/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2005-2007 Joseph Koshy
 * Copyright (c) 2007 The FreeBSD Foundation
 * Copyright (c) 2018 Matthew Macy
 * All rights reserved.
 *
 * Portions of this software were developed by A. Joseph Koshy under
 * sponsorship from the FreeBSD Foundation and Google, Inc.
 *
 * 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.
 *
 */

/*
 * Logging code for hwpmc(4)
 */

#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/domainset.h>
#include <sys/file.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/pmc.h>
#include <sys/pmckern.h>
#include <sys/pmclog.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/syslog.h>

#if defined(__i386__) || defined(__amd64__)
#include <machine/clock.h>
#endif

#define curdomain PCPU_GET(domain)

/*
 * Sysctl tunables
 */

SYSCTL_DECL(_kern_hwpmc);

/*
 * kern.hwpmc.logbuffersize -- size of the per-cpu owner buffers.
 */

static int pmclog_buffer_size = PMC_LOG_BUFFER_SIZE;
SYSCTL_INT(_kern_hwpmc, OID_AUTO, logbuffersize, CTLFLAG_RDTUN,
    &pmclog_buffer_size, 0, "size of log buffers in kilobytes");

/*
 * kern.hwpmc.nbuffers_pcpu -- number of global log buffers
 */

static int pmc_nlogbuffers_pcpu = PMC_NLOGBUFFERS_PCPU;
SYSCTL_INT(_kern_hwpmc, OID_AUTO, nbuffers_pcpu, CTLFLAG_RDTUN,
    &pmc_nlogbuffers_pcpu, 0, "number of log buffers per cpu");

/*
 * Global log buffer list and associated spin lock.
 */

static struct mtx pmc_kthread_mtx;      /* sleep lock */

#define PMCLOG_INIT_BUFFER_DESCRIPTOR(D, buf, domain) do {              \
        (D)->plb_fence = ((char *)(buf)) + 1024 * pmclog_buffer_size;   \
        (D)->plb_base = (D)->plb_ptr = ((char *)(buf));                 \
        (D)->plb_domain = domain;                                       \
} while (0)

#define PMCLOG_RESET_BUFFER_DESCRIPTOR(D) do {                          \
        (D)->plb_ptr = (D)->plb_base;                                   \
} while (0)

/*
 * Log file record constructors.
 */
#define _PMCLOG_TO_HEADER(T, L)                                         \
        ((PMCLOG_HEADER_MAGIC << 24) | (T << 16) | ((L) & 0xFFFF))

/* reserve LEN bytes of space and initialize the entry header */
#define _PMCLOG_RESERVE_SAFE(PO, TYPE, LEN, ACTION, TSC) do {           \
        uint32_t *_le;                                                  \
        int _len = roundup((LEN), sizeof(uint32_t));                    \
        struct pmclog_header *ph;                                       \
                                                                        \
        if ((_le = pmclog_reserve((PO), _len)) == NULL) {               \
                ACTION;                                                 \
        }                                                               \
        ph = (struct pmclog_header *)_le;                               \
        ph->pl_header =_PMCLOG_TO_HEADER(TYPE,_len);                    \
        ph->pl_tsc = (TSC);                                             \
        _le += sizeof(*ph) / 4  /* skip over timestamp */

/* reserve LEN bytes of space and initialize the entry header */
#define _PMCLOG_RESERVE(PO, TYPE, LEN, ACTION) do {                     \
        uint32_t *_le;                                                  \
        int _len = roundup((LEN), sizeof(uint32_t));                    \
        uint64_t tsc;                                                   \
        struct pmclog_header *ph;                                       \
                                                                        \
        tsc = pmc_rdtsc();                                              \
        spinlock_enter();                                               \
        if ((_le = pmclog_reserve((PO), _len)) == NULL) {               \
                spinlock_exit();                                        \
                ACTION;                                                 \
        }                                                               \
        ph = (struct pmclog_header *)_le;                               \
        ph->pl_header =_PMCLOG_TO_HEADER(TYPE,_len);                    \
        ph->pl_tsc = tsc;                                               \
        _le += sizeof(*ph) / 4  /* skip over timestamp */

#define PMCLOG_RESERVE_SAFE(P, T, L, TSC)                               \
        _PMCLOG_RESERVE_SAFE(P, T, L, return, TSC)
#define PMCLOG_RESERVE(P,T,L)                                           \
        _PMCLOG_RESERVE(P, T, L, return)
#define PMCLOG_RESERVE_WITH_ERROR(P, T, L)                              \
        _PMCLOG_RESERVE(P, T, L, error = ENOMEM; goto error)

#define PMCLOG_EMIT32(V)        do { *_le++ = (V); } while (0)
#define PMCLOG_EMIT64(V)        do {                                    \
        *_le++ = (uint32_t) ((V) & 0xFFFFFFFF);                         \
        *_le++ = (uint32_t) (((V) >> 32) & 0xFFFFFFFF);                 \
} while (0)


/* Emit a string.  Caution: does NOT update _le, so needs to be last */
#define PMCLOG_EMITSTRING(S,L)  do {                                    \
        bcopy((S), _le, (L));                                           \
} while (0)
#define PMCLOG_EMITNULLSTRING(L) do {                                   \
        bzero(_le, (L));                                                \
} while (0)

#define PMCLOG_DESPATCH_SAFE(PO)                                        \
        pmclog_release((PO));                                           \
} while (0)

#define PMCLOG_DESPATCH_SCHED_LOCK(PO)                                  \
        pmclog_release_flags((PO), 0);                                  \
} while (0)

#define PMCLOG_DESPATCH(PO)                                             \
        pmclog_release((PO));                                           \
        spinlock_exit();                                                \
} while (0)

