arch/ia64/include/asm/tlb.h

   1 #ifndef _ASM_IA64_TLB_H
   2 #define _ASM_IA64_TLB_H
   3 /*
   4  * Based on <asm-generic/tlb.h>.
   5  *
   6  * Copyright (C) 2002-2003 Hewlett-Packard Co
   7  *      David Mosberger-Tang <davidm@hpl.hp.com>
   8  */
   9 /*
  10  * Removing a translation from a page table (including TLB-shootdown) is a four-step
  11  * procedure:
  12  *
  13  *      (1) Flush (virtual) caches --- ensures virtual memory is coherent with kernel memory
  14  *          (this is a no-op on ia64).
  15  *      (2) Clear the relevant portions of the page-table
  16  *      (3) Flush the TLBs --- ensures that stale content is gone from CPU TLBs
  17  *      (4) Release the pages that were freed up in step (2).
  18  *
  19  * Note that the ordering of these steps is crucial to avoid races on MP machines.
  20  *
  21  * The Linux kernel defines several platform-specific hooks for TLB-shootdown.  When
  22  * unmapping a portion of the virtual address space, these hooks are called according to
  23  * the following template:
  24  *
  25  *      tlb <- tlb_gather_mmu(mm, full_mm_flush);       // start unmap for address space MM
  26  *      {
  27  *        for each vma that needs a shootdown do {
  28  *          tlb_start_vma(tlb, vma);
  29  *            for each page-table-entry PTE that needs to be removed do {
  30  *              tlb_remove_tlb_entry(tlb, pte, address);
  31  *              if (pte refers to a normal page) {
  32  *                tlb_remove_page(tlb, page);
  33  *              }
  34  *            }
  35  *          tlb_end_vma(tlb, vma);
  36  *        }
  37  *      }
  38  *      tlb_finish_mmu(tlb, start, end);        // finish unmap for address space MM
  39  */
  40 #include <linux/mm.h>
  41 #include <linux/pagemap.h>
  42 #include <linux/swap.h>
  43
  44 #include <asm/pgalloc.h>
  45 #include <asm/processor.h>
  46 #include <asm/tlbflush.h>
  47 #include <asm/machvec.h>
  48
  49 #ifdef CONFIG_SMP
  50 # define FREE_PTE_NR            2048
  51 # define tlb_fast_mode(tlb)     ((tlb)->nr == ~0U)
  52 #else
  53 # define FREE_PTE_NR            0
  54 # define tlb_fast_mode(tlb)     (1)
  55 #endif
  56
  57 struct mmu_gather {
  58         struct mm_struct        *mm;
  59         unsigned int            nr;             /* == ~0U => fast mode */
  60         unsigned char           fullmm;         /* non-zero means full mm flush */
  61         unsigned char           need_flush;     /* really unmapped some PTEs? */
  62         unsigned long           start_addr;
  63         unsigned long           end_addr;
  64         struct page             *pages[FREE_PTE_NR];
  65 };
  66
  67 struct ia64_tr_entry {
  68         u64 ifa;
  69         u64 itir;
  70         u64 pte;
  71         u64 rr;
  72 }; /*Record for tr entry!*/
  73
  74 extern int ia64_itr_entry(u64 target_mask, u64 va, u64 pte, u64 log_size);
  75 extern void ia64_ptr_entry(u64 target_mask, int slot);
  76
  77 extern struct ia64_tr_entry __per_cpu_idtrs[NR_CPUS][2][IA64_TR_ALLOC_MAX];
  78
  79 /*
  80  region register macros
  81 */
  82 #define RR_TO_VE(val)   (((val) >> 0) & 0x0000000000000001)
  83 #define RR_VE(val)      (((val) & 0x0000000000000001) << 0)
  84 #define RR_VE_MASK      0x0000000000000001L
  85 #define RR_VE_SHIFT     0
  86 #define RR_TO_PS(val)   (((val) >> 2) & 0x000000000000003f)
  87 #define RR_PS(val)      (((val) & 0x000000000000003f) << 2)
  88 #define RR_PS_MASK      0x00000000000000fcL
  89 #define RR_PS_SHIFT     2
  90 #define RR_RID_MASK     0x00000000ffffff00L
  91 #define RR_TO_RID(val)  ((val >> 8) & 0xffffff)
  92
  93 /* Users of the generic TLB shootdown code must declare this storage space. */
  94 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
  95
  96 /*
  97  * Flush the TLB for address range START to END and, if not in fast mode, release the
  98  * freed pages that where gathered up to this point.
  99  */
 100 static inline void
 101 ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
 102 {
 103         unsigned int nr;
 104
 105         if (!tlb->need_flush)
 106                 return;
 107         tlb->need_flush = 0;
 108
 109         if (tlb->fullmm) {
 110                 /*
 111                  * Tearing down the entire address space.  This happens both as a result
 112                  * of exit() and execve().  The latter case necessitates the call to
 113                  * flush_tlb_mm() here.
 114                  */
 115                 flush_tlb_mm(tlb->mm);
 116         } else if (unlikely (end - start >= 1024*1024*1024*1024UL
 117                              || REGION_NUMBER(start) != REGION_NUMBER(end - 1)))
 118         {
 119                 /*
 120                  * If we flush more than a tera-byte or across regions, we're probably
 121                  * better off just flushing the entire TLB(s).  This should be very rare
 122                  * and is not worth optimizing for.
