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 #include <linux/elf.h>
  18
  19 #include <asm/ia32.h>
  20 #include <asm/syscalls.h>
  21
  22 /*
  23  * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
  24  *
  25  * @flags denotes the allocation direction - bottomup or topdown -
  26  * or vDSO; see call sites below.
  27  */
  28 unsigned long align_addr(unsigned long addr, struct file *filp,
  29                          enum align_flags flags)
  30 {
  31         unsigned long tmp_addr;
  32
  33         /* handle 32- and 64-bit case with a single conditional */
  34         if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
  35                 return addr;
  36
  37         if (!(current->flags & PF_RANDOMIZE))
  38                 return addr;
  39
  40         if (!((flags & ALIGN_VDSO) || filp))
  41                 return addr;
  42
  43         tmp_addr = addr;
  44
  45         /*
  46          * We need an address which is <= than the original
  47          * one only when in topdown direction.
  48          */
  49         if (!(flags & ALIGN_TOPDOWN))
  50                 tmp_addr += va_align.mask;
  51
  52         tmp_addr &= ~va_align.mask;
  53
  54         return tmp_addr;
  55 }
  56
  57 static int __init control_va_addr_alignment(char *str)
  58 {
  59         /* guard against enabling this on other CPU families */
  60         if (va_align.flags < 0)
  61                 return 1;
  62
  63         if (*str == 0)
  64                 return 1;
  65
  66         if (*str == '=')
  67                 str++;
  68
  69         if (!strcmp(str, "32"))
  70                 va_align.flags = ALIGN_VA_32;
  71         else if (!strcmp(str, "64"))
  72                 va_align.flags = ALIGN_VA_64;
  73         else if (!strcmp(str, "off"))
  74                 va_align.flags = 0;
  75         else if (!strcmp(str, "on"))
  76                 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
  77         else
  78                 return 0;
  79
  80         return 1;
  81 }
  82 __setup("align_va_addr", control_va_addr_alignment);
  83
  84 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
  85                 unsigned long, prot, unsigned long, flags,
  86                 unsigned long, fd, unsigned long, off)
  87 {
  88         long error;
  89         error = -EINVAL;
  90         if (off & ~PAGE_MASK)
  91                 goto out;
  92
  93         error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
  94 out:
  95         return error;
  96 }
  97
  98 static void find_start_end(unsigned long flags, unsigned long *begin,
  99                            unsigned long *end)
 100 {
 101         if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
 102                 unsigned long new_begin;
 103                 /* This is usually used needed to map code in small
 104                    model, so it needs to be in the first 31bit. Limit
 105                    it to that.  This means we need to move the
 106                    unmapped base down for this case. This can give
 107                    conflicts with the heap, but we assume that glibc
 108                    malloc knows how to fall back to mmap. Give it 1GB
 109                    of playground for now. -AK */
 110                 *begin = 0x40000000;
 111                 *end = 0x80000000;
 112                 if (current->flags & PF_RANDOMIZE) {
 113                         new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
 114                         if (new_begin)
 115                                 *begin = new_begin;
 116                 }
 117         } else {
 118                 *begin = TASK_UNMAPPED_BASE;
 119                 *end = TASK_SIZE;
 120         }
 121 }
 122
 123 unsigned long
 124 arch_get_unmapped_area(struct file *filp, unsigned long addr,
 125                 unsigned long len, unsigned long pgoff, unsigned long flags)
 126 {
 127         struct mm_struct *mm = current->mm;
 128         struct vm_area_struct *vma;
 129         unsigned long start_addr;
 130         unsigned long begin, end;
 131
 132         if (flags & MAP_FIXED)
 133                 return addr;
 134
 135         find_start_end(flags, &begin, &end);
 136
 137         if (len > end)
 138                 return -ENOMEM;
 139
 140         if (addr) {
 141                 addr = PAGE_ALIGN(addr);
 142                 vma = find_vma(mm, addr);
 143                 if (end - len >= addr &&
 144                     (!vma || addr + len <= vma->vm_start))
 145                         return addr;
 146         }
 147         if (((flags & MAP_32BIT) || test_thread_flag(TIF_ADDR32))
 148             && len <= mm->cached_hole_size) {
 149                 mm->cached_hole_size = 0;
 150                 mm->free_area_cache = begin;
 151         }
 152         addr = mm->free_area_cache;
 153         if (addr < begin)
 154                 addr = begin;
 155         start_addr = addr;
 156
 157 full_search:
 158
 159         addr = align_addr(addr, filp, 0);
 160
 161         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 162                 /* At this point:  (!vma || addr < vma->vm_end). */
 163                 if (end - len < addr) {
 164                         /*
 165                          * Start a new search - just in case we missed
 166                          * some holes.
