1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __ALPHA_MMU_CONTEXT_H 3 #define __ALPHA_MMU_CONTEXT_H 4 5 /* 6 * get a new mmu context.. 7 * 8 * Copyright (C) 1996, Linus Torvalds 9 */ 10 11 #include <linux/mm_types.h> 12 #include <linux/sched.h> 13 14 #include <asm/machvec.h> 15 #include <asm/compiler.h> 16 #include <asm-generic/mm_hooks.h> 17 18 /* 19 * Force a context reload. This is needed when we change the page 20 * table pointer or when we update the ASN of the current process. 21 */ 22 23 /* Don't get into trouble with dueling __EXTERN_INLINEs. */ 24 #ifndef __EXTERN_INLINE 25 #include <asm/io.h> 26 #endif 27 28 29 static inline unsigned long 30 __reload_thread(struct pcb_struct *pcb) 31 { 32 register unsigned long a0 __asm__("$16"); 33 register unsigned long v0 __asm__("$0"); 34 35 a0 = virt_to_phys(pcb); 36 __asm__ __volatile__( 37 "call_pal %2 #__reload_thread" 38 : "=r"(v0), "=r"(a0) 39 : "i"(PAL_swpctx), "r"(a0) 40 : "$1", "$22", "$23", "$24", "$25"); 41 42 return v0; 43 } 44 45 46 /* 47 * The maximum ASN's the processor supports. On the EV4 this is 63 48 * but the PAL-code doesn't actually use this information. On the 49 * EV5 this is 127, and EV6 has 255. 50 * 51 * On the EV4, the ASNs are more-or-less useless anyway, as they are 52 * only used as an icache tag, not for TB entries. On the EV5 and EV6, 53 * ASN's also validate the TB entries, and thus make a lot more sense. 54 * 55 * The EV4 ASN's don't even match the architecture manual, ugh. And 56 * I quote: "If a processor implements address space numbers (ASNs), 57 * and the old PTE has the Address Space Match (ASM) bit clear (ASNs 58 * in use) and the Valid bit set, then entries can also effectively be 59 * made coherent by assigning a new, unused ASN to the currently 60 * running process and not reusing the previous ASN before calling the 61 * appropriate PALcode routine to invalidate the translation buffer (TB)". 62 * 63 * In short, the EV4 has a "kind of" ASN capability, but it doesn't actually 64 * work correctly and can thus not be used (explaining the lack of PAL-code 65 * support). 66 */ 67 #define EV4_MAX_ASN 63 68 #define EV5_MAX_ASN 127 69 #define EV6_MAX_ASN 255 70 71 #ifdef CONFIG_ALPHA_GENERIC 72 # define MAX_ASN (alpha_mv.max_asn) 73 #else 74 # ifdef CONFIG_ALPHA_EV4 75 # define MAX_ASN EV4_MAX_ASN 76 # elif defined(CONFIG_ALPHA_EV5) 77 # define MAX_ASN EV5_MAX_ASN 78 # else 79 # define MAX_ASN EV6_MAX_ASN 80 # endif 81 #endif 82 83 /* 84 * cpu_last_asn(processor): 85 * 63 0 86 * +-------------+----------------+--------------+ 87 * | asn version | this processor | hardware asn | 88 * +-------------+----------------+--------------+ 89 */ 90 91 #include <asm/smp.h> 92 #ifdef CONFIG_SMP 93 #define cpu_last_asn(cpuid) (cpu_data[cpuid].last_asn) 94 #else 95 extern unsigned long last_asn; 96 #define cpu_last_asn(cpuid) last_asn 97 #endif /* CONFIG_SMP */ 98 99 #define WIDTH_HARDWARE_ASN 8 100 #define ASN_FIRST_VERSION (1UL << WIDTH_HARDWARE_ASN) 101 #define HARDWARE_ASN_MASK ((1UL << WIDTH_HARDWARE_ASN) - 1) 102 103 /* 104 * NOTE! The way this is set up, the high bits of the "asn_cache" (and 105 * the "mm->context") are the ASN _version_ code. A version of 0 is 106 * always considered invalid, so to invalidate another process you only 107 * need to do "p->mm->context = 0". 108 * 109 * If we need more ASN's than the processor has, we invalidate the old 110 * user TLB's (tbiap()) and start a new ASN version. That will automatically 111 * force a new asn for any other processes the next time they want to 112 * run. 113 */ 114 115 #ifndef __EXTERN_INLINE 116 #define __EXTERN_INLINE extern inline 117 #define __MMU_EXTERN_INLINE 118 #endif 119 120 extern inline unsigned long 121 __get_new_mm_context(struct mm_struct *mm, long cpu) 122 { 123 unsigned long asn = cpu_last_asn(cpu); 124 unsigned long next = asn + 1; 125 126 if ((asn & HARDWARE_ASN_MASK) >= MAX_ASN) { 127 tbiap(); 