1 #include <stdbool.h>
2 #include <errno.h>
3
4 #include <linux/perf_event.h>
5
6 #include "../../perf.h"
7 #include <linux/types.h>
8 #include "../../util/debug.h"
9 #include "../../util/tsc.h"
10
perf_read_tsc_conversion(const struct perf_event_mmap_page * pc,struct perf_tsc_conversion * tc)11 int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
12 struct perf_tsc_conversion *tc)
13 {
14 bool cap_user_time_zero;
15 u32 seq;
16 int i = 0;
17
18 while (1) {
19 seq = pc->lock;
20 rmb();
21 tc->time_mult = pc->time_mult;
22 tc->time_shift = pc->time_shift;
23 tc->time_zero = pc->time_zero;
24 cap_user_time_zero = pc->cap_user_time_zero;
25 rmb();
26 if (pc->lock == seq && !(seq & 1))
27 break;
28 if (++i > 10000) {
29 pr_debug("failed to get perf_event_mmap_page lock\n");
30 return -EINVAL;
31 }
32 }
33
34 if (!cap_user_time_zero)
35 return -EOPNOTSUPP;
36
37 return 0;
38 }
39
rdtsc(void)40 u64 rdtsc(void)
41 {
42 unsigned int low, high;
43
44 asm volatile("rdtsc" : "=a" (low), "=d" (high));
45
46 return low | ((u64)high) << 32;
47 }
48
perf_event__synth_time_conv(const struct perf_event_mmap_page * pc,struct perf_tool * tool,perf_event__handler_t process,struct machine * machine)49 int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
50 struct perf_tool *tool,
51 perf_event__handler_t process,
52 struct machine *machine)
53 {
54 union perf_event event = {
55 .time_conv = {
56 .header = {
57 .type = PERF_RECORD_TIME_CONV,
58 .size = sizeof(struct time_conv_event),
59 },
60 },
61 };
62 struct perf_tsc_conversion tc;
63 int err;
64
65 if (!pc)
66 return 0;
67 err = perf_read_tsc_conversion(pc, &tc);
68 if (err == -EOPNOTSUPP)
69 return 0;
70 if (err)
71 return err;
72
73 pr_debug2("Synthesizing TSC conversion information\n");
74
75 event.time_conv.time_mult = tc.time_mult;
76 event.time_conv.time_shift = tc.time_shift;
77 event.time_conv.time_zero = tc.time_zero;
78
79 return process(tool, &event, NULL, machine);
80 }
81