tools/perf/tests/rdpmc.c

   1 #include <unistd.h>
   2 #include <stdlib.h>
   3 #include <signal.h>
   4 #include <sys/mman.h>
   5 #include "types.h"
   6 #include "perf.h"
   7 #include "debug.h"
   8 #include "tests.h"
   9
  10 #if defined(__x86_64__) || defined(__i386__)
  11
  12 #define barrier() asm volatile("" ::: "memory")
  13
  14 static u64 rdpmc(unsigned int counter)
  15 {
  16         unsigned int low, high;
  17
  18         asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter));
  19
  20         return low | ((u64)high) << 32;
  21 }
  22
  23 static u64 rdtsc(void)
  24 {
  25         unsigned int low, high;
  26
  27         asm volatile("rdtsc" : "=a" (low), "=d" (high));
  28
  29         return low | ((u64)high) << 32;
  30 }
  31
  32 static u64 mmap_read_self(void *addr)
  33 {
  34         struct perf_event_mmap_page *pc = addr;
  35         u32 seq, idx, time_mult = 0, time_shift = 0;
  36         u64 count, cyc = 0, time_offset = 0, enabled, running, delta;
  37
  38         do {
  39                 seq = pc->lock;
  40                 barrier();
  41
  42                 enabled = pc->time_enabled;
  43                 running = pc->time_running;
  44
  45                 if (enabled != running) {
  46                         cyc = rdtsc();
  47                         time_mult = pc->time_mult;
  48                         time_shift = pc->time_shift;
  49                         time_offset = pc->time_offset;
  50                 }
  51
  52                 idx = pc->index;
  53                 count = pc->offset;
  54                 if (idx)
  55                         count += rdpmc(idx - 1);
  56
  57                 barrier();
  58         } while (pc->lock != seq);
  59
  60         if (enabled != running) {
  61                 u64 quot, rem;
  62
  63                 quot = (cyc >> time_shift);
  64                 rem = cyc & ((1 << time_shift) - 1);
  65                 delta = time_offset + quot * time_mult +
  66                         ((rem * time_mult) >> time_shift);
  67
  68                 enabled += delta;
  69                 if (idx)
  70                         running += delta;
  71
  72                 quot = count / running;
  73                 rem = count % running;
  74                 count = quot * enabled + (rem * enabled) / running;
  75         }
  76
  77         return count;
  78 }
  79
  80 /*
  81  * If the RDPMC instruction faults then signal this back to the test parent task:
  82  */
  83 static void segfault_handler(int sig __maybe_unused,
  84                              siginfo_t *info __maybe_unused,
  85                              void *uc __maybe_unused)
  86 {
  87         exit(-1);
  88 }
  89
  90 static int __test__rdpmc(void)
  91 {
  92         volatile int tmp = 0;
  93         u64 i, loops = 1000;
  94         int n;
  95         int fd;
  96         void *addr;
  97         struct perf_event_attr attr = {
  98                 .type = PERF_TYPE_HARDWARE,
  99                 .config = PERF_COUNT_HW_INSTRUCTIONS,
 100                 .exclude_kernel = 1,
 101         };
 102         u64 delta_sum = 0;
 103         struct sigaction sa;
 104
 105         sigfillset(&sa.sa_mask);
 106         sa.sa_sigaction = segfault_handler;
 107         sigaction(SIGSEGV, &sa, NULL);
 108
 109         fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
 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