x86: Use generic init_task

Same code. Use the generic version. The special Makefile treatment is
pointless anyway as init_task.o contains only data which is handled by
the linker script. So no point on being treated like head text.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20120503085035.739963562@linutronix.de
Cc: x86@kernel.org

arch/x86/Kconfig

@@ -83,6 +83,7 @@ config X86
 	select GENERIC_IOMAP
 	select DCACHE_WORD_ACCESS if !DEBUG_PAGEALLOC
 	select GENERIC_SMP_IDLE_THREAD
+	select HAVE_GENERIC_INIT_TASK
 
 config INSTRUCTION_DECODER
 	def_bool (KPROBES || PERF_EVENTS)

arch/x86/Makefile

@@ -146,7 +146,6 @@ archheaders:
 head-y := arch/x86/kernel/head_$(BITS).o
 head-y += arch/x86/kernel/head$(BITS).o
 head-y += arch/x86/kernel/head.o
-head-y += arch/x86/kernel/init_task.o
 
 libs-y  += arch/x86/lib/
 

arch/x86/kernel/Makefile

@@ -2,7 +2,7 @@
 # Makefile for the linux kernel.
 #
 
-extra-y                := head_$(BITS).o head$(BITS).o head.o init_task.o vmlinux.lds
+extra-y                := head_$(BITS).o head$(BITS).o head.o vmlinux.lds
 
 CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE)
 

arch/x86/kernel/process.c

@@ -27,6 +27,15 @@
 #include <asm/debugreg.h>
 #include <asm/nmi.h>
 
+/*
+ * per-CPU TSS segments. Threads are completely 'soft' on Linux,
+ * no more per-task TSS's. The TSS size is kept cacheline-aligned
+ * so they are allowed to end up in the .data..cacheline_aligned
+ * section. Since TSS's are completely CPU-local, we want them
+ * on exact cacheline boundaries, to eliminate cacheline ping-pong.
+ */
+DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, init_tss) = INIT_TSS;
+
 #ifdef CONFIG_X86_64
 static DEFINE_PER_CPU(unsigned char, is_idle);
 static ATOMIC_NOTIFIER_HEAD(idle_notifier);