linux-user/uaccess.c

   1 /* User memory access */
   2 #include "qemu/osdep.h"
   3
   4 #include "qemu.h"
   5
   6 /* copy_from_user() and copy_to_user() are usually used to copy data
   7  * buffers between the target and host.  These internally perform
   8  * locking/unlocking of the memory.
   9  */
  10 abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len)
  11 {
  12     abi_long ret = 0;
  13     void *ghptr;
  14
  15     if ((ghptr = lock_user(VERIFY_READ, gaddr, len, 1))) {
  16         memcpy(hptr, ghptr, len);
  17         unlock_user(ghptr, gaddr, 0);
  18     } else
  19         ret = -TARGET_EFAULT;
  20
  21     return ret;
  22 }
  23
  24
  25 abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len)
  26 {
  27     abi_long ret = 0;
  28     void *ghptr;
  29
  30     if ((ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0))) {
  31         memcpy(ghptr, hptr, len);
  32         unlock_user(ghptr, gaddr, len);
  33     } else
  34         ret = -TARGET_EFAULT;
  35
  36     return ret;
  37 }
  38
  39 /* Return the length of a string in target memory or -TARGET_EFAULT if
  40    access error  */
  41 abi_long target_strlen(abi_ulong guest_addr1)
  42 {
  43     uint8_t *ptr;
  44     abi_ulong guest_addr;
  45     int max_len, len;
  46
  47     guest_addr = guest_addr1;
  48     for(;;) {
  49         max_len = TARGET_PAGE_SIZE - (guest_addr & ~TARGET_PAGE_MASK);
  50         ptr = lock_user(VERIFY_READ, guest_addr, max_len, 1);
  51         if (!ptr)
  52             return -TARGET_EFAULT;
  53         len = qemu_strnlen((const char *)ptr, max_len);
  54         unlock_user(ptr, guest_addr, 0);
  55         guest_addr += len;
  56         /* we don't allow wrapping or integer overflow */
  57         if (guest_addr == 0 ||
  58             (guest_addr - guest_addr1) > 0x7fffffff)
  59             return -TARGET_EFAULT;
  60         if (len != max_len)
  61             break;
  62     }
  63     return guest_addr - guest_addr1;
  64 }