s390/cpumf: add missing lpp magic initialization

Add the missing lpp magic initialization for cpu 0. Without this all
samples on cpu 0 do not have the most significant bit set in the
program parameter field, which we use to distinguish between guest and
host samples if the pid is also 0.

We did initialize the lpp magic in the absolute zero lowcore but
forgot that when switching to the allocated lowcore on cpu 0 only.

Reported-by: Shu Juan Zhang <zhshuj@cn.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: stable@vger.kernel.org # v4.4+
Fixes: e22cf8ca6f75 ("s390/cpumf: rework program parameter setting to detect guest samples")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index b1fbcc07c8710a60f3e3f6b7fe8798e5740b7997..cc46767e902e262b461b0ab76402fef94a04404f 100644 (file)
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -327,6 +327,7 @@ static void __init setup_lowcore(void)
                + PAGE_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
        lc->current_task = (unsigned long) init_thread_union.thread_info.task;
        lc->thread_info = (unsigned long) &init_thread_union;
+       lc->lpp = LPP_MAGIC;
        lc->machine_flags = S390_lowcore.machine_flags;
        lc->stfl_fac_list = S390_lowcore.stfl_fac_list;
        memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,