cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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gen_crc64table.c (2171B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Generate lookup table for the table-driven CRC64 calculation.
      4 *
      5 * gen_crc64table is executed in kernel build time and generates
      6 * lib/crc64table.h. This header is included by lib/crc64.c for
      7 * the table-driven CRC64 calculation.
      8 *
      9 * See lib/crc64.c for more information about which specification
     10 * and polynomial arithmetic that gen_crc64table.c follows to
     11 * generate the lookup table.
     12 *
     13 * Copyright 2018 SUSE Linux.
     14 *   Author: Coly Li <colyli@suse.de>
     15 */
     16#include <inttypes.h>
     17#include <stdio.h>
     18
     19#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL
     20#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL
     21
     22static uint64_t crc64_table[256] = {0};
     23static uint64_t crc64_rocksoft_table[256] = {0};
     24
     25static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly)
     26{
     27	uint64_t i, j, c, crc;
     28
     29	for (i = 0; i < 256; i++) {
     30		crc = 0ULL;
     31		c = i;
     32
     33		for (j = 0; j < 8; j++) {
     34			if ((crc ^ (c >> j)) & 1)
     35				crc = (crc >> 1) ^ poly;
     36			else
     37				crc >>= 1;
     38		}
     39		table[i] = crc;
     40	}
     41}
     42
     43static void generate_crc64_table(uint64_t table[256], uint64_t poly)
     44{
     45	uint64_t i, j, c, crc;
     46
     47	for (i = 0; i < 256; i++) {
     48		crc = 0;
     49		c = i << 56;
     50
     51		for (j = 0; j < 8; j++) {
     52			if ((crc ^ c) & 0x8000000000000000ULL)
     53				crc = (crc << 1) ^ poly;
     54			else
     55				crc <<= 1;
     56			c <<= 1;
     57		}
     58
     59		table[i] = crc;
     60	}
     61}
     62
     63static void output_table(uint64_t table[256])
     64{
     65	int i;
     66
     67	for (i = 0; i < 256; i++) {
     68		printf("\t0x%016" PRIx64 "ULL", table[i]);
     69		if (i & 0x1)
     70			printf(",\n");
     71		else
     72			printf(", ");
     73	}
     74	printf("};\n");
     75}
     76
     77static void print_crc64_tables(void)
     78{
     79	printf("/* this file is generated - do not edit */\n\n");
     80	printf("#include <linux/types.h>\n");
     81	printf("#include <linux/cache.h>\n\n");
     82	printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");
     83	output_table(crc64_table);
     84
     85	printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n");
     86	output_table(crc64_rocksoft_table);
     87}
     88
     89int main(int argc, char *argv[])
     90{
     91	generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);
     92	generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY);
     93	print_crc64_tables();
     94	return 0;
     95}