kernel/include/arch-x64/pagetable.h

   1 #ifndef _ARCH_PAGETABLE_H
   2 #define _ARCH_PAGETABLE_H
   3
   4 #include <lowlevel/misc.h>
   5 #include <lowlevel/atomic.h>
   6
   7 namespace Arch {
   8         union PTE {
   9                 typedef ulong Word;
  10
  11                 struct {
  12                         Word Valid:1;
  13                         Word Writeable:1;
  14                         Word User:1;
  15                         Word WriteThrough:1;
  16                         Word CacheDisable:1;
  17                         Word Accessed:1;
  18                         Word Dirty:1;
  19                         Word PageAttrTable:1;
  20                         Word Global:1;
  21                         Word Avail1:3;
  22                         Word Addr:40;
  23                         Word Avail2:11;
  24                         Word NoExec:1;
  25                 };
  26
  27                 Word raw;
  28
  29                 PTE(Word init) : raw(init)
  30                 {
  31                 }
  32
  33                 PTE() : raw(0)
  34                 {
  35                 }
  36
  37                 operator Word()
  38                 {
  39                         return raw;
  40                 }
  41
  42                 static Word addr_to_offset(Word addr, int shift)
  43                 {
  44                         int pages_per_table = page_size / sizeof(Word);
  45                         return (addr >> shift) & (pages_per_table - 1);
  46                 }
  47
  48                 Word pte_to_addr()
  49                 {
  50                         return raw & 0x000ffffffffff000;
  51                 }
  52
  53                 static PTE addr_to_pte(Word phys)
  54                 {
  55                         return phys & 0x000ffffffffff000;
  56                 }
  57
  58                 static void flags_to_pte(Mem::PTEFlags flagsin,
  59                                          Mem::PTEFlags maskin,
  60                                          PTE &flagsout,
  61                                          PTE &maskout)
  62                 {
  63                         maskout = ~0UL;
  64                         flagsout = 0;
  65
  66                         if (maskin.Valid) {
  67                                 maskout.Valid = 0;
  68                                 flagsout.Valid = flagsin.Valid;
  69                         }
  70
  71                         if (maskin.Writeable) {
  72                                 maskout.Writeable = 0;
  73                                 flagsout.Writeable = flagsin.Writeable;
  74                         }
  75
  76                         // FIXME: check for and enable NX support
  77                         if (0 && maskin.Executable) {
  78                                 maskout.NoExec = 0;
  79                                 flagsout.NoExec = !flagsin.Executable;
  80                         }
  81
  82                         if (maskin.User) {
  83                                 maskout.User = 0;
  84                                 flagsout.User = flagsin.User;
  85                         }
  86                 }
  87
  88                 Mem::PTEFlags pte_to_flags()
  89                 {
  90                         Mem::PTEFlags ret = 0;
  91
  92                         ret.Valid = Valid;
  93                         ret.User = User;
  94
  95                         if (Valid) {
  96                                 ret.Readable = 1;
  97                                 ret.Writeable = Writeable;
  98                                 ret.Executable = !NoExec;
  99                         }
 100
 101                         return ret;
 102                 }
 103
 104                 void set_pte(PTE *table, uint offset)
 105                 {
 106                         table[offset] = raw;
 107                 }
 108
 109                 PTE xchg_pte(PTE *table, uint offset)
 110                 {
 111                         return ll_xchg_long(reinterpret_cast<Word *>(&table[offset]), raw);
 112                 }
 113
 114                 bool valid_pte()
 115                 {
 116                         return Valid;
 117                 }
 118
 119                 bool dirty_pte()
 120                 {
 121                         return Dirty;
 122                 }
 123
 124                 static void invalidate_tlb_entry(Word addr)
 125                 {
 126                         ll_invalidate_tlb_entry(addr);
 127                 }
 128
 129                 enum {
 130                         page_size = Arch::page_size,
 131                         page_shift = Arch::page_shift,
 132
 133                         pages_per_table = page_size / sizeof(Word),
 134                         num_levels = 4,
 135                         shift_per_level = 9,
 136
 137                         // All "upper" addresses belong to the kernel.
 138
 139                         kmap_start = 256,
 140                         kmap_end = 511
 141                 };
 142         };
 143 }
 144
 145 #endif