1 /*- 2 * Copyright (c) 2017 Colin Percival 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/param.h> 31 #include <sys/sbuf.h> 32 #include <sys/sysctl.h> 33 #include <sys/systm.h> 34 #include <sys/tslog.h> 35 36 #include <machine/atomic.h> 37 #include <machine/cpu.h> 38 39 #ifndef TSLOGSIZE 40 #define TSLOGSIZE 262144 41 #endif 42 43 static volatile long nrecs = 0; 44 static struct timestamp { 45 void * td; 46 int type; 47 const char * f; 48 const char * s; 49 uint64_t tsc; 50 } timestamps[TSLOGSIZE]; 51 52 void 53 tslog(void * td, int type, const char * f, const char * s) 54 { 55 uint64_t tsc = get_cyclecount(); 56 long pos; 57 58 /* Grab a slot. */ 59 pos = atomic_fetchadd_long(&nrecs, 1); 60 61 /* Store record. */ 62 if (pos < nitems(timestamps)) { 63 timestamps[pos].td = td; 64 timestamps[pos].type = type; 65 timestamps[pos].f = f; 66 timestamps[pos].s = s; 67 timestamps[pos].tsc = tsc; 68 } 69 } 70 71 static int 72 sysctl_debug_tslog(SYSCTL_HANDLER_ARGS) 73 { 74 int error; 75 struct sbuf *sb; 76 size_t i, limit; 77 78 /* 79 * This code can race against the code in tslog() which stores 80 * records: Theoretically we could end up reading a record after 81 * its slots have been reserved but before it has been written. 82 * Since this code takes orders of magnitude longer to run than 83 * tslog() takes to write a record, it is highly unlikely that 84 * anyone will ever experience this race. 85 */ 86 sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req); 87 limit = MIN(nrecs, nitems(timestamps)); 88 for (i = 0; i < limit; i++) { 89 sbuf_printf(sb, "%p", timestamps[i].td); 90 sbuf_printf(sb, " %llu", 91 (unsigned long long)timestamps[i].tsc); 92 switch (timestamps[i].type) { 93 case TS_ENTER: 94 sbuf_printf(sb, " ENTER"); 95 break; 96 case TS_EXIT: 97 sbuf_printf(sb, " EXIT"); 98 break; 99 case TS_THREAD: 100 sbuf_printf(sb, " THREAD"); 101 break; 102 case TS_EVENT: 103 sbuf_printf(sb, " EVENT"); 104 break; 105 } 106 sbuf_printf(sb, " %s", timestamps[i].f ? timestamps[i].f : "(null)"); 107 if (timestamps[i].s) 108 sbuf_printf(sb, " %s\n", timestamps[i].s); 109 else 110 sbuf_printf(sb, "\n"); 111 } 112 error = sbuf_finish(sb); 113 sbuf_delete(sb); 114 return (error); 115 } 116 117 SYSCTL_PROC(_debug, OID_AUTO, tslog, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE, 118 0, 0, sysctl_debug_tslog, "", "Dump recorded event timestamps"); 119