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