Subject: x86: Reaplce cpu_pda() by per_cpu and get rid of _cpu_pda()

The pda is pointing to the pda which is at the beginning of the per cpu area.
This means that cpu_pda and _cpu_pda[] are both pointing at the percpu area!
In fact per_cpu() can be used instead of cpu_pda().

Typically the offsets to the per cpu areas are stored in an array _per_cpu_offet
(generic per cpu support can then provide more functionality).
Introduce that array for x86_64 and get rid of the pda arrays.

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

Index: linux-2.6/arch/x86/kernel/head64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head64.c	2008-05-23 20:43:39.000000000 -0700
+++ linux-2.6/arch/x86/kernel/head64.c	2008-05-23 20:49:31.000000000 -0700
@@ -119,6 +119,8 @@
 	}
 }
 
+static struct x8664_pda boot_cpu_pda[NR_CPUS] __cacheline_aligned;
+
 void __init x86_64_start_kernel(char * real_mode_data)
 {
 	int i;
@@ -156,11 +158,13 @@
 
 	early_printk("Kernel alive\n");
 
- 	for (i = 0; i < NR_CPUS; i++)
- 		cpu_pda(i) = &boot_cpu_pda[i];
+	/* Setup embryonic per cpu areas that consists only of the pdas */
+ 	for (i = 1; i < NR_CPUS; i++)
+ 		__per_cpu_offset[i] = (unsigned long)&boot_cpu_pda[i];
 
+	__per_cpu_offset[0] = (unsigned long)__per_cpu_load;
 	pda_init(0);
-	cpu_pda(0)->data_offset =(unsigned long)__per_cpu_load;
+	per_cpu(pda.data_offset, 0) = __per_cpu_offset[0];
 	copy_bootdata(__va(real_mode_data));
 
 	reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
Index: linux-2.6/arch/x86/kernel/irq_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/irq_64.c	2008-05-23 20:42:57.000000000 -0700
+++ linux-2.6/arch/x86/kernel/irq_64.c	2008-05-23 20:43:56.000000000 -0700
@@ -115,37 +115,37 @@
 	} else if (i == NR_IRQS) {
 		seq_printf(p, "NMI: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->__nmi_count);
+			seq_printf(p, "%10u ", per_cpu(pda.__nmi_count, j));
 		seq_printf(p, "  Non-maskable interrupts\n");
 		seq_printf(p, "LOC: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->apic_timer_irqs);
+			seq_printf(p, "%10u ", per_cpu(pda.apic_timer_irqs, j));
 		seq_printf(p, "  Local timer interrupts\n");
 #ifdef CONFIG_SMP
 		seq_printf(p, "RES: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_resched_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_resched_count, j));
 		seq_printf(p, "  Rescheduling interrupts\n");
 		seq_printf(p, "CAL: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_call_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_call_count, j));
 		seq_printf(p, "  function call interrupts\n");
 		seq_printf(p, "TLB: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_tlb_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_tlb_count, j));
 		seq_printf(p, "  TLB shootdowns\n");
 #endif
 		seq_printf(p, "TRM: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_thermal_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_thermal_count, j));
 		seq_printf(p, "  Thermal event interrupts\n");
 		seq_printf(p, "THR: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_threshold_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_threshold_count, j));
 		seq_printf(p, "  Threshold APIC interrupts\n");
 		seq_printf(p, "SPU: ");
 		for_each_online_cpu(j)
-			seq_printf(p, "%10u ", cpu_pda(j)->irq_spurious_count);
+			seq_printf(p, "%10u ", per_cpu(pda.irq_spurious_count, j));
 		seq_printf(p, "  Spurious interrupts\n");
 		seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
 	}
Index: linux-2.6/arch/x86/kernel/nmi_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/nmi_64.c	2008-05-23 20:42:57.000000000 -0700
+++ linux-2.6/arch/x86/kernel/nmi_64.c	2008-05-23 20:43:56.000000000 -0700
@@ -100,19 +100,19 @@
 #endif
 
