arch/x86/kernel/sys_x86_64.c

   1 #include <linux/errno.h>
   2 #include <linux/sched.h>
   3 #include <linux/syscalls.h>
   4 #include <linux/mm.h>
   5 #include <linux/fs.h>
   6 #include <linux/smp.h>
   7 #include <linux/sem.h>
   8 #include <linux/msg.h>
   9 #include <linux/shm.h>
  10 #include <linux/stat.h>
  11 #include <linux/mman.h>
  12 #include <linux/file.h>
  13 #include <linux/utsname.h>
  14 #include <linux/personality.h>
  15 #include <linux/random.h>
  16 #include <linux/uaccess.h>
  17
  18 #include <asm/ia32.h>
  19 #include <asm/syscalls.h>
  20
  21 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
  22                 unsigned long, prot, unsigned long, flags,
  23                 unsigned long, fd, unsigned long, off)
  24 {
  25         long error;
  26         error = -EINVAL;
  27         if (off & ~PAGE_MASK)
  28                 goto out;
  29
  30         error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
  31 out:
  32         return error;
  33 }
  34
  35 static void find_start_end(unsigned long flags, unsigned long *begin,
  36                            unsigned long *end)
  37 {
  38         if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT)) {
  39                 unsigned long new_begin;
  40                 /* This is usually used needed to map code in small
  41                    model, so it needs to be in the first 31bit. Limit
  42                    it to that.  This means we need to move the
  43                    unmapped base down for this case. This can give
  44                    conflicts with the heap, but we assume that glibc
  45                    malloc knows how to fall back to mmap. Give it 1GB
  46                    of playground for now. -AK */
  47                 *begin = 0x40000000;
  48                 *end = 0x80000000;
  49                 if (current->flags & PF_RANDOMIZE) {
  50                         new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
  51                         if (new_begin)
  52                                 *begin = new_begin;
  53                 }
  54         } else {
  55                 *begin = TASK_UNMAPPED_BASE;
  56                 *end = TASK_SIZE;
  57         }
  58 }
  59
  60 unsigned long
  61 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  62                 unsigned long len, unsigned long pgoff, unsigned long flags)
  63 {
  64         struct mm_struct *mm = current->mm;
  65         struct vm_area_struct *vma;
  66         unsigned long start_addr;
  67         unsigned long begin, end;
  68
  69         if (flags & MAP_FIXED)
  70                 return addr;
  71
  72         find_start_end(flags, &begin, &end);
  73
  74         if (len > end)
  75                 return -ENOMEM;
  76
  77         if (addr) {
  78                 addr = PAGE_ALIGN(addr);
  79                 vma = find_vma(mm, addr);
  80                 if (end - len >= addr &&
  81                     (!vma || addr + len <= vma->vm_start))
  82                         return addr;
  83         }
  84         if (((flags & MAP_32BIT) || test_thread_flag(TIF_IA32))
  85             && len <= mm->cached_hole_size) {
  86                 mm->cached_hole_size = 0;
  87                 mm->free_area_cache = begin;
  88         }
  89         addr = mm->free_area_cache;
  90         if (addr < begin)
  91                 addr = begin;
  92         start_addr = addr;
  93
  94 full_search:
  95         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
  96                 /* At this point:  (!vma || addr < vma->vm_end). */
  97                 if (end - len < addr) {
  98                         /*
  99                          * Start a new search - just in case we missed
 100                          * some holes.
 101                          */
 102                         if (start_addr != begin) {
 103                                 start_addr = addr = begin;
 104                                 mm->cached_hole_size = 0;
 105                                 goto full_search;
 106                         }
 107                         return -ENOMEM;
 108                 }
 109                 if (!vma || addr + len <= vma->vm_start) {
 110                         /*
 111                          * Remember the place where we stopped the search:
 112                          */
 113                         mm->free_area_cache = addr + len;
 114                         return addr;
 115                 }
 116                 if (addr + mm->cached_hole_size < vma->vm_start)
 117                         mm->cached_hole_size = vma->vm_start - addr;
 118
 119                 addr = vma->vm_end;
 120         }
 121 }
 122
 123
 124 unsigned long
 125 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 126                           const unsigned long len, const unsigned long pgoff,
 127                           const unsigned long flags)
 128 {
 129         struct vm_area_struct *vma;
 130         struct mm_struct *mm = current->mm;
 131         unsigned long addr = addr0;
 132
 133         /* requested length too big for entire address space */
 134         if (len > TASK_SIZE)
 135                 return -ENOMEM;
 136
 137         if (flags & MAP_FIXED)
 138                 return addr;
 139
 140         /* for MAP_32BIT mappings we force the legact mmap base */
 141         if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT))
 142                 goto bottomup;
 143
 144         /* requesting a specific address */
 145         if (addr) {
 146                 addr = PAGE_ALIGN(addr);
 147                 vma = find_vma(mm, addr);
 148                 if (TASK_SIZE - len >= addr &&
 149                                 (!vma || addr + len <= vma->vm_start))
 150                         return addr;
 151         }
 152
 153         /* check if free_area_cache is useful for us */
 154         if (len <= mm->cached_hole_size) {
 155                 mm->cached_hole_size = 0;
 156                 mm->free_area_cache = mm->mmap_base;
 157         }
 158
 159         /* either no address requested or can't fit in requested address hole */
 160         addr = mm->free_area_cache;
 161
 162         /* make sure it can fit in the remaining address space */
 163         if (addr > len) {
 164                 vma = find_vma(mm, addr-len);
 165                 if (!vma || addr <= vma->vm_start)
 166                         /* remember the address as a hint for next time */
 167                         return mm->free_area_cache = addr-len;
 168         }
 169
 170         if (mm->mmap_base < len)
 171                 goto bottomup;
 172
 173         addr = mm->mmap_base-len;
 174
 175         do {
 176                 /*
 177                  * Lookup failure means no vma is above this address,
 178                  * else if new region fits below vma->vm_start,
 179                  * return with success:
 180                  */
 181                 vma = find_vma(mm, addr);
 182                 if (!vma || addr+len <= vma->vm_start)
 183                         /* remember the address as a hint for next time */
 184                         return mm->free_area_cache = addr;
 185
 186                 /* remember the largest hole we saw so far */
 187                 if (addr + mm->cached_hole_size < vma->vm_start)
 188                         mm->cached_hole_size = vma->vm_start - addr;
 189
 190                 /* try just below the current vma->vm_start */
 191                 addr = vma->vm_start-len;
 192         } while (len < vma->vm_start);
 193
 194 bottomup:
 195         /*
 196          * A failed mmap() very likely causes application failure,
 197          * so fall back to the bottom-up function here. This scenario
 198          * can happen with large stack limits and large mmap()
 199          * allocations.
 200          */
 201         mm->cached_hole_size = ~0UL;
 202         mm->free_area_cache = TASK_UNMAPPED_BASE;
 203         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 204         /*
 205          * Restore the topdown base:
 206          */
 207         mm->free_area_cache = mm->mmap_base;
 208         mm->cached_hole_size = ~0UL;
 209
 210         return addr;
 211 }