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