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