sh: Replace __get_cpu_var uses

__get_cpu_var() is used for multiple purposes in the kernel source.  One
of them is address calculation via the form &__get_cpu_var(x).  This
calculates the address for the instance of the percpu variable of the
current processor based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))

__get_cpu_var() always only does an address determination.  However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less
registers are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well.  Once these
operations are used throughout then specialized macros can be defined in
non -x86 arches as well in order to optimize per cpu access by f.e.  using
a global register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

Signed-off-by: Christoph Lameter <cl@linux.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org> [compilation only]
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/sh/kernel/hw_breakpoint.c

@@ -52,7 +52,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 	int i;
 
 	for (i = 0; i < sh_ubc->num_events; i++) {
-		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+		struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]);
 
 		if (!*slot) {
 			*slot = bp;
@@ -84,7 +84,7 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 	int i;
 
 	for (i = 0; i < sh_ubc->num_events; i++) {
-		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+		struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]);
 
 		if (*slot == bp) {
 			*slot = NULL;

arch/sh/kernel/kprobes.c

@@ -102,7 +102,7 @@ int __kprobes kprobe_handle_illslot(unsigned long pc)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-	struct kprobe *saved = &__get_cpu_var(saved_next_opcode);
+	struct kprobe *saved = this_cpu_ptr(&saved_next_opcode);
 
 	if (saved->addr) {
 		arch_disarm_kprobe(p);
@@ -111,7 +111,7 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)
 		saved->addr = NULL;
 		saved->opcode = 0;
 
-		saved = &__get_cpu_var(saved_next_opcode2);
+		saved = this_cpu_ptr(&saved_next_opcode2);
 		if (saved->addr) {
 			arch_disarm_kprobe(saved);
 
@@ -129,14 +129,14 @@ static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 
 static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
-	__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+	__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
 	kcb->kprobe_status = kcb->prev_kprobe.status;
 }
 
 static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 					 struct kprobe_ctlblk *kcb)
 {
-	__get_cpu_var(current_kprobe) = p;
+	__this_cpu_write(current_kprobe, p);
 }
 
 /*
@@ -146,15 +146,15 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
  */
 static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 {
-	__get_cpu_var(saved_current_opcode).addr = (kprobe_opcode_t *)regs->pc;
+	__this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);
 
 	if (p != NULL) {
 		struct kprobe *op1, *op2;
 
 		arch_disarm_kprobe(p);
 
-		op1 = &__get_cpu_var(saved_next_opcode);
-		op2 = &__get_cpu_var(saved_next_opcode2);
+		op1 = this_cpu_ptr(&saved_next_opcode);
+		op2 = this_cpu_ptr(&saved_next_opcode2);
 
 		if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
 			unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
@@ -249,7 +249,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 			kcb->kprobe_status = KPROBE_REENTER;
 			return 1;
 		} else {
-			p = __get_cpu_var(current_kprobe);
+			p = __this_cpu_read(current_kprobe);
 			if (p->break_handler && p->break_handler(p, regs)) {
 				goto ss_probe;
 			}
@@ -336,9 +336,9 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 			continue;
 
 		if (ri->rp && ri->rp->handler) {
-			__get_cpu_var(current_kprobe) = &ri->rp->kp;
+			__this_cpu_write(current_kprobe, &ri->rp->kp);
 			ri->rp->handler(ri, regs);
-			__get_cpu_var(current_kprobe) = NULL;
+			__this_cpu_write(current_kprobe, NULL);
 		}
 
 		orig_ret_address = (unsigned long)ri->ret_addr;
@@ -383,19 +383,19 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
 		cur->post_handler(cur, regs, 0);
 	}
 
-	p = &__get_cpu_var(saved_next_opcode);
+	p = this_cpu_ptr(&saved_next_opcode);
 	if (p->addr) {
 		arch_disarm_kprobe(p);
 		p->addr = NULL;
 		p->opcode = 0;
 
-		addr = __get_cpu_var(saved_current_opcode).addr;
-		__get_cpu_var(saved_current_opcode).addr = NULL;
+		addr = __this_cpu_read(saved_current_opcode.addr);
+		__this_cpu_write(saved_current_opcode.addr, NULL);
 
 		p = get_kprobe(addr);
 		arch_arm_kprobe(p);
 
-		p = &__get_cpu_var(saved_next_opcode2);
+		p = this_cpu_ptr(&saved_next_opcode2);
 		if (p->addr) {
 			arch_disarm_kprobe(p);
 			p->addr = NULL;
@@ -511,7 +511,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 				if (kprobe_handler(args->regs)) {
 					ret = NOTIFY_STOP;
 				} else {
-					p = __get_cpu_var(current_kprobe);
+					p = __this_cpu_read(current_kprobe);
 					if (p->break_handler &&
 					    p->break_handler(p, args->regs))
 						ret = NOTIFY_STOP;

arch/sh/kernel/localtimer.c

@@ -32,7 +32,7 @@ static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
  */
 void local_timer_interrupt(void)
 {
-	struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
+	struct clock_event_device *clk = this_cpu_ptr(&local_clockevent);
 
 	irq_enter();
 	clk->event_handler(clk);

arch/sh/kernel/perf_event.c

@@ -227,7 +227,7 @@ static void sh_perf_event_update(struct perf_event *event,
 
 static void sh_pmu_stop(struct perf_event *event, int flags)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;
 
@@ -245,7 +245,7 @@ static void sh_pmu_stop(struct perf_event *event, int flags)
 
 static void sh_pmu_start(struct perf_event *event, int flags)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;
 
@@ -262,7 +262,7 @@ static void sh_pmu_start(struct perf_event *event, int flags)
 
 static void sh_pmu_del(struct perf_event *event, int flags)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 
 	sh_pmu_stop(event, PERF_EF_UPDATE);
 	__clear_bit(event->hw.idx, cpuc->used_mask);
@@ -272,7 +272,7 @@ static void sh_pmu_del(struct perf_event *event, int flags)
 
 static int sh_pmu_add(struct perf_event *event, int flags)
 {
-	struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	struct hw_perf_event *hwc = &event->hw;
 	int idx = hwc->idx;
 	int ret = -EAGAIN;

arch/sh/kernel/smp.c

@@ -111,7 +111,7 @@ void play_dead_common(void)
 	irq_ctx_exit(raw_smp_processor_id());
 	mb();
 
-	__get_cpu_var(cpu_state) = CPU_DEAD;
+	__this_cpu_write(cpu_state, CPU_DEAD);
 	local_irq_disable();
 }