releases/5.0.4/s390-setup-fix-early-warning-messages.patch

   1 From 8727638426b0aea59d7f904ad8ddf483f9234f88 Mon Sep 17 00:00:00 2001
   2 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
   3 Date: Thu, 14 Feb 2019 15:40:56 +0100
   4 Subject: s390/setup: fix early warning messages
   5
   6 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
   7
   8 commit 8727638426b0aea59d7f904ad8ddf483f9234f88 upstream.
   9
  10 The setup_lowcore() function creates a new prefix page for the boot CPU.
  11 The PSW mask for the system_call, external interrupt, i/o interrupt and
  12 the program check handler have the DAT bit set in this new prefix page.
  13
  14 At the time setup_lowcore is called the system still runs without virtual
  15 address translation, the paging_init() function creates the kernel page
  16 table and loads the CR13 with the kernel ASCE.
  17
  18 Any code between setup_lowcore() and the end of paging_init() that has
  19 a BUG or WARN statement will create a program check that can not be
  20 handled correctly as there is no kernel page table yet.
  21
  22 To allow early WARN statements initially setup the lowcore with DAT off
  23 and set the DAT bit only after paging_init() has completed.
  24
  25 Cc: stable@vger.kernel.org
  26 Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
  27 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  28
  29 ---
  30  arch/s390/kernel/setup.c |   32 +++++++++++++++++++++++---------
  31  1 file changed, 23 insertions(+), 9 deletions(-)
  32
  33 --- a/arch/s390/kernel/setup.c
  34 +++ b/arch/s390/kernel/setup.c
  35 @@ -369,7 +369,7 @@ void __init arch_call_rest_init(void)
  36                 : : [_frame] "a" (frame));
  37  }
  38
  39 -static void __init setup_lowcore(void)
  40 +static void __init setup_lowcore_dat_off(void)
  41  {
  42         struct lowcore *lc;
  43
  44 @@ -380,19 +380,16 @@ static void __init setup_lowcore(void)
  45         lc = memblock_alloc_low(sizeof(*lc), sizeof(*lc));
  46         lc->restart_psw.mask = PSW_KERNEL_BITS;
  47         lc->restart_psw.addr = (unsigned long) restart_int_handler;
  48 -       lc->external_new_psw.mask = PSW_KERNEL_BITS |
  49 -               PSW_MASK_DAT | PSW_MASK_MCHECK;
  50 +       lc->external_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
  51         lc->external_new_psw.addr = (unsigned long) ext_int_handler;
  52         lc->svc_new_psw.mask = PSW_KERNEL_BITS |
  53 -               PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
  54 +               PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
  55         lc->svc_new_psw.addr = (unsigned long) system_call;
  56 -       lc->program_new_psw.mask = PSW_KERNEL_BITS |
  57 -               PSW_MASK_DAT | PSW_MASK_MCHECK;
  58 +       lc->program_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
  59         lc->program_new_psw.addr = (unsigned long) pgm_check_handler;
  60         lc->mcck_new_psw.mask = PSW_KERNEL_BITS;
  61         lc->mcck_new_psw.addr = (unsigned long) mcck_int_handler;
  62 -       lc->io_new_psw.mask = PSW_KERNEL_BITS |
  63 -               PSW_MASK_DAT | PSW_MASK_MCHECK;
  64 +       lc->io_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
  65         lc->io_new_psw.addr = (unsigned long) io_int_handler;
  66         lc->clock_comparator = clock_comparator_max;
  67         lc->nodat_stack = ((unsigned long) &init_thread_union)
  68 @@ -452,6 +449,17 @@ static void __init setup_lowcore(void)
  69         lowcore_ptr[0] = lc;
  70  }
  71
  72 +static void __init setup_lowcore_dat_on(void)
  73 +{
  74 +       struct lowcore *lc;
  75 +
  76 +       lc = lowcore_ptr[0];
  77 +       lc->external_new_psw.mask |= PSW_MASK_DAT;
  78 +       lc->svc_new_psw.mask |= PSW_MASK_DAT;
  79 +       lc->program_new_psw.mask |= PSW_MASK_DAT;
  80 +       lc->io_new_psw.mask |= PSW_MASK_DAT;
  81 +}
  82 +
  83  static struct resource code_resource = {
  84         .name  = "Kernel code",
  85         .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
  86 @@ -1072,7 +1080,7 @@ void __init setup_arch(char **cmdline_p)
  87  #endif
  88
  89         setup_resources();
  90 -       setup_lowcore();
  91 +       setup_lowcore_dat_off();
  92         smp_fill_possible_mask();
  93         cpu_detect_mhz_feature();
  94          cpu_init();
  95 @@ -1085,6 +1093,12 @@ void __init setup_arch(char **cmdline_p)
  96          */
  97          paging_init();
  98
  99 +       /*
 100 +        * After paging_init created the kernel page table, the new PSWs
 101 +        * in lowcore can now run with DAT enabled.
 102 +        */
 103 +       setup_lowcore_dat_on();
 104 +
 105          /* Setup default console */
 106         conmode_default();
 107         set_preferred_console();