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				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
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 Muliplier  %" 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