1 files changed, 56 insertions, 2 deletions

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 5e641715c3f..165466233ab 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -212,7 +212,61 @@
 #ifdef __KERNEL__
 #ifndef __ASSEMBLY__
 extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][10];
-#endif
-#endif
+
+/*
+ * Load a segment. Fall back on loading the zero
+ * segment if something goes wrong..
+ */
+#define loadsegment(seg, value)                                         \
+do {                                                                    \
+        unsigned short __val = (value);                                 \
+                                                                        \
+        asm volatile("                                          \n"     \
+                     "1:        movl %k0,%%" #seg "             \n"     \
+                                                                        \
+                     ".section .fixup,\"ax\"                    \n"     \
+                     "2:        xorl %k0,%k0                    \n"     \
+                     "          jmp 1b                          \n"     \
+                     ".previous                                 \n"     \
+                                                                        \
+                     _ASM_EXTABLE(1b, 2b)                               \
+                                                                        \
+                     : "+r" (__val) : : "memory");                      \
+} while (0)
+
+/*
+ * Save a segment register away
+ */
+#define savesegment(seg, value)                         \
+        asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
+
+/*
+ * x86_32 user gs accessors.
+ */
+#ifdef CONFIG_X86_32
+#ifdef CONFIG_X86_32_LAZY_GS
+#define get_user_gs(regs)       (u16)({unsigned long v; savesegment(gs, v); v;})
+#define set_user_gs(regs, v)    loadsegment(gs, (unsigned long)(v))
+#define task_user_gs(tsk)       ((tsk)->thread.gs)
+#define lazy_save_gs(v)         savesegment(gs, (v))
+#define lazy_load_gs(v)         loadsegment(gs, (v))
+#else   /* X86_32_LAZY_GS */
+#define get_user_gs(regs)       (u16)((regs)->gs)
+#define set_user_gs(regs, v)    do { (regs)->gs = (v); } while (0)
+#define task_user_gs(tsk)       (task_pt_regs(tsk)->gs)
+#define lazy_save_gs(v)         do { } while (0)
+#define lazy_load_gs(v)         do { } while (0)
+#endif  /* X86_32_LAZY_GS */
+#endif  /* X86_32 */
+
+static inline unsigned long get_limit(unsigned long segment)
+{
+        unsigned long __limit;
+        asm("lsll %1,%0" : "=r" (__limit) : "r" (segment));
+        return __limit + 1;
+}
+
+#endif /* !__ASSEMBLY__ */
+#endif /* __KERNEL__ */
 
 #endif /* _ASM_X86_SEGMENT_H */