x86_64: Remove the data_offset field from the pda.

It is useless now since gs can always stand in for data_offset.

Move active_mm into the available slot in order to not upset the
established offsets.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
 arch/x86/kernel/asm-offsets_64.c |    1 -
 arch/x86/kernel/entry_64.S       |    7 ++-----
 arch/x86/kernel/setup64.c        |    6 ------
 include/asm-x86/pda.h            |    4 +---
 4 files changed, 3 insertions(+), 15 deletions(-)

Index: linux-2.6/arch/x86/kernel/asm-offsets_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/asm-offsets_64.c	2007-11-17 16:28:01.655785025 -0800
+++ linux-2.6/arch/x86/kernel/asm-offsets_64.c	2007-11-17 18:16:13.529022664 -0800
@@ -56,7 +56,6 @@ int main(void)
 	ENTRY(irqcount);
 	ENTRY(cpunumber);
 	ENTRY(irqstackptr);
-	ENTRY(data_offset);
 	BLANK();
 #undef ENTRY
 #ifdef CONFIG_IA32_EMULATION
Index: linux-2.6/arch/x86/kernel/entry_64.S
===================================================================
--- linux-2.6.orig/arch/x86/kernel/entry_64.S	2007-11-17 16:28:01.647784312 -0800
+++ linux-2.6/arch/x86/kernel/entry_64.S	2007-11-17 18:16:13.529022664 -0800
@@ -734,18 +734,15 @@ END(spurious_interrupt)
 	swapgs
 	xorl  %ebx,%ebx
 1:
-	.if \ist
-	movq	%gs:pda_data_offset, %rbp
-	.endif
 	movq %rsp,%rdi
 	movq ORIG_RAX(%rsp),%rsi
 	movq $-1,ORIG_RAX(%rsp)
 	.if \ist
-	subq	$EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
+	subq	$EXCEPTION_STKSZ, %gs: per_cpu__init_tss + TSS_ist
 	.endif
 	call \sym
 	.if \ist
-	addq	$EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
+	addq	$EXCEPTION_STKSZ, %gs: per_cpu__init_tss + TSS_ist
 	.endif
 	cli
 	.if \irqtrace
Index: linux-2.6/arch/x86/kernel/setup64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup64.c	2007-11-17 18:09:56.309022712 -0800
+++ linux-2.6/arch/x86/kernel/setup64.c	2007-11-17 18:16:13.529022664 -0800
@@ -105,12 +105,6 @@ void __init setup_per_cpu_areas(void)
 		char *base_for_cpu = CPU_PTR(base, i);
 		struct x8664_pda *pda_for_cpu;
 
-		/*
-		 * Must setup the data offset in the boot pda first because
-		 * we may need the data offset to calculate the per cpu address.
-		 */
-		cpu_pda(i)->data_offset = base_for_cpu - __per_cpu_start;
-
 		memcpy(base_for_cpu, __load_per_cpu_start, __per_cpu_end - __per_cpu_start);
 
 		pda_for_cpu = &per_cpu(pda, i);
Index: linux-2.6/include/asm-x86/pda.h
===================================================================
--- linux-2.6.orig/include/asm-x86/pda.h	2007-11-17 18:09:43.705522758 -0800
+++ linux-2.6/include/asm-x86/pda.h	2007-11-17 18:16:13.544883584 -0800
@@ -10,8 +10,7 @@
 /* Per processor datastructure. %gs points to it while the kernel runs */ 
 struct x8664_pda {
 	struct task_struct *pcurrent;	/* 0  Current process */
-	unsigned long data_offset;	/* 8 Per cpu data offset from linker
-					   address */
+	struct mm_struct *active_mm;
 	unsigned long kernelstack;  /* 16 top of kernel stack for current */
 	unsigned long oldrsp; 	    /* 24 user rsp for system call */
         int irqcount;		    /* 32 Irq nesting counter. Starts with -1 */
@@ -27,7 +26,6 @@ struct x8664_pda {
 	unsigned int __nmi_count;	/* number of NMI on this CPUs */
 	short mmu_state;
 	short isidle;
-	struct mm_struct *active_mm;
 	unsigned apic_timer_irqs;
 	unsigned irq0_irqs;
 	unsigned irq_resched_count;