1/* 2 * include/asm-xtensa/mmu_context.h 3 * 4 * Switch an MMU context. 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file "COPYING" in the main directory of this archive 8 * for more details. 9 * 10 * Copyright (C) 2001 - 2005 Tensilica Inc. 11 */ 12 13#ifndef _XTENSA_MMU_CONTEXT_H 14#define _XTENSA_MMU_CONTEXT_H 15 16#include <linux/stringify.h> 17#include <linux/sched.h> 18 19#include <asm/pgtable.h> 20#include <asm/cacheflush.h> 21#include <asm/tlbflush.h> 22#include <asm-generic/mm_hooks.h> 23 24#define XCHAL_MMU_ASID_BITS 8 25 26#if (XCHAL_HAVE_TLBS != 1) 27# error "Linux must have an MMU!" 28#endif 29 30extern unsigned long asid_cache; 31 32/* 33 * NO_CONTEXT is the invalid ASID value that we don't ever assign to 34 * any user or kernel context. 35 * 36 * 0 invalid 37 * 1 kernel 38 * 2 reserved 39 * 3 reserved 40 * 4...255 available 41 */ 42 43#define NO_CONTEXT 0 44#define ASID_USER_FIRST 4 45#define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1) 46#define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8)) 47 48static inline void set_rasid_register (unsigned long val) 49{ 50 __asm__ __volatile__ (" wsr %0, "__stringify(RASID)"\n\t" 51 " isync\n" : : "a" (val)); 52} 53 54static inline unsigned long get_rasid_register (void) 55{ 56 unsigned long tmp; 57 __asm__ __volatile__ (" rsr %0,"__stringify(RASID)"\n\t" : "=a" (tmp)); 58 return tmp; 59} 60 61static inline void 62__get_new_mmu_context(struct mm_struct *mm) 63{ 64 extern void flush_tlb_all(void); 65 if (! (++asid_cache & ASID_MASK) ) { 66 flush_tlb_all(); /* start new asid cycle */ 67 asid_cache += ASID_USER_FIRST; 68 } 69 mm->context = asid_cache; 70} 71 72static inline void 73__load_mmu_context(struct mm_struct *mm) 74{ 75 set_rasid_register(ASID_INSERT(mm->context)); 76 invalidate_page_directory(); 77} 78 79/* 80 * Initialize the context related info for a new mm_struct 81 * instance. 82 */ 83 84static inline int 85init_new_context(struct task_struct *tsk, struct mm_struct *mm) 86{ 87 mm->context = NO_CONTEXT; 88 return 0; 89} 90 91/* 92 * After we have set current->mm to a new value, this activates 93 * the context for the new mm so we see the new mappings. 94 */ 95static inline void 96activate_mm(struct mm_struct *prev, struct mm_struct *next) 97{ 98 /* Unconditionally get a new ASID. */ 99 100 __get_new_mmu_context(next); 101 __load_mmu_context(next); 102} 103 104 105static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 106 struct task_struct *tsk) 107{ 108 unsigned long asid = asid_cache; 109 110 /* Check if our ASID is of an older version and thus invalid */ 111 112 if (next->context == NO_CONTEXT || ((next->context^asid) & ~ASID_MASK)) 113 __get_new_mmu_context(next); 114 115 __load_mmu_context(next); 116} 117 118#define deactivate_mm(tsk, mm) do { } while(0) 119 120/* 121 * Destroy context related info for an mm_struct that is about 122 * to be put to rest. 123 */ 124static inline void destroy_context(struct mm_struct *mm) 125{ 126 invalidate_page_directory(); 127} 128 129 130static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 131{ 132 /* Nothing to do. */ 133 134} 135 136#endif /* _XTENSA_MMU_CONTEXT_H */ 137