arch/powerpc/mm/slb.c

   1 /*
   2  * PowerPC64 SLB support.
   3  *
   4  * Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, IBM
   5  * Based on earlier code written by:
   6  * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
   7  *    Copyright (c) 2001 Dave Engebretsen
   8  * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
   9  *
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  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/cacheflush.h>
  23 #include <asm/smp.h>
  24 #include <linux/compiler.h>
  25 #include <asm/udbg.h>
  26 #include <asm/code-patching.h>
  27
  28
  29 extern void slb_allocate_realmode(unsigned long ea);
  30 extern void slb_allocate_user(unsigned long ea);
  31
  32 static void slb_allocate(unsigned long ea)
  33 {
  34         /* Currently, we do real mode for all SLBs including user, but
  35          * that will change if we bring back dynamic VSIDs
  36          */
  37         slb_allocate_realmode(ea);
  38 }
  39
  40 #define slb_esid_mask(ssize)    \
  41         (((ssize) == MMU_SEGSIZE_256M)? ESID_MASK: ESID_MASK_1T)
  42
  43 static inline unsigned long mk_esid_data(unsigned long ea, int ssize,
  44                                          unsigned long slot)
  45 {
  46         return (ea & slb_esid_mask(ssize)) | SLB_ESID_V | slot;
  47 }
  48
  49 #define slb_vsid_shift(ssize)   \
  50         ((ssize) == MMU_SEGSIZE_256M? SLB_VSID_SHIFT: SLB_VSID_SHIFT_1T)
  51
  52 static inline unsigned long mk_vsid_data(unsigned long ea, int ssize,
  53                                          unsigned long flags)
  54 {
  55         return (get_kernel_vsid(ea, ssize) << slb_vsid_shift(ssize)) | flags |
  56                 ((unsigned long) ssize << SLB_VSID_SSIZE_SHIFT);
  57 }
  58
  59 static inline void slb_shadow_update(unsigned long ea, int ssize,
  60                                      unsigned long flags,
  61                                      unsigned long entry)
  62 {
  63         /*
  64          * Clear the ESID first so the entry is not valid while we are
  65          * updating it.  No write barriers are needed here, provided
  66          * we only update the current CPU's SLB shadow buffer.
  67          */
  68         get_slb_shadow()->save_area[entry].esid = 0;
  69         get_slb_shadow()->save_area[entry].vsid = mk_vsid_data(ea, ssize, flags);
  70         get_slb_shadow()->save_area[entry].esid = mk_esid_data(ea, ssize, entry);
  71 }
  72
  73 static inline void slb_shadow_clear(unsigned long entry)
  74 {
  75         get_slb_shadow()->save_area[entry].esid = 0;
  76 }
  77
  78 static inline void create_shadowed_slbe(unsigned long ea, int ssize,
  79                                         unsigned long flags,
  80                                         unsigned long entry)
  81 {
  82         /*
  83          * Updating the shadow buffer before writing the SLB ensures
  84          * we don't get a stale entry here if we get preempted by PHYP
  85          * between these two statements.
  86          */
  87         slb_shadow_update(ea, ssize, flags, entry);
  88
  89         asm volatile("slbmte  %0,%1" :
  90                      : "r" (mk_vsid_data(ea, ssize, flags)),
  91                        "r" (mk_esid_data(ea, ssize, entry))
  92                      : "memory" );
  93 }
  94
  95 static void __slb_flush_and_rebolt(void)
  96 {
  97         /* If you change this make sure you change SLB_NUM_BOLTED
  98          * appropriately too. */
  99         unsigned long linear_llp, vmalloc_llp, lflags, vflags;
 100         unsigned long ksp_esid_data, ksp_vsid_data;
 101
 102         linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
 103         vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
 104         lflags = SLB_VSID_KERNEL | linear_llp;
 105         vflags = SLB_VSID_KERNEL | vmalloc_llp;
 106
 107         ksp_esid_data = mk_esid_data(get_paca()->kstack, mmu_kernel_ssize, 2);
 108         if ((ksp_esid_data & ~0xfffffffUL) <= PAGE_OFFSET) {
 109                 ksp_esid_data &= ~SLB_ESID_V;
 110                 ksp_vsid_data = 0;
 111                 slb_shadow_clear(2);
 112         } else {
 113                 /* Update stack entry; others don't change */
 114                 slb_shadow_update(get_paca()->kstack, mmu_kernel_ssize, lflags, 2);
 115                 ksp_vsid_data = get_slb_shadow()->save_area[2].vsid;
 116         }
 117
 118         /* We need to do this all in asm, so we're sure we don't touch
 119          * the stack between the slbia and rebolting it. */
 120         asm volatile("isync\n"
 121                      "slbia\n"
 122                      /* Slot 1 - first VMALLOC segment */
 123                      "slbmte    %0,%1\n"
 124                      /* Slot 2 - kernel stack */
 125                      "slbmte    %2,%3\n"
 126                      "isync"
 127                      :: "r"(mk_vsid_data(VMALLOC_START, mmu_kernel_ssize, vflags)),
 128                         "r"(mk_esid_data(VMALLOC_START, mmu_kernel_ssize, 1)),
 129                         "r"(ksp_vsid_data),
 130                         "r"(ksp_esid_data)
 131                      : "memory");
 132 }
 133
 134 void slb_flush_and_rebolt(void)
 135 {
 136
 137         WARN_ON(!irqs_disabled());
 138
 139         /*
 140          * We can't take a PMU exception in the following code, so hard
 141          * disable interrupts.