#define PMCLOG_DESPATCH_SYNC(PO)                                        \
        pmclog_schedule_io((PO), 1);                                    \
        spinlock_exit();                                                \
} while (0)

#define TSDELTA 4
/*
 * Assertions about the log file format.
 */
CTASSERT(sizeof(struct pmclog_callchain) == 7*4 + TSDELTA +
    PMC_CALLCHAIN_DEPTH_MAX*sizeof(uintfptr_t));
CTASSERT(sizeof(struct pmclog_closelog) == 3*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_dropnotify) == 3*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_map_in) == PATH_MAX + TSDELTA +
    5*4 + sizeof(uintfptr_t));
CTASSERT(offsetof(struct pmclog_map_in,pl_pathname) ==
    5*4 + TSDELTA + sizeof(uintfptr_t));
CTASSERT(sizeof(struct pmclog_map_out) == 5*4 + 2*sizeof(uintfptr_t) + TSDELTA);
CTASSERT(sizeof(struct pmclog_pmcallocate) == 9*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_pmcattach) == 5*4 + PATH_MAX + TSDELTA);
CTASSERT(offsetof(struct pmclog_pmcattach,pl_pathname) == 5*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_pmcdetach) == 5*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_proccsw) == 7*4 + 8 + TSDELTA);
CTASSERT(sizeof(struct pmclog_procexec) == 5*4 + PATH_MAX +
    2*sizeof(uintptr_t) + TSDELTA);
CTASSERT(offsetof(struct pmclog_procexec,pl_pathname) == 5*4 + TSDELTA +
    2*sizeof(uintptr_t));
CTASSERT(sizeof(struct pmclog_procexit) == 5*4 + 8 + TSDELTA);
CTASSERT(sizeof(struct pmclog_procfork) == 5*4 + TSDELTA);
CTASSERT(sizeof(struct pmclog_sysexit) == 6*4);
CTASSERT(sizeof(struct pmclog_userdata) == 6*4);

/*
 * Log buffer structure
 */

struct pmclog_buffer {
        TAILQ_ENTRY(pmclog_buffer) plb_next;
        char            *plb_base;
        char            *plb_ptr;
        char            *plb_fence;
        uint16_t         plb_domain;
} __aligned(CACHE_LINE_SIZE);

/*
 * Prototypes
 */

static int pmclog_get_buffer(struct pmc_owner *po);
static void pmclog_loop(void *arg);
static void pmclog_release(struct pmc_owner *po);
static uint32_t *pmclog_reserve(struct pmc_owner *po, int length);
static void pmclog_schedule_io(struct pmc_owner *po, int wakeup);
static void pmclog_schedule_all(struct pmc_owner *po);
static void pmclog_stop_kthread(struct pmc_owner *po);

/*
 * Helper functions
 */

static inline void
pmc_plb_rele_unlocked(struct pmclog_buffer *plb)
{
        TAILQ_INSERT_HEAD(&pmc_dom_hdrs[plb->plb_domain]->pdbh_head, plb, plb_next);
}

static inline void
pmc_plb_rele(struct pmclog_buffer *plb)
{
        mtx_lock_spin(&pmc_dom_hdrs[plb->plb_domain]->pdbh_mtx);
        pmc_plb_rele_unlocked(plb);
        mtx_unlock_spin(&pmc_dom_hdrs[plb->plb_domain]->pdbh_mtx);
}

/*
 * Get a log buffer
 */
static int
pmclog_get_buffer(struct pmc_owner *po)
{
        struct pmclog_buffer *plb;
        int domain;

        KASSERT(po->po_curbuf[curcpu] == NULL,
            ("[pmclog,%d] po=%p current buffer still valid", __LINE__, po));

        domain = curdomain;
        MPASS(pmc_dom_hdrs[domain]);
        mtx_lock_spin(&pmc_dom_hdrs[domain]->pdbh_mtx);
        if ((plb = TAILQ_FIRST(&pmc_dom_hdrs[domain]->pdbh_head)) != NULL)
                TAILQ_REMOVE(&pmc_dom_hdrs[domain]->pdbh_head, plb, plb_next);
        mtx_unlock_spin(&pmc_dom_hdrs[domain]->pdbh_mtx);

        PMCDBG2(LOG,GTB,1, "po=%p plb=%p", po, plb);

#ifdef  HWPMC_DEBUG
        if (plb)
                KASSERT(plb->plb_ptr == plb->plb_base &&
                    plb->plb_base < plb->plb_fence,
                    ("[pmclog,%d] po=%p buffer invariants: ptr=%p "
                    "base=%p fence=%p", __LINE__, po, plb->plb_ptr,
                    plb->plb_base, plb->plb_fence));
#endif

        po->po_curbuf[curcpu] = plb;

        /* update stats */
        counter_u64_add(pmc_stats.pm_buffer_requests, 1);
        if (plb == NULL)
                counter_u64_add(pmc_stats.pm_buffer_requests_failed, 1);

        return (plb ? 0 : ENOMEM);
}

struct pmclog_proc_init_args {
        struct proc *kthr;
        struct pmc_owner *po;
        bool exit;
        bool acted;
};

int
pmclog_proc_create(struct thread *td, void **handlep)
{
        struct pmclog_proc_init_args *ia;
        int error;

        ia = malloc(sizeof(*ia), M_TEMP, M_WAITOK | M_ZERO);
        error = kproc_create(pmclog_loop, ia, &ia->kthr,
            RFHIGHPID, 0, "hwpmc: proc(%d)", td->td_proc->p_pid);
        if (error == 0)
                *handlep = ia;
        return (error);
}

void
pmclog_proc_ignite(void *handle, struct pmc_owner *po)
{
        struct pmclog_proc_init_args *ia;

        ia = handle;
        mtx_lock(&pmc_kthread_mtx);
        MPASS(!ia->acted);
        MPASS(ia->po == NULL);
        MPASS(!ia->exit);
        MPASS(ia->kthr != NULL);
        if (po == NULL) {
                ia->exit = true;
        } else {
                ia->po = po;
                KASSERT(po->po_kthread == NULL,
                    ("[pmclog,%d] po=%p kthread (%p) already present",
                    __LINE__, po, po->po_kthread));
                po->po_kthread = ia->kthr;
        }
        wakeup(ia);
        while (!ia->acted)
                msleep(ia, &pmc_kthread_mtx, PWAIT, "pmclogw", 0);
        mtx_unlock(&pmc_kthread_mtx);
        free(ia, M_TEMP);
}

