[S390] Save prefix register for dump on panic

The dump tools expect that the saved prefix register points to the
lowcore of the dump cpu. Since we set the prefix register to 0 during
reipl/dump, we have to save the original prefix register. Before we
start the dump program, we copy the original prefix register to the
designated location in the lowcore.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 48bfe402052b..9e9972e8a52b 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -995,6 +995,7 @@ static void do_reset_calls(void)
 
 extern void reset_mcck_handler(void);
 extern void reset_pgm_handler(void);
+extern __u32 dump_prefix_page;
 
 void s390_reset_system(void)
 {
@@ -1005,6 +1006,9 @@ void s390_reset_system(void)
         /* Stack for interrupt/machine check handler */
         lc->panic_stack = S390_lowcore.panic_stack;
 
+        /* Save prefix page address for dump case */
+        dump_prefix_page = (unsigned long) lc;
+
         /* Disable prefixing */
         set_prefix(0);