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