mm/vmalloc.c

   1 /*
   2  *  linux/mm/vmalloc.c
   3  *
   4  *  Copyright (C) 1993  Linus Torvalds
   5  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   6  *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
   7  */
   8
   9 #include <linux/malloc.h>
  10 #include <linux/vmalloc.h>
  11 #include <linux/spinlock.h>
  12
  13 #include <asm/uaccess.h>
  14 #include <asm/pgalloc.h>
  15
  16 rwlock_t vmlist_lock = RW_LOCK_UNLOCKED;
  17 struct vm_struct * vmlist = NULL;
  18
  19 static inline void free_area_pte(pmd_t * pmd, unsigned long address, unsigned long size)
  20 {
  21         pte_t * pte;
  22         unsigned long end;
  23
  24         if (pmd_none(*pmd))
  25                 return;
  26         if (pmd_bad(*pmd)) {
  27                 pmd_ERROR(*pmd);
  28                 pmd_clear(pmd);
  29                 return;
  30         }
  31         pte = pte_offset(pmd, address);
  32         address &= ~PMD_MASK;
  33         end = address + size;
  34         if (end > PMD_SIZE)
  35                 end = PMD_SIZE;
  36         do {
  37                 pte_t page = *pte;
  38                 pte_clear(pte);
  39                 address += PAGE_SIZE;
  40                 pte++;
  41                 if (pte_none(page))
  42                         continue;
  43                 if (pte_present(page)) {
  44                         unsigned long map_nr = pte_pagenr(page);
  45                         if ((map_nr < max_mapnr) &&
  46                                                 (!PageReserved(mem_map + map_nr)))
  47                                 __free_page(mem_map + map_nr);
  48                         continue;
  49                 }
  50                 printk(KERN_CRIT "Whee.. Swapped out page in kernel page table\n");
  51         } while (address < end);
  52 }
  53
  54 static inline void free_area_pmd(pgd_t * dir, unsigned long address, unsigned long size)
  55 {
  56         pmd_t * pmd;
  57         unsigned long end;
  58
  59         if (pgd_none(*dir))
  60                 return;
  61         if (pgd_bad(*dir)) {
  62                 pgd_ERROR(*dir);
  63                 pgd_clear(dir);
  64                 return;
  65         }
  66         pmd = pmd_offset(dir, address);
  67         address &= ~PGDIR_MASK;
  68         end = address + size;
  69         if (end > PGDIR_SIZE)
  70                 end = PGDIR_SIZE;
  71         do {
  72                 free_area_pte(pmd, address, end - address);
  73                 address = (address + PMD_SIZE) & PMD_MASK;
  74                 pmd++;
  75         } while (address < end);
  76 }
  77
  78 void vmfree_area_pages(unsigned long address, unsigned long size)
  79 {
  80         pgd_t * dir;
  81         unsigned long end = address + size;
  82
  83         dir = pgd_offset_k(address);
  84         flush_cache_all();
  85         do {
  86                 free_area_pmd(dir, address, end - address);
  87                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  88                 dir++;
  89         } while (address && (address < end));
  90         flush_tlb_all();
  91 }
  92
  93 static inline int alloc_area_pte (pte_t * pte, unsigned long address,
  94                         unsigned long size, int gfp_mask)
  95 {
  96         unsigned long end;
  97
  98         address &= ~PMD_MASK;
  99         end = address + size;
 100         if (end > PMD_SIZE)
 101                 end = PMD_SIZE;
 102         do {
 103                 struct page * page;
 104                 if (!pte_none(*pte))
 105                         printk(KERN_ERR "alloc_area_pte: page already exists\n");
 106                 page = alloc_page(gfp_mask);
 107                 if (!page)
 108                         return -ENOMEM;
 109                 set_pte(pte, mk_pte(page, PAGE_KERNEL));
 110                 address += PAGE_SIZE;
 111                 pte++;
 112         } while (address < end);
 113         return 0;
 114 }
 115
 116 static inline int alloc_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size, int gfp_mask)
 117 {
 118         unsigned long end;
 119
 120         address &= ~PGDIR_MASK;
 121         end = address + size;
 122         if (end > PGDIR_SIZE)
 123                 end = PGDIR_SIZE;
 124         do {
 125                 pte_t * pte = pte_alloc_kernel(pmd, address);
 126                 if (!pte)
 127                         return -ENOMEM;
 128                 if (alloc_area_pte(pte, address, end - address, gfp_mask))
 129                         return -ENOMEM;
 130                 address = (address + PMD_SIZE) & PMD_MASK;
 131                 pmd++;
 132         } while (address < end);
 133         return 0;
 134 }
 135
 136 inline int vmalloc_area_pages (unsigned long address,
 137                                         unsigned long size, int gfp_mask)
 138 {
 139         pgd_t * dir;
