xref: /openbmc/qemu/bsd-user/uaccess.c (revision ed75658a)
1 /* User memory access */
2 #include "qemu/osdep.h"
3 #include "qemu/cutils.h"
4 
5 #include "qemu.h"
6 
7 /* copy_from_user() and copy_to_user() are usually used to copy data
8  * buffers between the target and host.  These internally perform
9  * locking/unlocking of the memory.
10  */
11 abi_long copy_from_user(void *hptr, abi_ulong gaddr, size_t len)
12 {
13     abi_long ret = 0;
14     void *ghptr;
15 
16     if ((ghptr = lock_user(VERIFY_READ, gaddr, len, 1))) {
17         memcpy(hptr, ghptr, len);
18         unlock_user(ghptr, gaddr, 0);
19     } else
20         ret = -TARGET_EFAULT;
21 
22     return ret;
23 }
24 
25 
26 abi_long copy_to_user(abi_ulong gaddr, void *hptr, size_t len)
27 {
28     abi_long ret = 0;
29     void *ghptr;
30 
31     if ((ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0))) {
32         memcpy(ghptr, hptr, len);
33         unlock_user(ghptr, gaddr, len);
34     } else
35         ret = -TARGET_EFAULT;
36 
37     return ret;
38 }
39 
40 /* Return the length of a string in target memory or -TARGET_EFAULT if
41    access error  */
42 abi_long target_strlen(abi_ulong guest_addr1)
43 {
44     uint8_t *ptr;
45     abi_ulong guest_addr;
46     int max_len, len;
47 
48     guest_addr = guest_addr1;
49     for (;;) {
50         max_len = TARGET_PAGE_SIZE - (guest_addr & ~TARGET_PAGE_MASK);
51         ptr = lock_user(VERIFY_READ, guest_addr, max_len, 1);
52         if (!ptr)
53             return -TARGET_EFAULT;
54         len = qemu_strnlen((const char *)ptr, max_len);
55         unlock_user(ptr, guest_addr, 0);
56         guest_addr += len;
57         /* we don't allow wrapping or integer overflow */
58         if (guest_addr == 0 ||
59             (guest_addr - guest_addr1) > 0x7fffffff)
60             return -TARGET_EFAULT;
61         if (len != max_len)
62             break;
63     }
64     return guest_addr - guest_addr1;
65 }
66