kern_ktr.c

Go to the documentation of this file.

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2000 John Baldwin <jhb@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
/*
 * This module holds the global variables used by KTR and the ktr_tracepoint()
 * function that does the actual tracing.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_ddb.h"
#include "opt_ktr.h"
#include "opt_alq.h"
 
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/alq.h>
#include <sys/cons.h>
#include <sys/cpuset.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/libkern.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/time.h>
 
#include <machine/cpu.h>
 
#ifdef DDB
#include <ddb/ddb.h>
#include <ddb/db_output.h>
#endif
 
#ifndef KTR_BOOT_ENTRIES
#define KTR_BOOT_ENTRIES        1024
#endif
 
#ifndef KTR_ENTRIES
#define KTR_ENTRIES     1024
#endif
 
/* Limit the allocations to something manageable. */
#define KTR_ENTRIES_MAX (8 * 1024 * 1024)
 
#ifndef KTR_MASK
#define KTR_MASK        (0)
#endif
 
#ifndef KTR_CPUMASK
#define KTR_CPUMASK     CPUSET_FSET
#endif
 
#ifndef KTR_TIME
#define KTR_TIME        get_cyclecount()
#endif
 
#ifndef KTR_CPU
#define KTR_CPU         PCPU_GET(cpuid)
#endif
 
static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
 
FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
 
volatile int    ktr_idx = 0;
uint64_t ktr_mask = KTR_MASK;
uint64_t ktr_compile = KTR_COMPILE;
int     ktr_entries = KTR_BOOT_ENTRIES;
int     ktr_version = KTR_VERSION;
struct  ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
struct  ktr_entry *ktr_buf = ktr_buf_init;
cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
 
static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "KTR options");
 
SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
    &ktr_version, 0, "Version of the KTR interface");
 
SYSCTL_UQUAD(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
    &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
 
static int
sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
{
        char lktr_cpumask_str[CPUSETBUFSIZ];
        cpuset_t imask;
        int error;
 
        cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
        error = sysctl_handle_string(oidp, lktr_cpumask_str,
            sizeof(lktr_cpumask_str), req);
        if (error != 0 || req->newptr == NULL)
                return (error);
        if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
                return (EINVAL);
        CPU_COPY(&imask, &ktr_cpumask);
 
        return (error);
}
SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
    CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
    sysctl_debug_ktr_cpumask, "S",
    "Bitmask of CPUs on which KTR logging is enabled");
 
static int
sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
{
        int clear, error;
 
        clear = 0;
        error = sysctl_handle_int(oidp, &clear, 0, req);
        if (error || !req->newptr)
                return (error);
 
        if (clear) {
                bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
                ktr_idx = 0;
        }
 
        return (error);
}
SYSCTL_PROC(_debug_ktr, OID_AUTO, clear,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
    sysctl_debug_ktr_clear, "I",
    "Clear KTR Buffer");
 
/*
 * This is a sysctl proc so that it is serialized as !MPSAFE along with
 * the other ktr sysctl procs.
 */
static int
sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
{
        uint64_t mask;
        int error;
 
        mask = ktr_mask;
        error = sysctl_handle_64(oidp, &mask, 0, req);
        if (error || !req->newptr)
                return (error);
        ktr_mask = mask;
        return (error);
}
 
SYSCTL_PROC(_debug_ktr, OID_AUTO, mask,
    CTLTYPE_U64 | CTLFLAG_RWTUN | CTLFLAG_NEEDGIANT,
    0, 0, sysctl_debug_ktr_mask, "QU",
    "Bitmask of KTR event classes for which logging is enabled");
 
#if KTR_ENTRIES > KTR_BOOT_ENTRIES
/*
 * A simplified version of sysctl_debug_ktr_entries.
 * No need to care about SMP, scheduling, etc.
 */
static void
ktr_entries_initializer(void *dummy __unused)
{
        uint64_t mask;
 
