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