sh: Use a jump call table for debug trap handlers.

This rips out most of the needlessly complicated sh_bios and kgdb
trap handling, and forces it all through a common fast dispatch path.
As more debug traps are inserted, it's important to keep them in sync
for all of the parts, not just SH-3/4.

As the SH-2 parts are unable to do traps in the >= 0x40 range, we
restrict the debug traps to the 0x30-0x3f range on all parts, and
also bump the kgdb breakpoint trap down in to this range (from 0xff
to 0x3c) so it's possible to use for nommu.

Optionally, this table can be padded out to catch spurious traps for
SH-3/4, but we don't do that yet..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 21 insertions, 3 deletions

diff --git a/arch/sh/kernel/process.c b/arch/sh/kernel/process.c
index 486c06e1803..cc8f306fd68 100644
--- a/arch/sh/kernel/process.c
+++ b/arch/sh/kernel/process.c
@@ -493,9 +493,27 @@ asmlinkage void break_point_trap(void)
         force_sig(SIGTRAP, current);
 }
 
-asmlinkage void break_point_trap_software(unsigned long r4, unsigned long r5,
-                                          unsigned long r6, unsigned long r7,
-                                          struct pt_regs __regs)
+/*
+ * Generic trap handler.
+ */
+asmlinkage void debug_trap_handler(unsigned long r4, unsigned long r5,
+                                   unsigned long r6, unsigned long r7,
+                                   struct pt_regs __regs)
+{
+        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
+
+        /* Rewind */
+        regs->pc -= 2;
+
+        force_sig(SIGTRAP, current);
+}
+
+/*
+ * Special handler for BUG() traps.
+ */
+asmlinkage void bug_trap_handler(unsigned long r4, unsigned long r5,
+                                 unsigned long r6, unsigned long r7,
+                                 struct pt_regs __regs)
 {
         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);