LXR linux/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
  19static unsigned long als[] = { FACILITIES_ALS };
  20
  21static 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
  34static 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
  47static 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
  61static 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
  96static 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
 104void verify_facilities(void)
 105{
 106        int i;
 107
 108        __stfle(S390_lowcore.stfle_fac_list, ARRAY_SIZE(S390_lowcore.stfle_fac_list));
 109        for (i = 0; i < ARRAY_SIZE(als); i++) {
 110                if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
 111                        facility_mismatch();
 112        }
 113}
 114