microblaze_v8: exception handling

Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Stephen Neuendorffer <stephen.neuendorffer@xilinx.com>
Acked-by: John Linn <john.linn@xilinx.com>
Acked-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/include/asm/exceptions.h

+/*
+ * Preliminary support for HW exception handing for Microblaze
+ *
+ * Copyright (C) 2008 Michal Simek
+ * Copyright (C) 2008 PetaLogix
+ * Copyright (C) 2005 John Williams <jwilliams@itee.uq.edu.au>
+ *
+ * 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.
+ */
+
+#ifndef _ASM_MICROBLAZE_EXCEPTIONS_H
+#define _ASM_MICROBLAZE_EXCEPTIONS_H
+
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+
+/* Macros to enable and disable HW exceptions in the MSR */
+/* Define MSR enable bit for HW exceptions */
+#define HWEX_MSR_BIT (1 << 8)
+
+#if CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR
+#define __enable_hw_exceptions()					\
+	__asm__ __volatile__ ("	msrset	r0, %0;				\
+				nop;"					\
+				:					\
+				: "i" (HWEX_MSR_BIT)			\
+				: "memory")
+
+#define __disable_hw_exceptions()					\
+	__asm__ __volatile__ ("	msrclr r0, %0;				\
+				nop;"					\
+				:					\
+				: "i" (HWEX_MSR_BIT)			\
+				: "memory")
+#else /* !CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR */
+#define __enable_hw_exceptions()					\
+	__asm__ __volatile__ ("						\
+				mfs	r12, rmsr;			\
+				nop;					\
+				ori	r12, r12, %0;			\
+				mts	rmsr, r12;			\
+				nop;"					\
+				:					\
+				: "i" (HWEX_MSR_BIT)			\
+				: "memory", "r12")
+
+#define __disable_hw_exceptions()					\
+	__asm__ __volatile__ ("						\
+				mfs	r12, rmsr;			\
+				nop;					\
+				andi	r12, r12, ~%0;			\
+				mts	rmsr, r12;			\
+				nop;"					\
+				:					\
+				: "i" (HWEX_MSR_BIT)			\
+				: "memory", "r12")
+#endif /* CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR */
+
+asmlinkage void full_exception(struct pt_regs *regs, unsigned int type,
+							int fsr, int addr);
+
+#if defined(CONFIG_XMON)
+extern void xmon(struct pt_regs *regs);
+extern int xmon_bpt(struct pt_regs *regs);
+extern int xmon_sstep(struct pt_regs *regs);
+extern int xmon_iabr_match(struct pt_regs *regs);
+extern int xmon_dabr_match(struct pt_regs *regs);
+extern void (*xmon_fault_handler)(struct pt_regs *regs);
+
+void (*debugger)(struct pt_regs *regs) = xmon;
+int (*debugger_bpt)(struct pt_regs *regs) = xmon_bpt;
+int (*debugger_sstep)(struct pt_regs *regs) = xmon_sstep;
+int (*debugger_iabr_match)(struct pt_regs *regs) = xmon_iabr_match;
+int (*debugger_dabr_match)(struct pt_regs *regs) = xmon_dabr_match;
+void (*debugger_fault_handler)(struct pt_regs *regs);
+#elif defined(CONFIG_KGDB)
+void (*debugger)(struct pt_regs *regs);
+int (*debugger_bpt)(struct pt_regs *regs);
+int (*debugger_sstep)(struct pt_regs *regs);
+int (*debugger_iabr_match)(struct pt_regs *regs);
+int (*debugger_dabr_match)(struct pt_regs *regs);
+void (*debugger_fault_handler)(struct pt_regs *regs);
+#else
+#define debugger(regs)			do { } while (0)
+#define debugger_bpt(regs)		0
+#define debugger_sstep(regs)		0
+#define debugger_iabr_match(regs)	0
+#define debugger_dabr_match(regs)	0
+#define debugger_fault_handler		((void (*)(struct pt_regs *))0)
+#endif
+
+#endif /*__ASSEMBLY__ */
+#endif /* __KERNEL__ */
+#endif /* _ASM_MICROBLAZE_EXCEPTIONS_H */

