1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2012 ARM Ltd. 4 */ 5 #ifndef __ASM_MMU_H 6 #define __ASM_MMU_H 7 8 #include <asm/cputype.h> 9 10 #define MMCF_AARCH32 0x1 /* mm context flag for AArch32 executables */ 11 #define USER_ASID_BIT 48 12 #define USER_ASID_FLAG (UL(1) << USER_ASID_BIT) 13 #define TTBR_ASID_MASK (UL(0xffff) << 48) 14 15 #ifndef __ASSEMBLY__ 16 17 #include <linux/refcount.h> 18 #include <asm/cpufeature.h> 19 20 typedef struct { 21 atomic64_t id; 22 #ifdef CONFIG_COMPAT 23 void *sigpage; 24 #endif 25 refcount_t pinned; 26 void *vdso; 27 unsigned long flags; 28 } mm_context_t; 29 30 /* 31 * We use atomic64_read() here because the ASID for an 'mm_struct' can 32 * be reallocated when scheduling one of its threads following a 33 * rollover event (see new_context() and flush_context()). In this case, 34 * a concurrent TLBI (e.g. via try_to_unmap_one() and ptep_clear_flush()) 35 * may use a stale ASID. This is fine in principle as the new ASID is 36 * guaranteed to be clean in the TLB, but the TLBI routines have to take 37 * care to handle the following race: 38 * 39 * CPU 0 CPU 1 CPU 2 40 * 41 * // ptep_clear_flush(mm) 42 * xchg_relaxed(pte, 0) 43 * DSB ISHST 44 * old = ASID(mm) 45 * | <rollover> 46 * | new = new_context(mm) 47 * \-----------------> atomic_set(mm->context.id, new) 48 * cpu_switch_mm(mm) 49 * // Hardware walk of pte using new ASID 50 * TLBI(old) 51 * 52 * In this scenario, the barrier on CPU 0 and the dependency on CPU 1 53 * ensure that the page-table walker on CPU 1 *must* see the invalid PTE 54 * written by CPU 0. 55 */ 56 #define ASID(mm) (atomic64_read(&(mm)->context.id) & 0xffff) 57 58 static inline bool arm64_kernel_unmapped_at_el0(void) 59 { 60 return alternative_has_cap_unlikely(ARM64_UNMAP_KERNEL_AT_EL0); 61 } 62 63 extern void arm64_memblock_init(void); 64 extern void paging_init(void); 65 extern void bootmem_init(void); 66 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); 67 extern void create_mapping_noalloc(phys_addr_t phys, unsigned long virt, 68 phys_addr_t size, pgprot_t prot); 69 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, 70 unsigned long virt, phys_addr_t size, 71 pgprot_t prot, bool page_mappings_only); 72 extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot); 73 extern void mark_linear_text_alias_ro(void); 74 extern bool kaslr_requires_kpti(void); 75 76 #define INIT_MM_CONTEXT(name) \ 77 .pgd = init_pg_dir, 78 79 #endif /* !__ASSEMBLY__ */ 80 #endif 81