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
18u64 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
29u64 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
43int 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
74int 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: &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
111u64 __weak rdtsc(void)
112{
113 return 0;
114}
115
116size_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}
143

source code of linux/tools/perf/util/tsc.c