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 #include <asm-generic/mm_hooks.h> 22 23 void __check_kvm_seq(struct mm_struct *mm); 24 25 #ifdef CONFIG_CPU_HAS_ASID 26 27 /* 28 * On ARMv6, we have the following structure in the Context ID: 29 * 30 * 31 7 0 31 * +-------------------------+-----------+ 32 * | process ID | ASID | 33 * +-------------------------+-----------+ 34 * | context ID | 35 * +-------------------------------------+ 36 * 37 * The ASID is used to tag entries in the CPU caches and TLBs. 38 * The context ID is used by debuggers and trace logic, and 39 * should be unique within all running processes. 40 */ 41 #define ASID_BITS 8 42 #define ASID_MASK ((~0) << ASID_BITS) 43 #define ASID_FIRST_VERSION (1 << ASID_BITS) 44 45 extern unsigned int cpu_last_asid; 46 47 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm); 48 void __new_context(struct mm_struct *mm); 49 50 static inline void check_context(struct mm_struct *mm) 51 { 52 if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) 53 __new_context(mm); 54 55 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 56 __check_kvm_seq(mm); 57 } 58 59 #define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0) 60 61 #else 62 63 static inline void check_context(struct mm_struct *mm) 64 { 65 #ifdef CONFIG_MMU 66 if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq)) 67 __check_kvm_seq(mm); 68 #endif 69 } 70 71 #define init_new_context(tsk,mm) 0 72 73 #endif 74 75 #define destroy_context(mm) do { } while(0) 76 77 /* 78 * This is called when "tsk" is about to enter lazy TLB mode. 79 * 80 * mm: describes the currently active mm context 81 * tsk: task which is entering lazy tlb 82 * cpu: cpu number which is entering lazy tlb 83 * 84 * tsk->mm will be NULL 85 */ 86 static inline void 87 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 88 { 89 } 90 91 /* 92 * This is the actual mm switch as far as the scheduler 93 * is concerned. No registers are touched. We avoid 94 * calling the CPU specific function when the mm hasn't 95 * actually changed. 96 */ 97 static inline void 98 switch_mm(struct mm_struct *prev, struct mm_struct *next, 99 struct task_struct *tsk) 100 { 101 #ifdef CONFIG_MMU 102 unsigned int cpu = smp_processor_id(); 103 104 #ifdef CONFIG_SMP 105 /* check for possible thread migration */ 106 if (!cpus_empty(next->cpu_vm_mask) && !cpu_isset(cpu, next->cpu_vm_mask)) 107 __flush_icache_all(); 108 #endif 109 if (!cpu_test_and_set(cpu, next->cpu_vm_mask) || prev != next) { 110 check_context(next); 111 cpu_switch_mm(next->pgd, next); 112 if (cache_is_vivt()) 113 cpu_clear(cpu, prev->cpu_vm_mask); 114 } 115 #endif 116 } 117 118 #define deactivate_mm(tsk,mm) do { } while (0) 119 #define activate_mm(prev,next) switch_mm(prev, next, NULL) 120 121 #endif 122