1 /*
2  *  include/asm-s390/mmu_context.h
3  *
4  *  S390 version
5  *
6  *  Derived from "include/asm-i386/mmu_context.h"
7  */
8 
9 #ifndef __S390_MMU_CONTEXT_H
10 #define __S390_MMU_CONTEXT_H
11 
12 #include <asm/pgalloc.h>
13 #include <asm/uaccess.h>
14 #include <asm/tlbflush.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 	atomic_set(&mm->context.attach_count, 0);
21 	mm->context.flush_mm = 0;
22 	mm->context.asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
23 #ifdef CONFIG_64BIT
24 	mm->context.asce_bits |= _ASCE_TYPE_REGION3;
25 #endif
26 	if (current->mm->context.alloc_pgste) {
27 		/*
28 		 * alloc_pgste indicates, that any NEW context will be created
29 		 * with extended page tables. The old context is unchanged. The
30 		 * page table allocation and the page table operations will
31 		 * look at has_pgste to distinguish normal and extended page
32 		 * tables. The only way to create extended page tables is to
33 		 * set alloc_pgste and then create a new context (e.g. dup_mm).
34 		 * The page table allocation is called after init_new_context
35 		 * and if has_pgste is set, it will create extended page
36 		 * tables.
37 		 */
38 		mm->context.noexec = 0;
39 		mm->context.has_pgste = 1;
40 		mm->context.alloc_pgste = 1;
41 	} else {
42 		mm->context.noexec = (user_mode == SECONDARY_SPACE_MODE);
43 		mm->context.has_pgste = 0;
44 		mm->context.alloc_pgste = 0;
45 	}
46 	mm->context.asce_limit = STACK_TOP_MAX;
47 	crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
48 	return 0;
49 }
50 
51 #define destroy_context(mm)             do { } while (0)
52 
53 #ifndef __s390x__
54 #define LCTL_OPCODE "lctl"
55 #else
56 #define LCTL_OPCODE "lctlg"
57 #endif
58 
59 static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
60 {
61 	pgd_t *pgd = mm->pgd;
62 
63 	S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
64 	if (user_mode != HOME_SPACE_MODE) {
65 		/* Load primary space page table origin. */
66 		pgd = mm->context.noexec ? get_shadow_table(pgd) : pgd;
67 		S390_lowcore.user_exec_asce = mm->context.asce_bits | __pa(pgd);
68 		asm volatile(LCTL_OPCODE" 1,1,%0\n"
69 			     : : "m" (S390_lowcore.user_exec_asce) );
70 	} else
71 		/* Load home space page table origin. */
72 		asm volatile(LCTL_OPCODE" 13,13,%0"
73 			     : : "m" (S390_lowcore.user_asce) );
74 	set_fs(current->thread.mm_segment);
75 }
76 
77 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
78 			     struct task_struct *tsk)
79 {
80 	cpumask_set_cpu(smp_processor_id(), mm_cpumask(next));
81 	update_mm(next, tsk);
82 	atomic_dec(&prev->context.attach_count);
83 	WARN_ON(atomic_read(&prev->context.attach_count) < 0);
84 	atomic_inc(&next->context.attach_count);
85 	/* Check for TLBs not flushed yet */
86 	if (next->context.flush_mm)
87 		__tlb_flush_mm(next);
88 }
89 
90 #define enter_lazy_tlb(mm,tsk)	do { } while (0)
91 #define deactivate_mm(tsk,mm)	do { } while (0)
92 
93 static inline void activate_mm(struct mm_struct *prev,
94                                struct mm_struct *next)
95 {
96         switch_mm(prev, next, current);
97 }
98 
99 #endif /* __S390_MMU_CONTEXT_H */
100