Blackfin: improve double fault debug handling

Since the hardware only provides reporting for the last exception handled,
and the values are valid only when executing the exception handler, we
need to save the context for reporting at a later point.  While we do this
for one exception, it doesn't work properly when handling a second one as
the original exception is clobbered by the double fault.  So when double
fault debugging is enabled, create a dedicated shadow of these values and
save/restore out of there.  Now the crash report properly displays the
first exception as well as the second one.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/blackfin/include/asm/pda.h b/arch/blackfin/include/asm/pda.h
index 69b96b40c188..a6f95695731d 100644
--- a/arch/blackfin/include/asm/pda.h
+++ b/arch/blackfin/include/asm/pda.h
@@ -61,6 +61,12 @@ struct blackfin_pda {			/* Per-processor Data Area */
         unsigned long retx;
         unsigned long seqstat;
         unsigned int __nmi_count;       /* number of times NMI asserted on this CPU */
+#ifdef CONFIG_DEBUG_DOUBLEFAULT
+        unsigned long dcplb_doublefault_addr;
+        unsigned long icplb_doublefault_addr;
+        unsigned long retx_doublefault;
+        unsigned long seqstat_doublefault;
+#endif
 };
 
 extern struct blackfin_pda cpu_pda[];