1
2#include <errno.h>
3
4#include <linux/compiler.h>
5#include <linux/perf_event.h>
6#include <linux/stddef.h>
7#include <linux/types.h>
8
9#include <asm/barrier.h>
10
11#include "event.h"
12#include "synthetic-events.h"
13#include "debug.h"
14#include "tsc.h"
15
16u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
17{
18 u64 t, quot, rem;
19
20 t = ns - tc->time_zero;
21 quot = t / tc->time_mult;
22 rem = t % tc->time_mult;
23 return (quot << tc->time_shift) +
24 (rem << tc->time_shift) / tc->time_mult;
25}
26
27u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
28{
29 u64 quot, rem;
30
31 if (tc->cap_user_time_short)
32 cyc = tc->time_cycles +
33 ((cyc - tc->time_cycles) & tc->time_mask);
34
35 quot = cyc >> tc->time_shift;
36 rem = cyc & (((u64)1 << tc->time_shift) - 1);
37 return tc->time_zero + quot * tc->time_mult +
38 ((rem * tc->time_mult) >> tc->time_shift);
39}
40
41int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
42 struct perf_tsc_conversion *tc)
43{
44 u32 seq;
45 int i = 0;
46
47 while (1) {
48 seq = pc->lock;
49 rmb();
50 tc->time_mult = pc->time_mult;
51 tc->time_shift = pc->time_shift;
52 tc->time_zero = pc->time_zero;
53 tc->time_cycles = pc->time_cycles;
54 tc->time_mask = pc->time_mask;
55 tc->cap_user_time_zero = pc->cap_user_time_zero;
56 tc->cap_user_time_short = pc->cap_user_time_short;
57 rmb();
58 if (pc->lock == seq && !(seq & 1))
59 break;
60 if (++i > 10000) {
61 pr_debug("failed to get perf_event_mmap_page lock\n");
62 return -EINVAL;
63 }
64 }
65
66 if (!tc->cap_user_time_zero)
67 return -EOPNOTSUPP;
68
69 return 0;
70}
71
72int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
73 struct perf_tool *tool,
74 perf_event__handler_t process,
75 struct machine *machine)
76{
77 union perf_event event = {
78 .time_conv = {
79 .header = {
80 .type = PERF_RECORD_TIME_CONV,
81 .size = sizeof(struct perf_record_time_conv),
82 },
83 },
84 };
85 struct perf_tsc_conversion tc;
86 int err;
87
88 if (!pc)
89 return 0;
90 err = perf_read_tsc_conversion(pc, &tc);
91 if (err == -EOPNOTSUPP)
92 return 0;
93 if (err)
94 return err;
95
96 pr_debug2("Synthesizing TSC conversion information\n");
97
98 event.time_conv.time_mult = tc.time_mult;
99 event.time_conv.time_shift = tc.time_shift;
100 event.time_conv.time_zero = tc.time_zero;
101 event.time_conv.time_cycles = tc.time_cycles;
102 event.time_conv.time_mask = tc.time_mask;
103 event.time_conv.cap_user_time_zero = tc.cap_user_time_zero;
104 event.time_conv.cap_user_time_short = tc.cap_user_time_short;
105
106 return process(tool, &event, NULL, machine);
107}
108
109u64 __weak rdtsc(void)
110{
111 return 0;
112}
113
