s390/boot/als.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *    Copyright IBM Corp. 2016
0004  */
0005 #include <linux/kernel.h>
0006 #include <asm/processor.h>
0007 #include <asm/facility.h>
0008 #include <asm/lowcore.h>
0009 #include <asm/sclp.h>
0010 #include "boot.h"
0011
0012 /*
0013  * The code within this file will be called very early. It may _not_
0014  * access anything within the bss section, since that is not cleared
0015  * yet and may contain data (e.g. initrd) that must be saved by other
0016  * code.
0017  * For temporary objects the stack (16k) should be used.
0018  */
0019
0020 static unsigned long als[] = { FACILITIES_ALS };
0021
0022 static void u16_to_hex(char *str, u16 val)
0023 {
0024     int i, num;
0025
0026     for (i = 1; i <= 4; i++) {
0027         num = (val >> (16 - 4 * i)) & 0xf;
0028         if (num >= 10)
0029             num += 7;
0030         *str++ = '0' + num;
0031     }
0032     *str = '\0';
0033 }
0034
0035 static void print_machine_type(void)
0036 {
0037     static char mach_str[80] = "Detected machine-type number: ";
0038     char type_str[5];
0039     struct cpuid id;
0040
0041     get_cpu_id(&id);
0042     u16_to_hex(type_str, id.machine);
0043     strcat(mach_str, type_str);
0044     strcat(mach_str, "\n");
0045     sclp_early_printk(mach_str);
0046 }
0047
0048 static void u16_to_decimal(char *str, u16 val)
0049 {
0050     int div = 1;
0051
0052     while (div * 10 <= val)
0053         div *= 10;
0054     while (div) {
0055         *str++ = '0' + val / div;
0056         val %= div;
0057         div /= 10;
0058     }
0059     *str = '\0';
0060 }
0061
0062 void print_missing_facilities(void)
0063 {
0064     static char als_str[80] = "Missing facilities: ";
0065     unsigned long val;
0066     char val_str[6];
0067     int i, j, first;
0068
0069     first = 1;
0070     for (i = 0; i < ARRAY_SIZE(als); i++) {
0071         val = ~stfle_fac_list[i] & als[i];
0072         for (j = 0; j < BITS_PER_LONG; j++) {
0073             if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
0074                 continue;
0075             if (!first)
0076                 strcat(als_str, ",");
0077             /*
0078              * Make sure we stay within one line. Consider that
0079              * each facility bit adds up to five characters and
0080              * z/VM adds a four character prefix.
0081              */
0082             if (strlen(als_str) > 70) {
0083                 strcat(als_str, "\n");
0084                 sclp_early_printk(als_str);
0085                 *als_str = '\0';
0086             }
0087             u16_to_decimal(val_str, i * BITS_PER_LONG + j);
0088             strcat(als_str, val_str);
0089             first = 0;
0090         }
0091     }
0092     strcat(als_str, "\n");
0093     sclp_early_printk(als_str);
0094 }
0095
0096 static void facility_mismatch(void)
0097 {
0098     sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
0099     print_machine_type();
0100     print_missing_facilities();
0101     sclp_early_printk("See Principles of Operations for facility bits\n");
0102     disabled_wait();
0103 }
0104
0105 void verify_facilities(void)
0106 {
0107     int i;
0108
0109     __stfle(stfle_fac_list, ARRAY_SIZE(stfle_fac_list));
0110     for (i = 0; i < ARRAY_SIZE(als); i++) {
0111         if ((stfle_fac_list[i] & als[i]) != als[i])
0112             facility_mismatch();
0113     }
0114 }