kernel2/memkernel.c

   1 /*
   2     meinOS - A unix-like x86 microkernel operating system
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation, either version 3 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include <sys/types.h>
  20 #include <memkernel.h>
  21 #include <memuser.h>
  22 #include <memphys.h>
  23 #include <memmap.h>
  24 #include <paging.h>
  25 #include <malloc.h>
  26 #include <debug.h>
  27
  28 /**
  29  * Initializes kernel memory management
  30  *  @return 0=Success; -1=Failure
  31  */
  32 void *init_stack;
  33 size_t init_stacksize;
  34 void malloc_init(void *(*getpage)(size_t size),void (*freepage)(void *addr));
  35 void malloc_donatemem(void *addr,size_t size);
  36 int memkernel_init() {
  37   malloc_init(memkernel_alloc,memkernel_free);
  38   malloc_donatemem(init_stack,init_stacksize); // donate initial stack to memory allocator
  39   return 0;
  40 }
  41
  42 /**
  43  * Finds free virtual pages
  44  *  @param pages How many pages wanted
  45  *  @return Address of first page
  46  */
  47 void *memkernel_findvirt(size_t pages) {
  48   void *virt;
  49   size_t found = 0;
  50
  51   for (virt = (void*)KERNELDATA_ADDRESS;virt<(void*)KERNELDATA_ADDRESS+KERNELDATA_SIZE;virt+=PAGE_SIZE) {
  52     // check if enough pages are found
  53     if (found>=pages) return virt-found*PAGE_SIZE;
  54     if (ADDR2PTE(virt)==0) {
  55       // check for PDE
  56       if (!paging_getpde(virt).exists) {
  57         found += 1024;
  58         virt += 1024*(PAGE_SIZE-1);
  59         continue;
  60       }
  61     }
  62     // check for PTE
  63     if (paging_getpte(virt).exists) found = 0;
  64     else found++;
  65   }
  66
  67   return NULL;
  68 }
  69
  70 /**
  71  * Allocates memory for kernel allocator
  72  *  @param size How many memory to allocate (should be devidable by PAGE_SIZE)
  73  *  @return Address of allocated memory
  74  */
  75 void *memkernel_alloc(size_t size) {
  76   size_t pages = ADDR2PAGE(size);
  77   size_t i;
  78   void *virt = memkernel_findvirt(pages);
  79
  80   for (i=0;i<pages;i++) {
  81     paging_map(virt+i*PAGE_SIZE,memphys_alloc(),0,1);
  82     if (memuser_inited) memuser_syncpds(virt+i);
  83   }
  84   return virt;
  85 }
  86
  87 /**
  88  * Frees memory (one page) for kernel allocator
  89  */
  90 void memkernel_free(void *addr) {
  91   memphys_free(paging_unmap(addr));
  92 }