arch/s390/kernel/als.c

   1 /*
   2  *    Copyright IBM Corp. 2016
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/init.h>
   6 #include <asm/processor.h>
   7 #include <asm/facility.h>
   8 #include <asm/lowcore.h>
   9 #include <asm/sclp.h>
  10 #include "entry.h"
  11
  12 /*
  13  * The code within this file will be called very early. It may _not_
  14  * access anything within the bss section, since that is not cleared
  15  * yet and may contain data (e.g. initrd) that must be saved by other
  16  * code.
  17  * For temporary objects the stack (16k) should be used.
  18  */
  19
  20 static unsigned long als[] __initdata = { FACILITIES_ALS };
  21
  22 static void __init u16_to_hex(char *str, u16 val)
  23 {
  24         int i, num;
  25
  26         for (i = 1; i <= 4; i++) {
  27                 num = (val >> (16 - 4 * i)) & 0xf;
  28                 if (num >= 10)
  29                         num += 7;
  30                 *str++ = '0' + num;
  31         }
  32         *str = '\0';
  33 }
  34
  35 static void __init print_machine_type(void)
  36 {
  37         static char mach_str[80] __initdata = "Detected machine-type number: ";
  38         char type_str[5];
  39         struct cpuid id;
  40
  41         get_cpu_id(&id);
  42         u16_to_hex(type_str, id.machine);
  43         strcat(mach_str, type_str);
  44         strcat(mach_str, "\n");
  45         sclp_early_printk(mach_str);
  46 }
  47
  48 static void __init u16_to_decimal(char *str, u16 val)
  49 {
  50         int div = 1;
  51
  52         while (div * 10 <= val)
  53                 div *= 10;
  54         while (div) {
  55                 *str++ = '0' + val / div;
  56                 val %= div;
  57                 div /= 10;
  58         }
  59         *str = '\0';
  60 }
  61
  62 static void __init print_missing_facilities(void)
  63 {
  64         static char als_str[80] __initdata = "Missing facilities: ";
  65         unsigned long val;
  66         char val_str[6];
  67         int i, j, first;
  68
  69         first = 1;
  70         for (i = 0; i < ARRAY_SIZE(als); i++) {
  71                 val = ~S390_lowcore.stfle_fac_list[i] & als[i];
  72                 for (j = 0; j < BITS_PER_LONG; j++) {
  73                         if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
  74                                 continue;
  75                         if (!first)
  76                                 strcat(als_str, ",");
  77                         /*
  78                          * Make sure we stay within one line. Consider that
  79                          * each facility bit adds up to five characters and
  80                          * z/VM adds a four character prefix.
  81                          */
  82                         if (strlen(als_str) > 70) {
  83                                 strcat(als_str, "\n");
  84                                 sclp_early_printk(als_str);
  85                                 *als_str = '\0';
  86                         }
  87                         u16_to_decimal(val_str, i * BITS_PER_LONG + j);
  88                         strcat(als_str, val_str);
  89                         first = 0;
  90                 }
  91         }
  92         strcat(als_str, "\n");
  93         sclp_early_printk(als_str);
  94         sclp_early_printk("See Principles of Operations for facility bits\n");
  95 }
  96
  97 static void __init facility_mismatch(void)
  98 {
  99         sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
 100         print_machine_type();
 101         print_missing_facilities();
 102         disabled_wait(0x8badcccc);
 103 }
 104
 105 void __init verify_facilities(void)
 106 {
 107         int i;
 108
 109         for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
 110                 S390_lowcore.stfle_fac_list[i] = 0;
 111         asm volatile(
 112                 "       stfl    0(0)\n"
 113                 : "=m" (S390_lowcore.stfl_fac_list));
 114         S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
 115         if (S390_lowcore.stfl_fac_list & 0x01000000) {
 116                 register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
 117
 118                 asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
 119                              : "+d" (reg0)
 120                              : "a" (&S390_lowcore.stfle_fac_list)
 121                              : "memory", "cc");
 122         }
 123         for (i = 0; i < ARRAY_SIZE(als); i++) {
 124                 if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
 125                         facility_mismatch();
 126         }
 127 }