arch/microblaze/kernel/exceptions.c

+/*
+ * HW exception handling
+ *
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008 PetaLogix
+ *
+ * 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.
+ */
+
+/*
+ * This file handles the architecture-dependent parts of hardware exceptions
+ */
+
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kallsyms.h>
+#include <linux/module.h>
+
+#include <asm/exceptions.h>
+#include <asm/entry.h>		/* For KM CPU var */
+#include <asm/uaccess.h>
+#include <asm/errno.h>
+#include <asm/ptrace.h>
+#include <asm/current.h>
+
+#define MICROBLAZE_ILL_OPCODE_EXCEPTION	0x02
+#define MICROBLAZE_IBUS_EXCEPTION	0x03
+#define MICROBLAZE_DBUS_EXCEPTION	0x04
+#define MICROBLAZE_DIV_ZERO_EXCEPTION	0x05
+#define MICROBLAZE_FPU_EXCEPTION	0x06
+#define MICROBLAZE_PRIVILEG_EXCEPTION	0x07
+
+static DEFINE_SPINLOCK(die_lock);
+
+void die(const char *str, struct pt_regs *fp, long err)
+{
+	console_verbose();
+	spin_lock_irq(&die_lock);
+	printk(KERN_WARNING "Oops: %s, sig: %ld\n", str, err);
+	show_regs(fp);
+	spin_unlock_irq(&die_lock);
+	/* do_exit() should take care of panic'ing from an interrupt
+	 * context so we don't handle it here
+	 */
+	do_exit(err);
+}
+
+void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
+{
+	siginfo_t info;
+
+	if (kernel_mode(regs)) {
+		debugger(regs);
+		die("Exception in kernel mode", regs, signr);
+	}
+	info.si_signo = signr;
+	info.si_errno = 0;
+	info.si_code = code;
+	info.si_addr = (void __user *) addr;
+	force_sig_info(signr, &info, current);
+}
+
+asmlinkage void full_exception(struct pt_regs *regs, unsigned int type,
+							int fsr, int addr)
+{
+#if 0
+	printk(KERN_WARNING "Exception %02x in %s mode, FSR=%08x PC=%08x ESR=%08x\n",
+			type, user_mode(regs) ? "user" : "kernel", fsr,
+			(unsigned int) regs->pc, (unsigned int) regs->esr);
+#endif
+
+	switch (type & 0x1F) {
+	case MICROBLAZE_ILL_OPCODE_EXCEPTION:
+		_exception(SIGILL, regs, ILL_ILLOPC, addr);
+		break;
+	case MICROBLAZE_IBUS_EXCEPTION:
+		if (user_mode(regs)) {
+			printk(KERN_WARNING "Instruction bus error exception in user mode.\n");
+			_exception(SIGBUS, regs, BUS_ADRERR, addr);
+			return;
+		}
+		printk(KERN_WARNING "Instruction bus error exception in kernel mode.\n");
+		die("bus exception", regs, SIGBUS);
+		break;
+	case MICROBLAZE_DBUS_EXCEPTION:
+		if (user_mode(regs)) {
+			printk(KERN_WARNING "Data bus error exception in user mode.\n");
+			_exception(SIGBUS, regs, BUS_ADRERR, addr);
+			return;
+		}
+		printk(KERN_WARNING "Data bus error exception in kernel mode.\n");
+		die("bus exception", regs, SIGBUS);
+		break;
+	case MICROBLAZE_DIV_ZERO_EXCEPTION:
+		printk(KERN_WARNING "Divide by zero exception\n");
+		_exception(SIGILL, regs, ILL_ILLOPC, addr);
+		break;
+
+	case MICROBLAZE_FPU_EXCEPTION:
+		/* IEEE FP exception */
+		/* I removed fsr variable and use code var for storing fsr */
+		if (fsr & FSR_IO)
+			fsr = FPE_FLTINV;
+		else if (fsr & FSR_OF)
+			fsr = FPE_FLTOVF;
+		else if (fsr & FSR_UF)
+			fsr = FPE_FLTUND;
+		else if (fsr & FSR_DZ)
+			fsr = FPE_FLTDIV;
+		else if (fsr & FSR_DO)
+			fsr = FPE_FLTRES;
+		_exception(SIGFPE, regs, fsr, addr);
+		break;
+
+	default:
+		printk(KERN_WARNING "Unexpected exception %02x "
+			"PC=%08x in %s mode\n", type, (unsigned int) addr,
+			kernel_mode(regs) ? "kernel" : "user");
+	}
+	return;
+}