 167                          */
 168                         if (start_addr != begin) {
 169                                 start_addr = addr = begin;
 170                                 mm->cached_hole_size = 0;
 171                                 goto full_search;
 172                         }
 173                         return -ENOMEM;
 174                 }
 175                 if (!vma || addr + len <= vma->vm_start) {
 176                         /*
 177                          * Remember the place where we stopped the search:
 178                          */
 179                         mm->free_area_cache = addr + len;
 180                         return addr;
 181                 }
 182                 if (addr + mm->cached_hole_size < vma->vm_start)
 183                         mm->cached_hole_size = vma->vm_start - addr;
 184
 185                 addr = vma->vm_end;
 186                 addr = align_addr(addr, filp, 0);
 187         }
 188 }
 189
 190
 191 unsigned long
 192 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 193                           const unsigned long len, const unsigned long pgoff,
 194                           const unsigned long flags)
 195 {
 196         struct vm_area_struct *vma;
 197         struct mm_struct *mm = current->mm;
 198         unsigned long addr = addr0, start_addr;
 199
 200         /* requested length too big for entire address space */
 201         if (len > TASK_SIZE)
 202                 return -ENOMEM;
 203
 204         if (flags & MAP_FIXED)
 205                 return addr;
 206
 207         /* for MAP_32BIT mappings we force the legact mmap base */
 208         if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT))
 209                 goto bottomup;
 210
 211         /* requesting a specific address */
 212         if (addr) {
 213                 addr = PAGE_ALIGN(addr);
 214                 vma = find_vma(mm, addr);
 215                 if (TASK_SIZE - len >= addr &&
 216                                 (!vma || addr + len <= vma->vm_start))
 217                         return addr;
 218         }
 219
 220         /* check if free_area_cache is useful for us */
 221         if (len <= mm->cached_hole_size) {
 222                 mm->cached_hole_size = 0;
 223                 mm->free_area_cache = mm->mmap_base;
 224         }
 225
 226 try_again:
 227         /* either no address requested or can't fit in requested address hole */
 228         start_addr = addr = mm->free_area_cache;
 229
 230         if (addr < len)
 231                 goto fail;
 232
 233         addr -= len;
 234         do {
 235                 addr = align_addr(addr, filp, ALIGN_TOPDOWN);
 236
 237                 /*
 238                  * Lookup failure means no vma is above this address,
 239                  * else if new region fits below vma->vm_start,
 240                  * return with success:
 241                  */
 242                 vma = find_vma(mm, addr);
 243                 if (!vma || addr+len <= vma->vm_start)
 244                         /* remember the address as a hint for next time */
 245                         return mm->free_area_cache = addr;
 246
 247                 /* remember the largest hole we saw so far */
 248                 if (addr + mm->cached_hole_size < vma->vm_start)
 249                         mm->cached_hole_size = vma->vm_start - addr;
 250
 251                 /* try just below the current vma->vm_start */
 252                 addr = vma->vm_start-len;
 253         } while (len < vma->vm_start);
 254
 255 fail:
 256         /*
 257          * if hint left us with no space for the requested
 258          * mapping then try again:
 259          */
 260         if (start_addr != mm->mmap_base) {
 261                 mm->free_area_cache = mm->mmap_base;
 262                 mm->cached_hole_size = 0;
 263                 goto try_again;
 264         }
 265
 266 bottomup:
 267         /*
 268          * A failed mmap() very likely causes application failure,
 269          * so fall back to the bottom-up function here. This scenario
 270          * can happen with large stack limits and large mmap()
 271          * allocations.
 272          */
 273         mm->cached_hole_size = ~0UL;
 274         mm->free_area_cache = TASK_UNMAPPED_BASE;
 275         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 276         /*
 277          * Restore the topdown base:
 278          */
 279         mm->free_area_cache = mm->mmap_base;
 280         mm->cached_hole_size = ~0UL;
 281
 282         return addr;
 283 }