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-rw-r--r--arch/um/os-Linux/sys-i386/tls.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/um/os-Linux/sys-i386/tls.c b/arch/um/os-Linux/sys-i386/tls.c
new file mode 100644
index 00000000000..32ed41ec1a3
--- /dev/null
+++ b/arch/um/os-Linux/sys-i386/tls.c
@@ -0,0 +1,36 @@
1#include <errno.h>
2#include <linux/unistd.h>
3
4#include <sys/syscall.h>
5#include <unistd.h>
6
7#include "sysdep/tls.h"
8#include "user.h"
9
10/* Checks whether host supports TLS, and sets *tls_min according to the value
11 * valid on the host.
12 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
13void check_host_supports_tls(int *supports_tls, int *tls_min) {
14 /* Values for x86 and x86_64.*/
15 int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
16 int i;
17
18 for (i = 0; i < ARRAY_SIZE(val); i++) {
19 user_desc_t info;
20 info.entry_number = val[i];
21
22 if (syscall(__NR_get_thread_area, &info) == 0) {
23 *tls_min = val[i];
24 *supports_tls = 1;
25 return;
26 } else {
27 if (errno == EINVAL)
28 continue;
29 else if (errno == ENOSYS)
30 *supports_tls = 0;
31 return;
32 }
33 }
34
35 *supports_tls = 0;
36}