/*
 * Log handler loop.
 *
 * This function is executed by each pmc owner's helper thread.
 */
static void
pmclog_loop(void *arg)
{
        struct pmclog_proc_init_args *ia;
        struct pmc_owner *po;
        struct pmclog_buffer *lb;
        struct proc *p;
        struct ucred *ownercred;
        struct ucred *mycred;
        struct thread *td;
        sigset_t unb;
        struct uio auio;
        struct iovec aiov;
        size_t nbytes;
        int error;

        td = curthread;

        SIGEMPTYSET(unb);
        SIGADDSET(unb, SIGHUP);
        (void)kern_sigprocmask(td, SIG_UNBLOCK, &unb, NULL, 0);

        ia = arg;
        MPASS(ia->kthr == curproc);
        MPASS(!ia->acted);
        mtx_lock(&pmc_kthread_mtx);
        while (ia->po == NULL && !ia->exit)
                msleep(ia, &pmc_kthread_mtx, PWAIT, "pmclogi", 0);
        if (ia->exit) {
                ia->acted = true;
                wakeup(ia);
                mtx_unlock(&pmc_kthread_mtx);
                kproc_exit(0);
        }
        MPASS(ia->po != NULL);
        po = ia->po;
        ia->acted = true;
        wakeup(ia);
        mtx_unlock(&pmc_kthread_mtx);
        ia = NULL;

        p = po->po_owner;
        mycred = td->td_ucred;

        PROC_LOCK(p);
        ownercred = crhold(p->p_ucred);
        PROC_UNLOCK(p);

        PMCDBG2(LOG,INI,1, "po=%p kt=%p", po, po->po_kthread);
        KASSERT(po->po_kthread == curthread->td_proc,
            ("[pmclog,%d] proc mismatch po=%p po/kt=%p curproc=%p", __LINE__,
                po, po->po_kthread, curthread->td_proc));

        lb = NULL;


        /*
         * Loop waiting for I/O requests to be added to the owner
         * struct's queue.  The loop is exited when the log file
         * is deconfigured.
         */

        mtx_lock(&pmc_kthread_mtx);

        for (;;) {

                /* check if we've been asked to exit */
                if ((po->po_flags & PMC_PO_OWNS_LOGFILE) == 0)
                        break;

                if (lb == NULL) { /* look for a fresh buffer to write */
                        mtx_lock_spin(&po->po_mtx);
                        if ((lb = TAILQ_FIRST(&po->po_logbuffers)) == NULL) {
                                mtx_unlock_spin(&po->po_mtx);

                                /* No more buffers and shutdown required. */
                                if (po->po_flags & PMC_PO_SHUTDOWN)
                                        break;

                                (void) msleep(po, &pmc_kthread_mtx, PWAIT,
                                    "pmcloop", 250);
                                continue;
                        }

                        TAILQ_REMOVE(&po->po_logbuffers, lb, plb_next);
                        mtx_unlock_spin(&po->po_mtx);
                }

                mtx_unlock(&pmc_kthread_mtx);

                /* process the request */
                PMCDBG3(LOG,WRI,2, "po=%p base=%p ptr=%p", po,
                    lb->plb_base, lb->plb_ptr);
                /* change our thread's credentials before issuing the I/O */

                aiov.iov_base = lb->plb_base;
                aiov.iov_len  = nbytes = lb->plb_ptr - lb->plb_base;

                auio.uio_iov    = &aiov;
                auio.uio_iovcnt = 1;
                auio.uio_offset = -1;
                auio.uio_resid  = nbytes;
                auio.uio_rw     = UIO_WRITE;
                auio.uio_segflg = UIO_SYSSPACE;
                auio.uio_td     = td;

                /* switch thread credentials -- see kern_ktrace.c */
                td->td_ucred = ownercred;
                error = fo_write(po->po_file, &auio, ownercred, 0, td);
                td->td_ucred = mycred;

                if (error) {
                        /* XXX some errors are recoverable */
                        /* send a SIGIO to the owner and exit */
                        PROC_LOCK(p);
                        kern_psignal(p, SIGIO);
                        PROC_UNLOCK(p);

                        mtx_lock(&pmc_kthread_mtx);

                        po->po_error = error; /* save for flush log */

                        PMCDBG2(LOG,WRI,2, "po=%p error=%d", po, error);

                        break;
                }

                mtx_lock(&pmc_kthread_mtx);

                /* put the used buffer back into the global pool */
                PMCLOG_RESET_BUFFER_DESCRIPTOR(lb);

                pmc_plb_rele(lb);
                lb = NULL;
        }

        wakeup_one(po->po_kthread);
        po->po_kthread = NULL;

        mtx_unlock(&pmc_kthread_mtx);