 	for (cpu = 0; cpu < NR_CPUS; cpu++)
-		prev_nmi_count[cpu] = cpu_pda(cpu)->__nmi_count;
+		prev_nmi_count[cpu] = per_cpu(pda.__nmi_count, cpu);
 	local_irq_enable();
 	mdelay((20*1000)/nmi_hz); // wait 20 ticks
 
 	for_each_online_cpu(cpu) {
 		if (!per_cpu(wd_enabled, cpu))
 			continue;
-		if (cpu_pda(cpu)->__nmi_count - prev_nmi_count[cpu] <= 5) {
+		if (per_cpu(pda.__nmi_count, cpu) - prev_nmi_count[cpu] <= 5) {
 			printk(KERN_WARNING "WARNING: CPU#%d: NMI "
 			       "appears to be stuck (%d->%d)!\n",
 				cpu,
 				prev_nmi_count[cpu],
-				cpu_pda(cpu)->__nmi_count);
+				per_cpu(pda.__nmi_count, cpu));
 			per_cpu(wd_enabled, cpu) = 0;
 			atomic_dec(&nmi_active);
 		}
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c	2008-05-23 20:43:39.000000000 -0700
+++ linux-2.6/arch/x86/kernel/setup.c	2008-05-23 20:43:56.000000000 -0700
@@ -123,13 +123,11 @@
 		memcpy(ptr, __per_cpu_load, __per_cpu_size);
 
 #ifdef CONFIG_X86_64
-		cpu_pda(i)->data_offset = ptr - __per_cpu_start;
+		per_cpu(pda.data_offset, i) = ptr - __per_cpu_start;
 		/* Relocate the pda */
-		memcpy(ptr, cpu_pda(i), sizeof(struct x8664_pda));
-		cpu_pda(i) = (struct x8664_pda *)ptr;
-#else
-		__per_cpu_offset[i] = ptr - __per_cpu_start;
+		memcpy(ptr, &per_cpu(pda, i), sizeof(struct x8664_pda));
 #endif
+		__per_cpu_offset[i] = ptr - __per_cpu_start;
 
 		highest_cpu = i;
 	}
Index: linux-2.6/arch/x86/kernel/setup64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup64.c	2008-05-23 20:42:57.000000000 -0700
+++ linux-2.6/arch/x86/kernel/setup64.c	2008-05-23 20:48:34.000000000 -0700
@@ -34,9 +34,8 @@
 
 cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;
 
-struct x8664_pda *_cpu_pda[NR_CPUS] __read_mostly;
-EXPORT_SYMBOL(_cpu_pda);
-struct x8664_pda boot_cpu_pda[NR_CPUS] __cacheline_aligned;
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(__per_cpu_offset);
 
 struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };
 
@@ -89,7 +88,7 @@
 
 void pda_init(int cpu)
 { 
-	struct x8664_pda *pda = cpu_pda(cpu);
+	struct x8664_pda *pda = &per_cpu(pda, cpu);
 
 	/* Setup up data that may be needed in __get_free_pages early */
 	asm volatile("movl %0,%%fs ; movl %0,%%gs" :: "r" (0)); 
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c	2008-05-23 20:43:39.000000000 -0700
+++ linux-2.6/arch/x86/kernel/smpboot.c	2008-05-23 20:43:56.000000000 -0700
@@ -855,13 +855,6 @@
 		printk(KERN_ERR "Failed to allocate GDT for CPU %d\n", cpu);
 		return -1;
 	}
-
-	if (cpu_pda(cpu) == &boot_cpu_pda[cpu]) {
-		struct x8664_pda *ppda = &per_cpu(pda, cpu);
-
-		memcpy(ppda, cpu_pda(cpu), sizeof(struct x8664_pda));
-		cpu_pda(cpu) = ppda;
-	}
 #endif
 
