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-rw-r--r--arch/x86/kernel/tls.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 7fc5e84..9692a5e 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;
}