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 static unsigned long get_align_mask(void)
  26 {
  27         /* handle 32- and 64-bit case with a single conditional */
  28         if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
  29                 return 0;
  30
  31         if (!(current->flags & PF_RANDOMIZE))
  32                 return 0;
  33
  34         return va_align.mask;
  35 }
  36
  37 unsigned long align_vdso_addr(unsigned long addr)
  38 {
  39         unsigned long align_mask = get_align_mask();
  40         return (addr + align_mask) & ~align_mask;
  41 }
  42
  43 static int __init control_va_addr_alignment(char *str)
  44 {
  45         /* guard against enabling this on other CPU families */
  46         if (va_align.flags < 0)
  47                 return 1;
  48
  49         if (*str == 0)
  50                 return 1;
  51
  52         if (*str == '=')
  53                 str++;
  54
  55         if (!strcmp(str, "32"))
  56                 va_align.flags = ALIGN_VA_32;
  57         else if (!strcmp(str, "64"))
  58                 va_align.flags = ALIGN_VA_64;
  59         else if (!strcmp(str, "off"))
  60                 va_align.flags = 0;
  61         else if (!strcmp(str, "on"))
  62                 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
  63         else
  64                 return 0;
  65
  66         return 1;
  67 }
  68 __setup("align_va_addr", control_va_addr_alignment);
  69
  70 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
  71                 unsigned long, prot, unsigned long, flags,
  72                 unsigned long, fd, unsigned long, off)
  73 {
  74         long error;
  75         error = -EINVAL;
  76         if (off & ~PAGE_MASK)
  77                 goto out;
  78
  79         error = sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
  80 out:
  81         return error;
  82 }
  83
  84 static void find_start_end(unsigned long flags, unsigned long *begin,
  85                            unsigned long *end)
  86 {
  87         if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) {
  88                 unsigned long new_begin;
  89                 /* This is usually used needed to map code in small
  90                    model, so it needs to be in the first 31bit. Limit
  91                    it to that.  This means we need to move the
  92                    unmapped base down for this case. This can give
  93                    conflicts with the heap, but we assume that glibc
  94                    malloc knows how to fall back to mmap. Give it 1GB
  95                    of playground for now. -AK */
  96                 *begin = 0x40000000;
  97                 *end = 0x80000000;
  98                 if (current->flags & PF_RANDOMIZE) {
  99                         new_begin = randomize_range(*begin, *begin + 0x02000000, 0);
 100                         if (new_begin)
 101                                 *begin = new_begin;
 102                 }
 103         } else {
 104                 *begin = current->mm->mmap_legacy_base;
 105                 *end = TASK_SIZE;
 106         }
 107 }
 108
 109 unsigned long
 110 arch_get_unmapped_area(struct file *filp, unsigned long addr,
 111                 unsigned long len, unsigned long pgoff, unsigned long flags)
 112 {
 113         struct mm_struct *mm = current->mm;
 114         struct vm_area_struct *vma;
 115         struct vm_unmapped_area_info info;
 116         unsigned long begin, end;
 117
 118         if (flags & MAP_FIXED)
 119                 return addr;
 120
 121         find_start_end(flags, &begin, &end);
 122
 123         if (len > end)
 124                 return -ENOMEM;
 125
 126         if (addr) {
 127                 addr = PAGE_ALIGN(addr);
 128                 vma = find_vma(mm, addr);
 129                 if (end - len >= addr &&
 130                     (!vma || addr + len <= vma->vm_start))
 131                         return addr;
 132         }
 133
 134         info.flags = 0;
 135         info.length = len;
 136         info.low_limit = begin;
 137         info.high_limit = end;
 138         info.align_mask = filp ? get_align_mask() : 0;
 139         info.align_offset = pgoff << PAGE_SHIFT;
 140         return vm_unmapped_area(&info);
 141 }
 142
 143 unsigned long
 144 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 145                           const unsigned long len, const unsigned long pgoff,
 146                           const unsigned long flags)
 147 {
 148         struct vm_area_struct *vma;
 149         struct mm_struct *mm = current->mm;
 150         unsigned long addr = addr0;
 151         struct vm_unmapped_area_info info;
 152
 153         /* requested length too big for entire address space */
 154         if (len > TASK_SIZE)
 155                 return -ENOMEM;
 156
 157         if (flags & MAP_FIXED)
 158                 return addr;
 159
 160         /* for MAP_32BIT mappings we force the legacy mmap base */
 161         if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT))
 162                 goto bottomup;
 163
 164         /* requesting a specific address */
 165         if (addr) {
 166                 addr = PAGE_ALIGN(addr);
 167                 vma = find_vma(mm, addr);
 168                 if (TASK_SIZE - len >= addr &&
 169                                 (!vma || addr + len <= vma->vm_start))
 170                         return addr;
 171         }
 172
 173         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 174         info.length = len;
 175         info.low_limit = PAGE_SIZE;
 176         info.high_limit = mm->mmap_base;
 177         info.align_mask = filp ? get_align_mask() : 0;
 178         info.align_offset = pgoff << PAGE_SHIFT;
 179         addr = vm_unmapped_area(&info);
 180         if (!(addr & ~PAGE_MASK))
 181                 return addr;
 182         VM_BUG_ON(addr != -ENOMEM);
 183
 184 bottomup:
 185         /*
 186          * A failed mmap() very likely causes application failure,
 187          * so fall back to the bottom-up function here. This scenario
 188          * can happen with large stack limits and large mmap()
 189          * allocations.
 190          */
 191         return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 192 }