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
  17 #include <asm/uaccess.h>
  18 #include <asm/ia32.h>
  19 #include <asm/syscalls.h>
  20
  21 asmlinkage long sys_mmap(unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags,
  22         unsigned long fd, unsigned long off)
  23 {
  24         long error;
  25         struct file * file;
  26
  27         error = -EINVAL;
  28         if (off & ~PAGE_MASK)
  29                 goto out;
  30
  31         error = -EBADF;
  32         file = NULL;
  33         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
  34         if (!(flags & MAP_ANONYMOUS)) {
  35                 file = fget(fd);
  36                 if (!file)
  37                         goto out;
  38         }
  39         down_write(&current->mm->mmap_sem);
  40         error = do_mmap_pgoff(file, addr, len, prot, flags, off >> PAGE_SHIFT);
  41         up_write(&current->mm->mmap_sem);
  42
  43         if (file)
  44                 fput(file);
  45 out:
  46         return error;
  47 }
  48
  49 static void find_start_end(unsigned long flags, unsigned long *begin,
  50                            unsigned long *end)
  51 {
  52         if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT)) {
  53                 unsigned long new_begin;
  54                 /* This is usually used needed to map code in small
  55                    model, so it needs to be in the first 31bit. Limit
  56                    it to that.  This means we need to move the
  57                    unmapped base down for this case. This can give
  58                    conflicts with the heap, but we assume that glibc
  59                    malloc knows how to fall back to mmap. Give it 1GB
  60                    of playground for now. -AK */
  61                 *begin = 0x40000000;
  62                 *end = 0x80000000;
  63                 if (current->flags & PF_RANDOMIZE) {
  64                         new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
  65                         if (new_begin)
  66                                 *begin = new_begin;
  67                 }
  68         } else {
  69                 *begin = TASK_UNMAPPED_BASE;
  70                 *end = TASK_SIZE;
  71         }
  72 }
  73
  74 unsigned long
  75 arch_get_unmapped_area(struct file *filp, unsigned long addr,
  76                 unsigned long len, unsigned long pgoff, unsigned long flags)
  77 {
  78         struct mm_struct *mm = current->mm;
  79         struct vm_area_struct *vma;
  80         unsigned long start_addr;
  81         unsigned long begin, end;
  82
  83         if (flags & MAP_FIXED)
  84                 return addr;
  85
  86         find_start_end(flags, &begin, &end);
  87
  88         if (len > end)
  89                 return -ENOMEM;
  90
  91         if (addr) {
  92                 addr = PAGE_ALIGN(addr);
  93                 vma = find_vma(mm, addr);
  94                 if (end - len >= addr &&
  95                     (!vma || addr + len <= vma->vm_start))
  96                         return addr;
  97         }
  98         if (((flags & MAP_32BIT) || test_thread_flag(TIF_IA32))
  99             && len <= mm->cached_hole_size) {
 100                 mm->cached_hole_size = 0;
 101                 mm->free_area_cache = begin;
 102         }
 103         addr = mm->free_area_cache;
 104         if (addr < begin)
 105                 addr = begin;
 106         start_addr = addr;
 107
 108 full_search:
 109         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 110                 /* At this point:  (!vma || addr < vma->vm_end). */
 111                 if (end - len < addr) {
 112                         /*
 113                          * Start a new search - just in case we missed
 114                          * some holes.
 115                          */
 116                         if (start_addr != begin) {
 117                                 start_addr = addr = begin;
 118                                 mm->cached_hole_size = 0;
 119                                 goto full_search;
 120                         }
 121                         return -ENOMEM;
 122                 }
 123                 if (!vma || addr + len <= vma->vm_start) {
 124                         /*
 125                          * Remember the place where we stopped the search:
 126                          */
 127                         mm->free_area_cache = addr + len;
 128                         return addr;
 129                 }
 130                 if (addr + mm->cached_hole_size < vma->vm_start)
 131                         mm->cached_hole_size = vma->vm_start - addr;
 132
 133                 addr = vma->vm_end;
 134         }
 135 }
 136
 137
 138 unsigned long
 139 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 140                           const unsigned long len, const unsigned long pgoff,
 141                           const unsigned long flags)
 142 {
 143         struct vm_area_struct *vma;
 144         struct mm_struct *mm = current->mm;
 145         unsigned long addr = addr0;
 146
 147         /* requested length too big for entire address space */
 148         if (len > TASK_SIZE)
 149                 return -ENOMEM;
 150
 151         if (flags & MAP_FIXED)
 152                 return addr;
 153
 154         /* for MAP_32BIT mappings we force the legact mmap base */
 155         if (!test_thread_flag(TIF_IA32) && (flags & MAP_32BIT))
 156                 goto bottomup;
 157
 158         /* requesting a specific address */
 159         if (addr) {
 160                 addr = PAGE_ALIGN(addr);
 161                 vma = find_vma(mm, addr);
 162                 if (TASK_SIZE - len >= addr &&
 163                                 (!vma || addr + len <= vma->vm_start))
 164                         return addr;
 165         }
 166
 167         /* check if free_area_cache is useful for us */
 168         if (len <= mm->cached_hole_size) {
 169                 mm->cached_hole_size = 0;
 170                 mm->free_area_cache = mm->mmap_base;
 171         }
 172
 173         /* either no address requested or can't fit in requested address hole */
 174         addr = mm->free_area_cache;
 175
 176         /* make sure it can fit in the remaining address space */
 177         if (addr > len) {
 178                 vma = find_vma(mm, addr-len);
 179                 if (!vma || addr <= vma->vm_start)
 180                         /* remember the address as a hint for next time */
 181                         return (mm->free_area_cache = addr-len);
 182         }
 183
 184         if (mm->mmap_base < len)
 185                 goto bottomup;
 186
 187         addr = mm->mmap_base-len;
 188
 189         do {
 190                 /*
 191                  * Lookup failure means no vma is above this address,
 192                  * else if new region fits below vma->vm_start,
 193                  * return with success:
 194                  */
 195                 vma = find_vma(mm, addr);
 196                 if (!vma || addr+len <= vma->vm_start)
 197                         /* remember the address as a hint for next time */
 198                         return (mm->free_area_cache = addr);
 199
 200                 /* remember the largest hole we saw so far */
 201                 if (addr + mm->cached_hole_size < vma->vm_start)
 202                         mm->cached_hole_size = vma->vm_start - addr;
 203
 204                 /* try just below the current vma->vm_start */
 205                 addr = vma->vm_start-len;
 206         } while (len < vma->vm_start);
 207
 208 bottomup:
 209         /*
 210          * A failed mmap() very likely causes application failure,
 211          * so fall back to the bottom-up function here. This scenario
 212          * can happen with large stack limits and large mmap()
 213          * allocations.
 214          */
 215         mm->cached_hole_size = ~0UL;
 216         mm->free_area_cache = TASK_UNMAPPED_BASE;
 217         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 218         /*
 219          * Restore the topdown base:
 220          */
 221         mm->free_area_cache = mm->mmap_base;
 222         mm->cached_hole_size = ~0UL;
 223
 224         return addr;
 225 }
 226
 227
 228 asmlinkage long sys_uname(struct new_utsname __user * name)
 229 {
 230         int err;
 231         down_read(&uts_sem);
 232         err = copy_to_user(name, utsname(), sizeof (*name));
 233         up_read(&uts_sem);
 234         if (personality(current->personality) == PER_LINUX32)
 235                 err |= copy_to_user(&name->machine, "i686", 5);
 236         return err ? -EFAULT : 0;
 237 }