/* * Copyright (C) 2014 Linaro 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. */ #ifndef __ASM_CPUFEATURE_H #define __ASM_CPUFEATURE_H #include #include #include #include /* * In the arm64 world (as in the ARM world), elf_hwcap is used both internally * in the kernel and for user space to keep track of which optional features * are supported by the current system. So let's map feature 'x' to HWCAP_x. * Note that HWCAP_x constants are bit fields so we need to take the log. */ #define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap)) #define cpu_feature(x) ilog2(HWCAP_ ## x) #ifndef __ASSEMBLY__ #include #include #include /* * CPU feature register tracking * * The safe value of a CPUID feature field is dependent on the implications * of the values assigned to it by the architecture. Based on the relationship * between the values, the features are classified into 3 types - LOWER_SAFE, * HIGHER_SAFE and EXACT. * * The lowest value of all the CPUs is chosen for LOWER_SAFE and highest * for HIGHER_SAFE. It is expected that all CPUs have the same value for * a field when EXACT is specified, failing which, the safe value specified * in the table is chosen. */ enum ftr_type { FTR_EXACT, /* Use a predefined safe value */ FTR_LOWER_SAFE, /* Smaller value is safe */ FTR_HIGHER_SAFE, /* Bigger value is safe */ FTR_HIGHER_OR_ZERO_SAFE, /* Bigger value is safe, but 0 is biggest */ }; #define FTR_STRICT true /* SANITY check strict matching required */ #define FTR_NONSTRICT false /* SANITY check ignored */ #define FTR_SIGNED true /* Value should be treated as signed */ #define FTR_UNSIGNED false /* Value should be treated as unsigned */ #define FTR_VISIBLE true /* Feature visible to the user space */ #define FTR_HIDDEN false /* Feature is hidden from the user */ #define FTR_VISIBLE_IF_IS_ENABLED(config) \ (IS_ENABLED(config) ? FTR_VISIBLE : FTR_HIDDEN) struct arm64_ftr_bits { bool sign; /* Value is signed ? */ bool visible; bool strict; /* CPU Sanity check: strict matching required ? */ enum ftr_type type; u8 shift; u8 width; s64 safe_val; /* safe value for FTR_EXACT features */ }; /* * @arm64_ftr_reg - Feature register * @strict_mask Bits which should match across all CPUs for sanity. * @sys_val Safe value across the CPUs (system view) */ struct arm64_ftr_reg { const char *name; u64 strict_mask; u64 user_mask; u64 sys_val; u64 user_val; const struct arm64_ftr_bits *ftr_bits; }; extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0; /* * CPU capabilities: * * We use arm64_cpu_capabilities to represent system features, errata work * arounds (both used internally by kernel and tracked in cpu_hwcaps) and * ELF HWCAPs (which are exposed to user). * * To support systems with heterogeneous CPUs, we need to make sure that we * detect the capabilities correctly on the system and take appropriate * measures to ensure there are no incompatibilities. * * This comment tries to explain how we treat the capabilities. * Each capability has the following list of attributes : * * 1) Scope of Detection : The system detects a given capability by * performing some checks at runtime. This could be, e.g, checking the * value of a field in CPU ID feature register or checking the cpu * model. The capability provides a call back ( @matches() ) to * perform the check. Scope defines how the checks should be performed. * There are three cases: * * a) SCOPE_LOCAL_CPU: check all the CPUs and "detect" if at least one * matches. This implies, we have to run the check on all the * booting CPUs, until the system decides that state of the * capability is finalised. (See section 2 below) * Or * b) SCOPE_SYSTEM: check all the CPUs and "detect" if all the CPUs * matches. This implies, we run the check only once, when the * system decides to finalise the state of the capability. If the * capability relies on a field in one of the CPU ID feature * registers, we use the sanitised value of the register from the * CPU feature infrastructure to make the decision. * Or * c) SCOPE_BOOT_CPU: Check only on the primary boot CPU to detect the * feature. This category is for features that are "finalised" * (or used) by the kernel very early even before the SMP cpus * are brought up. * * The process of detection is usually denoted by "update" capability * state in the code. * * 2) Finalise the state : The kernel should finalise the state of a * capability at some point during its execution and take necessary * actions if any. Usually, this is done, after all the boot-time * enabled CPUs are brought up by the kernel, so that it can make * better decision based on the available set of CPUs. However, there * are some special cases, where