1 | /* arch_prctl call for Linux/x32. |
2 | Copyright (C) 2012-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <errno.h> |
20 | #include <sys/prctl.h> |
21 | #include <sys/syscall.h> |
22 | #include <sysdep.h> |
23 | #include <stdint.h> |
24 | |
25 | /* Since x32 arch_prctl stores 32-bit base address of segment registers |
26 | %fs and %gs as unsigned 64-bit value via ARCH_GET_FS and ARCH_GET_GS, |
27 | we use an unsigned 64-bit variable to hold the base address and copy |
28 | it to ADDR after the system call returns. */ |
29 | |
30 | int |
31 | __arch_prctl (int code, uintptr_t *addr) |
32 | { |
33 | int res; |
34 | uint64_t addr64; |
35 | void *prctl_arg = addr; |
36 | |
37 | switch (code) |
38 | { |
39 | case ARCH_GET_FS: |
40 | case ARCH_GET_GS: |
41 | prctl_arg = &addr64; |
42 | break; |
43 | } |
44 | |
45 | res = INLINE_SYSCALL (arch_prctl, 2, code, prctl_arg); |
46 | if (res == 0) |
47 | switch (code) |
48 | { |
49 | case ARCH_GET_FS: |
50 | case ARCH_GET_GS: |
51 | /* Check for a large value that overflows. */ |
52 | if ((uintptr_t) addr64 != addr64) |
53 | { |
54 | __set_errno (EOVERFLOW); |
55 | return -1; |
56 | } |
57 | *addr = (uintptr_t) addr64; |
58 | break; |
59 | } |
60 | |
61 | return res; |
62 | } |
63 | weak_alias (__arch_prctl, arch_prctl) |
64 | |