MIPS: Modularize COP2 handling

Away with the daemons of ifdef; get ready for future COP2 users.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/708/

arch/mips/cavium-octeon/Makefile

@@ -9,7 +9,7 @@
 # Copyright (C) 2005-2009 Cavium Networks
 #
 
-obj-y := setup.o serial.o octeon-platform.o octeon-irq.o csrc-octeon.o
+obj-y := cpu.o setup.o serial.o octeon-platform.o octeon-irq.o csrc-octeon.o
 obj-y += dma-octeon.o flash_setup.o
 obj-y += octeon-memcpy.o
 

arch/mips/cavium-octeon/cpu.c

+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2009 Wind River Systems,
+ *   written by Ralf Baechle <ralf@linux-mips.org>
+ */
+#include <linux/init.h>
+#include <linux/irqflags.h>
+#include <linux/notifier.h>
+#include <linux/prefetch.h>
+#include <linux/sched.h>
+
+#include <asm/cop2.h>
+#include <asm/current.h>
+#include <asm/mipsregs.h>
+#include <asm/page.h>
+#include <asm/octeon/octeon.h>
+
+static int cnmips_cu2_call(struct notifier_block *nfb, unsigned long action,
+	void *data)
+{
+	unsigned long flags;
+	unsigned int status;
+
+	switch (action) {
+	case CU2_EXCEPTION:
+		prefetch(&current->thread.cp2);
+		local_irq_save(flags);
+		KSTK_STATUS(current) |= ST0_CU2;
+		status = read_c0_status();
+		write_c0_status(status | ST0_CU2);
+		octeon_cop2_restore(&(current->thread.cp2));
+		write_c0_status(status & ~ST0_CU2);
+		local_irq_restore(flags);
+
+		return NOTIFY_BAD;	/* Don't call default notifier */
+	}
+
+	return NOTIFY_OK;		/* Let default notifier send signals */
+}
+
+static struct notifier_block cnmips_cu2_notifier = {
+	.notifier_call = cnmips_cu2_call,
+};
+
+static int cnmips_cu2_setup(void)
+{
+	return register_cu2_notifier(&cnmips_cu2_notifier);
+}
+early_initcall(cnmips_cu2_setup);

arch/mips/include/asm/cop2.h

+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2009 Wind River Systems,
+ *   written by Ralf Baechle <ralf@linux-mips.org>
+ */
+#ifndef __ASM_COP2_H
+#define __ASM_COP2_H
+
+enum cu2_ops {
+	CU2_EXCEPTION,
+	CU2_LWC2_OP,
+	CU2_LDC2_OP,
+	CU2_SWC2_OP,
+	CU2_SDC2_OP,
+};
+
+extern int register_cu2_notifier(struct notifier_block *nb);
+extern int cu2_notifier_call_chain(unsigned long val, void *v);
+
+#endif /* __ASM_COP2_H */

arch/mips/include/asm/octeon/octeon.h

@@ -47,6 +47,7 @@ struct octeon_cop2_state;
 extern unsigned long octeon_crypto_enable(struct octeon_cop2_state *state);
 extern void octeon_crypto_disable(struct octeon_cop2_state *state,
 				  unsigned long flags);
+extern asmlinkage void octeon_cop2_restore(struct octeon_cop2_state *task);
 
 extern void octeon_init_cvmcount(void);
 

arch/mips/kernel/traps.c

@@ -25,10 +25,12 @@
 #include <linux/ptrace.h>
 #include <linux/kgdb.h>
 #include <linux/kdebug.h>
+#include <linux/notifier.h>
 
 #include <asm/bootinfo.h>
 #include <asm/branch.h>
 #include <asm/break.h>
+#include <asm/cop2.h>
 #include <asm/cpu.h>
 #include <asm/dsp.h>
 #include <asm/fpu.h>
@@ -79,10 +81,6 @@ extern asmlinkage void handle_reserved(void);
 extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
 	struct mips_fpu_struct *ctx, int has_fpu);
 