the action is taken during the early * boot by the primary boot CPU. (e.g, running the kernel at EL2 with * Virtualisation Host Extensions). The kernel usually disallows any * changes to the state of a capability once it finalises the capability * and takes any action, as it may be impossible to execute the actions * safely. A CPU brought up after a capability is "finalised" is * referred to as "Late CPU" w.r.t the capability. e.g, all secondary * CPUs are treated "late CPUs" for capabilities determined by the boot * CPU. * * At the moment there are two passes of finalising the capabilities. * a) Boot CPU scope capabilities - Finalised by primary boot CPU via * setup_boot_cpu_capabilities(). * b) Everything except (a) - Run via setup_system_capabilities(). * * 3) Verification: When a CPU is brought online (e.g, by user or by the * kernel), the kernel should make sure that it is safe to use the CPU, * by verifying that the CPU is compliant with the state of the * capabilities finalised already. This happens via : * * secondary_start_kernel()-> check_local_cpu_capabilities() * * As explained in (2) above, capabilities could be finalised at * different points in the execution. Each newly booted CPU is verified * against the capabilities that have been finalised by the time it * boots. * * a) SCOPE_BOOT_CPU : All CPUs are verified against the capability * except for the primary boot CPU. * * b) SCOPE_LOCAL_CPU, SCOPE_SYSTEM: All CPUs hotplugged on by the * user after the kernel boot are verified against the capability. * * If there is a conflict, the kernel takes an action, based on the * severity (e.g, a CPU could be prevented from booting or cause a * kernel panic). The CPU is allowed to "affect" the state of the * capability, if it has not been finalised already. See section 5 * for more details on conflicts. * * 4) Action: As mentioned in (2), the kernel can take an action for each * detected capability, on all CPUs on the system. Appropriate actions * include, turning on an architectural feature, modifying the control * registers (e.g, SCTLR, TCR etc.) or patching the kernel via * alternatives. The kernel patching is batched and performed at later * point. The actions are always initiated only after the capability * is finalised. This is usally denoted by "enabling" the capability. * The actions are initiated as follows : * a) Action is triggered on all online CPUs, after the capability is * finalised, invoked within the stop_machine() context from * enable_cpu_capabilitie(). * * b) Any late CPU, brought up after (1), the action is triggered via: * * check_local_cpu_capabilities() -> verify_local_cpu_capabilities() * * 5) Conflicts: Based on the state of the capability on a late CPU vs. * the system state, we could have the following combinations : * * x-----------------------------x * | Type | System | Late CPU | * |-----------------------------| * | a | y | n | * |-----------------------------| * | b | n | y | * x-----------------------------x * * Two separate flag bits are defined to indicate whether each kind of * conflict can be allowed: * ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU - Case(a) is allowed * ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU - Case(b) is allowed * * Case (a) is not permitted for a capability that the system requires * all CPUs to have in order for the capability to be enabled. This is * typical for capabilities that represent enhanced functionality. * * Case (b) is not permitted for a capability that must be enabled * during boot if any CPU in the system requires it in order to run * safely. This is typical for erratum work arounds that cannot be * enabled after the corresponding capability is finalised. * * In some non-typical cases either both (a) and (b), or neither, * should be permitted. This can be described by including neither * or both flags in the capability's type field. */ /* * Decide how the capability is detected. * On any local CPU vs System wide vs the primary boot CPU */ #define ARM64_CPUCAP_SCOPE_LOCAL_CPU ((u16)BIT(0)) #define ARM64_CPUCAP_SCOPE_SYSTEM ((u16)BIT(1)) /* * The capabilitiy is detected on the Boot CPU and is used by kernel * during early boot. i.e, the capability should be "detected" and * "enabled" as early as possibly on all booting CPUs. */ #define ARM64_CPUCAP_SCOPE_BOOT_CPU ((u16)BIT(2)) #define ARM64_CPUCAP_SCOPE_MASK \ (ARM64_CPUCAP_SCOPE_SYSTEM | \ ARM64_CPUCAP_SCOPE_LOCAL_CPU | \ ARM64_CPUCAP_SCOPE_BOOT_CPU) #define SCOPE_SYSTEM ARM64_CPUCAP_SCOPE_SYSTEM #define SCOPE_LOCAL_CPU ARM64_CPUCAP_SCOPE_LOCAL_CPU #define SCOPE_BOOT_CPU ARM64_CPUCAP_SCOPE_BOOT_CPU #define SCOPE_ALL ARM64_CPUCAP_SCOPE_MASK /* * Is it permitted for a late CPU to have this capability when system * hasn't already enabled it ? */ #define ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU ((u16)BIT(4)) /* Is it safe for a late CPU to miss this capability when system has it */ #define ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU ((u16)BIT(5)) /* * CPU errata workarounds that need to be enabled at boot time if one or * more CPUs in the system requires it. When one of these capabilities * has been enabled, it is safe to allow any CPU to boot that doesn't * require the workaround. However, it is not safe if a "late" CPU * requires a workaround and the system hasn't enabled it already. */ #define ARM64_CPUCAP_LOCAL_CPU_ERRATUM \ (ARM64_CPUCAP_SCOPE_LOCAL_CPU | ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU) /* * CPU feature detected at boot time based on system-wide value of a * feature. It is safe for a late CPU to have this feature even though * the system hasn't enabled it, although the featuer will not be used * by Linux in this case. If the system has enabled this feature already, * then every late CPU must have it. */ #define ARM64_CPUCAP_SYSTEM_FEATURE \ (ARM64_CPUCAP_SCOPE_SYSTEM | ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU) /* * CPU feature detected at boot time based on feature of one or more CPUs. * All possible conflicts for a late CPU are ignored. */ #define ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE \ (ARM64_CPUCAP_SCOPE_LOCAL_CPU | \ ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU | \ ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU) /* * CPU feature detected at boot time, on one or more CPUs. A late CPU * is not allowed to have the capability when the system doesn't have it. * It is Ok for a late CPU to miss the feature. */ #define ARM64_CPUCAP_BOOT_RESTRICTED_CPU_LOCAL_FEATURE \ (ARM64_CPUCAP_SCOPE_LOCAL_CPU | \ ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU) /* * CPU feature used early in the boot based on the boot CPU. All secondary * CPUs must match the state of the capability as detected by the boot CPU. */ #define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE ARM64_CPUCAP_SCOPE_BOOT_CPU struct arm64_cpu_capabilities { const char *desc; u16 capability; u16 type; bool (*matches)(const struct arm64_cpu_capabilities *caps, int scope); /* * Take the appropriate actions to enable this capability for this CPU. * For each successfully booted CPU, this method is called for each * globally detected capability. */ void (*cpu_enable)(const struct arm64_cpu_capabilities *cap); union { struct { /* To be used for erratum handling only */ struct midr_range midr_range; const struct arm64_midr_revidr { u32 midr_rv; /* revision/variant */ u32 revidr_mask; } * const fixed_revs; }; const struct midr_range *midr_range_list; struct { /* Feature register checking */ u32 sys_reg; u8 field_pos; u8 min_field_value; u8 hwcap_type; bool sign; unsigned long hwcap; }; /* * A list of "matches/cpu_enable" pair for the same * "capability" of the same "type" as described by the parent. * Only matches(), cpu_enable() and fields relevant to these * methods are significant in the list. The cpu_enable is * invoked only if the corresponding entry "matches()". * However, if a cpu_enable() method is associated * with multiple matches(), care should be taken that either * the match criteria are mutually exclusive, or that the * method is robust against being called multiple times. */ const struct arm64_cpu_capabilities *match_list; }; }; static inline int cpucap_default_scope(const struct arm64_cpu_capabilities *cap) { return cap->type & ARM64_CPUCAP_SCOPE_MASK; } static inline bool cpucap_late_cpu_optional(const struct arm64_cpu_capabilities *cap) { return !!(cap->type & ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU); } static inline bool cpucap_late_cpu_permitted(const struct arm64_cpu_capabilities *cap) { return !!(cap->type & ARM64_CPUCAP_PERMITTED_FOR_LATE_CPU); } extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS]; extern struct static_key_false arm64_const_caps_ready; bool this_cpu_has_cap(unsigned int cap); static inline bool cpu_have_feature(unsigned int num) { return elf_hwcap & (1UL << num); } /* System capability check for constant caps */ static inline bool __cpus_have_const_cap(int num) { if (num >= ARM64_NCAPS) return false; return static_branch_unlikely(&cpu_hwcap_keys[num]); } static inline bool cpus_have_cap(unsigned int num) { if (num >= ARM64_NCAPS) return false; return test_bit(num, cpu_hwcaps); } static inline bool cpus_have_const_cap(int num) { if (static_branch_likely(&arm64_const_caps_ready)) return __cpus_have_const_cap(num); else return cpus_have_cap(num); } static inline void cpus_set_cap(unsigned int num) { if (num >= ARM64_NCAPS) { pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n", num, ARM64_NCAPS); } else { __set_bit(num, cpu_hwcaps); } } static inline int __attribute_const__ cpuid_feature_extract_signed_field_width(u64 features, int field, int width) { return (s64)(features << (64 - width - field)) >> (64 - width); } static inline int __attribute_const__ cpuid_feature_extract_signed_field(u64 features, int field) { return cpuid_feature_extract_signed_field_width(features, field, 4); } static inline unsigned int __attribute_const__ cpuid_feature_extract_unsigned_field_width(u64 features, int field, int width) { return (u64)(features << (64 - width - field)) >> (64 - width); } static inline unsigned int __attribute_const__ cpuid_feature_extract_unsigned_field(u64 features, int field) { return cpuid_feature_extract_unsigned_field_width(features, field, 4); } static inline u64 arm64_ftr_mask(const struct arm64_ftr_bits *ftrp) { return (u64)GENMASK(ftrp->shift + ftrp->width - 1, ftrp->shift); } static inline u64 arm64_ftr_reg_user_value(const struct arm64_ftr_reg *reg) { return (reg->user_val | (reg->sys_val & reg->user_mask)); } static inline int __attribute_const__ cpuid_feature_extract_field_width(u64 features, int field, int width, bool sign) { return (sign) ? cpuid_feature_extract_signed_field_width(features, field, width) : cpuid_feature_extract_unsigned_field_width(features, field, width); } static inline int __attribute_const__ cpuid_feature_extract_field(u64 features, int field, bool sign) { return cpuid_feature_extract_field_width(features, field, 4, sign); } static inline s64 arm64_ftr_value(const struct arm64_ftr_bits *ftrp, u64 val) { return (s64)cpuid_feature_extract_field_width(val, ftrp->shift, ftrp->width, ftrp->sign); } static inline bool id_aa64mmfr0_mixed_endian_el0(u64 mmfr0) { return cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_BIGENDEL_SHIFT) == 0x1 || cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_BIGENDEL0_SHIFT) == 0x1; } static inline bool id_aa64pfr0_32bit_el0(u64 pfr0) { u32 val = cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_EL0_SHIFT); return val == ID_AA64PFR0_EL0_32BIT_64BIT; } static inline bool id_aa64pfr0_sve(u64 pfr0) { u32 val = cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_SVE_SHIFT); return val > 0; } void __init setup_cpu_features(void); void check_local_cpu_capabilities(void); u64 read_sanitised_ftr_reg(u32 id); static inline bool cpu_supports_mixed_endian_el0(void) { return id_aa64mmfr0_mixed_endian_el0(read_cpuid(ID_AA64MMFR0_EL1)); } static inline bool supports_csv2p3(int scope) { u64 pfr0; u8 csv2_val; if (scope == SCOPE_LOCAL_CPU) pfr0 = read_sysreg_s(SYS_ID_AA64PFR0_EL1); else pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); csv2_val = cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_CSV2_SHIFT); return csv2_val == 3; } static inline bool supports_clearbhb(int scope) { u64 isar2; if (scope == SCOPE_LOCAL_CPU) isar2 = read_sysreg_s(SYS_ID_AA64ISAR2_EL1); else isar2 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR2_EL1); return cpuid_feature_extract_unsigned_field(isar2, ID_AA64ISAR2_CLEARBHB_SHIFT); } static inline bool system_supports_32bit_el0(void) { return cpus_have_const_cap(ARM64_HAS_32BIT_EL0); } static inline bool system_supports_mixed_endian_el0(void) { return id_aa64mmfr0_mixed_endian_el0(read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1)); } static inline bool system_supports_fpsimd(void) { return !cpus_have_const_cap(ARM64_HAS_NO_FPSIMD); } static inline bool system_uses_ttbr0_pan(void) { return IS_ENABLED(CONFIG_ARM64_SW_TTBR0_PAN) && !cpus_have_const_cap(ARM64_HAS_PAN); } static inline bool system_supports_sve(void) { return IS_ENABLED(CONFIG_ARM64_SVE) && cpus_have_const_cap(ARM64_SVE); } #define ARM64_SSBD_UNKNOWN -1 #define ARM64_SSBD_FORCE_DISABLE 0 #define ARM64_SSBD_KERNEL 1 #define ARM64_SSBD_FORCE_ENABLE 2 #define ARM64_SSBD_MITIGATED 3 static inline int arm64_get_ssbd_state(void) { #ifdef CONFIG_ARM64_SSBD extern int ssbd_state; return ssbd_state; #else return ARM64_SSBD_UNKNOWN; #endif } void arm64_set_ssbd_mitigation(bool state); /* Watch out, ordering is important here. */ enum mitigation_state { SPECTRE_UNAFFECTED, SPECTRE_MITIGATED, SPECTRE_VULNERABLE, }; enum mitigation_state arm64_get_spectre_bhb_state(void); bool is_spectre_bhb_affected(const struct arm64_cpu_capabilities *entry, int scope); u8 spectre_bhb_loop_affected(int scope); void spectre_bhb_enable_mitigation(const struct arm64_cpu_capabilities *__unused); #endif /* __ASSEMBLY__ */ #endif