 140         unsigned long end = address + size;
 141
 142         dir = pgd_offset_k(address);
 143         flush_cache_all();
 144         do {
 145                 pmd_t *pmd;
 146                 pgd_t olddir = *dir;
 147
 148                 pmd = pmd_alloc_kernel(dir, address);
 149                 if (!pmd)
 150                         return -ENOMEM;
 151                 if (alloc_area_pmd(pmd, address, end - address, gfp_mask))
 152                         return -ENOMEM;
 153                 if (pgd_val(olddir) != pgd_val(*dir))
 154                         set_pgdir(address, *dir);
 155                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 156                 dir++;
 157         } while (address && (address < end));
 158         flush_tlb_all();
 159         return 0;
 160 }
 161
 162 struct vm_struct * get_vm_area(unsigned long size, unsigned long flags)
 163 {
 164         unsigned long addr;
 165         struct vm_struct **p, *tmp, *area;
 166
 167         area = (struct vm_struct *) kmalloc(sizeof(*area), GFP_KERNEL);
 168         if (!area)
 169                 return NULL;
 170         addr = VMALLOC_START;
 171         write_lock(&vmlist_lock);
 172         for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
 173                 if (size + addr < (unsigned long) tmp->addr)
 174                         break;
 175                 addr = tmp->size + (unsigned long) tmp->addr;
 176                 if (addr > VMALLOC_END-size) {
 177                         write_unlock(&vmlist_lock);
 178                         kfree(area);
 179                         return NULL;
 180                 }
 181         }
 182         area->flags = flags;
 183         area->addr = (void *)addr;
 184         area->size = size + PAGE_SIZE;
 185         area->next = *p;
 186         *p = area;
 187         write_unlock(&vmlist_lock);
 188         return area;
 189 }
 190
 191 void vfree(void * addr)
 192 {
 193         struct vm_struct **p, *tmp;
 194
 195         if (!addr)
 196                 return;
 197         if ((PAGE_SIZE-1) & (unsigned long) addr) {
 198                 printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
 199                 return;
 200         }
 201         write_lock(&vmlist_lock);
 202         for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 203                 if (tmp->addr == addr) {
 204                         *p = tmp->next;
 205                         vmfree_area_pages(VMALLOC_VMADDR(tmp->addr), tmp->size);
 206                         kfree(tmp);
 207                         write_unlock(&vmlist_lock);
 208                         return;
 209                 }
 210         }
 211         write_unlock(&vmlist_lock);
 212         printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", addr);
 213 }
 214
 215 void * __vmalloc (unsigned long size, int gfp_mask)
 216 {
 217         void * addr;
 218         struct vm_struct *area;
 219
 220         size = PAGE_ALIGN(size);
 221         if (!size || (size >> PAGE_SHIFT) > num_physpages) {
 222                 BUG();
 223                 return NULL;
 224         }
 225         area = get_vm_area(size, VM_ALLOC);
 226         if (!area) {
 227                 BUG();
 228                 return NULL;
 229         }
 230         addr = area->addr;
 231         if (vmalloc_area_pages(VMALLOC_VMADDR(addr), size, gfp_mask)) {
 232                 vfree(addr);
 233                 BUG();
 234                 return NULL;
 235         }
 236         return addr;
 237 }
 238
 239 long vread(char *buf, char *addr, unsigned long count)
 240 {
 241         struct vm_struct *tmp;
 242         char *vaddr, *buf_start = buf;
 243         unsigned long n;
 244
 245         /* Don't allow overflow */
 246         if ((unsigned long) addr + count < count)
 247                 count = -(unsigned long) addr;
 248
 249         read_lock(&vmlist_lock);
 250         for (tmp = vmlist; tmp; tmp = tmp->next) {
 251                 vaddr = (char *) tmp->addr;
 252                 if (addr >= vaddr + tmp->size - PAGE_SIZE)
 253                         continue;
 254                 while (addr < vaddr) {
 255                         if (count == 0)
 256                                 goto finished;
 257                         *buf = '\0';
 258                         buf++;
 259                         addr++;
 260                         count--;
 261                 }
 262                 n = vaddr + tmp->size - PAGE_SIZE - addr;
 263                 do {
 264                         if (count == 0)
 265                                 goto finished;
 266                         *buf = *addr;
 267                         buf++;
 268                         addr++;
 269                         count--;
 270                 } while (--n > 0);
 271         }
 272 finished:
 273         read_unlock(&vmlist_lock);
 274         return buf - buf_start;
 275 }