1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  *  S390 version
4  *
5  *  Derived from "include/asm-i386/mmu_context.h"
6  */
7 
8 #ifndef __S390_MMU_CONTEXT_H
9 #define __S390_MMU_CONTEXT_H
10 
11 #include <asm/pgalloc.h>
12 #include <linux/uaccess.h>
13 #include <linux/mm_types.h>
14 #include <asm/tlbflush.h>
15 #include <asm/ctl_reg.h>
16 #include <asm-generic/mm_hooks.h>
17 
18 static inline int init_new_context(struct task_struct *tsk,
19 				   struct mm_struct *mm)
20 {
21 	spin_lock_init(&mm->context.lock);
22 	INIT_LIST_HEAD(&mm->context.pgtable_list);
23 	INIT_LIST_HEAD(&mm->context.gmap_list);
24 	cpumask_clear(&mm->context.cpu_attach_mask);
25 	atomic_set(&mm->context.flush_count, 0);
26 	mm->context.gmap_asce = 0;
27 	mm->context.flush_mm = 0;
28 #ifdef CONFIG_PGSTE
29 	mm->context.alloc_pgste = page_table_allocate_pgste ||
30 		test_thread_flag(TIF_PGSTE) ||
31 		current->mm->context.alloc_pgste;
32 	mm->context.has_pgste = 0;
33 	mm->context.use_skey = 0;
34 	mm->context.use_cmma = 0;
35 #endif
36 	switch (mm->context.asce_limit) {
37 	case _REGION2_SIZE:
38 		/*
39 		 * forked 3-level task, fall through to set new asce with new
40 		 * mm->pgd
41 		 */
42 	case 0:
43 		/* context created by exec, set asce limit to 4TB */
44 		mm->context.asce_limit = STACK_TOP_MAX;
45 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
46 				   _ASCE_USER_BITS | _ASCE_TYPE_REGION3;
47 		break;
48 	case -PAGE_SIZE:
49 		/* forked 5-level task, set new asce with new_mm->pgd */
50 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
51 			_ASCE_USER_BITS | _ASCE_TYPE_REGION1;
52 		break;
53 	case _REGION1_SIZE:
54 		/* forked 4-level task, set new asce with new mm->pgd */
55 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
56 				   _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
57 		break;
58 	case _REGION3_SIZE:
59 		/* forked 2-level compat task, set new asce with new mm->pgd */
60 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
61 				   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
62 		/* pgd_alloc() did not increase mm->nr_pmds */
63 		mm_inc_nr_pmds(mm);
64 	}
65 	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
66 	return 0;
67 }
68 
69 #define destroy_context(mm)             do { } while (0)
70 
71 static inline void set_user_asce(struct mm_struct *mm)
72 {
73 	S390_lowcore.user_asce = mm->context.asce;
74 	if (current->thread.mm_segment.ar4)
75 		__ctl_load(S390_lowcore.user_asce, 7, 7);
76 	set_cpu_flag(CIF_ASCE_PRIMARY);
77 }
78 
79 static inline void clear_user_asce(void)
80 {
81 	S390_lowcore.user_asce = S390_lowcore.kernel_asce;
82 
83 	__ctl_load(S390_lowcore.user_asce, 1, 1);
84 	__ctl_load(S390_lowcore.user_asce, 7, 7);
85 }
86 
87 static inline void load_kernel_asce(void)
88 {
89 	unsigned long asce;
90 
91 	__ctl_store(asce, 1, 1);
92 	if (asce != S390_lowcore.kernel_asce)
93 		__ctl_load(S390_lowcore.kernel_asce, 1, 1);
94 	set_cpu_flag(CIF_ASCE_PRIMARY);
95 }
96 
97 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
98 			     struct task_struct *tsk)
99 {
100 	int cpu = smp_processor_id();
101 
102 	S390_lowcore.user_asce = next->context.asce;
103 	if (prev == next)
104 		return;
105 	cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
106 	/* Clear old ASCE by loading the kernel ASCE. */
107 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);
108 	__ctl_load(S390_lowcore.kernel_asce, 7, 7);
109 	cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
110 }
111 
112 #define finish_arch_post_lock_switch finish_arch_post_lock_switch
113 static inline void finish_arch_post_lock_switch(void)
114 {
115 	struct task_struct *tsk = current;
116 	struct mm_struct *mm = tsk->mm;
117 
118 	load_kernel_asce();
119 	if (mm) {
120 		preempt_disable();
121 		while (atomic_read(&mm->context.flush_count))
122 			cpu_relax();
123 		cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
124 		__tlb_flush_mm_lazy(mm);
125 		preempt_enable();
126 	}
127 	set_fs(current->thread.mm_segment);
128 }
129 
130 #define enter_lazy_tlb(mm,tsk)	do { } while (0)
131 #define deactivate_mm(tsk,mm)	do { } while (0)
132 
133 static inline void activate_mm(struct mm_struct *prev,
134                                struct mm_struct *next)
135 {
136 	switch_mm(prev, next, current);
137 	cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
138 	set_user_asce(next);
139 }
140 
141 #endif /* __S390_MMU_CONTEXT_H */
142