        /* return the current I/O buffer to the global pool */
        if (lb) {
                PMCLOG_RESET_BUFFER_DESCRIPTOR(lb);

                pmc_plb_rele(lb);
        }

        /*
         * Exit this thread, signalling the waiter
         */

        crfree(ownercred);

        kproc_exit(0);
}

/*
 * Release and log entry and schedule an I/O if needed.
 */

static void
pmclog_release_flags(struct pmc_owner *po, int wakeup)
{
        struct pmclog_buffer *plb;

        plb = po->po_curbuf[curcpu];
        KASSERT(plb->plb_ptr >= plb->plb_base,
            ("[pmclog,%d] buffer invariants po=%p ptr=%p base=%p", __LINE__,
                po, plb->plb_ptr, plb->plb_base));
        KASSERT(plb->plb_ptr <= plb->plb_fence,
            ("[pmclog,%d] buffer invariants po=%p ptr=%p fenc=%p", __LINE__,
                po, plb->plb_ptr, plb->plb_fence));

        /* schedule an I/O if we've filled a buffer */
        if (plb->plb_ptr >= plb->plb_fence)
                pmclog_schedule_io(po, wakeup);

        PMCDBG1(LOG,REL,1, "po=%p", po);
}

static void
pmclog_release(struct pmc_owner *po)
{

        pmclog_release_flags(po, 1);
}


/*
 * Attempt to reserve 'length' bytes of space in an owner's log
 * buffer.  The function returns a pointer to 'length' bytes of space
 * if there was enough space or returns NULL if no space was
 * available.  Non-null returns do so with the po mutex locked.  The
 * caller must invoke pmclog_release() on the pmc owner structure
 * when done.
 */

static uint32_t *
pmclog_reserve(struct pmc_owner *po, int length)
{
        uintptr_t newptr, oldptr __diagused;
        struct pmclog_buffer *plb, **pplb;

        PMCDBG2(LOG,ALL,1, "po=%p len=%d", po, length);

        KASSERT(length % sizeof(uint32_t) == 0,
            ("[pmclog,%d] length not a multiple of word size", __LINE__));

        /* No more data when shutdown in progress. */
        if (po->po_flags & PMC_PO_SHUTDOWN)
                return (NULL);

        pplb = &po->po_curbuf[curcpu];
        if (*pplb == NULL && pmclog_get_buffer(po) != 0)
                goto fail;

        KASSERT(*pplb != NULL,
            ("[pmclog,%d] po=%p no current buffer", __LINE__, po));

        plb = *pplb;
        KASSERT(plb->plb_ptr >= plb->plb_base &&
            plb->plb_ptr <= plb->plb_fence,
            ("[pmclog,%d] po=%p buffer invariants: ptr=%p base=%p fence=%p",
                __LINE__, po, plb->plb_ptr, plb->plb_base,
                plb->plb_fence));

        oldptr = (uintptr_t) plb->plb_ptr;
        newptr = oldptr + length;

        KASSERT(oldptr != (uintptr_t) NULL,
            ("[pmclog,%d] po=%p Null log buffer pointer", __LINE__, po));

        /*
         * If we have space in the current buffer, return a pointer to
         * available space with the PO structure locked.
         */
        if (newptr <= (uintptr_t) plb->plb_fence) {
                plb->plb_ptr = (char *) newptr;
                goto done;
        }

        /*
         * Otherwise, schedule the current buffer for output and get a
         * fresh buffer.
         */
        pmclog_schedule_io(po, 0);

        if (pmclog_get_buffer(po) != 0)
                goto fail;

        plb = *pplb;
        KASSERT(plb != NULL,
            ("[pmclog,%d] po=%p no current buffer", __LINE__, po));

        KASSERT(plb->plb_ptr != NULL,
            ("[pmclog,%d] null return from pmc_get_log_buffer", __LINE__));

        KASSERT(plb->plb_ptr == plb->plb_base &&
            plb->plb_ptr <= plb->plb_fence,
            ("[pmclog,%d] po=%p buffer invariants: ptr=%p base=%p fence=%p",
                __LINE__, po, plb->plb_ptr, plb->plb_base,
                plb->plb_fence));

        oldptr = (uintptr_t) plb->plb_ptr;

 done:
        return ((uint32_t *) oldptr);
 fail:
        return (NULL);
}

/*
 * Schedule an I/O.
 *
 * Transfer the current buffer to the helper kthread.
 */

static void
pmclog_schedule_io(struct pmc_owner *po, int wakeup)
{
        struct pmclog_buffer *plb;

        plb = po->po_curbuf[curcpu];
        po->po_curbuf[curcpu] = NULL;
        KASSERT(plb != NULL,
            ("[pmclog,%d] schedule_io with null buffer po=%p", __LINE__, po));
        KASSERT(plb->plb_ptr >= plb->plb_base,
            ("[pmclog,%d] buffer invariants po=%p ptr=%p base=%p", __LINE__,
                po, plb->plb_ptr, plb->plb_base));
        KASSERT(plb->plb_ptr <= plb->plb_fence,
            ("[pmclog,%d] buffer invariants po=%p ptr=%p fenc=%p", __LINE__,
                po, plb->plb_ptr, plb->plb_fence));

        PMCDBG1(LOG,SIO, 1, "po=%p", po);

        /*
         * Add the current buffer to the tail of the buffer list and
         * wakeup the helper.
         */
        mtx_lock_spin(&po->po_mtx);
        TAILQ_INSERT_TAIL(&po->po_logbuffers, plb, plb_next);
        mtx_unlock_spin(&po->po_mtx);
        if (wakeup)
                wakeup_one(po);
}

/*
 * Stop the helper kthread.
 */

static void
pmclog_stop_kthread(struct pmc_owner *po)
{

        mtx_lock(&pmc_kthread_mtx);
        po->po_flags &= ~PMC_PO_OWNS_LOGFILE;
        if (po->po_kthread != NULL) {
                PROC_LOCK(po->po_kthread);
                kern_psignal(po->po_kthread, SIGHUP);
                PROC_UNLOCK(po->po_kthread);
        }
        wakeup_one(po);
        while (po->po_kthread)
                msleep(po->po_kthread, &pmc_kthread_mtx, PPAUSE, "pmckstp", 0);
        mtx_unlock(&pmc_kthread_mtx);
}

