kern_ktr.c revision 367457 
1/*-
2 * Copyright (c) 2000 John Baldwin <jhb@FreeBSD.org>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26/*
27 * This module holds the global variables used by KTR and the ktr_tracepoint()
28 * function that does the actual tracing.
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/11/sys/kern/kern_ktr.c 367457 2020-11-07 18:10:59Z dim $");
33
34#include "opt_ddb.h"
35#include "opt_ktr.h"
36#include "opt_alq.h"
37
38#include <sys/param.h>
39#include <sys/queue.h>
40#include <sys/alq.h>
41#include <sys/cons.h>
42#include <sys/cpuset.h>
43#include <sys/kdb.h>
44#include <sys/kernel.h>
45#include <sys/ktr.h>
46#include <sys/libkern.h>
47#include <sys/lock.h>
48#include <sys/malloc.h>
49#include <sys/mutex.h>
50#include <sys/proc.h>
51#include <sys/smp.h>
52#include <sys/sysctl.h>
53#include <sys/systm.h>
54#include <sys/time.h>
55
56#include <machine/cpu.h>
57
58#ifdef DDB
59#include <ddb/ddb.h>
60#include <ddb/db_output.h>
61#endif
62
63#ifndef KTR_BOOT_ENTRIES
64#define	KTR_BOOT_ENTRIES	1024
65#endif
66
67#ifndef KTR_ENTRIES
68#define	KTR_ENTRIES	1024
69#endif
70
71/* Limit the allocations to something manageable. */
72#define	KTR_ENTRIES_MAX	(8 * 1024 * 1024)
73
74#ifndef KTR_MASK
75#define	KTR_MASK	(0)
76#endif
77
78#ifndef KTR_CPUMASK
79#define	KTR_CPUMASK	CPUSET_FSET
80#endif
81
82#ifndef KTR_TIME
83#define	KTR_TIME	get_cyclecount()
84#endif
85
86#ifndef KTR_CPU
87#define	KTR_CPU		PCPU_GET(cpuid)
88#endif
89
90static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
91
92FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
93
94volatile int	ktr_idx = 0;
95uint64_t ktr_mask = KTR_MASK;
96uint64_t ktr_compile = KTR_COMPILE;
97int	ktr_entries = KTR_BOOT_ENTRIES;
98int	ktr_version = KTR_VERSION;
99struct	ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
100struct	ktr_entry *ktr_buf = ktr_buf_init;
101cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
102
103static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
104
105SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
106    &ktr_version, 0, "Version of the KTR interface");
107
108SYSCTL_UQUAD(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
109    &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
110
111static int
112sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
113{
114	char lktr_cpumask_str[CPUSETBUFSIZ];
115	cpuset_t imask;
116	int error;
117
118	cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
119	error = sysctl_handle_string(oidp, lktr_cpumask_str,
120	    sizeof(lktr_cpumask_str), req);
121	if (error != 0 || req->newptr == NULL)
122		return (error);
123	if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
124		return (EINVAL);
125	CPU_COPY(&imask, &ktr_cpumask);
126
127	return (error);
128}
129SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
130    CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
131    sysctl_debug_ktr_cpumask, "S",
132    "Bitmask of CPUs on which KTR logging is enabled");
133
134static int
135sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
136{
137	int clear, error;
138
139	clear = 0;
140	error = sysctl_handle_int(oidp, &clear, 0, req);
141	if (error || !req->newptr)
142		return (error);
143
144	if (clear) {
145		bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
146		ktr_idx = 0;
147	}
148
149	return (error);
150}
151SYSCTL_PROC(_debug_ktr, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
152    sysctl_debug_ktr_clear, "I", "Clear KTR Buffer");
153
154/*
155 * This is a sysctl proc so that it is serialized as !MPSAFE along with
156 * the other ktr sysctl procs.
157 */
158static int
159sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
160{
161	uint64_t mask;
162	int error;
163
164	mask = ktr_mask;
165	error = sysctl_handle_64(oidp, &mask, 0, req);
166	if (error || !req->newptr)
167		return (error);
168	ktr_mask = mask;
169	return (error);
170}
171
172SYSCTL_PROC(_debug_ktr, OID_AUTO, mask, CTLTYPE_U64 | CTLFLAG_RWTUN, 0, 0,
173    sysctl_debug_ktr_mask, "QU",
174    "Bitmask of KTR event classes for which logging is enabled");
175
176#if KTR_ENTRIES > KTR_BOOT_ENTRIES
177/*
178 * A simplified version of sysctl_debug_ktr_entries.
