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