1 /* 2 * Switch an MMU context. 3 * 4 * This file is subject to the terms and conditions of the GNU General Public 5 * License. See the file "COPYING" in the main directory of this archive 6 * for more details. 7 * 8 * Copyright (C) 2001 - 2013 Tensilica Inc. 9 */ 10 11 #ifndef _XTENSA_MMU_CONTEXT_H 12 #define _XTENSA_MMU_CONTEXT_H 13 14 #ifndef CONFIG_MMU 15 #include <asm/nommu_context.h> 16 #else 17 18 #include <linux/stringify.h> 19 #include <linux/sched.h> 20 #include <linux/mm_types.h> 21 22 #include <asm/vectors.h> 23 24 #include <asm/pgtable.h> 25 #include <asm/cacheflush.h> 26 #include <asm/tlbflush.h> 27 #include <asm-generic/mm_hooks.h> 28 #include <asm-generic/percpu.h> 29 30 #if (XCHAL_HAVE_TLBS != 1) 31 # error "Linux must have an MMU!" 32 #endif 33 34 DECLARE_PER_CPU(unsigned long, asid_cache); 35 #define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu) 36 37 /* 38 * NO_CONTEXT is the invalid ASID value that we don't ever assign to 39 * any user or kernel context. We use the reserved values in the 40 * ASID_INSERT macro below. 41 * 42 * 0 invalid 43 * 1 kernel 44 * 2 reserved 45 * 3 reserved 46 * 4...255 available 47 */ 48 49 #define NO_CONTEXT 0 50 #define ASID_USER_FIRST 4 51 #define ASID_MASK ((1 << XCHAL_MMU_ASID_BITS) - 1) 52 #define ASID_INSERT(x) (0x03020001 | (((x) & ASID_MASK) << 8)) 53 54 void init_mmu(void); 55 void init_kio(void); 56 57 static inline void set_rasid_register (unsigned long val) 58 { 59 __asm__ __volatile__ (" wsr %0, rasid\n\t" 60 " isync\n" : : "a" (val)); 61 } 62 63 static inline unsigned long get_rasid_register (void) 64 { 65 unsigned long tmp; 66 __asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp)); 67 return tmp; 68 } 69 70 static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu) 71 { 72 unsigned long asid = cpu_asid_cache(cpu); 73 if ((++asid & ASID_MASK) == 0) { 74 /* 75 * Start new asid cycle; continue counting with next 76 * incarnation bits; skipping over 0, 1, 2, 3. 77 */ 78 local_flush_tlb_all(); 79 asid += ASID_USER_FIRST; 80 } 81 cpu_asid_cache(cpu) = asid; 82 mm->context.asid[cpu] = asid; 83 mm->context.cpu = cpu; 84 } 85 86 static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu) 87 { 88 /* 89 * Check if our ASID is of an older version and thus invalid. 90 */ 91 92 if (mm) { 93 unsigned long asid = mm->context.asid[cpu]; 94 95 if (asid == NO_CONTEXT || 96 ((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK)) 97 get_new_mmu_context(mm, cpu); 98 } 99 } 100 101 static inline void activate_context(struct mm_struct *mm, unsigned int cpu) 102 { 103 get_mmu_context(mm, cpu); 104 set_rasid_register(ASID_INSERT(mm->context.asid[cpu])); 105 invalidate_page_directory(); 106 } 107 108 /* 109 * Initialize the context related info for a new mm_struct 110 * instance. Valid cpu values are 0..(NR_CPUS-1), so initializing 111 * to -1 says the process has never run on any core. 112 */ 113 114 static inline int init_new_context(struct task_struct *tsk, 115 struct mm_struct *mm) 116 { 117 int cpu; 118 for_each_possible_cpu(cpu) { 119 mm->context.asid[cpu] = NO_CONTEXT; 120 } 121 mm->context.cpu = -1; 122 return 0; 123 } 124 125 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 126 struct task_struct *tsk) 127 { 128 unsigned int cpu = smp_processor_id(); 129 int migrated = next->context.cpu != cpu; 130 /* Flush the icache if we migrated to a new core. */ 131 if (migrated) { 132 __invalidate_icache_all(); 133 next->context.cpu = cpu; 134 } 135 if (migrated || prev != next) 136 activate_context(next, cpu); 137 } 138 139 #define activate_mm(prev, next) switch_mm((prev), (next), NULL) 140 #define deactivate_mm(tsk, mm) do { } while (0) 141 142 /* 143 * Destroy context related info for an mm_struct that is about 144 * to be put to rest. 145 */ 146 static inline void destroy_context(struct mm_struct *mm) 147 { 148 invalidate_page_directory(); 149 } 150 151 152 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 153 { 154 /* Nothing to do. */ 155 156 } 157 158 #endif /* CONFIG_MMU */ 159 #endif /* _XTENSA_MMU_CONTEXT_H */ 160