/*
 * Public functions
 */

/*
 * Configure a log file for pmc owner 'po'.
 *
 * Parameter 'logfd' is a file handle referencing an open file in the
 * owner process.  This file needs to have been opened for writing.
 */

int
pmclog_configure_log(struct pmc_mdep *md, struct pmc_owner *po, int logfd)
{
        struct proc *p;
        struct timespec ts;
        int error;

        sx_assert(&pmc_sx, SA_XLOCKED);
        PMCDBG2(LOG,CFG,1, "config po=%p logfd=%d", po, logfd);

        p = po->po_owner;

        /* return EBUSY if a log file was already present */
        if (po->po_flags & PMC_PO_OWNS_LOGFILE)
                return (EBUSY);

        KASSERT(po->po_file == NULL,
            ("[pmclog,%d] po=%p file (%p) already present", __LINE__, po,
                po->po_file));

        /* get a reference to the file state */
        error = fget_write(curthread, logfd, &cap_write_rights, &po->po_file);
        if (error)
                goto error;

        /* mark process as owning a log file */
        po->po_flags |= PMC_PO_OWNS_LOGFILE;

        /* mark process as using HWPMCs */
        PROC_LOCK(p);
        p->p_flag |= P_HWPMC;
        PROC_UNLOCK(p);
        nanotime(&ts);
        /* create a log initialization entry */
        PMCLOG_RESERVE_WITH_ERROR(po, PMCLOG_TYPE_INITIALIZE,
            sizeof(struct pmclog_initialize));
        PMCLOG_EMIT32(PMC_VERSION);
        PMCLOG_EMIT32(md->pmd_cputype);
#if defined(__i386__) || defined(__amd64__)
        PMCLOG_EMIT64(tsc_freq);
#else
        /* other architectures will need to fill this in */
        PMCLOG_EMIT32(0);
        PMCLOG_EMIT32(0);
#endif
        memcpy(_le, &ts, sizeof(ts));
        _le += sizeof(ts)/4;
        PMCLOG_EMITSTRING(pmc_cpuid, PMC_CPUID_LEN);
        PMCLOG_DESPATCH_SYNC(po);

        return (0);

 error:
        KASSERT(po->po_kthread == NULL, ("[pmclog,%d] po=%p kthread not "
            "stopped", __LINE__, po));

        if (po->po_file)
                (void) fdrop(po->po_file, curthread);
        po->po_file  = NULL;    /* clear file and error state */
        po->po_error = 0;
        po->po_flags &= ~PMC_PO_OWNS_LOGFILE;

        return (error);
}


/*
 * De-configure a log file.  This will throw away any buffers queued
 * for this owner process.
 */

int
pmclog_deconfigure_log(struct pmc_owner *po)
{
        int error;
        struct pmclog_buffer *lb;
        struct pmc_binding pb;

        PMCDBG1(LOG,CFG,1, "de-config po=%p", po);

        if ((po->po_flags & PMC_PO_OWNS_LOGFILE) == 0)
                return (EINVAL);

        KASSERT(po->po_sscount == 0,
            ("[pmclog,%d] po=%p still owning SS PMCs", __LINE__, po));
        KASSERT(po->po_file != NULL,
            ("[pmclog,%d] po=%p no log file", __LINE__, po));

        /* stop the kthread, this will reset the 'OWNS_LOGFILE' flag */
        pmclog_stop_kthread(po);

        KASSERT(po->po_kthread == NULL,
            ("[pmclog,%d] po=%p kthread not stopped", __LINE__, po));

        /* return all queued log buffers to the global pool */
        while ((lb = TAILQ_FIRST(&po->po_logbuffers)) != NULL) {
                TAILQ_REMOVE(&po->po_logbuffers, lb, plb_next);
                PMCLOG_RESET_BUFFER_DESCRIPTOR(lb);
                pmc_plb_rele(lb);
        }
        pmc_save_cpu_binding(&pb);
        for (int i = 0; i < mp_ncpus; i++) {
                pmc_select_cpu(i);
                /* return the 'current' buffer to the global pool */
                if ((lb = po->po_curbuf[curcpu]) != NULL) {
                        PMCLOG_RESET_BUFFER_DESCRIPTOR(lb);
                        pmc_plb_rele(lb);
                }
        }
        pmc_restore_cpu_binding(&pb);

        /* drop a reference to the fd */
        if (po->po_file != NULL) {
                error = fdrop(po->po_file, curthread);
                po->po_file = NULL;
        } else
                error = 0;
        po->po_error = 0;

        return (error);
}

/*
 * Flush a process' log buffer.
 */

int
pmclog_flush(struct pmc_owner *po, int force)
{
        int error;

        PMCDBG1(LOG,FLS,1, "po=%p", po);

        /*
         * If there is a pending error recorded by the logger thread,
         * return that.
         */
        if (po->po_error)
                return (po->po_error);

        error = 0;

        /*
         * Check that we do have an active log file.
         */
        mtx_lock(&pmc_kthread_mtx);
        if ((po->po_flags & PMC_PO_OWNS_LOGFILE) == 0) {
                error = EINVAL;
                goto error;
        }

        pmclog_schedule_all(po);
 error:
        mtx_unlock(&pmc_kthread_mtx);

        return (error);
}

static void
pmclog_schedule_one_cond(struct pmc_owner *po)
{
        struct pmclog_buffer *plb;
        int cpu;

        spinlock_enter();
        cpu = curcpu;
        /* tell hardclock not to run again */
        if (PMC_CPU_HAS_SAMPLES(cpu))
                PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);

        plb = po->po_curbuf[cpu];
        if (plb && plb->plb_ptr != plb->plb_base)
                pmclog_schedule_io(po, 1);
        spinlock_exit();
}

static void
pmclog_schedule_all(struct pmc_owner *po)
{
        struct pmc_binding pb;

