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 	unsigned long asce_type, init_entry;
22 
23 	spin_lock_init(&mm->context.lock);
24 	INIT_LIST_HEAD(&mm->context.pgtable_list);
25 	INIT_LIST_HEAD(&mm->context.gmap_list);
26 	cpumask_clear(&mm->context.cpu_attach_mask);
27 	atomic_set(&mm->context.flush_count, 0);
28 	atomic_set(&mm->context.is_protected, 0);
29 	mm->context.gmap_asce = 0;
30 	mm->context.flush_mm = 0;
31 #ifdef CONFIG_PGSTE
32 	mm->context.alloc_pgste = page_table_allocate_pgste ||
33 		test_thread_flag(TIF_PGSTE) ||
34 		(current->mm && current->mm->context.alloc_pgste);
35 	mm->context.has_pgste = 0;
36 	mm->context.uses_skeys = 0;
37 	mm->context.uses_cmm = 0;
38 	mm->context.allow_gmap_hpage_1m = 0;
39 #endif
40 	switch (mm->context.asce_limit) {
41 	default:
42 		/*
43 		 * context created by exec, the value of asce_limit can
44 		 * only be zero in this case
45 		 */
46 		VM_BUG_ON(mm->context.asce_limit);
47 		/* continue as 3-level task */
48 		mm->context.asce_limit = _REGION2_SIZE;
49 		fallthrough;
50 	case _REGION2_SIZE:
51 		/* forked 3-level task */
52 		init_entry = _REGION3_ENTRY_EMPTY;
53 		asce_type = _ASCE_TYPE_REGION3;
54 		break;
55 	case TASK_SIZE_MAX:
56 		/* forked 5-level task */
57 		init_entry = _REGION1_ENTRY_EMPTY;
58 		asce_type = _ASCE_TYPE_REGION1;
59 		break;
60 	case _REGION1_SIZE:
61 		/* forked 4-level task */
62 		init_entry = _REGION2_ENTRY_EMPTY;
63 		asce_type = _ASCE_TYPE_REGION2;
64 		break;
65 	}
66 	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
67 			   _ASCE_USER_BITS | asce_type;
68 	crst_table_init((unsigned long *) mm->pgd, init_entry);
69 	return 0;
70 }
71 
72 #define destroy_context(mm)             do { } while (0)
73 
74 static inline void set_user_asce(struct mm_struct *mm)
75 {
76 	S390_lowcore.user_asce = mm->context.asce;
77 	__ctl_load(S390_lowcore.user_asce, 1, 1);
78 	clear_cpu_flag(CIF_ASCE_PRIMARY);
79 }
80 
81 static inline void clear_user_asce(void)
82 {
83 	S390_lowcore.user_asce = S390_lowcore.kernel_asce;
84 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);
85 	set_cpu_flag(CIF_ASCE_PRIMARY);
86 }
87 
88 mm_segment_t enable_sacf_uaccess(void);
89 void disable_sacf_uaccess(mm_segment_t old_fs);
90 
91 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
92 			     struct task_struct *tsk)
93 {
94 	int cpu = smp_processor_id();
95 
96 	S390_lowcore.user_asce = next->context.asce;
97 	cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
98 	/* Clear previous user-ASCE from CR1 and CR7 */
99 	if (!test_cpu_flag(CIF_ASCE_PRIMARY)) {
100 		__ctl_load(S390_lowcore.kernel_asce, 1, 1);
101 		set_cpu_flag(CIF_ASCE_PRIMARY);
102 	}
103 	if (test_cpu_flag(CIF_ASCE_SECONDARY)) {
104 		__ctl_load(S390_lowcore.vdso_asce, 7, 7);
105 		clear_cpu_flag(CIF_ASCE_SECONDARY);
106 	}
107 	if (prev != next)
108 		cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
109 }
110 
111 #define finish_arch_post_lock_switch finish_arch_post_lock_switch
112 static inline void finish_arch_post_lock_switch(void)
113 {
114 	struct task_struct *tsk = current;
115 	struct mm_struct *mm = tsk->mm;
116 
117 	if (mm) {
118 		preempt_disable();
119 		while (atomic_read(&mm->context.flush_count))
120 			cpu_relax();
121 		cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
122 		__tlb_flush_mm_lazy(mm);
123 		preempt_enable();
124 	}
125 	set_fs(current->thread.mm_segment);
126 }
127 
128 #define enter_lazy_tlb(mm,tsk)	do { } while (0)
129 #define deactivate_mm(tsk,mm)	do { } while (0)
130 
131 static inline void activate_mm(struct mm_struct *prev,
132                                struct mm_struct *next)
133 {
134 	switch_mm(prev, next, current);
135 	cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
136 	set_user_asce(next);
137 }
138 
139 #endif /* __S390_MMU_CONTEXT_H */
140