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/cachetype.h> 19 #include <asm/proc-fns.h> 20 #include <asm-generic/mm_hooks.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 46 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); 47 void __new_context(struct mm_struct *mm); 48 49 static inline void check_context(struct mm_struct *mm) 50 { 51 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) 52 __new_context(mm); 53 54 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 55 __check_kvm_seq(mm); 56 } 57 58 #define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0) 59 60 #else 61 62 static inline void check_context(struct mm_struct *mm) 63 { 64 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 65 __check_kvm_seq(mm); 66 } 67 68 #define init_new_context(tsk,mm) 0 69 70 #endif 71 72 #define destroy_context(mm) do { } while(0) 73 74 /* 75 * This is called when "tsk" is about to enter lazy TLB mode. 76 * 77 * mm: describes the currently active mm context 78 * tsk: task which is entering lazy tlb 79 * cpu: cpu number which is entering lazy tlb 80 * 81 * tsk->mm will be NULL 82 */ 83 static inline void 84 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 85 { 86 } 87 88 /* 89 * This is the actual mm switch as far as the scheduler 90 * is concerned. No registers are touched. We avoid 91 * calling the CPU specific function when the mm hasn't 92 * actually changed. 93 */ 94 static inline void 95 switch_mm(struct mm_struct *prev, struct mm_struct *next, 96 struct task_struct *tsk) 97 { 98 #ifdef CONFIG_MMU 99 unsigned int cpu = smp_processor_id(); 100 101 #ifdef CONFIG_SMP 102 /* check for possible thread migration */ 103 if (!cpus_empty(next->cpu_vm_mask) && !cpu_isset(cpu, next->cpu_vm_mask)) 104 __flush_icache_all(); 105 #endif 106 if (!cpu_test_and_set(cpu, next->cpu_vm_mask) || prev != next) { 107 check_context(next); 108 cpu_switch_mm(next->pgd, next); 109 if (cache_is_vivt()) 110 cpu_clear(cpu, prev->cpu_vm_mask); 111 } 112 #endif 113 } 114 115 #define deactivate_mm(tsk,mm) do { } while (0) 116 #define activate_mm(prev,next) switch_mm(prev, next, NULL) 117 118 #endif 119