        /* Temporarily disable ktr in case malloc() is being traced. */
        mask = ktr_mask;
        ktr_mask = 0;
        ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
            M_WAITOK | M_ZERO);
        memcpy(ktr_buf, ktr_buf_init + ktr_idx,
            (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
        if (ktr_idx != 0) {
                memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
                    ktr_idx * sizeof(*ktr_buf));
                ktr_idx = KTR_BOOT_ENTRIES;
        }
        ktr_entries = KTR_ENTRIES;
        ktr_mask = mask;
}
SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
    ktr_entries_initializer, NULL);
#endif
 
static int
sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
{
        uint64_t mask;
        int entries, error;
        struct ktr_entry *buf, *oldbuf;
 
        entries = ktr_entries;
        error = sysctl_handle_int(oidp, &entries, 0, req);
        if (error || !req->newptr)
                return (error);
        if (entries > KTR_ENTRIES_MAX)
                return (ERANGE);
        /* Disable ktr temporarily. */
        mask = ktr_mask;
        ktr_mask = 0;
        /* Wait for threads to go idle. */
        if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
                ktr_mask = mask;
                return (error);
        }
        if (ktr_buf != ktr_buf_init)
                oldbuf = ktr_buf;
        else
                oldbuf = NULL;
        /* Allocate a new buffer. */
        buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
        /* Install the new buffer and restart ktr. */
        ktr_buf = buf;
        ktr_entries = entries;
        ktr_idx = 0;
        ktr_mask = mask;
        if (oldbuf != NULL)
                free(oldbuf, M_KTR);
 
        return (error);
}
 
SYSCTL_PROC(_debug_ktr, OID_AUTO, entries,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
    0, 0, sysctl_debug_ktr_entries, "I",
    "Number of entries in the KTR buffer");
 
#ifdef KTR_VERBOSE
int     ktr_verbose = KTR_VERBOSE;
TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
#endif
 
#ifdef KTR_ALQ
struct alq *ktr_alq;
char    ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
int     ktr_alq_cnt = 0;
int     ktr_alq_depth = KTR_ENTRIES;
int     ktr_alq_enabled = 0;
int     ktr_alq_failed = 0;
int     ktr_alq_max = 0;
 
SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
    "Maximum number of entries to write");
SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
    "Current number of written entries");
SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
    "Number of times we overran the buffer");
SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
    "Number of items in the write buffer");
SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
    sizeof(ktr_alq_file), "KTR logging file");
 
static int
sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
{
        int error;
        int enable;
 
        enable = ktr_alq_enabled;
 
        error = sysctl_handle_int(oidp, &enable, 0, req);
        if (error || !req->newptr)
                return (error);
 
        if (enable) {
                if (ktr_alq_enabled)
                        return (0);
                error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
                    req->td->td_ucred, ALQ_DEFAULT_CMODE,
                    sizeof(struct ktr_entry), ktr_alq_depth);
                if (error == 0) {
                        ktr_alq_cnt = 0;
                        ktr_alq_failed = 0;
                        ktr_alq_enabled = 1;
                }
        } else {
                if (ktr_alq_enabled == 0)
                        return (0);
                ktr_alq_enabled = 0;
                alq_close(ktr_alq);
                ktr_alq = NULL;
        }
 
        return (error);
}
SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
    sysctl_debug_ktr_alq_enable, "I",
    "Enable KTR logging");
#endif
 
void
ktr_tracepoint(uint64_t mask, const char *file, int line, const char *format,
    u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
    u_long arg6)
{
        struct ktr_entry *entry;
#ifdef KTR_ALQ
        struct ale *ale = NULL;
#endif
        int newindex, saveindex;
#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
        struct thread *td;
#endif
        int cpu;
 
