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