avr32: Fix lockup after Java stack underflow in user mode

When using the Java Extension Module hardware, a Java stack underflow or
overflow trap may cause the system to enter an infinite exception loop.
Although there's no kernel support for the Java hardware yet, we need to
be able to recover from this situation and keep the system running.

This patch adds code to detect and fixup this situation in the critical
exception handler and terminate the faulting process. We may have to
rethink how to handle this more gracefully when the necessary kernel
support for hardware-accelerated Java is added.

Reported-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/avr32/kernel/asm-offsets.c b/arch/avr32/kernel/asm-offsets.c
index e4796c67a83..d6a8193a1d2 100644
--- a/arch/avr32/kernel/asm-offsets.c
+++ b/arch/avr32/kernel/asm-offsets.c
@@ -4,6 +4,8 @@
  * to extract and format the required data.
  */
 
+#include <linux/mm.h>
+#include <linux/sched.h>
 #include <linux/thread_info.h>
 #include <linux/kbuild.h>
 
@@ -17,4 +19,8 @@ void foo(void)
 	OFFSET(TI_rar_saved, thread_info, rar_saved);
 	OFFSET(TI_rsr_saved, thread_info, rsr_saved);
 	OFFSET(TI_restart_block, thread_info, restart_block);
+	BLANK();
+	OFFSET(TSK_active_mm, task_struct, active_mm);
+	BLANK();
+	OFFSET(MM_pgd, mm_struct, pgd);
 }