From 863981e96738983919de841ec669e157e6bdaeb0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?=
 <emulatorman@parabola.nu>
Date: Sun, 11 Sep 2016 04:34:46 -0300
Subject: Linux-libre 4.7.1-gnu

---
 arch/x86/kernel/tls.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

(limited to 'arch/x86/kernel/tls.c')

diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 7fc5e843f..9692a5e9f 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -114,6 +114,7 @@ int do_set_thread_area(struct task_struct *p, int idx,
 		       int can_allocate)
 {
 	struct user_desc info;
+	unsigned short __maybe_unused sel, modified_sel;
 
 	if (copy_from_user(&info, u_info, sizeof(info)))
 		return -EFAULT;
@@ -141,6 +142,47 @@ int do_set_thread_area(struct task_struct *p, int idx,
 
 	set_tls_desc(p, idx, &info, 1);
 
+	/*
+	 * If DS, ES, FS, or GS points to the modified segment, forcibly
+	 * refresh it.  Only needed on x86_64 because x86_32 reloads them
+	 * on return to user mode.
+	 */
+	modified_sel = (idx << 3) | 3;
+
+	if (p == current) {
+#ifdef CONFIG_X86_64
+		savesegment(ds, sel);
+		if (sel == modified_sel)
+			loadsegment(ds, sel);
+
+		savesegment(es, sel);
+		if (sel == modified_sel)
+			loadsegment(es, sel);
+
+		savesegment(fs, sel);
+		if (sel == modified_sel)
+			loadsegment(fs, sel);
+
+		savesegment(gs, sel);
+		if (sel == modified_sel)
+			load_gs_index(sel);
+#endif
+
+#ifdef CONFIG_X86_32_LAZY_GS
+		savesegment(gs, sel);
+		if (sel == modified_sel)
+			loadsegment(gs, sel);
+#endif
+	} else {
+#ifdef CONFIG_X86_64
+		if (p->thread.fsindex == modified_sel)
+			p->thread.fsbase = info.base_addr;
+
+		if (p->thread.gsindex == modified_sel)
+			p->thread.gsbase = info.base_addr;
+#endif
+	}
+
 	return 0;
 }
 
-- 
cgit v1.2.3