        /*
         * Schedule the current buffer if any and not empty.
         */
        pmc_save_cpu_binding(&pb);
        for (int i = 0; i < mp_ncpus; i++) {
                pmc_select_cpu(i);
                pmclog_schedule_one_cond(po);
        }
        pmc_restore_cpu_binding(&pb);
}

int
pmclog_close(struct pmc_owner *po)
{

        PMCDBG1(LOG,CLO,1, "po=%p", po);

        pmclog_process_closelog(po);

        mtx_lock(&pmc_kthread_mtx);
        /*
         * Initiate shutdown: no new data queued,
         * thread will close file on last block.
         */
        po->po_flags |= PMC_PO_SHUTDOWN;
        /* give time for all to see */
        DELAY(50);
        
        /*
         * Schedule the current buffer.
         */
        pmclog_schedule_all(po);
        wakeup_one(po);

        mtx_unlock(&pmc_kthread_mtx);

        return (0);
}

void
pmclog_process_callchain(struct pmc *pm, struct pmc_sample *ps)
{
        int n, recordlen;
        uint32_t flags;
        struct pmc_owner *po;

        PMCDBG3(LOG,SAM,1,"pm=%p pid=%d n=%d", pm, ps->ps_pid,
            ps->ps_nsamples);

        recordlen = offsetof(struct pmclog_callchain, pl_pc) +
            ps->ps_nsamples * sizeof(uintfptr_t);
        po = pm->pm_owner;
        flags = PMC_CALLCHAIN_TO_CPUFLAGS(ps->ps_cpu,ps->ps_flags);
        PMCLOG_RESERVE_SAFE(po, PMCLOG_TYPE_CALLCHAIN, recordlen, ps->ps_tsc);
        PMCLOG_EMIT32(ps->ps_pid);
        PMCLOG_EMIT32(ps->ps_tid);
        PMCLOG_EMIT32(pm->pm_id);
        PMCLOG_EMIT32(flags);
        for (n = 0; n < ps->ps_nsamples; n++)
                PMCLOG_EMITADDR(ps->ps_pc[n]);
        PMCLOG_DESPATCH_SAFE(po);
}

void
pmclog_process_closelog(struct pmc_owner *po)
{
        PMCLOG_RESERVE(po, PMCLOG_TYPE_CLOSELOG,
            sizeof(struct pmclog_closelog));
        PMCLOG_DESPATCH_SYNC(po);
}

void
pmclog_process_dropnotify(struct pmc_owner *po)
{
        PMCLOG_RESERVE(po, PMCLOG_TYPE_DROPNOTIFY,
            sizeof(struct pmclog_dropnotify));
        PMCLOG_DESPATCH(po);
}

void
pmclog_process_map_in(struct pmc_owner *po, pid_t pid, uintfptr_t start,
    const char *path)
{
        int pathlen, recordlen;

        KASSERT(path != NULL, ("[pmclog,%d] map-in, null path", __LINE__));

        pathlen = strlen(path) + 1;     /* #bytes for path name */
        recordlen = offsetof(struct pmclog_map_in, pl_pathname) +
            pathlen;

        PMCLOG_RESERVE(po, PMCLOG_TYPE_MAP_IN, recordlen);
        PMCLOG_EMIT32(pid);
        PMCLOG_EMIT32(0);
        PMCLOG_EMITADDR(start);
        PMCLOG_EMITSTRING(path,pathlen);
        PMCLOG_DESPATCH_SYNC(po);
}

void
pmclog_process_map_out(struct pmc_owner *po, pid_t pid, uintfptr_t start,
    uintfptr_t end)
{
        KASSERT(start <= end, ("[pmclog,%d] start > end", __LINE__));

        PMCLOG_RESERVE(po, PMCLOG_TYPE_MAP_OUT, sizeof(struct pmclog_map_out));
        PMCLOG_EMIT32(pid);
        PMCLOG_EMIT32(0);
        PMCLOG_EMITADDR(start);
        PMCLOG_EMITADDR(end);
        PMCLOG_DESPATCH(po);
}

void
pmclog_process_pmcallocate(struct pmc *pm)
{
        struct pmc_owner *po;
        struct pmc_soft *ps;

        po = pm->pm_owner;

        PMCDBG1(LOG,ALL,1, "pm=%p", pm);

        if (PMC_TO_CLASS(pm) == PMC_CLASS_SOFT) {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_PMCALLOCATEDYN,
                    sizeof(struct pmclog_pmcallocatedyn));
                PMCLOG_EMIT32(pm->pm_id);
                PMCLOG_EMIT32(pm->pm_event);
                PMCLOG_EMIT32(pm->pm_flags);
                PMCLOG_EMIT32(0);
                PMCLOG_EMIT64(pm->pm_sc.pm_reloadcount);
                ps = pmc_soft_ev_acquire(pm->pm_event);
                if (ps != NULL)
                        PMCLOG_EMITSTRING(ps->ps_ev.pm_ev_name,PMC_NAME_MAX);
                else
                        PMCLOG_EMITNULLSTRING(PMC_NAME_MAX);
                pmc_soft_ev_release(ps);
                PMCLOG_DESPATCH_SYNC(po);
        } else {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_PMCALLOCATE,
                    sizeof(struct pmclog_pmcallocate));
                PMCLOG_EMIT32(pm->pm_id);
                PMCLOG_EMIT32(pm->pm_event);
                PMCLOG_EMIT32(pm->pm_flags);
                PMCLOG_EMIT32(0);
                PMCLOG_EMIT64(pm->pm_sc.pm_reloadcount);
                PMCLOG_DESPATCH_SYNC(po);
        }
}

void
pmclog_process_pmcattach(struct pmc *pm, pid_t pid, char *path)
{
        int pathlen, recordlen;
        struct pmc_owner *po;

