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 30 extern 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 48 static 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 54 static 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 61 static 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 72 static 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 84 static inline int 85 init_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 */ 95 static inline void 96 activate_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 } 103 104 105 static 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 */ 124 static inline void destroy_context(struct mm_struct *mm) 125 { 126 invalidate_page_directory(); 127 } 128 129 130 static 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