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_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
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_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
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