diff options
Diffstat (limited to 'arch/arm64/include/asm/mmu.h')
-rw-r--r-- | arch/arm64/include/asm/mmu.h | 128 |
1 files changed, 36 insertions, 92 deletions
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index f217e3292919..2fcf51231d6e 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -12,122 +12,66 @@ #define USER_ASID_FLAG (UL(1) << USER_ASID_BIT) #define TTBR_ASID_MASK (UL(0xffff) << 48) -#define BP_HARDEN_EL2_SLOTS 4 - #ifndef __ASSEMBLY__ +#include <linux/refcount.h> +#include <asm/cpufeature.h> + typedef struct { atomic64_t id; +#ifdef CONFIG_COMPAT + void *sigpage; +#endif + refcount_t pinned; void *vdso; unsigned long flags; } mm_context_t; /* - * This macro is only used by the TLBI code, which cannot race with an - * ASID change and therefore doesn't need to reload the counter using - * atomic64_read. + * We use atomic64_read() here because the ASID for an 'mm_struct' can + * be reallocated when scheduling one of its threads following a + * rollover event (see new_context() and flush_context()). In this case, + * a concurrent TLBI (e.g. via try_to_unmap_one() and ptep_clear_flush()) + * may use a stale ASID. This is fine in principle as the new ASID is + * guaranteed to be clean in the TLB, but the TLBI routines have to take + * care to handle the following race: + * + * CPU 0 CPU 1 CPU 2 + * + * // ptep_clear_flush(mm) + * xchg_relaxed(pte, 0) + * DSB ISHST + * old = ASID(mm) + * | <rollover> + * | new = new_context(mm) + * \-----------------> atomic_set(mm->context.id, new) + * cpu_switch_mm(mm) + * // Hardware walk of pte using new ASID + * TLBI(old) + * + * In this scenario, the barrier on CPU 0 and the dependency on CPU 1 + * ensure that the page-table walker on CPU 1 *must* see the invalid PTE + * written by CPU 0. */ -#define ASID(mm) ((mm)->context.id.counter & 0xffff) +#define ASID(mm) (atomic64_read(&(mm)->context.id) & 0xffff) static inline bool arm64_kernel_unmapped_at_el0(void) { - return IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) && - cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0); -} - -static inline bool arm64_kernel_use_ng_mappings(void) -{ - bool tx1_bug; - - /* What's a kpti? Use global mappings if we don't know. */ - if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) - return false; - - /* - * Note: this function is called before the CPU capabilities have - * been configured, so our early mappings will be global. If we - * later determine that kpti is required, then - * kpti_install_ng_mappings() will make them non-global. - */ - if (arm64_kernel_unmapped_at_el0()) - return true; - - if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) - return false; - - /* - * KASLR is enabled so we're going to be enabling kpti on non-broken - * CPUs regardless of their susceptibility to Meltdown. Rather - * than force everybody to go through the G -> nG dance later on, - * just put down non-global mappings from the beginning. - */ - if (!IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) { - tx1_bug = false; -#ifndef MODULE - } else if (!static_branch_likely(&arm64_const_caps_ready)) { - extern const struct midr_range cavium_erratum_27456_cpus[]; - - tx1_bug = is_midr_in_range_list(read_cpuid_id(), - cavium_erratum_27456_cpus); -#endif - } else { - tx1_bug = __cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_27456); - } - - return !tx1_bug && kaslr_offset() > 0; -} - -typedef void (*bp_hardening_cb_t)(void); - -struct bp_hardening_data { - int hyp_vectors_slot; - bp_hardening_cb_t fn; -}; - -#if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) || \ - defined(CONFIG_HARDEN_EL2_VECTORS)) -extern char __bp_harden_hyp_vecs_start[], __bp_harden_hyp_vecs_end[]; -extern atomic_t arm64_el2_vector_last_slot; -#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */ - -#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR -DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data); - -static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void) -{ - return this_cpu_ptr(&bp_hardening_data); -} - -static inline void arm64_apply_bp_hardening(void) -{ - struct bp_hardening_data *d; - - if (!cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR)) - return; - - d = arm64_get_bp_hardening_data(); - if (d->fn) - d->fn(); + return alternative_has_cap_unlikely(ARM64_UNMAP_KERNEL_AT_EL0); } -#else -static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void) -{ - return NULL; -} - -static inline void arm64_apply_bp_hardening(void) { } -#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */ extern void arm64_memblock_init(void); extern void paging_init(void); extern void bootmem_init(void); extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); -extern void init_mem_pgprot(void); +extern void create_mapping_noalloc(phys_addr_t phys, unsigned long virt, + phys_addr_t size, pgprot_t prot); extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot, bool page_mappings_only); extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot); extern void mark_linear_text_alias_ro(void); +extern bool kaslr_requires_kpti(void); #define INIT_MM_CONTEXT(name) \ .pgd = init_pg_dir, |