1 // SPDX-License-Identifier: GPL-2.0 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 16 u64 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 27 u64 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 41 int 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 72 int 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 } 108 109 u64 __weak rdtsc(void) 110 { 111 return 0; 112 } 113