arch/s390/boot/als.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Copyright IBM Corp. 2016
   4  */
   5 #include <linux/kernel.h>
   6 #include <asm/processor.h>
   7 #include <asm/facility.h>
   8 #include <asm/lowcore.h>
   9 #include <asm/sclp.h>
  10
  11 /*
  12  * The code within this file will be called very early. It may _not_
  13  * access anything within the bss section, since that is not cleared
  14  * yet and may contain data (e.g. initrd) that must be saved by other
  15  * code.
  16  * For temporary objects the stack (16k) should be used.
  17  */
  18
  19 static unsigned long als[] = { FACILITIES_ALS };
  20
  21 static void u16_to_hex(char *str, u16 val)
  22 {
  23         int i, num;
  24
  25         for (i = 1; i <= 4; i++) {
  26                 num = (val >> (16 - 4 * i)) & 0xf;
  27                 if (num >= 10)
  28                         num += 7;
  29                 *str++ = '0' + num;
  30         }
  31         *str = '\0';
  32 }
  33
  34 static void print_machine_type(void)
  35 {
  36         static char mach_str[80] = "Detected machine-type number: ";
  37         char type_str[5];
  38         struct cpuid id;
  39
  40         get_cpu_id(&id);
  41         u16_to_hex(type_str, id.machine);
  42         strcat(mach_str, type_str);
  43         strcat(mach_str, "\n");
  44         sclp_early_printk(mach_str);
  45 }
  46
  47 static void 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 print_missing_facilities(void)
  62 {
  63         static char als_str[80] = "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                                 strcat(als_str, "\n");
  83                                 sclp_early_printk(als_str);
  84                                 *als_str = '\0';
  85                         }
  86                         u16_to_decimal(val_str, i * BITS_PER_LONG + j);
  87                         strcat(als_str, val_str);
  88                         first = 0;
  89                 }
  90         }
  91         strcat(als_str, "\n");
  92         sclp_early_printk(als_str);
  93         sclp_early_printk("See Principles of Operations for facility bits\n");
  94 }
  95
  96 static void facility_mismatch(void)
  97 {
  98         sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
  99         print_machine_type();
 100         print_missing_facilities();
 101         disabled_wait(0x8badcccc);
 102 }
 103
 104 void verify_facilities(void)
 105 {
 106         int i;
 107
 108         for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
 109                 S390_lowcore.stfle_fac_list[i] = 0;
 110         asm volatile(
 111                 "       stfl    0(0)\n"
 112                 : "=m" (S390_lowcore.stfl_fac_list));
 113         S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
 114         if (S390_lowcore.stfl_fac_list & 0x01000000) {
 115                 register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
 116
 117                 asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
 118                              : "+d" (reg0)
 119                              : "a" (&S390_lowcore.stfle_fac_list)
 120                              : "memory", "cc");
 121         }
 122         for (i = 0; i < ARRAY_SIZE(als); i++) {
 123                 if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
 124                         facility_mismatch();
 125         }
 126 }