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