[ARM] 3707/1: iwmmxt: use the generic thread notifier infrastructure

Patch from Lennert Buytenhek

This patch makes the iWMMXt context switch hook use the generic
thread notifier infrastructure that was recently merged in commit
d6551e8.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/Makefile

@@ -25,7 +25,7 @@ obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 obj-$(CONFIG_CRUNCH)		+= crunch.o crunch-bits.o
 AFLAGS_crunch-bits.o		:= -Wa,-mcpu=ep9312
 
-obj-$(CONFIG_IWMMXT)		+= iwmmxt.o
+obj-$(CONFIG_IWMMXT)		+= iwmmxt.o iwmmxt-notifier.o
 AFLAGS_iwmmxt.o			:= -Wa,-mcpu=iwmmxt
 
 ifneq ($(CONFIG_ARCH_EBSA110),y)

arch/arm/kernel/entry-armv.S

@@ -590,9 +590,7 @@ ENTRY(__switch_to)
 #ifdef CONFIG_MMU
 	mcr	p15, 0, r6, c3, c0, 0		@ Set domain register
 #endif
-#if defined(CONFIG_IWMMXT)
-	bl	iwmmxt_task_switch
-#elif defined(CONFIG_CPU_XSCALE)
+#if defined(CONFIG_CPU_XSCALE) && !defined(CONFIG_IWMMXT)
 	add	r4, r2, #TI_CPU_DOMAIN + 40	@ cpu_context_save->extra
 	ldmib	r4, {r4, r5}
 	mar	acc0, r4, r5

arch/arm/kernel/iwmmxt-notifier.c

@@ -0,0 +1,64 @@
+/*
+ *  linux/arch/arm/kernel/iwmmxt-notifier.c
+ *
+ *  XScale iWMMXt (Concan) context switching and handling
+ *
+ *  Initial code:
+ *  Copyright (c) 2003, Intel Corporation
+ *
+ *  Full lazy switching support, optimizations and more, by Nicolas Pitre
+ *  Copyright (c) 2003-2004, MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <asm/thread_notify.h>
+#include <asm/io.h>
+
+static int iwmmxt_do(struct notifier_block *self, unsigned long cmd, void *t)
+{
+	struct thread_info *thread = t;
+
+	switch (cmd) {
+	case THREAD_NOTIFY_FLUSH:
+		/*
+		 * flush_thread() zeroes thread->fpstate, so no need
+		 * to do anything here.
+		 *
+		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
+		 * initialised state information on the first fault.
+		 */
+
+	case THREAD_NOTIFY_RELEASE:
+		iwmmxt_task_release(thread);
+		break;
+
+	case THREAD_NOTIFY_SWITCH:
+		iwmmxt_task_switch(thread);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block iwmmxt_notifier_block = {
+	.notifier_call	= iwmmxt_do,
+};
+
+static int __init iwmmxt_init(void)
+{
+	thread_register_notifier(&iwmmxt_notifier_block);
+
+	return 0;
+}
+
+late_initcall(iwmmxt_init);

arch/arm/kernel/iwmmxt.S

@@ -271,30 +271,27 @@ ENTRY(iwmmxt_task_restore)
 /*
  * Concan handling on task switch
  *
- * r0 = previous task_struct pointer (must be preserved)
- * r1 = previous thread_info pointer
- * r2 = next thread_info pointer (must be preserved)
+ * r0 = next thread_info pointer
  *
- * Called only from __switch_to with task preemption disabled.
- * No need to care about preserving r4 and above.
+ * Called only from the iwmmxt notifier with task preemption disabled.
  */
 ENTRY(iwmmxt_task_switch)
 
-	mrc	p15, 0, r4, c15, c1, 0
-	tst	r4, #0x3			@ CP0 and CP1 accessible?
+	mrc	p15, 0, r1, c15, c1, 0
+	tst	r1, #0x3			@ CP0 and CP1 accessible?
 	bne	1f				@ yes: block them for next task
 
-	ldr	r5, =concan_owner
-	add	r6, r2, #TI_IWMMXT_STATE	@ get next task Concan save area
-	ldr	r5, [r5]			@ get current Concan owner
-	teq	r5, r6				@ next task owns it?
+	ldr	r2, =concan_owner
+	add	r3, r0, #TI_IWMMXT_STATE	@ get next task Concan save area
+	ldr	r2, [r2]			@ get current Concan owner
+	teq	r2, r3				@ next task owns it?
 	movne	pc, lr				@ no: leave Concan disabled
 
-1:	eor	r4, r4, #3			@ flip Concan access
-	mcr	p15, 0, r4, c15, c1, 0
+1:	eor	r1, r1, #3			@ flip Concan access
+	mcr	p15, 0, r1, c15, c1, 0
 
-	mrc	p15, 0, r4, c2, c0, 0
-	sub	pc, lr, r4, lsr #32		@ cpwait and return
+	mrc	p15, 0, r1, c2, c0, 0
+	sub	pc, lr, r1, lsr #32		@ cpwait and return
 
 /*
  * Remove Concan ownership of given task

arch/arm/kernel/process.c

@@ -353,19 +353,13 @@ void flush_thread(void)
 	memset(&thread->fpstate, 0, sizeof(union fp_state));
 
 	thread_notify(THREAD_NOTIFY_FLUSH, thread);
-#if defined(CONFIG_IWMMXT)
-	iwmmxt_task_release(thread);
-#endif
 }
 
 void release_thread(struct task_struct *dead_task)
 {
 	struct thread_info *thread = task_thread_info(dead_task);
 
 	thread_notify(THREAD_NOTIFY_RELEASE, thread);
-#if defined(CONFIG_IWMMXT)
-	iwmmxt_task_release(thread);
-#endif
 }
 
 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");

include/asm-arm/thread_info.h

@@ -111,6 +111,7 @@ extern void iwmmxt_task_disable(struct thread_info *);
 extern void iwmmxt_task_copy(struct thread_info *, void *);
 extern void iwmmxt_task_restore(struct thread_info *, void *);
 extern void iwmmxt_task_release(struct thread_info *);
+extern void iwmmxt_task_switch(struct thread_info *);
 
 #endif