        PMCDBG2(LOG,ATT,1,"pm=%p pid=%d", pm, pid);

        po = pm->pm_owner;

        pathlen = strlen(path) + 1;     /* #bytes for the string */
        recordlen = offsetof(struct pmclog_pmcattach, pl_pathname) + pathlen;

        PMCLOG_RESERVE(po, PMCLOG_TYPE_PMCATTACH, recordlen);
        PMCLOG_EMIT32(pm->pm_id);
        PMCLOG_EMIT32(pid);
        PMCLOG_EMITSTRING(path, pathlen);
        PMCLOG_DESPATCH_SYNC(po);
}

void
pmclog_process_pmcdetach(struct pmc *pm, pid_t pid)
{
        struct pmc_owner *po;

        PMCDBG2(LOG,ATT,1,"!pm=%p pid=%d", pm, pid);

        po = pm->pm_owner;

        PMCLOG_RESERVE(po, PMCLOG_TYPE_PMCDETACH,
            sizeof(struct pmclog_pmcdetach));
        PMCLOG_EMIT32(pm->pm_id);
        PMCLOG_EMIT32(pid);
        PMCLOG_DESPATCH_SYNC(po);
}

void
pmclog_process_proccreate(struct pmc_owner *po, struct proc *p, int sync)
{
        if (sync) {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_PROC_CREATE,
                    sizeof(struct pmclog_proccreate));
                PMCLOG_EMIT32(p->p_pid);
                PMCLOG_EMIT32(p->p_flag);
                PMCLOG_EMITSTRING(p->p_comm, MAXCOMLEN+1);
                PMCLOG_DESPATCH_SYNC(po);
        } else {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_PROC_CREATE,
                    sizeof(struct pmclog_proccreate));
                PMCLOG_EMIT32(p->p_pid);
                PMCLOG_EMIT32(p->p_flag);
                PMCLOG_EMITSTRING(p->p_comm, MAXCOMLEN+1);
                PMCLOG_DESPATCH(po);
        }
}

/*
 * Log a context switch event to the log file.
 */

void
pmclog_process_proccsw(struct pmc *pm, struct pmc_process *pp, pmc_value_t v, struct thread *td)
{
        struct pmc_owner *po;

        KASSERT(pm->pm_flags & PMC_F_LOG_PROCCSW,
            ("[pmclog,%d] log-process-csw called gratuitously", __LINE__));

        PMCDBG3(LOG,SWO,1,"pm=%p pid=%d v=%jx", pm, pp->pp_proc->p_pid,
            v);

        po = pm->pm_owner;

        PMCLOG_RESERVE_SAFE(po, PMCLOG_TYPE_PROCCSW,
            sizeof(struct pmclog_proccsw), pmc_rdtsc());
        PMCLOG_EMIT64(v);
        PMCLOG_EMIT32(pm->pm_id);
        PMCLOG_EMIT32(pp->pp_proc->p_pid);
        PMCLOG_EMIT32(td->td_tid);
        PMCLOG_EMIT32(0);
        PMCLOG_DESPATCH_SCHED_LOCK(po);
}

void
pmclog_process_procexec(struct pmc_owner *po, pmc_id_t pmid, pid_t pid,
    uintptr_t baseaddr, uintptr_t dynaddr, char *path)
{
        int pathlen, recordlen;

        PMCDBG3(LOG,EXC,1,"po=%p pid=%d path=\"%s\"", po, pid, path);

        pathlen   = strlen(path) + 1;   /* #bytes for the path */
        recordlen = offsetof(struct pmclog_procexec, pl_pathname) + pathlen;
        PMCLOG_RESERVE(po, PMCLOG_TYPE_PROCEXEC, recordlen);
        PMCLOG_EMIT32(pid);
        PMCLOG_EMIT32(pmid);
        PMCLOG_EMITADDR(baseaddr);
        PMCLOG_EMITADDR(dynaddr);
        PMCLOG_EMITSTRING(path,pathlen);
        PMCLOG_DESPATCH_SYNC(po);
}

/*
 * Log a process exit event (and accumulated pmc value) to the log file.
 */

void
pmclog_process_procexit(struct pmc *pm, struct pmc_process *pp)
{
        int ri;
        struct pmc_owner *po;

        ri = PMC_TO_ROWINDEX(pm);
        PMCDBG3(LOG,EXT,1,"pm=%p pid=%d v=%jx", pm, pp->pp_proc->p_pid,
            pp->pp_pmcs[ri].pp_pmcval);

        po = pm->pm_owner;

        PMCLOG_RESERVE(po, PMCLOG_TYPE_PROCEXIT,
            sizeof(struct pmclog_procexit));
        PMCLOG_EMIT32(pm->pm_id);
        PMCLOG_EMIT32(pp->pp_proc->p_pid);
        PMCLOG_EMIT64(pp->pp_pmcs[ri].pp_pmcval);
        PMCLOG_DESPATCH(po);
}

/*
 * Log a fork event.
 */

void
pmclog_process_procfork(struct pmc_owner *po, pid_t oldpid, pid_t newpid)
{
        PMCLOG_RESERVE(po, PMCLOG_TYPE_PROCFORK,
            sizeof(struct pmclog_procfork));
        PMCLOG_EMIT32(oldpid);
        PMCLOG_EMIT32(newpid);
        PMCLOG_DESPATCH(po);
}