128 imb(); 129 next = (asn & ~HARDWARE_ASN_MASK) + ASN_FIRST_VERSION; 130 } 131 cpu_last_asn(cpu) = next; 132 return next; 133 } 134 135 __EXTERN_INLINE void 136 ev5_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm, 137 struct task_struct *next) 138 { 139 /* Check if our ASN is of an older version, and thus invalid. */ 140 unsigned long asn; 141 unsigned long mmc; 142 long cpu = smp_processor_id(); 143 144 #ifdef CONFIG_SMP 145 cpu_data[cpu].asn_lock = 1; 146 barrier(); 147 #endif 148 asn = cpu_last_asn(cpu); 149 mmc = next_mm->context[cpu]; 150 if ((mmc ^ asn) & ~HARDWARE_ASN_MASK) { 151 mmc = __get_new_mm_context(next_mm, cpu); 152 next_mm->context[cpu] = mmc; 153 } 154 #ifdef CONFIG_SMP 155 else 156 cpu_data[cpu].need_new_asn = 1; 157 #endif 158 159 /* Always update the PCB ASN. Another thread may have allocated 160 a new mm->context (via flush_tlb_mm) without the ASN serial 161 number wrapping. We have no way to detect when this is needed. */ 162 task_thread_info(next)->pcb.asn = mmc & HARDWARE_ASN_MASK; 163 } 164 165 __EXTERN_INLINE void 166 ev4_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm, 167 struct task_struct *next) 168 { 169 /* As described, ASN's are broken for TLB usage. But we can 170 optimize for switching between threads -- if the mm is 171 unchanged from current we needn't flush. */ 172 /* ??? May not be needed because EV4 PALcode recognizes that 173 ASN's are broken and does a tbiap itself on swpctx, under 174 the "Must set ASN or flush" rule. At least this is true 175 for a 1992 SRM, reports Joseph Martin (jmartin@hlo.dec.com). 176 I'm going to leave this here anyway, just to Be Sure. -- r~ */ 177 if (prev_mm != next_mm) 178 tbiap(); 179 180 /* Do continue to allocate ASNs, because we can still use them 181 to avoid flushing the icache. */ 182 ev5_switch_mm(prev_mm, next_mm, next); 183 } 184 185 extern void __load_new_mm_context(struct mm_struct *); 186 187 #ifdef CONFIG_SMP 188 #define check_mmu_context() \ 189 do { \ 190 int cpu = smp_processor_id(); \ 191 cpu_data[cpu].asn_lock = 0; \ 192 barrier(); \ 193 if (cpu_data[cpu].need_new_asn) { \ 194 struct mm_struct * mm = current->active_mm; \ 195 cpu_data[cpu].need_new_asn = 0; \ 196 if (!mm->context[cpu]) \ 197 __load_new_mm_context(mm); \ 198 } \ 199 } while(0) 200 #else 201 #define check_mmu_context() do { } while(0) 202 #endif 203 204 __EXTERN_INLINE void 205 ev5_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm) 206 { 207 __load_new_mm_context(next_mm); 208 } 209 210 __EXTERN_INLINE void 211 ev4_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm) 212 { 213 __load_new_mm_context(next_mm); 214 tbiap(); 215 } 216 217 #define deactivate_mm(tsk,mm) do { } while (0) 218 219 #ifdef CONFIG_ALPHA_GENERIC 220 # define switch_mm(a,b,c) alpha_mv.mv_switch_mm((a),(b),(c)) 221 # define activate_mm(x,y) alpha_mv.mv_activate_mm((x),(y)) 222 #else 223 # ifdef CONFIG_ALPHA_EV4 224 # define switch_mm(a,b,c) ev4_switch_mm((a),(b),(c)) 225 # define activate_mm(x,y) ev4_activate_mm((x),(y)) 226 # else 227 # define switch_mm(a,b,c) ev5_switch_mm((a),(b),(c)) 228 # define activate_mm(x,y) ev5_activate_mm((x),(y)) 229 # endif 230 #endif 231 232 static inline int 233 init_new_context(struct task_struct *tsk, struct mm_struct *mm) 234 { 235 int i; 236 237 for_each_online_cpu(i) 238 mm->context[i] = 0; 239 if (tsk != current) 240 task_thread_info(tsk)->pcb.ptbr 241 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; 242 return 0; 243 } 244 245 extern inline void 246 destroy_context(struct mm_struct *mm) 247 { 248 /* Nothing to do. */ 249 } 250 251 static inline void 252 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) 253 { 254 task_thread_info(tsk)->pcb.ptbr 255 = ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT; 256 } 257 258 #ifdef __MMU_EXTERN_INLINE 259 #undef __EXTERN_INLINE 260 #undef __MMU_EXTERN_INLINE 261 #endif 262 263 #endif /* __ALPHA_MMU_CONTEXT_H */ 264