sparc: Add kgdb support.

Current limitations:

1) On SMP single stepping has some fundamental issues,
   shared with other sw single-step architectures such
   as mips and arm.

2) On 32-bit sparc we don't support SMP kgdb yet.  That
   requires some reworking of the IPI mechanisms and
   infrastructure on that platform.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/kernel/head.S b/arch/sparc/kernel/head.S
index b7f1e81..8bec05f 100644
--- a/arch/sparc/kernel/head.S
+++ b/arch/sparc/kernel/head.S
@@ -191,7 +191,8 @@
 t_baded:BAD_TRAP(0xed) BAD_TRAP(0xee) BAD_TRAP(0xef) BAD_TRAP(0xf0) BAD_TRAP(0xf1)
 t_badf2:BAD_TRAP(0xf2) BAD_TRAP(0xf3) BAD_TRAP(0xf4) BAD_TRAP(0xf5) BAD_TRAP(0xf6)
 t_badf7:BAD_TRAP(0xf7) BAD_TRAP(0xf8) BAD_TRAP(0xf9) BAD_TRAP(0xfa) BAD_TRAP(0xfb)
-t_badfc:BAD_TRAP(0xfc) BAD_TRAP(0xfd)
+t_badfc:BAD_TRAP(0xfc)
+t_kgdb:	KGDB_TRAP(0xfd)
 dbtrap:	BAD_TRAP(0xfe)                      /* Debugger/PROM breakpoint #1   */
 dbtrap2:BAD_TRAP(0xff)                      /* Debugger/PROM breakpoint #2   */	
 
@@ -267,7 +268,7 @@
 	BAD_TRAP(0xed) BAD_TRAP(0xee) BAD_TRAP(0xef) BAD_TRAP(0xf0) BAD_TRAP(0xf1)
 	BAD_TRAP(0xf2) BAD_TRAP(0xf3) BAD_TRAP(0xf4) BAD_TRAP(0xf5) BAD_TRAP(0xf6)
 	BAD_TRAP(0xf7) BAD_TRAP(0xf8) BAD_TRAP(0xf9) BAD_TRAP(0xfa) BAD_TRAP(0xfb)
-	BAD_TRAP(0xfc) BAD_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
+	BAD_TRAP(0xfc) KGDB_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
 
 trapbase_cpu2:
 	BAD_TRAP(0x0) SRMMU_TFAULT TRAP_ENTRY(0x2, bad_instruction)
@@ -335,7 +336,7 @@
 	BAD_TRAP(0xed) BAD_TRAP(0xee) BAD_TRAP(0xef) BAD_TRAP(0xf0) BAD_TRAP(0xf1)
 	BAD_TRAP(0xf2) BAD_TRAP(0xf3) BAD_TRAP(0xf4) BAD_TRAP(0xf5) BAD_TRAP(0xf6)
 	BAD_TRAP(0xf7) BAD_TRAP(0xf8) BAD_TRAP(0xf9) BAD_TRAP(0xfa) BAD_TRAP(0xfb)
-	BAD_TRAP(0xfc) BAD_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
+	BAD_TRAP(0xfc) KGDB_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
 
 trapbase_cpu3:
 	BAD_TRAP(0x0) SRMMU_TFAULT TRAP_ENTRY(0x2, bad_instruction)
@@ -403,7 +404,7 @@
 	BAD_TRAP(0xed) BAD_TRAP(0xee) BAD_TRAP(0xef) BAD_TRAP(0xf0) BAD_TRAP(0xf1)
 	BAD_TRAP(0xf2) BAD_TRAP(0xf3) BAD_TRAP(0xf4) BAD_TRAP(0xf5) BAD_TRAP(0xf6)
 	BAD_TRAP(0xf7) BAD_TRAP(0xf8) BAD_TRAP(0xf9) BAD_TRAP(0xfa) BAD_TRAP(0xfb)
-	BAD_TRAP(0xfc) BAD_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
+	BAD_TRAP(0xfc) KGDB_TRAP(0xfd) BAD_TRAP(0xfe) BAD_TRAP(0xff)
 
 #endif
 	.align PAGE_SIZE