[MIPS] kgdb: add arch support for the kernel's kgdb core

The new kgdb architecture specific handler registers and unregisters
dynamically for exceptions depending on when you configure a kgdb I/O
driver.

Aside from initializing the exceptions earlier in the boot process,
kgdb should have no impact on a device when it is compiled in so long
as an I/O module is not configured for use.

There have been quite a number of contributors during the existence of
this patch (see arch/mips/kernel/kgdb.c).  Most recently Jason
re-wrote the mips kgdb logic to use the die notification handlers.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index b8ea4e9d0d87..426cced1e9dc 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -23,6 +23,8 @@
 #include <linux/bootmem.h>
 #include <linux/interrupt.h>
 #include <linux/ptrace.h>
+#include <linux/kgdb.h>
+#include <linux/kdebug.h>
 
 #include <asm/bootinfo.h>
 #include <asm/branch.h>
@@ -425,6 +427,10 @@ asmlinkage void do_be(struct pt_regs *regs)
         printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n",
                data ? "Data" : "Instruction",
                field, regs->cp0_epc, field, regs->regs[31]);
+        if (notify_die(DIE_OOPS, "bus error", regs, SIGBUS, 0, 0)
+            == NOTIFY_STOP)
+                return;
+
         die_if_kernel("Oops", regs);
         force_sig(SIGBUS, current);
 }
@@ -623,6 +629,9 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 {
         siginfo_t info;
 
+        if (notify_die(DIE_FP, "FP exception", regs, SIGFPE, 0, 0)
+            == NOTIFY_STOP)
+                return;
         die_if_kernel("FP exception in kernel code", regs);
 
         if (fcr31 & FPU_CSR_UNI_X) {
@@ -682,6 +691,9 @@ static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
         siginfo_t info;
         char b[40];
 
+        if (notify_die(DIE_TRAP, str, regs, code, 0, 0) == NOTIFY_STOP)
+                return;
+
         /*
          * A short test says that IRIX 5.3 sends SIGTRAP for all trap
          * insns, even for trap and break codes that indicate arithmetic
@@ -762,6 +774,10 @@ asmlinkage void do_ri(struct pt_regs *regs)
         unsigned int opcode = 0;
         int status = -1;
 
+        if (notify_die(DIE_RI, "RI Fault", regs, SIGSEGV, 0, 0)
+            == NOTIFY_STOP)
+                return;
+
         die_if_kernel("Reserved instruction in kernel code", regs);
 
         if (unlikely(compute_return_epc(regs) < 0))
@@ -1537,6 +1553,11 @@ void __init trap_init(void)
         extern char except_vec4;
         unsigned long i;
 
+#if defined(CONFIG_KGDB)
+        if (kgdb_early_setup)
+                return; /* Already done */
+#endif
+
         if (cpu_has_veic || cpu_has_vint)
                 ebase = (unsigned long) alloc_bootmem_low_pages(0x200 + VECTORSPACING*64);
         else