uaccess_flush.c

  1// SPDX-License-Identifier: GPL-2.0+
  2
  3/*
  4 * Copyright 2018 IBM Corporation.
  5 * Copyright 2020 Canonical Ltd.
  6 */
  7
  8#define __SANE_USERSPACE_TYPES__
  9
 10#include <sys/types.h>
 11#include <stdint.h>
 12#include <malloc.h>
 13#include <unistd.h>
 14#include <signal.h>
 15#include <stdlib.h>
 16#include <string.h>
 17#include <stdio.h>
 18#include "utils.h"
 19#include "flush_utils.h"
 20
 21int uaccess_flush_test(void)
 22{
 23	char *p;
 24	int repetitions = 10;
 25	int fd, passes = 0, iter, rc = 0;
 26	struct perf_event_read v;
 27	__u64 l1d_misses_total = 0;
 28	unsigned long iterations = 100000, zero_size = 24 * 1024;
 29	unsigned long l1d_misses_expected;
 30	int rfi_flush_orig;
 31	int entry_flush_orig;
 32	int uaccess_flush, uaccess_flush_orig;
 33
 34	SKIP_IF(geteuid() != 0);
 35
 36	// The PMU event we use only works on Power7 or later
 37	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
 38
 39	if (read_debugfs_int("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
 40		perror("Unable to read powerpc/rfi_flush debugfs file");
 41		SKIP_IF(1);
 42	}
 43
 44	if (read_debugfs_int("powerpc/entry_flush", &entry_flush_orig) < 0) {
 45		perror("Unable to read powerpc/entry_flush debugfs file");
 46		SKIP_IF(1);
 47	}
 48
 49	if (read_debugfs_int("powerpc/uaccess_flush", &uaccess_flush_orig) < 0) {
 50		perror("Unable to read powerpc/entry_flush debugfs file");
 51		SKIP_IF(1);
 52	}
 53
 54	if (rfi_flush_orig != 0) {
 55		if (write_debugfs_int("powerpc/rfi_flush", 0) < 0) {
 56			perror("error writing to powerpc/rfi_flush debugfs file");
 57			FAIL_IF(1);
 58		}
 59	}
 60
 61	if (entry_flush_orig != 0) {
 62		if (write_debugfs_int("powerpc/entry_flush", 0) < 0) {
 63			perror("error writing to powerpc/entry_flush debugfs file");
 64			FAIL_IF(1);
 65		}
 66	}
 67
 68	uaccess_flush = uaccess_flush_orig;
 69
 70	fd = perf_event_open_counter(PERF_TYPE_HW_CACHE, PERF_L1D_READ_MISS_CONFIG, -1);
 71	FAIL_IF(fd < 0);
 72
 73	p = (char *)memalign(zero_size, CACHELINE_SIZE);
 74
 75	FAIL_IF(perf_event_enable(fd));
 76
 77	// disable L1 prefetching
 78	set_dscr(1);
 79
 80	iter = repetitions;
 81
 82	/*
 83	 * We expect to see l1d miss for each cacheline access when entry_flush
 84	 * is set. Allow a small variation on this.
 85	 */
 86	l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);
 87
 88again:
 89	FAIL_IF(perf_event_reset(fd));
 90
 91	syscall_loop_uaccess(p, iterations, zero_size);
 92
 93	FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));
 94
 95	if (uaccess_flush && v.l1d_misses >= l1d_misses_expected)
 96		passes++;
 97	else if (!uaccess_flush && v.l1d_misses < (l1d_misses_expected / 2))
 98		passes++;
 99
100	l1d_misses_total += v.l1d_misses;
101
102	while (--iter)
103		goto again;
104
105	if (passes < repetitions) {
106		printf("FAIL (L1D misses with uaccess_flush=%d: %llu %c %lu) [%d/%d failures]\n",
107		       uaccess_flush, l1d_misses_total, uaccess_flush ? '<' : '>',
108		       uaccess_flush ? repetitions * l1d_misses_expected :
109		       repetitions * l1d_misses_expected / 2,
110		       repetitions - passes, repetitions);
111		rc = 1;
112	} else {
113		printf("PASS (L1D misses with uaccess_flush=%d: %llu %c %lu) [%d/%d pass]\n",
114		       uaccess_flush, l1d_misses_total, uaccess_flush ? '>' : '<',
115		       uaccess_flush ? repetitions * l1d_misses_expected :
116		       repetitions * l1d_misses_expected / 2,
117		       passes, repetitions);
118	}
119
120	if (uaccess_flush == uaccess_flush_orig) {
121		uaccess_flush = !uaccess_flush_orig;
122		if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush) < 0) {
123			perror("error writing to powerpc/uaccess_flush debugfs file");
124			return 1;
125		}
126		iter = repetitions;
127		l1d_misses_total = 0;
128		passes = 0;
129		goto again;
130	}
131
132	perf_event_disable(fd);
133	close(fd);
134
135	set_dscr(0);
136
137	if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
138		perror("unable to restore original value of powerpc/rfi_flush debugfs file");
139		return 1;
140	}
141
142	if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
143		perror("unable to restore original value of powerpc/entry_flush debugfs file");
144		return 1;
145	}
146
147	if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush_orig) < 0) {
148		perror("unable to restore original value of powerpc/uaccess_flush debugfs file");
149		return 1;
150	}
151
152	return rc;
153}
154
155int main(int argc, char *argv[])
156{
157	return test_harness(uaccess_flush_test, "uaccess_flush_test");
158}