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}