1 // SPDX-License-Identifier: GPL-2.0-or-later 1
2 /*
3 * This file contains the routines for handlin
4 * PowerPC implementations where the MMU subst
5 * architecture specification. This includes
6 * and 8260 implementations but excludes the 8
7 * -- paulus
8 *
9 * Derived from arch/ppc/mm/init.c:
10 * Copyright (C) 1995-1996 Gary Thomas (gdt
11 *
12 * Modifications by Paul Mackerras (PowerMac)
13 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
14 * Copyright (C) 1996 Paul Mackerras
15 *
16 * Derived from "arch/i386/mm/init.c"
17 * Copyright (C) 1991, 1992, 1993, 1994 Li
18 */
19
20 #include <linux/mm.h>
21 #include <linux/init.h>
22 #include <linux/export.h>
23
24 #include <asm/mmu_context.h>
25
26 /*
27 * Room for two PTE pointers, usually the kern
28 * to their respective root page table.
29 */
30 void *abatron_pteptrs[2];
31
32 /*
33 * On 32-bit PowerPC 6xx/7xx/7xxx CPUs, we use
34 * (virtual segment identifiers) for each cont
35 * hardware supports 24-bit VSIDs, and thus >1
36 * we only use 32,768 of them. That is ample,
37 * at most around 30,000 tasks in the system a
38 * that we can use a bitmap to indicate which
39 * Using a bitmap means that we entirely avoid
40 * that we used to have when the context numbe
41 * particularly on SMP systems.
42 * -- paulus.
43 */
44 #define NO_CONTEXT ((unsigned lon
45 #define LAST_CONTEXT 32767
46 #define FIRST_CONTEXT 1
47
48 static unsigned long next_mmu_context;
49 static unsigned long context_map[LAST_CONTEXT
50
51 unsigned long __init_new_context(void)
52 {
53 unsigned long ctx = next_mmu_context;
54
55 while (test_and_set_bit(ctx, context_m
56 ctx = find_next_zero_bit(conte
57 if (ctx > LAST_CONTEXT)
58 ctx = 0;
59 }
60 next_mmu_context = (ctx + 1) & LAST_CO
61
62 return ctx;
63 }
64 EXPORT_SYMBOL_GPL(__init_new_context);
65
66 /*
67 * Set up the context for a new address space.
68 */
69 int init_new_context(struct task_struct *t, st
70 {
71 mm->context.id = __init_new_context();
72 mm->context.sr0 = CTX_TO_VSID(mm->cont
73
74 if (IS_ENABLED(CONFIG_PPC_KUEP))
75 mm->context.sr0 |= SR_NX;
76 if (!kuap_is_disabled())
77 mm->context.sr0 |= SR_KS;
78
79 return 0;
80 }
81
82 /*
83 * Free a context ID. Make sure to call this w
84 */
85 void __destroy_context(unsigned long ctx)
86 {
87 clear_bit(ctx, context_map);
88 }
89 EXPORT_SYMBOL_GPL(__destroy_context);
90
91 /*
92 * We're finished using the context for an add
93 */
94 void destroy_context(struct mm_struct *mm)
95 {
96 preempt_disable();
97 if (mm->context.id != NO_CONTEXT) {
98 __destroy_context(mm->context.
99 mm->context.id = NO_CONTEXT;
100 }
101 preempt_enable();
102 }
103
104 /*
105 * Initialize the context management stuff.
106 */
107 void __init mmu_context_init(void)
108 {
109 /* Reserve context 0 for kernel use */
110 context_map[0] = (1 << FIRST_CONTEXT)
111 next_mmu_context = FIRST_CONTEXT;
112 }
113
114 void switch_mmu_context(struct mm_struct *prev
115 {
116 long id = next->context.id;
117
118 if (id < 0)
119 panic("mm_struct %p has no con
120
121 isync();
122
123 update_user_segments(next->context.sr0
124
125 if (IS_ENABLED(CONFIG_BDI_SWITCH))
126 abatron_pteptrs[1] = next->pgd
127
128 if (!mmu_has_feature(MMU_FTR_HPTE_TABL
129 mtspr(SPRN_SDR1, rol32(__pa(ne
130
131 mb(); /* sync */
132 isync();
133 }
134 EXPORT_SYMBOL(switch_mmu_context);
135
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