK,
	.pstate_val = PSR_MODE_EL0t,
	.fn = emulate_mrs,
};

static int __init enable_mrs_emulation(void)
{
	register_undef_hook(&mrs_hook);
	return 0;
}

core_initcall(enable_mrs_emulation);