 123                  */
 124                 flush_tlb_all();
 125         } else {
 126                 /*
 127                  * XXX fix me: flush_tlb_range() should take an mm pointer instead of a
 128                  * vma pointer.
 129                  */
 130                 struct vm_area_struct vma;
 131
 132                 vma.vm_mm = tlb->mm;
 133                 /* flush the address range from the tlb: */
 134                 flush_tlb_range(&vma, start, end);
 135                 /* now flush the virt. page-table area mapping the address range: */
 136                 flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end));
 137         }
 138
 139         /* lastly, release the freed pages */
 140         nr = tlb->nr;
 141         if (!tlb_fast_mode(tlb)) {
 142                 unsigned long i;
 143                 tlb->nr = 0;
 144                 tlb->start_addr = ~0UL;
 145                 for (i = 0; i < nr; ++i)
 146                         free_page_and_swap_cache(tlb->pages[i]);
 147         }
 148 }
 149
 150 /*
 151  * Return a pointer to an initialized struct mmu_gather.
 152  */
 153 static inline struct mmu_gather *
 154 tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
 155 {
 156         struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
 157
 158         tlb->mm = mm;
 159         /*
 160          * Use fast mode if only 1 CPU is online.
 161          *
 162          * It would be tempting to turn on fast-mode for full_mm_flush as well.  But this
 163          * doesn't work because of speculative accesses and software prefetching: the page
 164          * table of "mm" may (and usually is) the currently active page table and even
 165          * though the kernel won't do any user-space accesses during the TLB shoot down, a
 166          * compiler might use speculation or lfetch.fault on what happens to be a valid
 167          * user-space address.  This in turn could trigger a TLB miss fault (or a VHPT
 168          * walk) and re-insert a TLB entry we just removed.  Slow mode avoids such
 169          * problems.  (We could make fast-mode work by switching the current task to a
 170          * different "mm" during the shootdown.) --davidm 08/02/2002
 171          */
 172         tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
 173         tlb->fullmm = full_mm_flush;
 174         tlb->start_addr = ~0UL;
 175         return tlb;
 176 }
 177
 178 /*
 179  * Called at the end of the shootdown operation to free up any resources that were
 180  * collected.
 181  */
 182 static inline void
 183 tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
 184 {
 185         /*
 186          * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
 187          * tlb->end_addr.
 188          */
 189         ia64_tlb_flush_mmu(tlb, start, end);
 190
 191         /* keep the page table cache within bounds */
 192         check_pgt_cache();
 193
 194         put_cpu_var(mmu_gathers);
 195 }
 196
 197 /*
 198  * Logically, this routine frees PAGE.  On MP machines, the actual freeing of the page
 199  * must be delayed until after the TLB has been flushed (see comments at the beginning of
 200  * this file).
 201  */
 202 static inline void
 203 tlb_remove_page (struct mmu_gather *tlb, struct page *page)
 204 {
 205         tlb->need_flush = 1;
 206
 207         if (tlb_fast_mode(tlb)) {
 208                 free_page_and_swap_cache(page);
 209                 return;
 210         }
 211         tlb->pages[tlb->nr++] = page;
 212         if (tlb->nr >= FREE_PTE_NR)
 213                 ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
 214 }
 215
 216 /*
 217  * Remove TLB entry for PTE mapped at virtual address ADDRESS.  This is called for any
 218  * PTE, not just those pointing to (normal) physical memory.
 219  */
 220 static inline void
 221 __tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
 222 {
 223         if (tlb->start_addr == ~0UL)
 224                 tlb->start_addr = address;
 225         tlb->end_addr = address + PAGE_SIZE;
 226 }
 227
 228 #define tlb_migrate_finish(mm)  platform_tlb_migrate_finish(mm)
 229
 230 #define tlb_start_vma(tlb, vma)                 do { } while (0)
 231 #define tlb_end_vma(tlb, vma)                   do { } while (0)
 232
 233 #define tlb_remove_tlb_entry(tlb, ptep, addr)           \
 234 do {                                                    \
 235         tlb->need_flush = 1;                            \
 236         __tlb_remove_tlb_entry(tlb, ptep, addr);        \
 237 } while (0)
 238
 239 #define pte_free_tlb(tlb, ptep, address)                \
 240 do {                                                    \
 241         tlb->need_flush = 1;                            \
 242         __pte_free_tlb(tlb, ptep, address);             \
 243 } while (0)
 244
 245 #define pmd_free_tlb(tlb, ptep, address)                \
 246 do {                                                    \
 247         tlb->need_flush = 1;                            \
 248         __pmd_free_tlb(tlb, ptep, address);             \
 249 } while (0)
 250
 251 #define pud_free_tlb(tlb, pudp, address)                \
 252 do {                                                    \
 253         tlb->need_flush = 1;                            \
 254         __pud_free_tlb(tlb, pudp, address);             \
 255 } while (0)
 256
 257 #endif /* _ASM_IA64_TLB_H */