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

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