[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>

3 files changed, 13 insertions, 2 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);
 
diff --git a/arch/s390/kernel/reipl.S b/arch/s390/kernel/reipl.S
index f9434d42ce9f..c3f4d9b95083 100644
--- a/arch/s390/kernel/reipl.S
+++ b/arch/s390/kernel/reipl.S
@@ -16,7 +16,7 @@ do_reipl_asm:	basr	%r13,0
                 stm     %r0,%r15,__LC_GPREGS_SAVE_AREA
                 stctl   %c0,%c15,__LC_CREGS_SAVE_AREA
                 stam    %a0,%a15,__LC_AREGS_SAVE_AREA
-                stpx    __LC_PREFIX_SAVE_AREA
+                mvc     __LC_PREFIX_SAVE_AREA(4),dump_prefix_page-.Lpg0(%r13)
                 stckc   .Lclkcmp-.Lpg0(%r13)
                 mvc     __LC_CLOCK_COMP_SAVE_AREA(8),.Lclkcmp-.Lpg0(%r13)
                 stpt    __LC_CPU_TIMER_SAVE_AREA
@@ -79,3 +79,7 @@ do_reipl_asm:	basr	%r13,0
                 .long   0x00000000,0x00000000
                 .long   0x00000000,0x00000000
                 .long   0x00000000,0x00000000
+        .globl dump_prefix_page
+dump_prefix_page:
+        .long 0x00000000
+
diff --git a/arch/s390/kernel/reipl64.S b/arch/s390/kernel/reipl64.S
index f18ef260ca23..dbb3eed38865 100644
--- a/arch/s390/kernel/reipl64.S
+++ b/arch/s390/kernel/reipl64.S
@@ -20,7 +20,7 @@ do_reipl_asm:	basr	%r13,0
                 stg     %r0,__LC_GPREGS_SAVE_AREA-0x1000+8(%r1)
                 stctg   %c0,%c15,__LC_CREGS_SAVE_AREA-0x1000(%r1)
                 stam    %a0,%a15,__LC_AREGS_SAVE_AREA-0x1000(%r1)
-                stpx    __LC_PREFIX_SAVE_AREA-0x1000(%r1)
+                mvc     __LC_PREFIX_SAVE_AREA-0x1000(4,%r1),dump_prefix_page-.Lpg0(%r13)
                 stfpc   __LC_FP_CREG_SAVE_AREA-0x1000(%r1)
                 stckc   .Lclkcmp-.Lpg0(%r13)
                 mvc     __LC_CLOCK_COMP_SAVE_AREA-0x1000(8,%r1),.Lclkcmp-.Lpg0(%r13)
@@ -103,3 +103,6 @@ do_reipl_asm:	basr	%r13,0
                 .long   0x00000000,0x00000000
                 .long   0x00000000,0x00000000
                 .long   0x00000000,0x00000000
+        .globl dump_prefix_page
+dump_prefix_page:
+        .long 0x00000000