 	alternatives_smp_switch(1);
@@ -902,7 +895,7 @@
 	stack_start.sp = (void *) c_idle.idle->thread.sp;
 	irq_ctx_init(cpu);
 #else
-	cpu_pda(cpu)->pcurrent = c_idle.idle;
+	per_cpu(pda.pcurrent, cpu) = c_idle.idle;
 	init_rsp = c_idle.idle->thread.sp;
 	load_sp0(&per_cpu(init_tss, cpu), &c_idle.idle->thread);
 	initial_code = (unsigned long)start_secondary;
Index: linux-2.6/arch/x86/kernel/traps_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/traps_64.c	2008-05-23 20:42:57.000000000 -0700
+++ linux-2.6/arch/x86/kernel/traps_64.c	2008-05-23 20:43:56.000000000 -0700
@@ -263,7 +263,8 @@
 		const struct stacktrace_ops *ops, void *data)
 {
 	const unsigned cpu = get_cpu();
-	unsigned long *irqstack_end = (unsigned long*)cpu_pda(cpu)->irqstackptr;
+	unsigned long *irqstack_end =
+		(unsigned long*)per_cpu(pda.irqstackptr, cpu);
 	unsigned used = 0;
 	struct thread_info *tinfo;
 
@@ -397,8 +398,8 @@
 	unsigned long *stack;
 	int i;
 	const int cpu = smp_processor_id();
-	unsigned long *irqstack_end = (unsigned long *) (cpu_pda(cpu)->irqstackptr);
-	unsigned long *irqstack = (unsigned long *) (cpu_pda(cpu)->irqstackptr - IRQSTACKSIZE);
+	unsigned long *irqstack_end = (unsigned long *)per_cpu(pda.irqstackptr, cpu);
+	unsigned long *irqstack = (unsigned long *)(per_cpu(pda.irqstackptr, cpu) - IRQSTACKSIZE);
 
 	// debugging aid: "show_stack(NULL, NULL);" prints the
 	// back trace for this cpu.
@@ -462,7 +463,7 @@
 	int i;
 	unsigned long sp;
 	const int cpu = smp_processor_id();
-	struct task_struct *cur = cpu_pda(cpu)->pcurrent;
+	struct task_struct *cur = per_cpu(pda.pcurrent, cpu);
 	u8 *ip;
 	unsigned int code_prologue = code_bytes * 43 / 64;
 	unsigned int code_len = code_bytes;
Index: linux-2.6/include/asm-x86/pda.h
===================================================================
--- linux-2.6.orig/include/asm-x86/pda.h	2008-05-23 20:43:35.000000000 -0700
+++ linux-2.6/include/asm-x86/pda.h	2008-05-23 20:47:36.000000000 -0700
@@ -37,12 +37,8 @@
 	unsigned irq_spurious_count;
 } ____cacheline_aligned_in_smp;
 
-extern struct x8664_pda *_cpu_pda[];
-extern struct x8664_pda boot_cpu_pda[];
 extern void pda_init(int);
 
-#define cpu_pda(i) (_cpu_pda[i])
-
 /*
  * There is no fast way to get the base address of the PDA, all the accesses
  * have to mention %fs/%gs.  So it needs to be done this Torvaldian way.
Index: linux-2.6/include/asm-x86/percpu.h
===================================================================
--- linux-2.6.orig/include/asm-x86/percpu.h	2008-05-23 20:43:41.000000000 -0700
+++ linux-2.6/include/asm-x86/percpu.h	2008-05-23 20:43:56.000000000 -0700
@@ -6,9 +6,7 @@
 #include <asm/pda.h>
 
 #ifdef CONFIG_SMP
-#define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
 #define __my_cpu_offset read_pda(data_offset)
-#define per_cpu_offset(x) (__per_cpu_offset(x))
 #endif
 
 #define __percpu_seg "%%gs:"