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

   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 }