kernel/arch/x64/mem.cc

   1 // arch/x64/mem.cc -- x64 misc. memory management
   2 //
   3 // This software is copyright (c) 2006 Scott Wood <scott@buserror.net>.
   4 //
   5 // Permission is hereby granted, free of charge, to any person obtaining a copy of
   6 // this software and associated documentation files (the "Software"), to deal with
   7 // the Software without restriction, including without limitation the rights to
   8 // use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
   9 // of the Software, and to permit persons to whom the Software is furnished to do
  10 // so, subject to the following condition:
  11 //
  12 // The above copyright notice and this permission notice shall be
  13 // included in all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  17 // FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  18 // CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
  21 // SOFTWARE.
  22
  23 #include <kern/kernel.h>
  24 #include <kern/mem.h>
  25 #include <kern/pagealloc.h>
  26 #include <kern/libc.h>
  27
  28 // Initial page tables have the first 4 MiB mapped, using large pages.
  29
  30 __attribute__((aligned(4096))) u64 x64_init_ptbl_l2[512] = {
  31         0x87,
  32         0x00200087,
  33 };
  34
  35 // The ORing of 7 into these entries will be done in entry.S;
  36 // doing it here causes the compiler to emit runtime code
  37 // to do it.
  38
  39 __attribute__((aligned(4096))) u64 x64_init_ptbl_l3[512] = {
  40         reinterpret_cast<u64>(x64_init_ptbl_l2) - KERNEL_START
  41 };
  42
  43 __attribute__((aligned(4096))) u64 x64_init_ptbl_l4[512] = {
  44         reinterpret_cast<u64>(x64_init_ptbl_l3) - KERNEL_START
  45 };
  46
  47 extern int _end;
  48
  49 using Mem::PageAllocZone;
  50
  51 namespace Arch {
  52         size_t mem_end;
  53
  54         PageAllocZone *pagezones[3];
  55
  56         namespace Priv {
  57                 PageAllocZone isadmazone, dma32zone, highzone;
  58
  59                 PageAllocZone *isadmazonelist[2] = { &isadmazone, NULL };
  60                 PageAllocZone *dma32zonelist[3];
  61                 PageAllocZone *normalzonelist[4];
  62         }
  63
  64         PageAllocZone **pagezonelists[3] = { Priv::normalzonelist,
  65                                              Priv::dma32zonelist,
  66                                              Priv::isadmazonelist };
  67
  68         uintptr_t next_free_bootmem = reinterpret_cast<uintptr_t>(&_end) -
  69                                       KERNEL_START + PHYSMEM_START;
  70
  71         namespace Priv {
  72                 void early_adjust_mappings()
  73                 {
  74                         using Mem::get_bootmem;
  75
  76                         // Clear low-address mappings and invalidate TLB
  77                         x64_init_ptbl_l4[0] = 0;
  78                         x64_init_ptbl_l3[0] = 0;
  79                         asm volatile("movq %0, %%cr3" : : "r" (kvirt_to_phys(x64_init_ptbl_l4)));
  80
  81                         // Mark the ktext mapping global now that it's not mapped at address
  82                         // zero.
  83
  84                         x64_init_ptbl_l2[0] |= 0x100;
  85                         x64_init_ptbl_l2[1] |= 0x100;
  86
  87                         u64 l3phys = kvirt_to_phys(get_bootmem(page_size, page_size));
  88                         u64 *l3 = static_cast<u64 *>(phys_to_ktext(l3phys));
  89                         bzero(l3, page_size);
  90                         x64_init_ptbl_l4[0x100] = l3phys | 7;
  91
  92                         u64 l2phys = kvirt_to_phys(get_bootmem(page_size, page_size));
  93                         u64 *l2 = static_cast<u64 *>(phys_to_ktext(l2phys));
  94                         bzero(l2, page_size);
  95                         l3[0] = l2phys | 7;
  96
  97                         // Map at least as much as is mapped in ktext, so that
  98                         // things like the VGA driver can use it early without
  99                         // having to know about phys_to_ktext, and so map_physmem
 100                         // doesn't need to special-case the use of phys_to_ktext
 101                         // for the first couple pages.
 102
 103                         l2[0] = 0x187;
 104                         l2[1] = 0x00200187;
 105                 }
 106
 107                 void map_physmem()
 108                 {
 109                         using Mem::get_bootmem;
 110
 111                         // phys_to_ktext can be used for the first
 112                         // 2MiB-minus-size-of-kernel of bootmem allocations.
 113
 114                         for (uintptr_t physpage = 2; physpage <= (mem_end - 1) / 512; physpage++)
 115                         {
 116                                 uintptr_t virtpage = physpage + (PHYSMEM_START >> 21);
 117
 118                                 u64 *l3;
 119                                 u64 l3phys = x64_init_ptbl_l4[(virtpage >> 18) & 511] &
 120                                              ~(page_size - 1);
 121
 122                                 if (!l3phys) {
 123                                         l3 = static_cast<u64 *>(get_bootmem(page_size, page_size));
 124                                         bzero(l3, page_size);
 125                                         x64_init_ptbl_l4[(virtpage >> 18) & 511] =
 126                                                 kvirt_to_phys(l3) | 7;
 127                                 } else {
 128                                         l3 = static_cast<u64 *>(phys_to_kvirt(l3phys));
 129                                 }
 130
 131                                 u64 *l2;
 132                                 u64 l2phys = l3[(virtpage >> 9) & 511] & ~(page_size - 1);
 133
 134                                 if (!l2phys) {
 135                                         l2 = static_cast<u64 *>(get_bootmem(page_size, page_size));
 136                                         bzero(l2, page_size);
 137                                         l3[(virtpage >> 9) & 511] = kvirt_to_phys(l2) | 7;
 138                                 } else {
 139                                         l2 = static_cast<u64 *>(phys_to_kvirt(l2phys));
 140                                 }
 141
 142                                 l2[virtpage & 511] = (physpage << 21) | 0x187;
 143                         }
 144
 145                         size_t pages_size = mem_end * sizeof(Mem::Page);
 146                         Mem::pages = static_cast<Mem::Page *>(get_bootmem(pages_size, 8));
 147                         Mem::last_page = Mem::pages + pages_size - 1;
 148                         bzero(Mem::pages, pages_size);
 149
 150                         int normal = 0, dma = 0;
 151                         uintptr_t highstart = highzonestart;
 152                         uintptr_t dma32start = dma32zonestart;
 153
 154                         if (mem_end > highstart) {
 155                                 normalzonelist[normal++] = &highzone;
 156                                 highzone.init(highstart, mem_end - highstart);
 157                         } else {
 158                                 highstart = mem_end;
 159                         }
 160
 161                         if (mem_end > dma32start) {
 162                                 normalzonelist[normal++] = &dma32zone;
 163                                 dma32zonelist[dma++] = &dma32zone;
 164                                 dma32zone.init(dma32start, highstart - dma32start);
 165                         } else {
 166                                 dma32start = mem_end;
 167                         }
 168
 169                         normalzonelist[normal++] = &isadmazone;
 170                         dma32zonelist[dma++] = &isadmazone;
 171
 172                         isadmazone.init(mem_start, dma32start);
 173                 }
 174         }
 175 }