x86/paravirt, 64-bit: make load_gs_index() a paravirt operation

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/entry_64.S

@@ -944,7 +944,7 @@ KPROBE_END(error_entry)
 	
        /* Reload gs selector with exception handling */
        /* edi:  new selector */ 
-ENTRY(load_gs_index)
+ENTRY(native_load_gs_index)
 	CFI_STARTPROC
 	pushf
 	CFI_ADJUST_CFA_OFFSET 8
@@ -958,7 +958,7 @@ gs_change:
 	CFI_ADJUST_CFA_OFFSET -8
         ret
 	CFI_ENDPROC
-ENDPROC(load_gs_index)
+ENDPROC(native_load_gs_index)
        
         .section __ex_table,"a"
         .align 8

arch/x86/kernel/paravirt.c

@@ -329,6 +329,9 @@ struct pv_cpu_ops pv_cpu_ops = {
 	.store_idt = native_store_idt,
 	.store_tr = native_store_tr,
 	.load_tls = native_load_tls,
+#ifdef CONFIG_X86_64
+	.load_gs_index = native_load_gs_index,
+#endif
 	.write_ldt_entry = native_write_ldt_entry,
 	.write_gdt_entry = native_write_gdt_entry,
 	.write_idt_entry = native_write_idt_entry,

include/asm-x86/elf.h

@@ -83,9 +83,9 @@ extern unsigned int vdso_enabled;
 	(((x)->e_machine == EM_386) || ((x)->e_machine == EM_486))
 
 #include <asm/processor.h>
+#include <asm/system.h>
 
 #ifdef CONFIG_X86_32
-#include <asm/system.h>		/* for savesegment */
 #include <asm/desc.h>
 
 #define elf_check_arch(x)	elf_check_arch_ia32(x)

include/asm-x86/paravirt.h

@@ -115,6 +115,9 @@ struct pv_cpu_ops {
 	void (*set_ldt)(const void *desc, unsigned entries);
 	unsigned long (*store_tr)(void);
 	void (*load_tls)(struct thread_struct *t, unsigned int cpu);
+#ifdef CONFIG_X86_64
+	void (*load_gs_index)(unsigned int idx);
+#endif
 	void (*write_ldt_entry)(struct desc_struct *ldt, int entrynum,
 				const void *desc);
 	void (*write_gdt_entry)(struct desc_struct *,
@@ -845,6 +848,13 @@ static inline void load_TLS(struct thread_struct *t, unsigned cpu)
 	PVOP_VCALL2(pv_cpu_ops.load_tls, t, cpu);
 }
 
+#ifdef CONFIG_X86_64
+static inline void load_gs_index(unsigned int gs)
+{
+	PVOP_VCALL1(pv_cpu_ops.load_gs_index, gs);
+}
+#endif
+
 static inline void write_ldt_entry(struct desc_struct *dt, int entry,
 				   const void *desc)
 {

include/asm-x86/system.h

@@ -136,7 +136,7 @@ __asm__ __volatile__ ("movw %%dx,%1\n\t" \
 #define set_base(ldt, base) _set_base(((char *)&(ldt)) , (base))
 #define set_limit(ldt, limit) _set_limit(((char *)&(ldt)) , ((limit)-1))
 
-extern void load_gs_index(unsigned);
+extern void native_load_gs_index(unsigned);
 
 /*
  * Load a segment. Fall back on loading the zero
@@ -282,6 +282,7 @@ static inline void native_wbinvd(void)
 #ifdef CONFIG_X86_64
 #define read_cr8()	(native_read_cr8())
 #define write_cr8(x)	(native_write_cr8(x))
+#define load_gs_index   native_load_gs_index
 #endif
 
 /* Clear the 'TS' bit */