nios2: Traps exception handling

This patch contains traps exception handling.
Signed-off-by: Ley Foon Tan <lftan@altera.com>

arch/nios2/include/asm/traps.h

+/*
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *
+ * 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_NIOS2_TRAPS_H
+#define _ASM_NIOS2_TRAPS_H
+
+#define TRAP_ID_SYSCALL		0
+
+#ifndef __ASSEMBLY__
+void _exception(int signo, struct pt_regs *regs, int code, unsigned long addr);
+#endif
+
+#endif /* _ASM_NIOS2_TRAPS_H */

arch/nios2/kernel/traps.c

+/*
+ * Hardware exception handling
+ *
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ * Copyright (C) 2001 Vic Phillips
+ *
+ * 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.
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/ptrace.h>
+
+#include <asm/traps.h>
+#include <asm/sections.h>
+#include <asm/uaccess.h>
+
+static DEFINE_SPINLOCK(die_lock);
+
+void die(const char *str, struct pt_regs *regs, long err)
+{
+	console_verbose();
+	spin_lock_irq(&die_lock);
+	pr_warn("Oops: %s, sig: %ld\n", str, err);
+	show_regs(regs);
+	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 signo, struct pt_regs *regs, int code, unsigned long addr)
+{
+	siginfo_t info;
+
+	if (!user_mode(regs))
+		die("Exception in kernel mode", regs, signo);
+
+	info.si_signo = signo;
+	info.si_errno = 0;
+	info.si_code = code;
+	info.si_addr = (void __user *) addr;
+	force_sig_info(signo, &info, current);
+}
+
+/*
+ * The show_stack is an external API which we do not use ourselves.
+ */
+
+int kstack_depth_to_print = 48;
+
+void show_stack(struct task_struct *task, unsigned long *stack)
+{
+	unsigned long *endstack, addr;
+	int i;
+
+	if (!stack) {
+		if (task)
+			stack = (unsigned long *)task->thread.ksp;
+		else
+			stack = (unsigned long *)&stack;
+	}
+
+	addr = (unsigned long) stack;
+	endstack = (unsigned long *) PAGE_ALIGN(addr);
+
+	pr_emerg("Stack from %08lx:", (unsigned long)stack);
+	for (i = 0; i < kstack_depth_to_print; i++) {
+		if (stack + 1 > endstack)
+			break;
+		if (i % 8 == 0)
+			pr_emerg("\n       ");
+		pr_emerg(" %08lx", *stack++);
+	}
+
+	pr_emerg("\nCall Trace:");
+	i = 0;
+	while (stack + 1 <= endstack) {
+		addr = *stack++;
+		/*
+		 * If the address is either in the text segment of the
+		 * kernel, or in the region which contains vmalloc'ed
+		 * memory, it *may* be the address of a calling
+		 * routine; if so, print it so that someone tracing
+		 * down the cause of the crash will be able to figure
+		 * out the call path that was taken.
+		 */
+		if (((addr >= (unsigned long) _stext) &&
+		     (addr <= (unsigned long) _etext))) {
+			if (i % 4 == 0)
+				pr_emerg("\n       ");
+			pr_emerg(" [<%08lx>]", addr);
+			i++;
+		}
+	}
+	pr_emerg("\n");
+}
+
+void __init trap_init(void)
+{
+	/* Nothing to do here */
+}
+
+/* Breakpoint handler */
+asmlinkage void breakpoint_c(struct pt_regs *fp)
+{
+	/*
+	 * The breakpoint entry code has moved the PC on by 4 bytes, so we must
+	 * move it back. This could be done on the host but we do it here
+	 * because monitor.S of JTAG gdbserver does it too.
+	 */
+	fp->ea -= 4;
+	_exception(SIGTRAP, fp, TRAP_BRKPT, fp->ea);
+}
+
+#ifndef CONFIG_NIOS2_ALIGNMENT_TRAP
+/* Alignment exception handler */
+asmlinkage void handle_unaligned_c(struct pt_regs *fp, int cause)
+{
+	unsigned long addr = RDCTL(CTL_BADADDR);
+
+	cause >>= 2;
+	fp->ea -= 4;
+
+	if (fixup_exception(fp))
+		return;
+
+	if (!user_mode(fp)) {
+		pr_alert("Unaligned access from kernel mode, this might be a hardware\n");
+		pr_alert("problem, dump registers and restart the instruction\n");
+		pr_alert("  BADADDR 0x%08lx\n", addr);
+		pr_alert("  cause   %d\n", cause);
+		pr_alert("  op-code 0x%08lx\n", *(unsigned long *)(fp->ea));
+		show_regs(fp);
+		return;
+	}
+
+	_exception(SIGBUS, fp, BUS_ADRALN, addr);
+}
+#endif /* CONFIG_NIOS2_ALIGNMENT_TRAP */
+
+/* Illegal instruction handler */
+asmlinkage void handle_illegal_c(struct pt_regs *fp)
+{
+	fp->ea -= 4;
+	_exception(SIGILL, fp, ILL_ILLOPC, fp->ea);
+}
+
+/* Supervisor instruction handler */
+asmlinkage void handle_supervisor_instr(struct pt_regs *fp)
+{
+	fp->ea -= 4;
+	_exception(SIGILL, fp, ILL_PRVOPC, fp->ea);
+}
+
+/* Division error handler */
+asmlinkage void handle_diverror_c(struct pt_regs *fp)
+{
+	fp->ea -= 4;
+	_exception(SIGFPE, fp, FPE_INTDIV, fp->ea);
+}
+
+/* Unhandled exception handler */
+asmlinkage void unhandled_exception(struct pt_regs *regs, int cause)
+{
+	unsigned long addr = RDCTL(CTL_BADADDR);
+
+	cause /= 4;
+
+	pr_emerg("Unhandled exception #%d in %s mode (badaddr=0x%08lx)\n",
+			cause, user_mode(regs) ? "user" : "kernel", addr);
+
+	regs->ea -= 4;
+	show_regs(regs);
+
+	pr_emerg("opcode: 0x%08lx\n", *(unsigned long *)(regs->ea));
+}