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 <asm/cacheflush.h> 18 #include <asm/proc-fns.h> 19 #include <asm-generic/mm_hooks.h> 20 21 void __check_kvm_seq(struct mm_struct *mm); 22 23 #ifdef CONFIG_CPU_HAS_ASID 24 25 /* 26 * On ARMv6, we have the following structure in the Context ID: 27 * 28 * 31 7 0 29 * +-------------------------+-----------+ 30 * | process ID | ASID | 31 * +-------------------------+-----------+ 32 * | context ID | 33 * +-------------------------------------+ 34 * 35 * The ASID is used to tag entries in the CPU caches and TLBs. 36 * The context ID is used by debuggers and trace logic, and 37 * should be unique within all running processes. 38 */ 39 #define ASID_BITS 8 40 #define ASID_MASK ((~0) << ASID_BITS) 41 #define ASID_FIRST_VERSION (1 << ASID_BITS) 42 43 extern unsigned int cpu_last_asid; 44 45 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); 46 void __new_context(struct mm_struct *mm); 47 48 static inline void check_context(struct mm_struct *mm) 49 { 50 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) 51 __new_context(mm); 52 53 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 54 __check_kvm_seq(mm); 55 } 56 57 #define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0) 58 59 #else 60 61 static inline void check_context(struct mm_struct *mm) 62 { 63 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 64 __check_kvm_seq(mm); 65 } 66 67 #define init_new_context(tsk,mm) 0 68 69 #endif 70 71 #define destroy_context(mm) do { } while(0) 72 73 /* 74 * This is called when "tsk" is about to enter lazy TLB mode. 75 * 76 * mm: describes the currently active mm context 77 * tsk: task which is entering lazy tlb 78 * cpu: cpu number which is entering lazy tlb 79 * 80 * tsk->mm will be NULL 81 */ 82 static inline void 83 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 84 { 85 } 86 87 /* 88 * This is the actual mm switch as far as the scheduler 89 * is concerned. No registers are touched. We avoid 90 * calling the CPU specific function when the mm hasn't 91 * actually changed. 92 */ 93 static inline void 94 switch_mm(struct mm_struct *prev, struct mm_struct *next, 95 struct task_struct *tsk) 96 { 97 #ifdef CONFIG_MMU 98 unsigned int cpu = smp_processor_id(); 99 100 #ifdef CONFIG_SMP 101 /* check for possible thread migration */ 102 if (!cpus_empty(next->cpu_vm_mask) && !cpu_isset(cpu, next->cpu_vm_mask)) 103 __flush_icache_all(); 104 #endif 105 if (!cpu_test_and_set(cpu, next->cpu_vm_mask) || prev != next) { 106 check_context(next); 107 cpu_switch_mm(next->pgd, next); 108 if (cache_is_vivt()) 109 cpu_clear(cpu, prev->cpu_vm_mask); 110 } 111 #endif 112 } 113 114 #define deactivate_mm(tsk,mm) do { } while (0) 115 #define activate_mm(prev,next) switch_mm(prev, next, NULL) 116 117 #endif 118