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 
uaccess_flush_test(void)21 int 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_file("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_file("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_file("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_file("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_file("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 
88 again:
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_file("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_file("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_file("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_file("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 
main(int argc,char * argv[])155 int main(int argc, char *argv[])
156 {
157 	return test_harness(uaccess_flush_test, "uaccess_flush_test");
158 }
159