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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find-bit-bench.c (3563B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Benchmark find_next_bit and related bit operations.
      4 *
      5 * Copyright 2020 Google LLC.
      6 */
      7#include <stdlib.h>
      8#include "bench.h"
      9#include "../util/stat.h"
     10#include <linux/bitmap.h>
     11#include <linux/bitops.h>
     12#include <linux/time64.h>
     13#include <subcmd/parse-options.h>
     14
     15static unsigned int outer_iterations = 5;
     16static unsigned int inner_iterations = 100000;
     17
     18static const struct option options[] = {
     19	OPT_UINTEGER('i', "outer-iterations", &outer_iterations,
     20		"Number of outer iterations used"),
     21	OPT_UINTEGER('j', "inner-iterations", &inner_iterations,
     22		"Number of inner iterations used"),
     23	OPT_END()
     24};
     25
     26static const char *const bench_usage[] = {
     27	"perf bench mem find_bit <options>",
     28	NULL
     29};
     30
     31static unsigned int accumulator;
     32static unsigned int use_of_val;
     33
     34static noinline void workload(int val)
     35{
     36	use_of_val += val;
     37	accumulator++;
     38}
     39
     40#if (defined(__i386__) || defined(__x86_64__)) && defined(__GCC_ASM_FLAG_OUTPUTS__)
     41static bool asm_test_bit(long nr, const unsigned long *addr)
     42{
     43	bool oldbit;
     44
     45	asm volatile("bt %2,%1"
     46		     : "=@ccc" (oldbit)
     47		     : "m" (*(unsigned long *)addr), "Ir" (nr) : "memory");
     48
     49	return oldbit;
     50}
     51#else
     52#define asm_test_bit test_bit
     53#endif
     54
     55static int do_for_each_set_bit(unsigned int num_bits)
     56{
     57	unsigned long *to_test = bitmap_zalloc(num_bits);
     58	struct timeval start, end, diff;
     59	u64 runtime_us;
     60	struct stats fb_time_stats, tb_time_stats;
     61	double time_average, time_stddev;
     62	unsigned int bit, i, j;
     63	unsigned int set_bits, skip;
     64	unsigned int old;
     65
     66	init_stats(&fb_time_stats);
     67	init_stats(&tb_time_stats);
     68
     69	for (set_bits = 1; set_bits <= num_bits; set_bits <<= 1) {
     70		bitmap_zero(to_test, num_bits);
     71		skip = num_bits / set_bits;
     72		for (i = 0; i < num_bits; i += skip)
     73			set_bit(i, to_test);
     74
     75		for (i = 0; i < outer_iterations; i++) {
     76			old = accumulator;
     77			gettimeofday(&start, NULL);
     78			for (j = 0; j < inner_iterations; j++) {
     79				for_each_set_bit(bit, to_test, num_bits)
     80					workload(bit);
     81			}
     82			gettimeofday(&end, NULL);
     83			assert(old + (inner_iterations * set_bits) == accumulator);
     84			timersub(&end, &start, &diff);
     85			runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
     86			update_stats(&fb_time_stats, runtime_us);
     87
     88			old = accumulator;
     89			gettimeofday(&start, NULL);
     90			for (j = 0; j < inner_iterations; j++) {
     91				for (bit = 0; bit < num_bits; bit++) {
     92					if (asm_test_bit(bit, to_test))
     93						workload(bit);
     94				}
     95			}
     96			gettimeofday(&end, NULL);
     97			assert(old + (inner_iterations * set_bits) == accumulator);
     98			timersub(&end, &start, &diff);
     99			runtime_us = diff.tv_sec * USEC_PER_SEC + diff.tv_usec;
    100			update_stats(&tb_time_stats, runtime_us);
    101		}
    102
    103		printf("%d operations %d bits set of %d bits\n",
    104			inner_iterations, set_bits, num_bits);
    105		time_average = avg_stats(&fb_time_stats);
    106		time_stddev = stddev_stats(&fb_time_stats);
    107		printf("  Average for_each_set_bit took: %.3f usec (+- %.3f usec)\n",
    108			time_average, time_stddev);
    109		time_average = avg_stats(&tb_time_stats);
    110		time_stddev = stddev_stats(&tb_time_stats);
    111		printf("  Average test_bit loop took:    %.3f usec (+- %.3f usec)\n",
    112			time_average, time_stddev);
    113
    114		if (use_of_val == accumulator)  /* Try to avoid compiler tricks. */
    115			printf("\n");
    116	}
    117	bitmap_free(to_test);
    118	return 0;
    119}
    120
    121int bench_mem_find_bit(int argc, const char **argv)
    122{
    123	int err = 0, i;
    124
    125	argc = parse_options(argc, argv, options, bench_usage, 0);
    126	if (argc) {
    127		usage_with_options(bench_usage, options);
    128		exit(EXIT_FAILURE);
    129	}
    130
    131	for (i = 1; i <= 2048; i <<= 1)
    132		do_for_each_set_bit(i);
    133
    134	return err;
    135}