        if (KERNEL_PANICKED() || kdb_active)
                return;
        if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
                return;
        cpu = KTR_CPU;
        if (!CPU_ISSET(cpu, &ktr_cpumask))
                return;
#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
        td = curthread;
        if (td->td_pflags & TDP_INKTR)
                return;
        td->td_pflags |= TDP_INKTR;
#endif
#ifdef KTR_ALQ
        if (ktr_alq_enabled) {
                if (td->td_critnest == 0 &&
                    (TD_IS_IDLETHREAD(td)) == 0 &&
                    td != ald_thread) {
                        if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
                                goto done;
                        if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
                                ktr_alq_failed++;
                                goto done;
                        }
                        ktr_alq_cnt++;
                        entry = (struct ktr_entry *)ale->ae_data;
                } else {
                        goto done;
                }
        } else
#endif
        {
                do {
                        saveindex = ktr_idx;
                        newindex = (saveindex + 1) % ktr_entries;
                } while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
                entry = &ktr_buf[saveindex];
        }
        entry->ktr_timestamp = KTR_TIME;
        entry->ktr_cpu = cpu;
        entry->ktr_thread = curthread;
        if (file != NULL)
                while (strncmp(file, "../", 3) == 0)
                        file += 3;
        entry->ktr_file = file;
        entry->ktr_line = line;
#ifdef KTR_VERBOSE
        if (ktr_verbose) {
#ifdef SMP
                printf("cpu%d ", cpu);
#endif
                if (ktr_verbose > 1) {
                        printf("%s.%d\t", entry->ktr_file,
                            entry->ktr_line);
                }
                printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
                printf("\n");
        }
#endif
        entry->ktr_desc = format;
        entry->ktr_parms[0] = arg1;
        entry->ktr_parms[1] = arg2;
        entry->ktr_parms[2] = arg3;
        entry->ktr_parms[3] = arg4;
        entry->ktr_parms[4] = arg5;
        entry->ktr_parms[5] = arg6;
#ifdef KTR_ALQ
        if (ktr_alq_enabled && ale)
                alq_post(ktr_alq, ale);
done:
#endif
#if defined(KTR_VERBOSE) || defined(KTR_ALQ)
        td->td_pflags &= ~TDP_INKTR;
#endif
}
 
#ifdef DDB
 
struct tstate {
        int     cur;
        int     first;
};
static  struct tstate tstate;
static  int db_ktr_verbose;
static  int db_mach_vtrace(void);
 
DB_SHOW_COMMAND(ktr, db_ktr_all)
{
 
        tstate.cur = (ktr_idx - 1) % ktr_entries;
        tstate.first = -1;
        db_ktr_verbose = 0;
        db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
        db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestamp please */
        if (strchr(modif, 'a') != NULL) {
                db_disable_pager();
                while (cncheckc() == -1)
                        if (db_mach_vtrace() == 0)
                                break;
        } else {
                while (!db_pager_quit)
                        if (db_mach_vtrace() == 0)
                                break;
        }
}
 
static int
db_mach_vtrace(void)
{
        struct ktr_entry        *kp;
 
        if (tstate.cur == tstate.first || ktr_buf == NULL) {
                db_printf("--- End of trace buffer ---\n");
                return (0);
        }
        kp = &ktr_buf[tstate.cur];
 
        /* Skip over unused entries. */
        if (kp->ktr_desc == NULL) {
                db_printf("--- End of trace buffer ---\n");
                return (0);
        }
        db_printf("%d (%p", tstate.cur, kp->ktr_thread);
#ifdef SMP
        db_printf(":cpu%d", kp->ktr_cpu);
#endif
        db_printf(")");
        if (db_ktr_verbose >= 1) {
                db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
        }
        if (db_ktr_verbose >= 2) {
                db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
        }
        db_printf(": ");
        db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
            kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
            kp->ktr_parms[5]);
        db_printf("\n");
 
        if (tstate.first == -1)
                tstate.first = tstate.cur;
 
        if (--tstate.cur < 0)
                tstate.cur = ktr_entries - 1;
 
        return (1);
}
 
#endif  /* DDB */