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