tools/perf/tests/rdpmc.c

   1 #include <unistd.h>
   2 #include <stdlib.h>
   3 #include <signal.h>
   4 #include <sys/mman.h>
   5 #include <linux/types.h>
   6 #include "perf.h"
   7 #include "debug.h"
   8 #include "tests.h"
   9 #include "cloexec.h"
  10
  11 #if defined(__x86_64__) || defined(__i386__)
  12
  13 static u64 rdpmc(unsigned int counter)
  14 {
  15         unsigned int low, high;
  16
  17         asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
  18
  19         return low | ((u64)high) << 32;
  20 }
  21
  22 static u64 rdtsc(void)
  23 {
  24         unsigned int low, high;
  25
  26         asm volatile("rdtsc" : "=a" (low), "=d" (high));
  27
  28         return low | ((u64)high) << 32;
  29 }
  30
  31 static u64 mmap_read_self(void *addr)
  32 {
  33         struct perf_event_mmap_page *pc = addr;
  34         u32 seq, idx, time_mult = 0, time_shift = 0;
  35         u64 count, cyc = 0, time_offset = 0, enabled, running, delta;
  36
  37         do {
  38                 seq = pc->lock;
  39                 barrier();
  40
  41                 enabled = pc->time_enabled;
  42                 running = pc->time_running;
  43
  44                 if (enabled != running) {
  45                         cyc = rdtsc();
  46                         time_mult = pc->time_mult;
  47                         time_shift = pc->time_shift;
  48                         time_offset = pc->time_offset;
  49                 }
  50
  51                 idx = pc->index;
  52                 count = pc->offset;
  53                 if (idx)
  54                         count += rdpmc(idx - 1);
  55
  56                 barrier();
  57         } while (pc->lock != seq);
  58
  59         if (enabled != running) {
  60                 u64 quot, rem;
  61
  62                 quot = (cyc >> time_shift);
  63                 rem = cyc & ((1 << time_shift) - 1);
  64                 delta = time_offset + quot * time_mult +
  65                         ((rem * time_mult) >> time_shift);
  66
  67                 enabled += delta;
  68                 if (idx)
  69                         running += delta;
  70
  71                 quot = count / running;
  72                 rem = count % running;
  73                 count = quot * enabled + (rem * enabled) / running;
  74         }
  75
  76         return count;
  77 }
  78
  79 /*
  80  * If the RDPMC instruction faults then signal this back to the test parent task:
  81  */
  82 static void segfault_handler(int sig __maybe_unused,
  83                              siginfo_t *info __maybe_unused,
  84                              void *uc __maybe_unused)
  85 {
  86         exit(-1);
  87 }
  88
  89 static int __test__rdpmc(void)
  90 {
  91         volatile int tmp = 0;
  92         u64 i, loops = 1000;
  93         int n;
  94         int fd;
  95         void *addr;
  96         struct perf_event_attr attr = {
  97                 .type = PERF_TYPE_HARDWARE,
  98                 .config = PERF_COUNT_HW_INSTRUCTIONS,
  99                 .exclude_kernel = 1,
 100         };
 101         u64 delta_sum = 0;
 102         struct sigaction sa;
 103
 104         sigfillset(&sa.sa_mask);
 105         sa.sa_sigaction = segfault_handler;
 106         sigaction(SIGSEGV, &sa, NULL);
 107
 108         fd = sys_perf_event_open(&attr, 0, -1, -1,
 109                                  perf_event_open_cloexec_flag());
 110         if (fd < 0) {
 111                 pr_err("Error: sys_perf_event_open() syscall returned "
 112                        "with %d (%s)\n", fd, strerror(errno));
 113                 return -1;
 114         }
 115
 116         addr = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
 117         if (addr == (void *)(-1)) {
 118                 pr_err("Error: mmap() syscall returned with (%s)\n",
 119                        strerror(errno));
 120                 goto out_close;
 121         }
 122
 123         for (n = 0; n < 6; n++) {
 124                 u64 stamp, now, delta;
 125
 126                 stamp = mmap_read_self(addr);
 127
 128                 for (i = 0; i < loops; i++)
 129                         tmp++;
 130
 131                 now = mmap_read_self(addr);
 132                 loops *= 10;
 133
 134                 delta = now - stamp;
 135                 pr_debug("%14d: %14Lu\n", n, (long long)delta);
 136
 137                 delta_sum += delta;
 138         }
 139
 140         munmap(addr, page_size);
 141         pr_debug("   ");
 142 out_close:
 143         close(fd);
 144
 145         if (!delta_sum)
 146                 return -1;
 147
 148         return 0;
 149 }
 150
 151 int test__rdpmc(void)
 152 {
 153         int status = 0;
 154         int wret = 0;
 155         int ret;
 156         int pid;
 157
 158         pid = fork();
 159         if (pid < 0)
 160                 return -1;
 161
 162         if (!pid) {
 163                 ret = __test__rdpmc();
 164
 165                 exit(ret);
 166         }
 167
 168         wret = waitpid(pid, &status, 0);
 169         if (wret < 0 || status)
 170                 return -1;
 171
 172         return 0;
 173 }
 174
 175 #endif