Blackfin arch: add supporting for double fault debug handling

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/arch/blackfin/Kconfig.debug b/arch/blackfin/Kconfig.debug
index c468624d55f0..0afa89818722 100644
--- a/arch/blackfin/Kconfig.debug
+++ b/arch/blackfin/Kconfig.debug
@@ -22,6 +22,44 @@ config DEBUG_HWERR
           hardware error interrupts and need to know where they are coming
           from.
 
+config DEBUG_DOUBLEFAULT
+        bool "Debug Double Faults"
+        default n
+        help
+          If an exception is caused while executing code within the exception
+          handler, the NMI handler, the reset vector, or in emulator mode,
+          a double fault occurs. On the Blackfin, this is a unrecoverable
+          event. You have two options:
+          - RESET exactly when double fault occurs. The excepting
+            instruction address is stored in RETX, where the next kernel
+            boot will print it out.
+          - Print debug message. This is much more error prone, although
+            easier to handle. It is error prone since:
+            - The excepting instruction is not committed.
+            - All writebacks from the instruction are prevented.
+            - The generated exception is not taken.
+            - The EXCAUSE field is updated with an unrecoverable event
+            The only way to check this is to see if EXCAUSE contains the
+            unrecoverable event value at every exception return. By selecting
+            this option, you are skipping over the faulting instruction, and 
+            hoping things stay together enough to print out a debug message.
+
+          This does add a little kernel code, but is the only method to debug
+          double faults - if unsure say "Y"
+
+choice
+        prompt "Double Fault Failure Method"
+        default DEBUG_DOUBLEFAULT_PRINT
+        depends on DEBUG_DOUBLEFAULT
+
+config DEBUG_DOUBLEFAULT_PRINT
+        bool "Print"
+
+config DEBUG_DOUBLEFAULT_RESET
+        bool "Reset"
+
+endchoice
+
 config DEBUG_ICACHE_CHECK
         bool "Check Instruction cache coherency"
         depends on DEBUG_KERNEL