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