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Linux kernel mirror (for testing)
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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
20typedef 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
58static inline bool arm64_kernel_unmapped_at_el0(void)
59{
60 return cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
61}
62
63extern void arm64_memblock_init(void);
64extern void paging_init(void);
65extern void bootmem_init(void);
66extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
67extern void init_mem_pgprot(void);
68extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
69 unsigned long virt, phys_addr_t size,
70 pgprot_t prot, bool page_mappings_only);
71extern void *fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot);
72extern void mark_linear_text_alias_ro(void);
73extern bool kaslr_requires_kpti(void);
74
75#define INIT_MM_CONTEXT(name) \
76 .pgd = init_pg_dir,
77
78#endif /* !__ASSEMBLY__ */
79#endif