4.14-stable review patch. If anyone has any objections, please let me know.
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From: Martin Schwidefsky schwidefsky@de.ibm.com
commit 86a86804e4f18fc3880541b3d5a07f4df0fe29cb upstream.
The fix to make WARN work in the early boot code created a problem on older machines without EDAT-1. The setup_lowcore_dat_on function uses the pointer from lowcore_ptr[0] to set the DAT bit in the new PSWs. That does not work if the kernel page table is set up with 4K pages as the prefix address maps to absolute zero.
To make this work the PSWs need to be changed with via address 0 in form of the S390_lowcore definition.
Reported-by: Guenter Roeck linux@roeck-us.net Tested-by: Cornelia Huck cohuck@redhat.com Fixes: 94f85ed3e2f8 ("s390/setup: fix early warning messages") Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/kernel/setup.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
--- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -390,13 +390,12 @@ static void __init setup_lowcore_dat_off
static void __init setup_lowcore_dat_on(void) { - struct lowcore *lc; - - lc = lowcore_ptr[0]; - lc->external_new_psw.mask |= PSW_MASK_DAT; - lc->svc_new_psw.mask |= PSW_MASK_DAT; - lc->program_new_psw.mask |= PSW_MASK_DAT; - lc->io_new_psw.mask |= PSW_MASK_DAT; + __ctl_clear_bit(0, 28); + S390_lowcore.external_new_psw.mask |= PSW_MASK_DAT; + S390_lowcore.svc_new_psw.mask |= PSW_MASK_DAT; + S390_lowcore.program_new_psw.mask |= PSW_MASK_DAT; + S390_lowcore.io_new_psw.mask |= PSW_MASK_DAT; + __ctl_set_bit(0, 28); }
static struct resource code_resource = {