1 /* 2 * arch/arm/include/asm/mmu_context.h 3 * 4 * Copyright (C) 1996 Russell King. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Changelog: 11 * 27-06-1996 RMK Created 12 */ 13 #ifndef __ASM_ARM_MMU_CONTEXT_H 14 #define __ASM_ARM_MMU_CONTEXT_H 15 16 #include <linux/compiler.h> 17 #include <linux/sched.h> 18 #include <asm/cacheflush.h> 19 #include <asm/cachetype.h> 20 #include <asm/proc-fns.h> 21 22 void __check_kvm_seq(struct mm_struct *mm); 23 24 #ifdef CONFIG_CPU_HAS_ASID 25 26 /* 27 * On ARMv6, we have the following structure in the Context ID: 28 * 29 * 31 7 0 30 * +-------------------------+-----------+ 31 * | process ID | ASID | 32 * +-------------------------+-----------+ 33 * | context ID | 34 * +-------------------------------------+ 35 * 36 * The ASID is used to tag entries in the CPU caches and TLBs. 37 * The context ID is used by debuggers and trace logic, and 38 * should be unique within all running processes. 39 */ 40 #define ASID_BITS 8 41 #define ASID_MASK ((~0) << ASID_BITS) 42 #define ASID_FIRST_VERSION (1 << ASID_BITS) 43 44 extern unsigned int cpu_last_asid; 45 #ifdef CONFIG_SMP 46 DECLARE_PER_CPU(struct mm_struct *, current_mm); 47 #endif 48 49 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); 50 void __new_context(struct mm_struct *mm); 51 52 static inline void check_context(struct mm_struct *mm) 53 { 54 /* 55 * This code is executed with interrupts enabled. Therefore, 56 * mm->context.id cannot be updated to the latest ASID version 57 * on a different CPU (and condition below not triggered) 58 * without first getting an IPI to reset the context. The 59 * alternative is to take a read_lock on mm->context.id_lock 60 * (after changing its type to rwlock_t). 61 */ 62 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) 63 __new_context(mm); 64 65 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 66 __check_kvm_seq(mm); 67 } 68 69 #define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0) 70 71 #else 72 73 static inline void check_context(struct mm_struct *mm) 74 { 75 #ifdef CONFIG_MMU 76 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 77 __check_kvm_seq(mm); 78 #endif 79 } 80 81 #define init_new_context(tsk,mm) 0 82 83 #endif 84 85 #define destroy_context(mm) do { } while(0) 86 87 /* 88 * This is called when "tsk" is about to enter lazy TLB mode. 89 * 90 * mm: describes the currently active mm context 91 * tsk: task which is entering lazy tlb 92 * cpu: cpu number which is entering lazy tlb 93 * 94 * tsk->mm will be NULL 95 */ 96 static inline void 97 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 98 { 99 } 100 101 /* 102 * This is the actual mm switch as far as the scheduler 103 * is concerned. No registers are touched. We avoid 104 * calling the CPU specific function when the mm hasn't 105 * actually changed. 106 */ 107 static inline void 108 switch_mm(struct mm_struct *prev, struct mm_struct *next, 109 struct task_struct *tsk) 110 { 111 #ifdef CONFIG_MMU 112 unsigned int cpu = smp_processor_id(); 113 114 #ifdef CONFIG_SMP 115 /* check for possible thread migration */ 116 if (!cpumask_empty(mm_cpumask(next)) && 117 !cpumask_test_cpu(cpu, mm_cpumask(next))) 118 __flush_icache_all(); 119 #endif 120 if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) { 121 #ifdef CONFIG_SMP 122 struct mm_struct **crt_mm = &per_cpu(current_mm, cpu); 123 *crt_mm = next; 124 #endif 125 check_context(next); 126 cpu_switch_mm(next->pgd, next); 127 if (cache_is_vivt()) 128 cpumask_clear_cpu(cpu, mm_cpumask(prev)); 129 } 130 #endif 131 } 132 133 #define deactivate_mm(tsk,mm) do { } while (0) 134 #define activate_mm(prev,next) switch_mm(prev, next, NULL) 135 136 /* 137 * We are inserting a "fake" vma for the user-accessible vector page so 138 * gdb and friends can get to it through ptrace and /proc/<pid>/mem. 139 * But we also want to remove it before the generic code gets to see it 140 * during process exit or the unmapping of it would cause total havoc. 141 * (the macro is used as remove_vma() is static to mm/mmap.c) 142 */ 143 #define arch_exit_mmap(mm) \ 144 do { \ 145 struct vm_area_struct *high_vma = find_vma(mm, 0xffff0000); \ 146 if (high_vma) { \ 147 BUG_ON(high_vma->vm_next); /* it should be last */ \ 148 if (high_vma->vm_prev) \ 149 high_vma->vm_prev->vm_next = NULL; \ 150 else \ 151 mm->mmap = NULL; \ 152 rb_erase(&high_vma->vm_rb, &mm->mm_rb); \ 153 mm->mmap_cache = NULL; \ 154 mm->map_count--; \ 155 remove_vma(high_vma); \ 156 } \ 157 } while (0) 158 159 static inline void arch_dup_mmap(struct mm_struct *oldmm, 160 struct mm_struct *mm) 161 { 162 } 163 164 #endif 165