s390/kexec: turn DAT mode off immediately before purgatory

The kernel code is not guaranteed DAT-off mode safe.
Turn the DAT mode off immediately before entering the
purgatory.

Further, to avoid subtle side effects reset the system
immediately before turning DAT mode off while making
all necessary preparations in advance.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 2a8e73266428e360bf0992d0d4eb28bb0c1aa78a..eb473fc835b2398d738a4c72f693a1a35d1dc53a 100644 (file)
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -254,14 +254,13 @@ static void __do_machine_kexec(void *data)
        relocate_kernel_t data_mover;
        struct kimage *image = data;
 
-       s390_reset_system();
        data_mover = (relocate_kernel_t) page_to_phys(image->control_code_page);
-
-       __arch_local_irq_stnsm(0xfb); /* disable DAT - avoid no-execute */
-       /* Call the moving routine */
        diag308_subcode = DIAG308_CLEAR_RESET;
        if (sclp.has_iplcc)
                diag308_subcode |= DIAG308_FLAG_EI;
+       s390_reset_system();
+
+       __arch_local_irq_stnsm(0xfb); /* disable DAT - avoid no-execute */
        (*data_mover)(&image->head, image->start, diag308_subcode);
 
        /* Die if kexec returns */