1 // SPDX-License-Identifier: GPL-2.0
2 #include <errno.h>
3 #include <linux/unistd.h>
4
5 #include <sys/ptrace.h>
6 #include <sys/syscall.h>
7 #include <unistd.h>
8
9 #include <os.h>
10 #include <sysdep/tls.h>
11
12 #ifndef PTRACE_GET_THREAD_AREA
13 #define PTRACE_GET_THREAD_AREA 25
14 #endif
15
16 #ifndef PTRACE_SET_THREAD_AREA
17 #define PTRACE_SET_THREAD_AREA 26
18 #endif
19
20 /* Checks whether host supports TLS, and sets *tls_min according to the value
21 * valid on the host.
22 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
23 void check_host_supports_tls(int *supports_tls, int *tls_min)
24 {
25 /* Values for x86 and x86_64.*/
26 int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
27 int i;
28
29 for (i = 0; i < ARRAY_SIZE(val); i++) {
30 user_desc_t info;
31 info.entry_number = val[i];
32
33 if (syscall(__NR_get_thread_area, &info) == 0) {
34 *tls_min = val[i];
35 *supports_tls = 1;
36 return;
37 } else {
38 if (errno == EINVAL)
39 continue;
40 else if (errno == ENOSYS)
41 *supports_tls = 0;
42 return;
43 }
44 }
45
46 *supports_tls = 0;
47 }
48
49 int os_set_thread_area(user_desc_t *info, int pid)
50 {
51 int ret;
52
53 ret = ptrace(PTRACE_SET_THREAD_AREA, pid, info->entry_number,
54 (unsigned long) info);
55 if (ret < 0)
56 ret = -errno;
57 return ret;
58 }
59
60 int os_get_thread_area(user_desc_t *info, int pid)
61 {
62 int ret;
63
64 ret = ptrace(PTRACE_GET_THREAD_AREA, pid, info->entry_number,
65 (unsigned long) info);
66 if (ret < 0)
67 ret = -errno;
68 return ret;
69 }
70
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