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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. */
check_host_supports_tls(int * supports_tls,int * tls_min)21 void 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 
os_set_thread_area(user_desc_t * info,int pid)47 int 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 
os_get_thread_area(user_desc_t * info,int pid)58 int 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