cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

als.c (2511B)

      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#include "boot.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[] = { FACILITIES_ALS };
     21
     22static void 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 print_machine_type(void)
     36{
     37	static char mach_str[80] = "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	strcat(mach_str, "\n");
     45	sclp_early_printk(mach_str);
     46}
     47
     48static void u16_to_decimal(char *str, u16 val)
     49{
     50	int div = 1;
     51
     52	while (div * 10 <= val)
     53		div *= 10;
     54	while (div) {
     55		*str++ = '0' + val / div;
     56		val %= div;
     57		div /= 10;
     58	}
     59	*str = '\0';
     60}
     61
     62void print_missing_facilities(void)
     63{
     64	static char als_str[80] = "Missing facilities: ";
     65	unsigned long val;
     66	char val_str[6];
     67	int i, j, first;
     68
     69	first = 1;
     70	for (i = 0; i < ARRAY_SIZE(als); i++) {
     71		val = ~stfle_fac_list[i] & als[i];
     72		for (j = 0; j < BITS_PER_LONG; j++) {
     73			if (!(val & (1UL << (BITS_PER_LONG - 1 - j))))
     74				continue;
     75			if (!first)
     76				strcat(als_str, ",");
     77			/*
     78			 * Make sure we stay within one line. Consider that
     79			 * each facility bit adds up to five characters and
     80			 * z/VM adds a four character prefix.
     81			 */
     82			if (strlen(als_str) > 70) {
     83				strcat(als_str, "\n");
     84				sclp_early_printk(als_str);
     85				*als_str = '\0';
     86			}
     87			u16_to_decimal(val_str, i * BITS_PER_LONG + j);
     88			strcat(als_str, val_str);
     89			first = 0;
     90		}
     91	}
     92	strcat(als_str, "\n");
     93	sclp_early_printk(als_str);
     94}
     95
     96static 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	sclp_early_printk("See Principles of Operations for facility bits\n");
    102	disabled_wait();
    103}
    104
    105void verify_facilities(void)
    106{
    107	int i;
    108
    109	__stfle(stfle_fac_list, ARRAY_SIZE(stfle_fac_list));
    110	for (i = 0; i < ARRAY_SIZE(als); i++) {
    111		if ((stfle_fac_list[i] & als[i]) != als[i])
    112			facility_mismatch();
    113	}
    114}