1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *    Copyright IBM Corp. 2016
  4 */
  5#include <linux/kernel.h>
  6#include <linux/init.h>
  7#include <asm/processor.h>
  8#include <asm/facility.h>
  9#include <asm/lowcore.h>
 10#include <asm/sclp.h>
 11#include "entry.h"
 12
 13/*
 14 * The code within this file will be called very early. It may _not_
 15 * access anything within the bss section, since that is not cleared
 16 * yet and may contain data (e.g. initrd) that must be saved by other
 17 * code.
 18 * For temporary objects the stack (16k) should be used.
 19 */
 20
 21static unsigned long als[] __initdata = { FACILITIES_ALS };
 22
 23static void __init u16_to_hex(char *str, u16 val)
 24{
 25	int i, num;
 26
 27	for (i = 1; i <= 4; i++) {
 28		num = (val >> (16 - 4 * i)) & 0xf;
 29		if (num >= 10)
 30			num += 7;
 31		*str++ = '0' + num;
 32	}
 33	*str = '\0';
 34}
 35
 36static void __init print_machine_type(void)
 37{
 38	static char mach_str[80] __initdata = "Detected machine-type number: ";
 39	char type_str[5];
 40	struct cpuid id;
 41
 42	get_cpu_id(&id);
 43	u16_to_hex(type_str, id.machine);
 44	strcat(mach_str, type_str);
 45	strcat(mach_str, "\n");
 46	sclp_early_printk(mach_str);
 47}
 48
 49static void __init u16_to_decimal(char *str, u16 val)
 50{
 51	int div = 1;
 52
 53	while (div * 10 <= val)
 54		div *= 10;
 55	while (div) {
 56		*str++ = '0' + val / div;
 57		val %= div;
 58		div /= 10;
 59	}
 60	*str = '\0';
 61}
 62
 63static void __init print_missing_facilities(void)
 64{
 65	static char als_str[80] __initdata = "Missing facilities: ";
 66	unsigned long val;
 67	char val_str[6];
 68	int i, j, first;
 69
 70	first = 1;
 71	for (i = 0; i < ARRAY_SIZE(als); i++) {
 72		val = ~S390_lowcore.stfle_fac_list[i] & als[i];
 73		for (j = 0; j < BITS_PER_LONG; j++) {
 74			if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
 75				continue;
 76			if (!first)
 77				strcat(als_str, ",");
 78			/*
 79			 * Make sure we stay within one line. Consider that
 80			 * each facility bit adds up to five characters and
 81			 * z/VM adds a four character prefix.
 82			 */
 83			if (strlen(als_str) > 70) {
 84				strcat(als_str, "\n");
 85				sclp_early_printk(als_str);
 86				*als_str = '\0';
 87			}
 88			u16_to_decimal(val_str, i * BITS_PER_LONG + j);
 89			strcat(als_str, val_str);
 90			first = 0;
 91		}
 92	}
 93	strcat(als_str, "\n");
 94	sclp_early_printk(als_str);
 95	sclp_early_printk("See Principles of Operations for facility bits\n");
 96}
 97
 98static void __init facility_mismatch(void)
 99{
100	sclp_early_printk("The Linux kernel requires more recent processor hardware\n");
101	print_machine_type();
102	print_missing_facilities();
103	disabled_wait(0x8badcccc);
104}
105
106void __init verify_facilities(void)
107{
108	int i;
109
110	for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++)
111		S390_lowcore.stfle_fac_list[i] = 0;
112	asm volatile(
113		"	stfl	0(0)\n"
114		: "=m" (S390_lowcore.stfl_fac_list));
115	S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32;
116	if (S390_lowcore.stfl_fac_list & 0x01000000) {
117		register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1;
118
119		asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
120			     : "+d" (reg0)
121			     : "a" (&S390_lowcore.stfle_fac_list)
122			     : "memory", "cc");
123	}
124	for (i = 0; i < ARRAY_SIZE(als); i++) {
125		if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i])
126			facility_mismatch();
127	}
128}