179 * No need to care about SMP, scheduling, etc.
180 */
181static void
182ktr_entries_initializer(void *dummy __unused)
183{
184	uint64_t mask;
185
186	/* Temporarily disable ktr in case malloc() is being traced. */
187	mask = ktr_mask;
188	ktr_mask = 0;
189	ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
190	    M_WAITOK | M_ZERO);
191	memcpy(ktr_buf, ktr_buf_init + ktr_idx,
192	    (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
193	if (ktr_idx != 0) {
194		memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
195		    ktr_idx * sizeof(*ktr_buf));
196		ktr_idx = KTR_BOOT_ENTRIES;
197	}
198	ktr_entries = KTR_ENTRIES;
199	ktr_mask = mask;
200}
201SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
202    ktr_entries_initializer, NULL);
203#endif
204
205static int
206sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
207{
208	uint64_t mask;
209	int entries, error;
210	struct ktr_entry *buf, *oldbuf;
211
212	entries = ktr_entries;
213	error = sysctl_handle_int(oidp, &entries, 0, req);
214	if (error || !req->newptr)
215		return (error);
216	if (entries > KTR_ENTRIES_MAX)
217		return (ERANGE);
218	/* Disable ktr temporarily. */
219	mask = ktr_mask;
220	ktr_mask = 0;
221	/* Wait for threads to go idle. */
222	if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
223		ktr_mask = mask;
224		return (error);
225	}
226	if (ktr_buf != ktr_buf_init)
227		oldbuf = ktr_buf;
228	else
229		oldbuf = NULL;
230	/* Allocate a new buffer. */
231	buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
232	/* Install the new buffer and restart ktr. */
233	ktr_buf = buf;
234	ktr_entries = entries;
235	ktr_idx = 0;
236	ktr_mask = mask;
237	if (oldbuf != NULL)
238		free(oldbuf, M_KTR);
239
240	return (error);
241}
242
243SYSCTL_PROC(_debug_ktr, OID_AUTO, entries, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
244    sysctl_debug_ktr_entries, "I", "Number of entries in the KTR buffer");
245
246#ifdef KTR_VERBOSE
247int	ktr_verbose = KTR_VERBOSE;
248TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
249SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
250#endif
251
252#ifdef KTR_ALQ
253struct alq *ktr_alq;
254char	ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
255int	ktr_alq_cnt = 0;
256int	ktr_alq_depth = KTR_ENTRIES;
257int	ktr_alq_enabled = 0;
258int	ktr_alq_failed = 0;
259int	ktr_alq_max = 0;
260
261SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
262    "Maximum number of entries to write");
263SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
264    "Current number of written entries");
265SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
266    "Number of times we overran the buffer");
267SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
268    "Number of items in the write buffer");
269SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
270    sizeof(ktr_alq_file), "KTR logging file");
271
272static int
273sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
274{
275	int error;
276	int enable;
277
278	enable = ktr_alq_enabled;
279
280	error = sysctl_handle_int(oidp, &enable, 0, req);
281	if (error || !req->newptr)
282		return (error);
283
284	if (enable) {
285		if (ktr_alq_enabled)
286			return (0);
287		error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
288		    req->td->td_ucred, ALQ_DEFAULT_CMODE,
289		    sizeof(struct ktr_entry), ktr_alq_depth);
290		if (error == 0) {
291			ktr_alq_cnt = 0;
292			ktr_alq_failed = 0;
293			ktr_alq_enabled = 1;
294		}
295	} else {
296		if (ktr_alq_enabled == 0)
297			return (0);
298		ktr_alq_enabled = 0;
299		alq_close(ktr_alq);
300		ktr_alq = NULL;
301	}
302
303	return (error);
304}
305SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
306    CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_debug_ktr_alq_enable,
307    "I", "Enable KTR logging");
308#endif
309
310void
311ktr_tracepoint(uint64_t mask, const char *file, int line, const char *format,
312    u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