 142          */
 143         hard_irq_disable();
 144
 145         __slb_flush_and_rebolt();
 146         get_paca()->slb_cache_ptr = 0;
 147 }
 148
 149 void slb_vmalloc_update(void)
 150 {
 151         unsigned long vflags;
 152
 153         vflags = SLB_VSID_KERNEL | mmu_psize_defs[mmu_vmalloc_psize].sllp;
 154         slb_shadow_update(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
 155         slb_flush_and_rebolt();
 156 }
 157
 158 /* Helper function to compare esids.  There are four cases to handle.
 159  * 1. The system is not 1T segment size capable.  Use the GET_ESID compare.
 160  * 2. The system is 1T capable, both addresses are < 1T, use the GET_ESID compare.
 161  * 3. The system is 1T capable, only one of the two addresses is > 1T.  This is not a match.
 162  * 4. The system is 1T capable, both addresses are > 1T, use the GET_ESID_1T macro to compare.
 163  */
 164 static inline int esids_match(unsigned long addr1, unsigned long addr2)
 165 {
 166         int esid_1t_count;
 167
 168         /* System is not 1T segment size capable. */
 169         if (!mmu_has_feature(MMU_FTR_1T_SEGMENT))
 170                 return (GET_ESID(addr1) == GET_ESID(addr2));
 171
 172         esid_1t_count = (((addr1 >> SID_SHIFT_1T) != 0) +
 173                                 ((addr2 >> SID_SHIFT_1T) != 0));
 174
 175         /* both addresses are < 1T */
 176         if (esid_1t_count == 0)
 177                 return (GET_ESID(addr1) == GET_ESID(addr2));
 178
 179         /* One address < 1T, the other > 1T.  Not a match */
 180         if (esid_1t_count == 1)
 181                 return 0;
 182
 183         /* Both addresses are > 1T. */
 184         return (GET_ESID_1T(addr1) == GET_ESID_1T(addr2));
 185 }
 186
 187 /* Flush all user entries from the segment table of the current processor. */
 188 void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
 189 {
 190         unsigned long offset;
 191         unsigned long slbie_data = 0;
 192         unsigned long pc = KSTK_EIP(tsk);
 193         unsigned long stack = KSTK_ESP(tsk);
 194         unsigned long exec_base;
 195
 196         /*
 197          * We need interrupts hard-disabled here, not just soft-disabled,
 198          * so that a PMU interrupt can't occur, which might try to access
 199          * user memory (to get a stack trace) and possible cause an SLB miss
 200          * which would update the slb_cache/slb_cache_ptr fields in the PACA.
 201          */
 202         hard_irq_disable();
 203         offset = get_paca()->slb_cache_ptr;
 204         if (!mmu_has_feature(MMU_FTR_NO_SLBIE_B) &&
 205             offset <= SLB_CACHE_ENTRIES) {
 206                 int i;
 207                 asm volatile("isync" : : : "memory");
 208                 for (i = 0; i < offset; i++) {
 209                         slbie_data = (unsigned long)get_paca()->slb_cache[i]
 210                                 << SID_SHIFT; /* EA */
 211                         slbie_data |= user_segment_size(slbie_data)
 212                                 << SLBIE_SSIZE_SHIFT;
 213                         slbie_data |= SLBIE_C; /* C set for user addresses */
 214                         asm volatile("slbie %0" : : "r" (slbie_data));
 215                 }
 216                 asm volatile("isync" : : : "memory");
 217         } else {
 218                 __slb_flush_and_rebolt();
 219         }
 220
 221         /* Workaround POWER5 < DD2.1 issue */
 222         if (offset == 1 || offset > SLB_CACHE_ENTRIES)
 223                 asm volatile("slbie %0" : : "r" (slbie_data));
 224
 225         get_paca()->slb_cache_ptr = 0;
 226         get_paca()->context = mm->context;
 227
 228         /*
 229          * preload some userspace segments into the SLB.
