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Linux/tools/perf/arch/x86/tests/rdpmc.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <errno.h>
  3 #include <unistd.h>
  4 #include <stdlib.h>
  5 #include <signal.h>
  6 #include <sys/mman.h>
  7 #include <sys/types.h>
  8 #include <sys/wait.h>
  9 #include <linux/types.h>
 10 #include "perf.h"
 11 #include "debug.h"
 12 #include "tests/tests.h"
 13 #include "cloexec.h"
 14 #include "util.h"
 15 #include "arch-tests.h"
 16 
 17 static u64 rdpmc(unsigned int counter)
 18 {
 19         unsigned int low, high;
 20 
 21         asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
 22 
 23         return low | ((u64)high) << 32;
 24 }
 25 
 26 static u64 rdtsc(void)
 27 {
 28         unsigned int low, high;
 29 
 30         asm volatile("rdtsc" : "=a" (low), "=d" (high));
 31 
 32         return low | ((u64)high) << 32;
 33 }
 34 
 35 static u64 mmap_read_self(void *addr)
 36 {
 37         struct perf_event_mmap_page *pc = addr;
 38         u32 seq, idx, time_mult = 0, time_shift = 0;
 39         u64 count, cyc = 0, time_offset = 0, enabled, running, delta;
 40 
 41         do {
 42                 seq = pc->lock;
 43                 barrier();
 44 
 45                 enabled = pc->time_enabled;
 46                 running = pc->time_running;
 47 
 48                 if (enabled != running) {
 49                         cyc = rdtsc();
 50                         time_mult = pc->time_mult;
 51                         time_shift = pc->time_shift;
 52                         time_offset = pc->time_offset;
 53                 }
 54 
 55                 idx = pc->index;
 56                 count = pc->offset;
 57                 if (idx)
 58                         count += rdpmc(idx - 1);
 59 
 60                 barrier();
 61         } while (pc->lock != seq);
 62 
 63         if (enabled != running) {
 64                 u64 quot, rem;
 65 
 66                 quot = (cyc >> time_shift);
 67                 rem = cyc & (((u64)1 << time_shift) - 1);
 68                 delta = time_offset + quot * time_mult +
 69                         ((rem * time_mult) >> time_shift);
 70 
 71                 enabled += delta;
 72                 if (idx)
 73                         running += delta;
 74 
 75                 quot = count / running;
 76                 rem = count % running;
 77                 count = quot * enabled + (rem * enabled) / running;
 78         }
 79 
 80         return count;
 81 }
 82 
 83 /*
 84  * If the RDPMC instruction faults then signal this back to the test parent task:
 85  */
 86 static void segfault_handler(int sig __maybe_unused,
 87                              siginfo_t *info __maybe_unused,
 88                              void *uc __maybe_unused)
 89 {
 90         exit(-1);
 91 }
 92 
 93 static int __test__rdpmc(void)
 94 {
 95         volatile int tmp = 0;
 96         u64 i, loops = 1000;
 97         int n;
 98         int fd;
 99         void *addr;
100         struct perf_event_attr attr = {
101                 .type = PERF_TYPE_HARDWARE,
102                 .config = PERF_COUNT_HW_INSTRUCTIONS,
103                 .exclude_kernel = 1,
104         };
105         u64 delta_sum = 0;
106         struct sigaction sa;
107         char sbuf[STRERR_BUFSIZE];
108 
109         sigfillset(&sa.sa_mask);
110         sa.sa_sigaction = segfault_handler;
111         sa.sa_flags = 0;
112         sigaction(SIGSEGV, &sa, NULL);
113 
114         fd = sys_perf_event_open(&attr, 0, -1, -1,
115                                  perf_event_open_cloexec_flag());
116         if (fd < 0) {
117                 pr_err("Error: sys_perf_event_open() syscall returned "
118                        "with %d (%s)\n", fd,
119                        str_error_r(errno, sbuf, sizeof(sbuf)));
120                 return -1;
121         }
122 
123         addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
124         if (addr == (void *)(-1)) {
125                 pr_err("Error: mmap() syscall returned with (%s)\n",
126                        str_error_r(errno, sbuf, sizeof(sbuf)));
127                 goto out_close;
128         }
129 
130         for (n = 0; n < 6; n++) {
131                 u64 stamp, now, delta;
132 
133                 stamp = mmap_read_self(addr);
134 
135                 for (i = 0; i < loops; i++)
136                         tmp++;
137 
138                 now = mmap_read_self(addr);
139                 loops *= 10;
140 
141                 delta = now - stamp;
142                 pr_debug("%14d: %14Lu\n", n, (long long)delta);
143 
144                 delta_sum += delta;
145         }
146 
147         munmap(addr, page_size);
148         pr_debug("   ");
149 out_close:
150         close(fd);
151 
152         if (!delta_sum)
153                 return -1;
154 
155         return 0;
156 }
157 
158 int test__rdpmc(struct test *test __maybe_unused, int subtest __maybe_unused)
159 {
160         int status = 0;
161         int wret = 0;
162         int ret;
163         int pid;
164 
165         pid = fork();
166         if (pid < 0)
167                 return -1;
168 
169         if (!pid) {
170                 ret = __test__rdpmc();
171 
172                 exit(ret);
173         }
174 
175         wret = waitpid(pid, &status, 0);
176         if (wret < 0 || status)
177                 return -1;
178 
179         return 0;
180 }
181 

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