1 /*
2  *  S390 version
3  *
4  *  Derived from "include/asm-i386/mmu_context.h"
5  */
6 
7 #ifndef __S390_MMU_CONTEXT_H
8 #define __S390_MMU_CONTEXT_H
9 
10 #include <asm/pgalloc.h>
11 #include <linux/uaccess.h>
12 #include <linux/mm_types.h>
13 #include <asm/tlbflush.h>
14 #include <asm/ctl_reg.h>
15 
16 static inline int init_new_context(struct task_struct *tsk,
17 				   struct mm_struct *mm)
18 {
19 	spin_lock_init(&mm->context.pgtable_lock);
20 	INIT_LIST_HEAD(&mm->context.pgtable_list);
21 	spin_lock_init(&mm->context.gmap_lock);
22 	INIT_LIST_HEAD(&mm->context.gmap_list);
23 	cpumask_clear(&mm->context.cpu_attach_mask);
24 	atomic_set(&mm->context.flush_count, 0);
25 	mm->context.gmap_asce = 0;
26 	mm->context.flush_mm = 0;
27 #ifdef CONFIG_PGSTE
28 	mm->context.alloc_pgste = page_table_allocate_pgste;
29 	mm->context.has_pgste = 0;
30 	mm->context.use_skey = 0;
31 #endif
32 	switch (mm->context.asce_limit) {
33 	case 1UL << 42:
34 		/*
35 		 * forked 3-level task, fall through to set new asce with new
36 		 * mm->pgd
37 		 */
38 	case 0:
39 		/* context created by exec, set asce limit to 4TB */
40 		mm->context.asce_limit = STACK_TOP_MAX;
41 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
42 				   _ASCE_USER_BITS | _ASCE_TYPE_REGION3;
43 		break;
44 	case 1UL << 53:
45 		/* forked 4-level task, set new asce with new mm->pgd */
46 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
47 				   _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
48 		break;
49 	case 1UL << 31:
50 		/* forked 2-level compat task, set new asce with new mm->pgd */
51 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
52 				   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
53 		/* pgd_alloc() did not increase mm->nr_pmds */
54 		mm_inc_nr_pmds(mm);
55 	}
56 	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
57 	return 0;
58 }
59 
60 #define destroy_context(mm)             do { } while (0)
61 
62 static inline void set_user_asce(struct mm_struct *mm)
63 {
64 	S390_lowcore.user_asce = mm->context.asce;
65 	if (current->thread.mm_segment.ar4)
66 		__ctl_load(S390_lowcore.user_asce, 7, 7);
67 	set_cpu_flag(CIF_ASCE_PRIMARY);
68 }
69 
70 static inline void clear_user_asce(void)
71 {
72 	S390_lowcore.user_asce = S390_lowcore.kernel_asce;
73 
74 	__ctl_load(S390_lowcore.user_asce, 1, 1);
75 	__ctl_load(S390_lowcore.user_asce, 7, 7);
76 }
77 
78 static inline void load_kernel_asce(void)
79 {
80 	unsigned long asce;
81 
82 	__ctl_store(asce, 1, 1);
83 	if (asce != S390_lowcore.kernel_asce)
84 		__ctl_load(S390_lowcore.kernel_asce, 1, 1);
85 	set_cpu_flag(CIF_ASCE_PRIMARY);
86 }
87 
88 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
89 			     struct task_struct *tsk)
90 {
91 	int cpu = smp_processor_id();
92 
93 	S390_lowcore.user_asce = next->context.asce;
94 	if (prev == next)
95 		return;
96 	cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
97 	cpumask_set_cpu(cpu, mm_cpumask(next));
98 	/* Clear old ASCE by loading the kernel ASCE. */
99 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);
100 	__ctl_load(S390_lowcore.kernel_asce, 7, 7);
101 	cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
102 }
103 
104 #define finish_arch_post_lock_switch finish_arch_post_lock_switch
105 static inline void finish_arch_post_lock_switch(void)
106 {
107 	struct task_struct *tsk = current;
108 	struct mm_struct *mm = tsk->mm;
109 
110 	load_kernel_asce();
111 	if (mm) {
112 		preempt_disable();
113 		while (atomic_read(&mm->context.flush_count))
114 			cpu_relax();
115 
116 		if (mm->context.flush_mm)
117 			__tlb_flush_mm(mm);
118 		preempt_enable();
119 	}
120 	set_fs(current->thread.mm_segment);
121 }
122 
123 #define enter_lazy_tlb(mm,tsk)	do { } while (0)
124 #define deactivate_mm(tsk,mm)	do { } while (0)
125 
126 static inline void activate_mm(struct mm_struct *prev,
127                                struct mm_struct *next)
128 {
129 	switch_mm(prev, next, current);
130 	set_user_asce(next);
131 }
132 
133 static inline void arch_dup_mmap(struct mm_struct *oldmm,
134 				 struct mm_struct *mm)
135 {
136 }
137 
138 static inline void arch_exit_mmap(struct mm_struct *mm)
139 {
140 }
141 
142 static inline void arch_unmap(struct mm_struct *mm,
143 			struct vm_area_struct *vma,
144 			unsigned long start, unsigned long end)
145 {
146 }
147 
148 static inline void arch_bprm_mm_init(struct mm_struct *mm,
149 				     struct vm_area_struct *vma)
150 {
151 }
152 
153 static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
154 		bool write, bool execute, bool foreign)
155 {
156 	/* by default, allow everything */
157 	return true;
158 }
159 
160 static inline bool arch_pte_access_permitted(pte_t pte, bool write)
161 {
162 	/* by default, allow everything */
163 	return true;
164 }
165 #endif /* __S390_MMU_CONTEXT_H */
166