313    u_long arg6)
314{
315	struct ktr_entry *entry;
316#ifdef KTR_ALQ
317	struct ale *ale = NULL;
318#endif
319	int newindex, saveindex;
320#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
321	struct thread *td;
322#endif
323	int cpu;
324
325	if (panicstr || kdb_active)
326		return;
327	if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
328		return;
329	cpu = KTR_CPU;
330	if (!CPU_ISSET(cpu, &ktr_cpumask))
331		return;
332#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
333	td = curthread;
334	if (td->td_pflags & TDP_INKTR)
335		return;
336	td->td_pflags |= TDP_INKTR;
337#endif
338#ifdef KTR_ALQ
339	if (ktr_alq_enabled) {
340		if (td->td_critnest == 0 &&
341		    (TD_IS_IDLETHREAD(td)) == 0 &&
342		    td != ald_thread) {
343			if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
344				goto done;
345			if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
346				ktr_alq_failed++;
347				goto done;
348			}
349			ktr_alq_cnt++;
350			entry = (struct ktr_entry *)ale->ae_data;
351		} else {
352			goto done;
353		}
354	} else
355#endif
356	{
357		do {
358			saveindex = ktr_idx;
359			newindex = (saveindex + 1) % ktr_entries;
360		} while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
361		entry = &ktr_buf[saveindex];
362	}
363	entry->ktr_timestamp = KTR_TIME;
364	entry->ktr_cpu = cpu;
365	entry->ktr_thread = curthread;
366	if (file != NULL)
367		while (strncmp(file, "../", 3) == 0)
368			file += 3;
369	entry->ktr_file = file;
370	entry->ktr_line = line;
371#ifdef KTR_VERBOSE
372	if (ktr_verbose) {
373#ifdef SMP
374		printf("cpu%d ", cpu);
375#endif
376		if (ktr_verbose > 1) {
377			printf("%s.%d\t", entry->ktr_file,
378			    entry->ktr_line);
379		}
380		printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
381		printf("\n");
382	}
383#endif
384	entry->ktr_desc = format;
385	entry->ktr_parms[0] = arg1;
386	entry->ktr_parms[1] = arg2;
387	entry->ktr_parms[2] = arg3;
388	entry->ktr_parms[3] = arg4;
389	entry->ktr_parms[4] = arg5;
390	entry->ktr_parms[5] = arg6;
391#ifdef KTR_ALQ
392	if (ktr_alq_enabled && ale)
393		alq_post(ktr_alq, ale);
394done:
395#endif
396#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
397	td->td_pflags &= ~TDP_INKTR;
398#endif
399}
400
401#ifdef DDB
402
403struct tstate {
404	int	cur;
405	int	first;
406};
407static	struct tstate tstate;
408static	int db_ktr_verbose;
409static	int db_mach_vtrace(void);
410
411DB_SHOW_COMMAND(ktr, db_ktr_all)
412{
413
414	tstate.cur = (ktr_idx - 1) % ktr_entries;
415	tstate.first = -1;
416	db_ktr_verbose = 0;
417	db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
418	db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestap please */
419	if (strchr(modif, 'a') != NULL) {
420		db_disable_pager();
421		while (cncheckc() == -1)
422			if (db_mach_vtrace() == 0)
423				break;
424	} else {
425		while (!db_pager_quit)
426			if (db_mach_vtrace() == 0)
427				break;
428	}
429}
430
431static int
432db_mach_vtrace(void)
433{
434	struct ktr_entry	*kp;
435
436	if (tstate.cur == tstate.first || ktr_buf == NULL) {
437		db_printf("--- End of trace buffer ---\n");
438		return (0);
439	}
440	kp = &ktr_buf[tstate.cur];
441
442	/* Skip over unused entries. */
443	if (kp->ktr_desc == NULL) {
444		db_printf("--- End of trace buffer ---\n");
445		return (0);
446	}
447	db_printf("%d (%p", tstate.cur, kp->ktr_thread);
448#ifdef SMP
449	db_printf(":cpu%d", kp->ktr_cpu);
450#endif
451	db_printf(")");
452	if (db_ktr_verbose >= 1) {
453		db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
454	}
455	if (db_ktr_verbose >= 2) {
456		db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
457	}
458	db_printf(": ");
459	db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
460	    kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
461	    kp->ktr_parms[5]);
462	db_printf("\n");
463
464	if (tstate.first == -1)
465		tstate.first = tstate.cur;
466
467	if (--tstate.cur < 0)
468		tstate.cur = ktr_entries - 1;
469
470	return (1);
471}
472
473#endif	/* DDB */
474