David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 1 | /* MN10300 MMU context management |
| 2 | * |
| 3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. |
| 4 | * Modified by David Howells (dhowells@redhat.com) |
| 5 | * - Derived from include/asm-m32r/mmu_context.h |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU General Public Licence |
| 9 | * as published by the Free Software Foundation; either version |
| 10 | * 2 of the Licence, or (at your option) any later version. |
| 11 | * |
| 12 | * |
| 13 | * This implements an algorithm to provide TLB PID mappings to provide |
| 14 | * selective access to the TLB for processes, thus reducing the number of TLB |
| 15 | * flushes required. |
| 16 | * |
| 17 | * Note, however, that the M32R algorithm is technically broken as it does not |
| 18 | * handle version wrap-around, and could, theoretically, have a problem with a |
| 19 | * very long lived program that sleeps long enough for the version number to |
| 20 | * wrap all the way around so that its TLB mappings appear valid once again. |
| 21 | */ |
| 22 | #ifndef _ASM_MMU_CONTEXT_H |
| 23 | #define _ASM_MMU_CONTEXT_H |
| 24 | |
Arun Sharma | 60063497 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 25 | #include <linux/atomic.h> |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 26 | #include <asm/pgalloc.h> |
| 27 | #include <asm/tlbflush.h> |
| 28 | #include <asm-generic/mm_hooks.h> |
| 29 | |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 30 | #define MMU_CONTEXT_TLBPID_NR 256 |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 31 | #define MMU_CONTEXT_TLBPID_MASK 0x000000ffUL |
| 32 | #define MMU_CONTEXT_VERSION_MASK 0xffffff00UL |
| 33 | #define MMU_CONTEXT_FIRST_VERSION 0x00000100UL |
| 34 | #define MMU_NO_CONTEXT 0x00000000UL |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 35 | #define MMU_CONTEXT_TLBPID_LOCK_NR 0 |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 36 | |
| 37 | #define enter_lazy_tlb(mm, tsk) do {} while (0) |
| 38 | |
Akira Takeuchi | 965ea4b | 2010-10-27 17:28:51 +0100 | [diff] [blame] | 39 | static inline void cpu_ran_vm(int cpu, struct mm_struct *mm) |
| 40 | { |
| 41 | #ifdef CONFIG_SMP |
| 42 | cpumask_set_cpu(cpu, mm_cpumask(mm)); |
| 43 | #endif |
| 44 | } |
| 45 | |
| 46 | static inline bool cpu_maybe_ran_vm(int cpu, struct mm_struct *mm) |
| 47 | { |
| 48 | #ifdef CONFIG_SMP |
| 49 | return cpumask_test_and_set_cpu(cpu, mm_cpumask(mm)); |
| 50 | #else |
| 51 | return true; |
| 52 | #endif |
| 53 | } |
| 54 | |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 55 | #ifdef CONFIG_MN10300_TLB_USE_PIDR |
| 56 | extern unsigned long mmu_context_cache[NR_CPUS]; |
| 57 | #define mm_context(mm) (mm->context.tlbpid[smp_processor_id()]) |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 58 | |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 59 | /** |
| 60 | * allocate_mmu_context - Allocate storage for the arch-specific MMU data |
| 61 | * @mm: The userspace VM context being set up |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 62 | */ |
| 63 | static inline unsigned long allocate_mmu_context(struct mm_struct *mm) |
| 64 | { |
| 65 | unsigned long *pmc = &mmu_context_cache[smp_processor_id()]; |
| 66 | unsigned long mc = ++(*pmc); |
| 67 | |
| 68 | if (!(mc & MMU_CONTEXT_TLBPID_MASK)) { |
| 69 | /* we exhausted the TLB PIDs of this version on this CPU, so we |
| 70 | * flush this CPU's TLB in its entirety and start new cycle */ |
David Howells | 492e675 | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 71 | local_flush_tlb_all(); |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 72 | |
