1 files changed, 35 insertions, 0 deletions

diff --git a/arch/x86/um/os-Linux/tls.c b/arch/x86/um/os-Linux/tls.c
new file mode 100644
index 000000000000..281e83ecce3d
--- /dev/null
+++ b/arch/x86/um/os-Linux/tls.c
@@ -0,0 +1,35 @@
+#include <errno.h>
+#include <linux/unistd.h>
+
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "sysdep/tls.h"
+
+/* Checks whether host supports TLS, and sets *tls_min according to the value
+ * valid on the host.
+ * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
+void check_host_supports_tls(int *supports_tls, int *tls_min) {
+        /* Values for x86 and x86_64.*/
+        int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(val); i++) {
+                user_desc_t info;
+                info.entry_number = val[i];
+
+                if (syscall(__NR_get_thread_area, &info) == 0) {
+                        *tls_min = val[i];
+                        *supports_tls = 1;
+                        return;
+                } else {
+                        if (errno == EINVAL)
+                                continue;
+                        else if (errno == ENOSYS)
+                                *supports_tls = 0;
+                                return;
+                }
+        }
+
+        *supports_tls = 0;
+}