LXR linux/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
  20static unsigned long als[] __initdata = { FACILITIES_ALS };
  21
  22static 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
  35static 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
  47static 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
  61static 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
  94static 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
 102void __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}
 125