| 73 | /* fix the TLB version if needed (we avoid version #0 so as to |
| 74 | * distingush MMU_NO_CONTEXT) */ |
| 75 | if (!mc) |
| 76 | *pmc = mc = MMU_CONTEXT_FIRST_VERSION; |
| 77 | } |
| 78 | mm_context(mm) = mc; |
| 79 | return mc; |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * get an MMU context if one is needed |
| 84 | */ |
| 85 | static inline unsigned long get_mmu_context(struct mm_struct *mm) |
| 86 | { |
| 87 | unsigned long mc = MMU_NO_CONTEXT, cache; |
| 88 | |
| 89 | if (mm) { |
| 90 | cache = mmu_context_cache[smp_processor_id()]; |
| 91 | mc = mm_context(mm); |
| 92 | |
| 93 | /* if we have an old version of the context, replace it */ |
| 94 | if ((mc ^ cache) & MMU_CONTEXT_VERSION_MASK) |
| 95 | mc = allocate_mmu_context(mm); |
| 96 | } |
| 97 | return mc; |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | * initialise the context related info for a new mm_struct instance |
| 102 | */ |
| 103 | static inline int init_new_context(struct task_struct *tsk, |
| 104 | struct mm_struct *mm) |
| 105 | { |
| 106 | int num_cpus = NR_CPUS, i; |
| 107 | |
| 108 | for (i = 0; i < num_cpus; i++) |
| 109 | mm->context.tlbpid[i] = MMU_NO_CONTEXT; |
| 110 | return 0; |
| 111 | } |
| 112 | |
| 113 | /* |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 114 | * after we have set current->mm to a new value, this activates the context for |
| 115 | * the new mm so we see the new mappings. |
| 116 | */ |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 117 | static inline void activate_context(struct mm_struct *mm) |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 118 | { |
| 119 | PIDR = get_mmu_context(mm) & MMU_CONTEXT_TLBPID_MASK; |
| 120 | } |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 121 | #else /* CONFIG_MN10300_TLB_USE_PIDR */ |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 122 | |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 123 | #define init_new_context(tsk, mm) (0) |
| 124 | #define activate_context(mm) local_flush_tlb() |
| 125 | |
| 126 | #endif /* CONFIG_MN10300_TLB_USE_PIDR */ |
| 127 | |
| 128 | /** |
| 129 | * destroy_context - Destroy mm context information |
| 130 | * @mm: The MM being destroyed. |
| 131 | * |
| 132 | * Destroy context related info for an mm_struct that is about to be put to |
| 133 | * rest |
| 134 | */ |
| 135 | #define destroy_context(mm) do {} while (0) |
| 136 | |
| 137 | /** |
| 138 | * switch_mm - Change between userspace virtual memory contexts |
| 139 | * @prev: The outgoing MM context. |
| 140 | * @next: The incoming MM context. |
| 141 | * @tsk: The incoming task. |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 142 | */ |
| 143 | static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, |
| 144 | struct task_struct *tsk) |
| 145 | { |
Akira Takeuchi | 965ea4b | 2010-10-27 17:28:51 +0100 | [diff] [blame] | 146 | int cpu = smp_processor_id(); |
| 147 | |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 148 | if (prev != next) { |
Akira Takeuchi | 965ea4b | 2010-10-27 17:28:51 +0100 | [diff] [blame] | 149 | #ifdef CONFIG_SMP |
| 150 | per_cpu(cpu_tlbstate, cpu).active_mm = next; |
| 151 | #endif |
| 152 | cpu_ran_vm(cpu, next); |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 153 | PTBR = (unsigned long) next->pgd; |
Akira Takeuchi | a9bc60e | 2010-10-27 17:28:49 +0100 | [diff] [blame] | 154 | activate_context(next); |
David Howells | b920de1 | 2008-02-08 04:19:31 -0800 | [diff] [blame] | 155 | } |
| 156 | } |
| 157 | |
| 158 | #define deactivate_mm(tsk, mm) do {} while (0) |
| 159 | #define activate_mm(prev, next) switch_mm((prev), (next), NULL) |
| 160 | |
| 161 | #endif /* _ASM_MMU_CONTEXT_H */ |