tools/perf/util/tsc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <errno.h>
   3 #include <inttypes.h>
   4 #include <string.h>
   5
   6 #include <linux/compiler.h>
   7 #include <linux/perf_event.h>
   8 #include <linux/stddef.h>
   9 #include <linux/types.h>
  10
  11 #include <asm/barrier.h>
  12
  13 #include "event.h"
  14 #include "synthetic-events.h"
  15 #include "debug.h"
  16 #include "tsc.h"
  17
  18 u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
  19 {
  20         u64 t, quot, rem;
  21
  22         t = ns - tc->time_zero;
  23         quot = t / tc->time_mult;
  24         rem  = t % tc->time_mult;
  25         return (quot << tc->time_shift) +
  26                (rem << tc->time_shift) / tc->time_mult;
  27 }
  28
  29 u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
  30 {
  31         u64 quot, rem;
  32
  33         if (tc->cap_user_time_short)
  34                 cyc = tc->time_cycles +
  35                         ((cyc - tc->time_cycles) & tc->time_mask);
  36
  37         quot = cyc >> tc->time_shift;
  38         rem  = cyc & (((u64)1 << tc->time_shift) - 1);
  39         return tc->time_zero + quot * tc->time_mult +
  40                ((rem * tc->time_mult) >> tc->time_shift);
  41 }
  42
  43 int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
  44                              struct perf_tsc_conversion *tc)
  45 {
  46         u32 seq;
  47         int i = 0;
  48
  49         while (1) {
  50                 seq = pc->lock;
  51                 rmb();
  52                 tc->time_mult = pc->time_mult;
  53                 tc->time_shift = pc->time_shift;
  54                 tc->time_zero = pc->time_zero;
  55                 tc->time_cycles = pc->time_cycles;
  56                 tc->time_mask = pc->time_mask;
  57                 tc->cap_user_time_zero = pc->cap_user_time_zero;
  58                 tc->cap_user_time_short = pc->cap_user_time_short;
  59                 rmb();
  60                 if (pc->lock == seq && !(seq & 1))
  61                         break;
  62                 if (++i > 10000) {
  63                         pr_debug("failed to get perf_event_mmap_page lock\n");
  64                         return -EINVAL;
  65                 }
  66         }
  67
  68         if (!tc->cap_user_time_zero)
  69                 return -EOPNOTSUPP;
  70
  71         return 0;
  72 }
  73
  74 int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
  75                                 const struct perf_tool *tool,
  76                                 perf_event__handler_t process,
  77                                 struct machine *machine)
  78 {
  79         union perf_event event = {
  80                 .time_conv = {
  81                         .header = {
  82                                 .type = PERF_RECORD_TIME_CONV,
  83                                 .size = sizeof(struct perf_record_time_conv),
  84                         },
  85                 },
  86         };
  87         struct perf_tsc_conversion tc;
  88         int err;
  89
  90         if (!pc)
  91                 return 0;
  92         err = perf_read_tsc_conversion(pc, &tc);
  93         if (err == -EOPNOTSUPP)
  94                 return 0;
  95         if (err)
  96                 return err;
  97
  98         pr_debug2("Synthesizing TSC conversion information\n");
  99
 100         event.time_conv.time_mult  = tc.time_mult;
 101         event.time_conv.time_shift = tc.time_shift;
 102         event.time_conv.time_zero  = tc.time_zero;
 103         event.time_conv.time_cycles = tc.time_cycles;
 104         event.time_conv.time_mask = tc.time_mask;
 105         event.time_conv.cap_user_time_zero = tc.cap_user_time_zero;
 106         event.time_conv.cap_user_time_short = tc.cap_user_time_short;
 107
 108         return process(tool, &event, NULL, machine);
 109 }
 110
 111 u64 __weak rdtsc(void)
 112 {
 113         return 0;
 114 }
 115
 116 size_t perf_event__fprintf_time_conv(union perf_event *event, FILE *fp)
 117 {
 118         struct perf_record_time_conv *tc = (struct perf_record_time_conv *)event;
 119         size_t ret;
 120
 121         ret  = fprintf(fp, "\n... Time Shift      %" PRI_lu64 "\n", tc->time_shift);
 122         ret += fprintf(fp, "... Time Multiplier %" PRI_lu64 "\n", tc->time_mult);
 123         ret += fprintf(fp, "... Time Zero       %" PRI_lu64 "\n", tc->time_zero);
 124
 125         /*
 126          * The event TIME_CONV was extended for the fields from "time_cycles"
 127          * when supported cap_user_time_short, for backward compatibility,
 128          * prints the extended fields only if they are contained in the event.
 129          */
 130         if (event_contains(*tc, time_cycles)) {
 131                 ret += fprintf(fp, "... Time Cycles     %" PRI_lu64 "\n",
 132                                tc->time_cycles);
 133                 ret += fprintf(fp, "... Time Mask       %#" PRI_lx64 "\n",
 134                                tc->time_mask);
 135                 ret += fprintf(fp, "... Cap Time Zero   %" PRId32 "\n",
 136                                tc->cap_user_time_zero);
 137                 ret += fprintf(fp, "... Cap Time Short  %" PRId32 "\n",
 138                                tc->cap_user_time_short);
 139         }
 140
 141         return ret;
 142 }