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07037db5 PD |
1 | /* |
2 | * Copyright (C) 2012 Regents of the University of California | |
08f051ed | 3 | * Copyright (C) 2017 SiFive |
07037db5 PD |
4 | * |
5 | * This program is free software; you can redistribute it and/or | |
6 | * modify it under the terms of the GNU General Public License | |
7 | * as published by the Free Software Foundation, version 2. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | */ | |
14 | ||
15 | #ifndef _ASM_RISCV_MMU_CONTEXT_H | |
16 | #define _ASM_RISCV_MMU_CONTEXT_H | |
17 | ||
741fc3ff | 18 | #include <linux/mm_types.h> |
07037db5 PD |
19 | #include <asm-generic/mm_hooks.h> |
20 | ||
21 | #include <linux/mm.h> | |
22 | #include <linux/sched.h> | |
23 | #include <asm/tlbflush.h> | |
08f051ed | 24 | #include <asm/cacheflush.h> |
07037db5 PD |
25 | |
26 | static inline void enter_lazy_tlb(struct mm_struct *mm, | |
27 | struct task_struct *task) | |
28 | { | |
29 | } | |
30 | ||
31 | /* Initialize context-related info for a new mm_struct */ | |
32 | static inline int init_new_context(struct task_struct *task, | |
33 | struct mm_struct *mm) | |
34 | { | |
35 | return 0; | |
36 | } | |
37 | ||
38 | static inline void destroy_context(struct mm_struct *mm) | |
39 | { | |
40 | } | |
41 | ||
42 | static inline pgd_t *current_pgdir(void) | |
43 | { | |
44 | return pfn_to_virt(csr_read(sptbr) & SPTBR_PPN); | |
45 | } | |
46 | ||
47 | static inline void set_pgdir(pgd_t *pgd) | |
48 | { | |
49 | csr_write(sptbr, virt_to_pfn(pgd) | SPTBR_MODE); | |
50 | } | |
51 | ||
08f051ed AW |
52 | /* |
53 | * When necessary, performs a deferred icache flush for the given MM context, | |
54 | * on the local CPU. RISC-V has no direct mechanism for instruction cache | |
55 | * shoot downs, so instead we send an IPI that informs the remote harts they | |
56 | * need to flush their local instruction caches. To avoid pathologically slow | |
57 | * behavior in a common case (a bunch of single-hart processes on a many-hart | |
58 | * machine, ie 'make -j') we avoid the IPIs for harts that are not currently | |
59 | * executing a MM context and instead schedule a deferred local instruction | |
60 | * cache flush to be performed before execution resumes on each hart. This | |
61 | * actually performs that local instruction cache flush, which implicitly only | |
62 | * refers to the current hart. | |
63 | */ | |
64 | static inline void flush_icache_deferred(struct mm_struct *mm) | |
65 | { | |
66 | #ifdef CONFIG_SMP | |
67 | unsigned int cpu = smp_processor_id(); | |
68 | cpumask_t *mask = &mm->context.icache_stale_mask; | |
69 | ||
70 | if (cpumask_test_cpu(cpu, mask)) { | |
71 | cpumask_clear_cpu(cpu, mask); | |
72 | /* | |
73 | * Ensure the remote hart's writes are visible to this hart. | |
74 | * This pairs with a barrier in flush_icache_mm. | |
75 | */ | |
76 | smp_mb(); | |
77 | local_flush_icache_all(); | |
78 | } | |
79 | #endif | |
80 | } | |
81 | ||
07037db5 PD |
82 | static inline void switch_mm(struct mm_struct *prev, |
83 | struct mm_struct *next, struct task_struct *task) | |
84 | { | |
85 | if (likely(prev != next)) { | |
08f051ed AW |
86 | /* |
87 | * Mark the current MM context as inactive, and the next as | |
88 | * active. This is at least used by the icache flushing | |
89 | * routines in order to determine who should | |
90 | */ | |
91 | unsigned int cpu = smp_processor_id(); | |
92 | ||
93 | cpumask_clear_cpu(cpu, mm_cpumask(prev)); | |
94 | cpumask_set_cpu(cpu, mm_cpumask(next)); | |
95 | ||
07037db5 PD |
96 | set_pgdir(next->pgd); |
97 | local_flush_tlb_all(); | |
08f051ed AW |
98 | |
99 | flush_icache_deferred(next); | |
07037db5 PD |
100 | } |
101 | } | |
102 | ||
103 | static inline void activate_mm(struct mm_struct *prev, | |
104 | struct mm_struct *next) | |
105 | { | |
106 | switch_mm(prev, next, NULL); | |
107 | } | |
108 | ||
109 | static inline void deactivate_mm(struct task_struct *task, | |
110 | struct mm_struct *mm) | |
111 | { | |
112 | } | |
113 | ||
114 | #endif /* _ASM_RISCV_MMU_CONTEXT_H */ |