1/* 2 * PowerPC64 Segment Translation Support. 3 * 4 * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com 5 * Copyright (c) 2001 Dave Engebretsen 6 * 7 * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 */ 14 15#include <linux/memblock.h> 16 17#include <asm/pgtable.h> 18#include <asm/mmu.h> 19#include <asm/mmu_context.h> 20#include <asm/paca.h> 21#include <asm/cputable.h> 22#include <asm/prom.h> 23#include <asm/abs_addr.h> 24#include <asm/firmware.h> 25#include <asm/iseries/hv_call.h> 26 27struct stab_entry { 28 unsigned long esid_data; 29 unsigned long vsid_data; 30}; 31 32#define NR_STAB_CACHE_ENTRIES 8 33static DEFINE_PER_CPU(long, stab_cache_ptr); 34static DEFINE_PER_CPU(long [NR_STAB_CACHE_ENTRIES], stab_cache); 35 36/* 37 * Create a segment table entry for the given esid/vsid pair. 38 */ 39static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid) 40{ 41 unsigned long esid_data, vsid_data; 42 unsigned long entry, group, old_esid, castout_entry, i; 43 unsigned int global_entry; 44 struct stab_entry *ste, *castout_ste; 45 unsigned long kernel_segment = (esid << SID_SHIFT) >= PAGE_OFFSET; 46 47 vsid_data = vsid << STE_VSID_SHIFT; 48 esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V; 49 if (! kernel_segment) 50 esid_data |= STE_ESID_KS; 51 52 /* Search the primary group first. */ 53 global_entry = (esid & 0x1f) << 3; 54 ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7)); 55 56 /* Find an empty entry, if one exists. */ 57 for (group = 0; group < 2; group++) { 58 for (entry = 0; entry < 8; entry++, ste++) { 59 if (!(ste->esid_data & STE_ESID_V)) { 60 ste->vsid_data = vsid_data; 61 eieio(); 62 ste->esid_data = esid_data; 63 return (global_entry | entry); 64 } 65 } 66 /* Now search the secondary group. */ 67 global_entry = ((~esid) & 0x1f) << 3; 68 ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7)); 69 } 70 71 /* 72 * Could not find empty entry, pick one with a round robin selection. 73 * Search all entries in the two groups. 74 */ 75 castout_entry = get_paca()->stab_rr; 76 for (i = 0; i < 16; i++) { 77 if (castout_entry < 8) { 78 global_entry = (esid & 0x1f) << 3; 79 ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7)); 80 castout_ste = ste + castout_entry; 81 } else { 82 global_entry = ((~esid) & 0x1f) << 3; 83 ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7)); 84 castout_ste = ste + (castout_entry - 8); 85 } 86 87 /* Dont cast out the first kernel segment */ 88 if ((castout_ste->esid_data & ESID_MASK) != PAGE_OFFSET) 89 break; 90 91 castout_entry = (castout_entry + 1) & 0xf; 92 } 93 94 get_paca()->stab_rr = (castout_entry + 1) & 0xf; 95 96 /* Modify the old entry to the new value. */ 97 98 /* Force previous translations to complete. DRENG */ 99 asm volatile("isync" : : : "memory"); 100 101 old_esid = castout_ste->esid_data >> SID_SHIFT; 102 castout_ste->esid_data = 0; /* Invalidate old entry */ 103 104 asm volatile("sync" : : : "memory"); /* Order update */ 105 106 castout_ste->vsid_data = vsid_data; 107 eieio(); /* Order update */ 108 castout_ste->esid_data = esid_data; 109 110 asm volatile("slbie %0" : : "r" (old_esid << SID_SHIFT)); 111 /* Ensure completion of slbie */ 112 asm volatile("sync" : : : "memory"); 113 114 return (global_entry | (castout_entry & 0x7)); 115} 116 117/* 118 * Allocate a segment table entry for the given ea and mm 119 */ 120static int __ste_allocate(unsigned long ea, struct mm_struct *mm) 121{ 122 unsigned long vsid; 123 unsigned char stab_entry; 124 unsigned long offset; 125 126 /* Kernel or user address? */ 127 if (is_kernel_addr(ea)) { 128 vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M); 129 } else { 130 if ((ea >= TASK_SIZE_USER64) || (! mm)) 131 return 1; 132 133 vsid = get_vsid(mm->context.id, ea, MMU_SEGSIZE_256M); 134 } 135 136 stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid); 137 138 if (!is_kernel_addr(ea)) { 139 offset = __get_cpu_var(stab_cache_ptr); 140 if (offset < NR_STAB_CACHE_ENTRIES) 141 __get_cpu_var(stab_cache[offset++]) = stab_entry; 142 else 143 offset = NR_STAB_CACHE_ENTRIES+1; 144 __get_cpu_var(stab_cache_ptr) = offset; 145 146 /* Order update */ 147 asm volatile("sync":::"memory"); 148 } 149 150 return 0; 151} 152 153int ste_allocate(unsigned long ea) 154{ 155 return __ste_allocate(ea, current->mm); 156} 157 158/* 159 * Do the segment table work for a context switch: flush all user 160 * entries from the table, then preload some probably useful entries 161 * for the new task 162 */ 163void switch_stab(struct task_struct *tsk, struct mm_struct *mm) 164{ 165 struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr; 166 struct stab_entry *ste; 167 unsigned long offset; 168 unsigned long pc = KSTK_EIP(tsk); 169 unsigned long stack = KSTK_ESP(tsk); 170 unsigned long unmapped_base; 171 172 /* Force previous translations to complete. DRENG */ 173 asm volatile("isync" : : : "memory"); 174 175 /* 176 * We need interrupts hard-disabled here, not just soft-disabled, 177 * so that a PMU interrupt can't occur, which might try to access 178 * user memory (to get a stack trace) and possible cause an STAB miss 179 * which would update the stab_cache/stab_cache_ptr per-cpu variables. 180 */ 181 hard_irq_disable(); 182 183 offset = __get_cpu_var(stab_cache_ptr); 184 if (offset <= NR_STAB_CACHE_ENTRIES) { 185 int i; 186 187 for (i = 0; i < offset; i++) { 188 ste = stab + __get_cpu_var(stab_cache[i]); 189 ste->esid_data = 0; /* invalidate entry */ 190 } 191 } else { 192 unsigned long entry; 193 194 /* Invalidate all entries. */ 195 ste = stab; 196 197 /* Never flush the first entry. */ 198 ste += 1; 199 for (entry = 1; 200 entry < (HW_PAGE_SIZE / sizeof(struct stab_entry)); 201 entry++, ste++) { 202 unsigned long ea; 203 ea = ste->esid_data & ESID_MASK; 204 if (!is_kernel_addr(ea)) { 205 ste->esid_data = 0; 206 } 207 } 208 } 209 210 asm volatile("sync; slbia; sync":::"memory"); 211 212 __get_cpu_var(stab_cache_ptr) = 0; 213 214 /* Now preload some entries for the new task */ 215 if (test_tsk_thread_flag(tsk, TIF_32BIT)) 216 unmapped_base = TASK_UNMAPPED_BASE_USER32; 217 else 218 unmapped_base = TASK_UNMAPPED_BASE_USER64; 219 220 __ste_allocate(pc, mm); 221 222 if (GET_ESID(pc) == GET_ESID(stack)) 223 return; 224 225 __ste_allocate(stack, mm); 226 227 if ((GET_ESID(pc) == GET_ESID(unmapped_base)) 228 || (GET_ESID(stack) == GET_ESID(unmapped_base))) 229 return; 230 231 __ste_allocate(unmapped_base, mm); 232 233 /* Order update */ 234 asm volatile("sync" : : : "memory"); 235} 236 237/* 238 * Allocate segment tables for secondary CPUs. These must all go in 239 * the first (bolted) segment, so that do_stab_bolted won't get a 240 * recursive segment miss on the segment table itself. 241 */ 242void __init stabs_alloc(void) 243{ 244 int cpu; 245 246 if (cpu_has_feature(CPU_FTR_SLB)) 247 return; 248 249 for_each_possible_cpu(cpu) { 250 unsigned long newstab; 251 252 if (cpu == 0) 253 continue; /* stab for CPU 0 is statically allocated */ 254 255 newstab = memblock_alloc_base(HW_PAGE_SIZE, HW_PAGE_SIZE, 256 1<<SID_SHIFT); 257 newstab = (unsigned long)__va(newstab); 258 259 memset((void *)newstab, 0, HW_PAGE_SIZE); 260 261 paca[cpu].stab_addr = newstab; 262 paca[cpu].stab_real = virt_to_abs(newstab); 263 printk(KERN_INFO "Segment table for CPU %d at 0x%llx " 264 "virtual, 0x%llx absolute\n", 265 cpu, paca[cpu].stab_addr, paca[cpu].stab_real); 266 } 267} 268 269/* 270 * Build an entry for the base kernel segment and put it into 271 * the segment table or SLB. All other segment table or SLB 272 * entries are faulted in. 273 */ 274void stab_initialize(unsigned long stab) 275{ 276 unsigned long vsid = get_kernel_vsid(PAGE_OFFSET, MMU_SEGSIZE_256M); 277 unsigned long stabreal; 278 279 asm volatile("isync; slbia; isync":::"memory"); 280 make_ste(stab, GET_ESID(PAGE_OFFSET), vsid); 281 282 /* Order update */ 283 asm volatile("sync":::"memory"); 284 285 /* Set ASR */ 286 stabreal = get_paca()->stab_real | 0x1ul; 287 288#ifdef CONFIG_PPC_ISERIES 289 if (firmware_has_feature(FW_FEATURE_ISERIES)) { 290 HvCall1(HvCallBaseSetASR, stabreal); 291 return; 292 } 293#endif /* CONFIG_PPC_ISERIES */ 294 295 mtspr(SPRN_ASR, stabreal); 296} 297