[S390] hibernation: fix lowcore handling

Our swsusp_arch_suspend() backend implementation disables prefixing
by setting the contents of the prefix register to 0.
However afterwards common code functions are called which might
access percpu data structures.
Since the lowcore contains e.g. the percpu base pointer this isn't
a good idea. So fix this by copying the hibernating cpu's lowcore to
absolute address zero.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 10 insertions, 7 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index f9b144049dc9..8d15314381e0 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -210,7 +210,7 @@ static noinline __init void detect_machine_type(void)
                 machine_flags |= MACHINE_FLAG_VM;
 }
 
-static void early_pgm_check_handler(void)
+static __init void early_pgm_check_handler(void)
 {
         unsigned long addr;
         const struct exception_table_entry *fixup;
@@ -222,7 +222,7 @@ static void early_pgm_check_handler(void)
         S390_lowcore.program_old_psw.addr = fixup->fixup | PSW_ADDR_AMODE;
 }
 
-void setup_lowcore_early(void)
+static noinline __init void setup_lowcore_early(void)
 {
         psw_t psw;
 
diff --git a/arch/s390/power/swsusp_asm64.S b/arch/s390/power/swsusp_asm64.S
index 76d688da32fa..e27bd3164897 100644
--- a/arch/s390/power/swsusp_asm64.S
+++ b/arch/s390/power/swsusp_asm64.S
@@ -40,11 +40,11 @@ swsusp_arch_suspend:
         /* Store prefix register on stack */
         stpx    __SF_EMPTY(%r15)
 
-        /* Setup base register for lowcore (absolute 0) */
-        llgf    %r1,__SF_EMPTY(%r15)
+        /* Save prefix register contents for lowcore */
+        llgf    %r4,__SF_EMPTY(%r15)
 
         /* Get pointer to save area */
-        aghi    %r1,0x1000
+        lghi    %r1,0x1000
 
         /* Store registers */
         mvc     0x318(4,%r1),__SF_EMPTY(%r15)   /* move prefix to lowcore */
@@ -79,8 +79,11 @@ swsusp_arch_suspend:
         xc      __SF_EMPTY(4,%r15),__SF_EMPTY(%r15)
         spx     __SF_EMPTY(%r15)
 
-        /* Setup lowcore */
-        brasl   %r14,setup_lowcore_early
+        lghi    %r2,0
+        lghi    %r3,2*PAGE_SIZE
+        lghi    %r5,2*PAGE_SIZE
+1:      mvcle   %r2,%r4,0
+        jo      1b
 
         /* Save image */
         brasl   %r14,swsusp_save