-#ifdef CONFIG_CPU_CAVIUM_OCTEON
-extern asmlinkage void octeon_cop2_restore(struct octeon_cop2_state *task);
-#endif
-
 void (*board_be_init)(void);
 int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
 void (*board_nmi_handler_setup)(void);
@@ -857,6 +855,44 @@ static void mt_ase_fp_affinity(void)
 #endif /* CONFIG_MIPS_MT_FPAFF */
 }
 
+/*
+ * No lock; only written during early bootup by CPU 0.
+ */
+static RAW_NOTIFIER_HEAD(cu2_chain);
+
+int __ref register_cu2_notifier(struct notifier_block *nb)
+{
+	return raw_notifier_chain_register(&cu2_chain, nb);
+}
+
+int cu2_notifier_call_chain(unsigned long val, void *v)
+{
+	return raw_notifier_call_chain(&cu2_chain, val, v);
+}
+
+static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
+        void *data)
+{
+	struct pt_regs *regs = data;
+
+	switch (action) {
+	default:
+		die_if_kernel("Unhandled kernel unaligned access or invalid "
+			      "instruction", regs);
+		/* Fall through  */
+
+	case CU2_EXCEPTION:
+		force_sig(SIGILL, current);
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block default_cu2_notifier = {
+	.notifier_call	= default_cu2_call,
+	.priority	= 0x80000000,		/* Run last  */
+};
+
 asmlinkage void do_cpu(struct pt_regs *regs)
 {
 	unsigned int __user *epc;
@@ -920,17 +956,9 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 		return;
 
 	case 2:
-#ifdef CONFIG_CPU_CAVIUM_OCTEON
-		prefetch(&current->thread.cp2);
-		local_irq_save(flags);
-		KSTK_STATUS(current) |= ST0_CU2;
-		status = read_c0_status();
-		write_c0_status(status | ST0_CU2);
-		octeon_cop2_restore(&(current->thread.cp2));
-		write_c0_status(status & ~ST0_CU2);
-		local_irq_restore(flags);
-		return;
-#endif
+		raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
+		break;
+
 	case 3:
 		break;
 	}
@@ -1760,4 +1788,6 @@ void __init trap_init(void)
 	flush_tlb_handlers();
 
 	sort_extable(__start___dbe_table, __stop___dbe_table);
+
+	register_cu2_notifier(&default_cu2_notifier);
 }

arch/mips/kernel/unaligned.c

@@ -81,6 +81,7 @@
 #include <asm/asm.h>
 #include <asm/branch.h>
 #include <asm/byteorder.h>
+#include <asm/cop2.h>
 #include <asm/inst.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -451,17 +452,27 @@ static void emulate_load_store_insn(struct pt_regs *regs,
 		 */
 		goto sigbus;
 
+	/*
+	 * COP2 is available to implementor for application specific use.
+	 * It's up to applications to register a notifier chain and do
+	 * whatever they have to do, including possible sending of signals.
+	 */
 	case lwc2_op:
+		cu2_notifier_call_chain(CU2_LWC2_OP, regs);
+		break;
+
 	case ldc2_op:
+		cu2_notifier_call_chain(CU2_LDC2_OP, regs);
+		break;
+
 	case swc2_op:
+		cu2_notifier_call_chain(CU2_SWC2_OP, regs);
+		break;
+
 	case sdc2_op:
-		/*
-		 * These are the coprocessor 2 load/stores.  The current
-		 * implementations don't use cp2 and cp2 should always be
-		 * disabled in c0_status.  So send SIGILL.
-                 * (No longer true: The Sony Praystation uses cp2 for
-                 * 3D matrix operations.  Dunno if that thingy has a MMU ...)
-		 */
+		cu2_notifier_call_chain(CU2_SDC2_OP, regs);
+		break;
+
 	default:
 		/*
 		 * Pheeee...  We encountered an yet unknown instruction or