ARC: Unaligned access emulation

ARC700 doesn't natively support unaligned access, but can be emulated
-Unaligned Access Exception
-Disassembly at the Fault address to find the exact insn (long/short)

Also per Arnd's comment, we runtime control it using 2 sysctl knobs:
* SYSCTL_ARCH_UNALIGN_ALLOW: Runtime enable/disble
* SYSCTL_ARCH_UNALIGN_NO_WARN: Warn on each emulation attempt

Originally contributed by Tim Yao <tim.yao@amlogic.com>

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Tim Yao <tim.yao@amlogic.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 32 insertions, 1 deletions

diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 78e982d..b24089c 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -52,7 +52,6 @@ generic-y += topology.h
 generic-y += trace_clock.h
 generic-y += types.h
 generic-y += ucontext.h
-generic-y += unaligned.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 063ed00..df5b952 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -97,6 +97,9 @@ struct callee_regs {
 	sp;			\
 })
 
+/* return 1 if PC in delay slot */
+#define delay_mode(regs) ((regs->status32 & STATUS_DE_MASK) == STATUS_DE_MASK)
+
 #define in_syscall(regs)    (regs->event & orig_r8_IS_SCALL)
 #define in_brkpt_trap(regs) (regs->event & orig_r8_IS_BRKPT)
 
diff --git a/arch/arc/include/asm/unaligned.h b/arch/arc/include/asm/unaligned.h
new file mode 100644
index 0000000..5dbe63f
--- /dev/null
+++ b/arch/arc/include/asm/unaligned.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * 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.
+ */
+
+#ifndef _ASM_ARC_UNALIGNED_H
+#define _ASM_ARC_UNALIGNED_H
+
+/* ARC700 can't handle unaligned Data accesses. */
+
+#include <asm-generic/unaligned.h>
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_ARC_MISALIGN_ACCESS
+int misaligned_fixup(unsigned long address, struct pt_regs *regs,
+		     unsigned long cause, struct callee_regs *cregs);
+#else
+static inline int
+misaligned_fixup(unsigned long address, struct pt_regs *regs,
+		 unsigned long cause, struct callee_regs *cregs)
+{
+	return 0;
+}
+#endif
+
+#endif /* _ASM_ARC_UNALIGNED_H */