 230          * Almost all 32 and 64bit PowerPC executables are linked at
 231          * 0x10000000 so it makes sense to preload this segment.
 232          */
 233         exec_base = 0x10000000;
 234
 235         if (is_kernel_addr(pc) || is_kernel_addr(stack) ||
 236             is_kernel_addr(exec_base))
 237                 return;
 238
 239         slb_allocate(pc);
 240
 241         if (!esids_match(pc, stack))
 242                 slb_allocate(stack);
 243
 244         if (!esids_match(pc, exec_base) &&
 245             !esids_match(stack, exec_base))
 246                 slb_allocate(exec_base);
 247 }
 248
 249 static inline void patch_slb_encoding(unsigned int *insn_addr,
 250                                       unsigned int immed)
 251 {
 252         int insn = (*insn_addr & 0xffff0000) | immed;
 253         patch_instruction(insn_addr, insn);
 254 }
 255
 256 void slb_set_size(u16 size)
 257 {
 258         extern unsigned int *slb_compare_rr_to_size;
 259
 260         if (mmu_slb_size == size)
 261                 return;
 262
 263         mmu_slb_size = size;
 264         patch_slb_encoding(slb_compare_rr_to_size, mmu_slb_size);
 265 }
 266
 267 void slb_initialize(void)
 268 {
 269         unsigned long linear_llp, vmalloc_llp, io_llp;
 270         unsigned long lflags, vflags;
 271         static int slb_encoding_inited;
 272         extern unsigned int *slb_miss_kernel_load_linear;
 273         extern unsigned int *slb_miss_kernel_load_io;
 274         extern unsigned int *slb_compare_rr_to_size;
 275 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 276         extern unsigned int *slb_miss_kernel_load_vmemmap;
 277         unsigned long vmemmap_llp;
 278 #endif
 279
 280         /* Prepare our SLB miss handler based on our page size */
 281         linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
 282         io_llp = mmu_psize_defs[mmu_io_psize].sllp;
 283         vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
 284         get_paca()->vmalloc_sllp = SLB_VSID_KERNEL | vmalloc_llp;
 285 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 286         vmemmap_llp = mmu_psize_defs[mmu_vmemmap_psize].sllp;
 287 #endif
 288         if (!slb_encoding_inited) {
 289                 slb_encoding_inited = 1;
 290                 patch_slb_encoding(slb_miss_kernel_load_linear,
 291                                    SLB_VSID_KERNEL | linear_llp);
 292                 patch_slb_encoding(slb_miss_kernel_load_io,
 293                                    SLB_VSID_KERNEL | io_llp);
 294                 patch_slb_encoding(slb_compare_rr_to_size,
 295                                    mmu_slb_size);
 296
 297                 pr_devel("SLB: linear  LLP = %04lx\n", linear_llp);
 298                 pr_devel("SLB: io      LLP = %04lx\n", io_llp);
 299
 300 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 301                 patch_slb_encoding(slb_miss_kernel_load_vmemmap,
 302                                    SLB_VSID_KERNEL | vmemmap_llp);
 303                 pr_devel("SLB: vmemmap LLP = %04lx\n", vmemmap_llp);
 304 #endif
 305         }
 306
 307         get_paca()->stab_rr = SLB_NUM_BOLTED;
 308
 309         lflags = SLB_VSID_KERNEL | linear_llp;
 310         vflags = SLB_VSID_KERNEL | vmalloc_llp;
 311
 312         /* Invalidate the entire SLB (even slot 0) & all the ERATS */
 313         asm volatile("isync":::"memory");
 314         asm volatile("slbmte  %0,%0"::"r" (0) : "memory");
 315         asm volatile("isync; slbia; isync":::"memory");
 316         create_shadowed_slbe(PAGE_OFFSET, mmu_kernel_ssize, lflags, 0);
 317
 318         create_shadowed_slbe(VMALLOC_START, mmu_kernel_ssize, vflags, 1);
 319
 320         /* For the boot cpu, we're running on the stack in init_thread_union,
 321          * which is in the first segment of the linear mapping, and also
 322          * get_paca()->kstack hasn't been initialized yet.
 323          * For secondary cpus, we need to bolt the kernel stack entry now.
 324          */
 325         slb_shadow_clear(2);
 326         if (raw_smp_processor_id() != boot_cpuid &&
 327             (get_paca()->kstack & slb_esid_mask(mmu_kernel_ssize)) > PAGE_OFFSET)
 328                 create_shadowed_slbe(get_paca()->kstack,
 329                                      mmu_kernel_ssize, lflags, 2);
 330
 331         asm volatile("isync":::"memory");
 332 }