arch/s390/kernel/als.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Copyright IBM Corp. 2016
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/init.h>
   7 #include <asm/processor.h>
   8 #include <asm/facility.h>
   9 #include <asm/lowcore.h>
  10 #include <asm/sclp.h>
  11 #include "entry.h"
  12
  13 /*
  14  * The code within this file will be called very early. It may _not_
  15  * access anything within the bss section, since that is not cleared
  16  * yet and may contain data (e.g. initrd) that must be saved by other
  17  * code.
  18  * For temporary objects the stack (16k) should be used.
  19  */
  20
  21 static unsigned long als[] __initdata = { FACILITIES_ALS };
  22
  23 static void __init u16_to_hex(char *str, u16 val)
  24 {
  25         int i, num;
  26
  27         for (i = 1; i <= 4; i++) {
  28                 num = (val >> (16 - 4 * i)) & 0xf;
  29                 if (num >= 10)
  30                         num += 7;
  31                 *str++ = '0' + num;
  32         }
  33         *str = '\0';
  34 }
  35
  36 static void __init print_machine_type(void)
  37 {
  38         static char mach_str[80] __initdata = "Detected machine-type number: ";
  39         char type_str[5];
  40         struct cpuid id;
  41
  42         get_cpu_id(&id);
  43         u16_to_hex(type_str, id.machine);
  44         strcat(mach_str, type_str);
  45         strcat(mach_str, "\n");
  46         sclp_early_printk(mach_str);
  47 }
  48
  49 static void __init u16_to_decimal(char *str, u16 val)
  50 {
  51         int div = 1;
  52
  53         while (div * 10 <= val)
  54                 div *= 10;
  55         while (div) {
  56                 *str++ = '0' + val / div;
  57                 val %= div;
  58                 div /= 10;
  59         }
  60         *str = '\0';
  61 }
  62
  63 static void __init print_missing_facilities(void)
  64 {
  65         static char als_str[80] __initdata = "Missing facilities: ";
  66         unsigned long val;
  67         char val_str[6];
  68         int i, j, first;
  69
  70         first = 1;
  71         for (i = 0; i < ARRAY_SIZE(als); i++) {
  72                 val = ~S390_lowcore.stfle_fac_list[i] & als[i];
  73                 for (j = 0; j < BITS_PER_LONG; j++) {
  74                         if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
  75                                 continue;
  76                         if (!first)
  77                                 strcat(als_str, ",");
  78                         /*
  79                          * Make sure we stay within one line. Consider that
  80                          * each facility bit adds up to five characters and
  81                          * z/VM adds a four character prefix.
  82                          */
  83                         if (strlen(als_str) > 70) {
  84                                 strcat(als_str, "\n");
  85                                 sclp_early_printk(als_str);
  86                                 *als_str = '\0';
  87                         }
  88                         u16_to_decimal(val_str, i * BITS_PER_LONG + j);
  89                         strcat(als_str, val_str);
  90                         first = 0;
  91                 }
  92         }
  93         strcat(als_str, "\n");
  94         sclp_early_printk(als_str);
  95         sclp_early_printk("See Principles of Operations for facility bits\n");
  96 }
  97
  98 static void __init facility_mismatch(void)
  99 {
 100         sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
 101         print_machine_type();
 102         print_missing_facilities();
 103         disabled_wait(0x8badcccc);
 104 }
 105
 106 void __init verify_facilities(void)
 107 {
 108         int i;
 109
 110         for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
 111                 S390_lowcore.stfle_fac_list[i] = 0;
 112         asm volatile(
 113                 "       stfl    0(0)\n"
 114                 : "=m" (S390_lowcore.stfl_fac_list));
 115         S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
 116         if (S390_lowcore.stfl_fac_list & 0x01000000) {
 117                 register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
 118
 119                 asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
 120                              : "+d" (reg0)
 121                              : "a" (&S390_lowcore.stfle_fac_list)
 122                              : "memory", "cc");
 123         }
 124         for (i = 0; i < ARRAY_SIZE(als); i++) {
 125                 if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
 126                         facility_mismatch();
 127         }
 128 }