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 19 static unsigned long als[] = { FACILITIES_ALS }; 20 21 static 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 34 static 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 47 static 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 61 static 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 96 static 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 } 103 104 void verify_facilities(void) 105 { 106 int i; 107 108 for (i = 0; i < ARRAY_SIZE(S390_lowcore.stfle_fac_list); i++) 109 S390_lowcore.stfle_fac_list[i] = 0; 110 asm volatile( 111 " stfl 0(0)\n" 112 : "=m" (S390_lowcore.stfl_fac_list)); 113 S390_lowcore.stfle_fac_list[0] = (u64)S390_lowcore.stfl_fac_list << 32; 114 if (S390_lowcore.stfl_fac_list & 0x01000000) { 115 register unsigned long reg0 asm("0") = ARRAY_SIZE(als) - 1; 116 117 asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */ 118 : "+d" (reg0) 119 : "a" (&S390_lowcore.stfle_fac_list) 120 : "memory", "cc"); 121 } 122 for (i = 0; i < ARRAY_SIZE(als); i++) { 123 if ((S390_lowcore.stfle_fac_list[i] & als[i]) != als[i]) 124 facility_mismatch(); 125 } 126 } 127