microblaze: Add KGDB support

Kgdb uses brki r16, 0x18 instruction to call
low level _debug_exception function which save
current state to pt_regs and call microblaze_kgdb_break
function. _debug_exception should be called only from
the kernel space. User space calling is not supported
because user application debugging uses different handling.

pt_regs_to_gdb_regs loads additional special registers
which can't be changed

 * Enable KGDB in Kconfig
 * Remove ancient not-tested KGDB support
 * Remove ancient _debug_exception code from entry.S

Only MMU KGDB support is supported.

Signed-off-by: Michal Simek <monstr@monstr.eu>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: John Williams <john.williams@petalogix.com>
CC: Edgar E. Iglesias <edgar.iglesias@petalogix.com>
CC: linux-kernel@vger.kernel.org
Acked-by: Jason Wessel <jason.wessel@windriver.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/arch/microblaze/kernel/exceptions.c b/arch/microblaze/kernel/exceptions.c
index e0c6f8c2bd9d..b98ee8d0c1cd 100644
--- a/arch/microblaze/kernel/exceptions.c
+++ b/arch/microblaze/kernel/exceptions.c
@@ -59,7 +59,6 @@ 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;