/*
 * Log a process exit event of the form suitable for system-wide PMCs.
 */

void
pmclog_process_sysexit(struct pmc_owner *po, pid_t pid)
{
        PMCLOG_RESERVE(po, PMCLOG_TYPE_SYSEXIT, sizeof(struct pmclog_sysexit));
        PMCLOG_EMIT32(pid);
        PMCLOG_DESPATCH(po);
}

void
pmclog_process_threadcreate(struct pmc_owner *po, struct thread *td, int sync)
{
        struct proc *p;

        p = td->td_proc;
        if (sync) {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_THR_CREATE,
                    sizeof(struct pmclog_threadcreate));
                PMCLOG_EMIT32(td->td_tid);
                PMCLOG_EMIT32(p->p_pid);
                PMCLOG_EMIT32(p->p_flag);
                PMCLOG_EMIT32(0);
                PMCLOG_EMITSTRING(td->td_name, MAXCOMLEN+1);
                PMCLOG_DESPATCH_SYNC(po);
        } else {
                PMCLOG_RESERVE(po, PMCLOG_TYPE_THR_CREATE,
                    sizeof(struct pmclog_threadcreate));
                PMCLOG_EMIT32(td->td_tid);
                PMCLOG_EMIT32(p->p_pid);
                PMCLOG_EMIT32(p->p_flag);
                PMCLOG_EMIT32(0);
                PMCLOG_EMITSTRING(td->td_name, MAXCOMLEN+1);
                PMCLOG_DESPATCH(po);
        }
}

void
pmclog_process_threadexit(struct pmc_owner *po, struct thread *td)
{

        PMCLOG_RESERVE(po, PMCLOG_TYPE_THR_EXIT,
            sizeof(struct pmclog_threadexit));
        PMCLOG_EMIT32(td->td_tid);
        PMCLOG_DESPATCH(po);
}

/*
 * Write a user log entry.
 */

int
pmclog_process_userlog(struct pmc_owner *po, struct pmc_op_writelog *wl)
{
        int error;

        PMCDBG2(LOG,WRI,1, "writelog po=%p ud=0x%x", po, wl->pm_userdata);

        error = 0;

        PMCLOG_RESERVE_WITH_ERROR(po, PMCLOG_TYPE_USERDATA,
            sizeof(struct pmclog_userdata));
        PMCLOG_EMIT32(wl->pm_userdata);
        PMCLOG_DESPATCH(po);

 error:
        return (error);
}

/*
 * Initialization.
 *
 * Create a pool of log buffers and initialize mutexes.
 */

void
pmclog_initialize(void)
{
        struct pmclog_buffer *plb;
        int domain, ncpus, total;

        if (pmclog_buffer_size <= 0 ||
            pmclog_buffer_size > PMC_LOG_BUFFER_SIZE_MAX) {
                log(LOG_WARNING,
                    "hwpmc: logbuffersize=%d must be greater than zero "
                    "and less than or equal to %d, resetting to %d\n",
                    pmclog_buffer_size, PMC_LOG_BUFFER_SIZE_MAX,
                    PMC_LOG_BUFFER_SIZE);

                pmclog_buffer_size = PMC_LOG_BUFFER_SIZE;
        }

        if (pmc_nlogbuffers_pcpu <= 0) {
                log(LOG_WARNING,
                    "hwpmc: nbuffers_pcpu=%d must be greater than zero, "
                    "resetting to %d\n",
                    pmc_nlogbuffers_pcpu, PMC_NLOGBUFFERS_PCPU);

                pmc_nlogbuffers_pcpu = PMC_NLOGBUFFERS_PCPU;
        }

        if (pmc_nlogbuffers_pcpu * pmclog_buffer_size >
            PMC_NLOGBUFFERS_PCPU_MEM_MAX) {
                log(LOG_WARNING,
                    "hwpmc: nbuffers_pcpu=%d * logbuffersize=%d exceeds "
                    "%dMB per CPU limit, resetting to defaults (%d * %d)\n",
                    pmc_nlogbuffers_pcpu, pmclog_buffer_size,
                    PMC_NLOGBUFFERS_PCPU_MEM_MAX / 1024,
                    PMC_NLOGBUFFERS_PCPU, PMC_LOG_BUFFER_SIZE);

                pmc_nlogbuffers_pcpu = PMC_NLOGBUFFERS_PCPU;
                pmclog_buffer_size = PMC_LOG_BUFFER_SIZE;
        }

        for (domain = 0; domain < vm_ndomains; domain++) {
                ncpus = pmc_dom_hdrs[domain]->pdbh_ncpus;
                total = ncpus * pmc_nlogbuffers_pcpu;

                plb = malloc_domainset(sizeof(struct pmclog_buffer) * total,
                    M_PMC, DOMAINSET_PREF(domain), M_WAITOK | M_ZERO);
                pmc_dom_hdrs[domain]->pdbh_plbs = plb;
                for (; total > 0; total--, plb++) {
                        void *buf;

                        buf = malloc_domainset(1024 * pmclog_buffer_size, M_PMC,
                            DOMAINSET_PREF(domain), M_WAITOK | M_ZERO);
                        PMCLOG_INIT_BUFFER_DESCRIPTOR(plb, buf, domain);
                        pmc_plb_rele_unlocked(plb);
                }
        }

        mtx_init(&pmc_kthread_mtx, "pmc-kthread", "pmc-sleep", MTX_DEF);
}

/*
 * Shutdown logging.
 *
 * Destroy mutexes and release memory back the to free pool.
 */

void
pmclog_shutdown(void)
{
        struct pmclog_buffer *plb;
        int domain;

        mtx_destroy(&pmc_kthread_mtx);

        for (domain = 0; domain < vm_ndomains; domain++) {
                while ((plb = TAILQ_FIRST(&pmc_dom_hdrs[domain]->pdbh_head)) != NULL) {
                        TAILQ_REMOVE(&pmc_dom_hdrs[domain]->pdbh_head, plb, plb_next);
                        free(plb->plb_base, M_PMC);
                }
                free(pmc_dom_hdrs[domain]->pdbh_plbs, M_PMC);
        }
}