perf/util/tsc.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <errno.h>
0003 #include <inttypes.h>
0004 #include <string.h>
0005
0006 #include <linux/compiler.h>
0007 #include <linux/perf_event.h>
0008 #include <linux/stddef.h>
0009 #include <linux/types.h>
0010
0011 #include <asm/barrier.h>
0012
0013 #include "event.h"
0014 #include "synthetic-events.h"
0015 #include "debug.h"
0016 #include "tsc.h"
0017
0018 u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
0019 {
0020     u64 t, quot, rem;
0021
0022     t = ns - tc->time_zero;
0023     quot = t / tc->time_mult;
0024     rem  = t % tc->time_mult;
0025     return (quot << tc->time_shift) +
0026            (rem << tc->time_shift) / tc->time_mult;
0027 }
0028
0029 u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
0030 {
0031     u64 quot, rem;
0032
0033     if (tc->cap_user_time_short)
0034         cyc = tc->time_cycles +
0035             ((cyc - tc->time_cycles) & tc->time_mask);
0036
0037     quot = cyc >> tc->time_shift;
0038     rem  = cyc & (((u64)1 << tc->time_shift) - 1);
0039     return tc->time_zero + quot * tc->time_mult +
0040            ((rem * tc->time_mult) >> tc->time_shift);
0041 }
0042
0043 int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
0044                  struct perf_tsc_conversion *tc)
0045 {
0046     u32 seq;
0047     int i = 0;
0048
0049     while (1) {
0050         seq = pc->lock;
0051         rmb();
0052         tc->time_mult = pc->time_mult;
0053         tc->time_shift = pc->time_shift;
0054         tc->time_zero = pc->time_zero;
0055         tc->time_cycles = pc->time_cycles;
0056         tc->time_mask = pc->time_mask;
0057         tc->cap_user_time_zero = pc->cap_user_time_zero;
0058         tc->cap_user_time_short = pc->cap_user_time_short;
0059         rmb();
0060         if (pc->lock == seq && !(seq & 1))
0061             break;
0062         if (++i > 10000) {
0063             pr_debug("failed to get perf_event_mmap_page lock\n");
0064             return -EINVAL;
0065         }
0066     }
0067
0068     if (!tc->cap_user_time_zero)
0069         return -EOPNOTSUPP;
0070
0071     return 0;
0072 }
0073
0074 int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
0075                 struct perf_tool *tool,
0076                 perf_event__handler_t process,
0077                 struct machine *machine)
0078 {
0079     union perf_event event = {
0080         .time_conv = {
0081             .header = {
0082                 .type = PERF_RECORD_TIME_CONV,
0083                 .size = sizeof(struct perf_record_time_conv),
0084             },
0085         },
0086     };
0087     struct perf_tsc_conversion tc;
0088     int err;
0089
0090     if (!pc)
0091         return 0;
0092     err = perf_read_tsc_conversion(pc, &tc);
0093     if (err == -EOPNOTSUPP)
0094         return 0;
0095     if (err)
0096         return err;
0097
0098     pr_debug2("Synthesizing TSC conversion information\n");
0099
0100     event.time_conv.time_mult  = tc.time_mult;
0101     event.time_conv.time_shift = tc.time_shift;
0102     event.time_conv.time_zero  = tc.time_zero;
0103     event.time_conv.time_cycles = tc.time_cycles;
0104     event.time_conv.time_mask = tc.time_mask;
0105     event.time_conv.cap_user_time_zero = tc.cap_user_time_zero;
0106     event.time_conv.cap_user_time_short = tc.cap_user_time_short;
0107
0108     return process(tool, &event, NULL, machine);
0109 }
0110
0111 u64 __weak rdtsc(void)
0112 {
0113     return 0;
0114 }
0115
0116 size_t perf_event__fprintf_time_conv(union perf_event *event, FILE *fp)
0117 {
0118     struct perf_record_time_conv *tc = (struct perf_record_time_conv *)event;
0119     size_t ret;
0120
0121     ret  = fprintf(fp, "\n... Time Shift      %" PRI_lu64 "\n", tc->time_shift);
0122     ret += fprintf(fp, "... Time Muliplier  %" PRI_lu64 "\n", tc->time_mult);
0123     ret += fprintf(fp, "... Time Zero       %" PRI_lu64 "\n", tc->time_zero);
0124
0125     /*
0126      * The event TIME_CONV was extended for the fields from "time_cycles"
0127      * when supported cap_user_time_short, for backward compatibility,
0128      * prints the extended fields only if they are contained in the event.
0129      */
0130     if (event_contains(*tc, time_cycles)) {
0131         ret += fprintf(fp, "... Time Cycles     %" PRI_lu64 "\n",
0132                    tc->time_cycles);
0133         ret += fprintf(fp, "... Time Mask       %#" PRI_lx64 "\n",
0134                    tc->time_mask);
0135         ret += fprintf(fp, "... Cap Time Zero   %" PRId32 "\n",
0136                    tc->cap_user_time_zero);
0137         ret += fprintf(fp, "... Cap Time Short  %" PRId32 "\n",
0138                    tc->cap_user_time_short);
0139     }
0140
0141     return ret;
0142 }