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, 15 deletions

diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index b224c650a18d..57bd2a09610c 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -37,10 +37,6 @@
 #include <linux/uaccess.h>
 #include <asm/exceptions.h>
 
-#if defined(CONFIG_KGDB)
-int debugger_kernel_faults = 1;
-#endif
-
 static unsigned long pte_misses;        /* updated by do_page_fault() */
 static unsigned long pte_errors;        /* updated by do_page_fault() */
 
@@ -81,10 +77,6 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
         }
 
         /* kernel has accessed a bad area */
-#if defined(CONFIG_KGDB)
-        if (debugger_kernel_faults)
-                debugger(regs);
-#endif
         die("kernel access of bad area", regs, sig);
 }
 
@@ -115,13 +107,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
         if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
                 is_write = 0;
 
-#if defined(CONFIG_KGDB)
-        if (debugger_fault_handler && regs->trap == 0x300) {
-                debugger_fault_handler(regs);
-                return;
-        }
-#endif /* CONFIG_KGDB */
-
         if (unlikely(in_atomic() || !mm)) {
                 if (kernel_mode(regs))
                         goto bad_area_nosemaphore;