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         _sclp_print_early(mach_str);
  45 }
  46
  47 static void __init u16_to_decimal(char *str, u16 val)
  48 {
  49         int div = 1;
  50
  51         while (div * 10 <= val)
  52                 div *= 10;
  53         while (div) {
  54                 *str++ = '0' + val / div;
  55                 val %= div;
  56                 div /= 10;
  57         }
  58         *str = '\0';
  59 }
  60
  61 static void __init print_missing_facilities(void)
  62 {
  63         static char als_str[80] __initdata = "Missing facilities: ";
  64         unsigned long val;
  65         char val_str[6];
  66         int i, j, first;
  67
  68         first = 1;
  69         for (i = 0; i < ARRAY_SIZE(als); i++) {
  70                 val = ~S390_lowcore.stfle_fac_list[i] & als[i];
  71                 for (j = 0; j < BITS_PER_LONG; j++) {
  72                         if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
  73                                 continue;
  74                         if (!first)
  75                                 strcat(als_str, ",");
  76                         /*
  77                          * Make sure we stay within one line. Consider that
  78                          * each facility bit adds up to five characters and
  79                          * z/VM adds a four character prefix.
  80                          */
  81                         if (strlen(als_str) > 70) {
  82                                 _sclp_print_early(als_str);
  83                                 *als_str = '\0';
  84                         }
  85                         u16_to_decimal(val_str, i * BITS_PER_LONG + j);
  86                         strcat(als_str, val_str);
  87                         first = 0;
  88                 }
  89         }
  90         _sclp_print_early(als_str);
  91         _sclp_print_early("See Principles of Operations for facility bits");
  92 }
  93
  94 static void __init facility_mismatch(void)
  95 {
  96         _sclp_print_early("The Linux kernel requires more recent processor hardware");
  97         print_machine_type();
  98         print_missing_facilities();
  99         disabled_wait(0x8badcccc);
 100 }
 101
 102 void __init verify_facilities(void)
 103 {
 104         int i;
 105
 106         for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
 107                 S390_lowcore.stfle_fac_list[i] = 0;
 108         asm volatile(
 109                 "       stfl    0(0)\n"
 110                 : "=m" (S390_lowcore.stfl_fac_list));
 111         S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
 112         if (S390_lowcore.stfl_fac_list & 0x01000000) {
 113                 register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
 114
 115                 asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
 116                              : "+d" (reg0)
 117                              : "a" (&S390_lowcore.stfle_fac_list)
 118                              : "memory", "cc");
 119         }
 120         for (i = 0; i < ARRAY_SIZE(als); i++) {
 121                 if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
 122                         facility_mismatch();
 123         }
 124 }