1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __PARISC_MMU_CONTEXT_H
3 #define __PARISC_MMU_CONTEXT_H
4 
5 #include <linux/mm.h>
6 #include <linux/sched.h>
7 #include <linux/atomic.h>
8 #include <asm/pgalloc.h>
9 #include <asm-generic/mm_hooks.h>
10 
11 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
12 {
13 }
14 
15 /* on PA-RISC, we actually have enough contexts to justify an allocator
16  * for them.  prumpf */
17 
18 extern unsigned long alloc_sid(void);
19 extern void free_sid(unsigned long);
20 
21 static inline int
22 init_new_context(struct task_struct *tsk, struct mm_struct *mm)
23 {
24 	BUG_ON(atomic_read(&mm->mm_users) != 1);
25 
26 	mm->context = alloc_sid();
27 	return 0;
28 }
29 
30 static inline void
31 destroy_context(struct mm_struct *mm)
32 {
33 	free_sid(mm->context);
34 	mm->context = 0;
35 }
36 
37 static inline unsigned long __space_to_prot(mm_context_t context)
38 {
39 #if SPACEID_SHIFT == 0
40 	return context << 1;
41 #else
42 	return context >> (SPACEID_SHIFT - 1);
43 #endif
44 }
45 
46 static inline void load_context(mm_context_t context)
47 {
48 	mtsp(context, 3);
49 	mtctl(__space_to_prot(context), 8);
50 }
51 
52 static inline void switch_mm_irqs_off(struct mm_struct *prev,
53 		struct mm_struct *next, struct task_struct *tsk)
54 {
55 	if (prev != next) {
56 		mtctl(__pa(next->pgd), 25);
57 		load_context(next->context);
58 	}
59 }
60 
61 static inline void switch_mm(struct mm_struct *prev,
62 		struct mm_struct *next, struct task_struct *tsk)
63 {
64 	unsigned long flags;
65 
66 	if (prev == next)
67 		return;
68 
69 	local_irq_save(flags);
70 	switch_mm_irqs_off(prev, next, tsk);
71 	local_irq_restore(flags);
72 }
73 #define switch_mm_irqs_off switch_mm_irqs_off
74 
75 #define deactivate_mm(tsk,mm)	do { } while (0)
76 
77 static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
78 {
79 	/*
80 	 * Activate_mm is our one chance to allocate a space id
81 	 * for a new mm created in the exec path. There's also
82 	 * some lazy tlb stuff, which is currently dead code, but
83 	 * we only allocate a space id if one hasn't been allocated
84 	 * already, so we should be OK.
85 	 */
86 
87 	BUG_ON(next == &init_mm); /* Should never happen */
88 
89 	if (next->context == 0)
90 	    next->context = alloc_sid();
91 
92 	switch_mm(prev,next,current);
93 }
94 #endif
95