x86: load new GDT after setting up boot cpu per-cpu area

Impact: sync 32 and 64-bit code

Merge load_gs_base() into switch_to_new_gdt().  Load the GDT and
per-cpu state for the boot cpu when its new area is set up.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

3 files changed, 12 insertions, 14 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 794234eba317..befa20b4a68c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -394,11 +394,6 @@ union irq_stack_union {
 
 DECLARE_PER_CPU(union irq_stack_union, irq_stack_union);
 DECLARE_PER_CPU(char *, irq_stack_ptr);
-
-static inline void load_gs_base(int cpu)
-{
-        wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
-}
 #endif
 
 extern void print_cpu_info(struct cpuinfo_x86 *);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 67e30c8a282c..0c766b80d915 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -258,12 +258,17 @@ __u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;
 void switch_to_new_gdt(void)
 {
         struct desc_ptr gdt_descr;
+        int cpu = smp_processor_id();
 
-        gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id());
+        gdt_descr.address = (long)get_cpu_gdt_table(cpu);
         gdt_descr.size = GDT_SIZE - 1;
         load_gdt(&gdt_descr);
+        /* Reload the per-cpu base */
 #ifdef CONFIG_X86_32
-        asm("mov %0, %%fs" : : "r" (__KERNEL_PERCPU) : "memory");
+        loadsegment(fs, __KERNEL_PERCPU);
+#else
+        loadsegment(gs, 0);
+        wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
 #endif
 }
 
@@ -968,10 +973,6 @@ void __cpuinit cpu_init(void)
         struct task_struct *me;
         int i;
 
-        loadsegment(fs, 0);
-        loadsegment(gs, 0);
-        load_gs_base(cpu);
-
 #ifdef CONFIG_NUMA
         if (cpu != 0 && percpu_read(node_number) == 0 &&
             cpu_to_node(cpu) != NUMA_NO_NODE)
@@ -993,6 +994,8 @@ void __cpuinit cpu_init(void)
          */
 
         switch_to_new_gdt();
+        loadsegment(fs, 0);
+
         load_idt((const struct desc_ptr *)&idt_descr);
 
         memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index bcca3a7b3748..4caa78d7cb15 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -113,13 +113,13 @@ void __init setup_per_cpu_areas(void)
                 per_cpu(x86_cpu_to_node_map, cpu) =
                                 early_per_cpu_map(x86_cpu_to_node_map, cpu);
 #endif
+#endif
                 /*
                  * Up to this point, the boot CPU has been using .data.init
-                 * area.  Reload %gs offset for the boot CPU.
+                 * area.  Reload any changed state for the boot CPU.
                  */
                 if (cpu == boot_cpu_id)
-                        load_gs_base(cpu);
-#endif
+                        switch_to_new_gdt();
 
                 DBG("PERCPU: cpu %4d %p\n", cpu, ptr);
         }