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 #include <asm-generic/mm_hooks.h>
16 
17 static inline int init_new_context(struct task_struct *tsk,
18 				   struct mm_struct *mm)
19 {
20 	spin_lock_init(&mm->context.lock);
21 	INIT_LIST_HEAD(&mm->context.pgtable_list);
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 _REGION2_SIZE:
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 -PAGE_SIZE:
48 		/* forked 5-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_REGION1;
51 		break;
52 	case _REGION1_SIZE:
53 		/* forked 4-level task, set new asce with new mm->pgd */
54 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
55 				   _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
56 		break;
57 	case _REGION3_SIZE:
58 		/* forked 2-level compat task, set new asce with new mm->pgd */
59 		mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
60 				   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
61 		/* pgd_alloc() did not increase mm->nr_pmds */
62 		mm_inc_nr_pmds(mm);
63 	}
64 	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
65 	return 0;
66 }
67 
68 #define destroy_context(mm)             do { } while (0)
69 
70 static inline void set_user_asce(struct mm_struct *mm)
71 {
72 	S390_lowcore.user_asce = mm->context.asce;
73 	if (current->thread.mm_segment.ar4)
74 		__ctl_load(S390_lowcore.user_asce, 7, 7);
75 	set_cpu_flag(CIF_ASCE_PRIMARY);
76 }
77 
78 static inline void clear_user_asce(void)
79 {
80 	S390_lowcore.user_asce = S390_lowcore.kernel_asce;
81 
82 	__ctl_load(S390_lowcore.user_asce, 1, 1);
83 	__ctl_load(S390_lowcore.user_asce, 7, 7);
84 }
85 
86 static inline void load_kernel_asce(void)
87 {
88 	unsigned long asce;
89 
90 	__ctl_store(asce, 1, 1);
91 	if (asce != S390_lowcore.kernel_asce)
92 		__ctl_load(S390_lowcore.kernel_asce, 1, 1);
93 	set_cpu_flag(CIF_ASCE_PRIMARY);
94 }
95 
96 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
97 			     struct task_struct *tsk)
98 {
99 	int cpu = smp_processor_id();
100 
101 	S390_lowcore.user_asce = next->context.asce;
102 	if (prev == next)
103 		return;
104 	cpumask_set_cpu(cpu, &next->context.cpu_attach_mask);
105 	/* Clear old ASCE by loading the kernel ASCE. */
106 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);
107 	__ctl_load(S390_lowcore.kernel_asce, 7, 7);
108 	cpumask_clear_cpu(cpu, &prev->context.cpu_attach_mask);
109 }
110 
111 #define finish_arch_post_lock_switch finish_arch_post_lock_switch
112 static inline void finish_arch_post_lock_switch(void)
113 {
114 	struct task_struct *tsk = current;
115 	struct mm_struct *mm = tsk->mm;
116 
117 	load_kernel_asce();
118 	if (mm) {
119 		preempt_disable();
120 		while (atomic_read(&mm->context.flush_count))
121 			cpu_relax();
122 		cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
123 		__tlb_flush_mm_lazy(mm);
124 		preempt_enable();
125 	}
126 	set_fs(current->thread.mm_segment);
127 }
128 
129 #define enter_lazy_tlb(mm,tsk)	do { } while (0)
130 #define deactivate_mm(tsk,mm)	do { } while (0)
131 
132 static inline void activate_mm(struct mm_struct *prev,
133                                struct mm_struct *next)
134 {
135 	switch_mm(prev, next, current);
136 	cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
137 	set_user_asce(next);
138 }
139 
140 #endif /* __S390_MMU_CONTEXT_H */
141