kern_thr.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2003, Jeffrey Roberson <jeff@freebsd.org>
 * All rights reserved.
 *
 * 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 unmodified, 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 ``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 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.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include "opt_posix.h"
#include "opt_hwpmc_hooks.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/posix4.h>
#include <sys/ptrace.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/smp.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/ucontext.h>
#include <sys/thr.h>
#include <sys/rtprio.h>
#include <sys/umtxvar.h>
#include <sys/limits.h>
#ifdef  HWPMC_HOOKS
#include <sys/pmckern.h>
#endif
 
#include <machine/frame.h>
 
#include <security/audit/audit.h>
 
static SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "thread allocation");
 
int max_threads_per_proc = 1500;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_per_proc, CTLFLAG_RW,
    &max_threads_per_proc, 0, "Limit on threads per proc");
 
static int max_threads_hits;
SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
    &max_threads_hits, 0, "kern.threads.max_threads_per_proc hit count");
 
#ifdef COMPAT_FREEBSD32
 
static inline int
suword_lwpid(void *addr, lwpid_t lwpid)
{
        int error;
 
        if (SV_CURPROC_FLAG(SV_LP64))
                error = suword(addr, lwpid);
        else
                error = suword32(addr, lwpid);
        return (error);
}
 
#else
#define suword_lwpid    suword
#endif
 
/*
 * System call interface.
 */
 
struct thr_create_initthr_args {
        ucontext_t ctx;
        long *tid;
};
 
static int
thr_create_initthr(struct thread *td, void *thunk)
{
        struct thr_create_initthr_args *args;
 
        /* Copy out the child tid. */
        args = thunk;
        if (args->tid != NULL && suword_lwpid(args->tid, td->td_tid))
                return (EFAULT);
 
        return (set_mcontext(td, &args->ctx.uc_mcontext));
}
 
int
sys_thr_create(struct thread *td, struct thr_create_args *uap)
    /* ucontext_t *ctx, long *id, int flags */
{
        struct thr_create_initthr_args args;
        int error;
 
        if ((error = copyin(uap->ctx, &args.ctx, sizeof(args.ctx))))
                return (error);
        args.tid = uap->id;
        return (thread_create(td, NULL, thr_create_initthr, &args));
}
 
int
sys_thr_new(struct thread *td, struct thr_new_args *uap)
    /* struct thr_param * */
{
        struct thr_param param;
        int error;
 
        if (uap->param_size < 0 || uap->param_size > sizeof(param))
                return (EINVAL);
        bzero(&param, sizeof(param));
        if ((error = copyin(uap->param, &param, uap->param_size)))
                return (error);
        return (kern_thr_new(td, &param));
}
 
static int
thr_new_initthr(struct thread *td, void *thunk)
{
        stack_t stack;
        struct thr_param *param;
 
        /*
         * Here we copy out tid to two places, one for child and one
         * for parent, because pthread can create a detached thread,
         * if parent wants to safely access child tid, it has to provide
         * its storage, because child thread may exit quickly and
         * memory is freed before parent thread can access it.
         */
        param = thunk;
        if ((param->child_tid != NULL &&
            suword_lwpid(param->child_tid, td->td_tid)) ||
            (param->parent_tid != NULL &&
            suword_lwpid(param->parent_tid, td->td_tid)))
                return (EFAULT);
 
        /* Set up our machine context. */
        stack.ss_sp = param->stack_base;
        stack.ss_size = param->stack_size;
        /* Set upcall address to user thread entry function. */
        cpu_set_upcall(td, param->start_func, param->arg, &stack);
        /* Setup user TLS address and TLS pointer register. */
        return (cpu_set_user_tls(td, param->tls_base));
}
 
int
kern_thr_new(struct thread *td, struct thr_param *param)
{
        struct rtprio rtp, *rtpp;
        int error;
 
        rtpp = NULL;
        if (param->rtp != 0) {
                error = copyin(param->rtp, &rtp, sizeof(struct rtprio));
                if (error)
                        return (error);
                rtpp = &rtp;
        }
        return (thread_create(td, rtpp, thr_new_initthr, param));
}
 
int
thread_create(struct thread *td, struct rtprio *rtp,
    int (*initialize_thread)(struct thread *, void *), void *thunk)
{
        struct thread *newtd;
        struct proc *p;
        int error;
 
        p = td->td_proc;
 
        if (rtp != NULL) {
                switch(rtp->type) {
                case RTP_PRIO_REALTIME:
                case RTP_PRIO_FIFO:
                        /* Only root can set scheduler policy */
                        if (priv_check(td, PRIV_SCHED_SETPOLICY) != 0)
                                return (EPERM);
                        if (rtp->prio > RTP_PRIO_MAX)
                                return (EINVAL);
                        break;
                case RTP_PRIO_NORMAL:
                        rtp->prio = 0;
                        break;
                default:
                        return (EINVAL);
                }
        }
 
#ifdef RACCT
        if (racct_enable) {
                PROC_LOCK(p);
                error = racct_add(p, RACCT_NTHR, 1);
                PROC_UNLOCK(p);
                if (error != 0)
                        return (EPROCLIM);
        }
#endif
 
        /* Initialize our td */
        error = kern_thr_alloc(p, 0, &newtd);
        if (error)
                goto fail;
 
        cpu_copy_thread(newtd, td);
 
        bzero(&newtd->td_startzero,
            __rangeof(struct thread, td_startzero, td_endzero));
        bcopy(&td->td_startcopy, &newtd->td_startcopy,
            __rangeof(struct thread, td_startcopy, td_endcopy));
        newtd->td_proc = td->td_proc;
        newtd->td_rb_list = newtd->td_rbp_list = newtd->td_rb_inact = 0;
        thread_cow_get(newtd, td);
 
        error = initialize_thread(newtd, thunk);
        if (error != 0) {
                thread_cow_free(newtd);
                thread_free(newtd);
                goto fail;
        }
 
        PROC_LOCK(p);
        p->p_flag |= P_HADTHREADS;
        thread_link(newtd, p);
        bcopy(p->p_comm, newtd->td_name, sizeof(newtd->td_name));
        thread_lock(td);
        /* let the scheduler know about these things. */
        sched_fork_thread(td, newtd);
        thread_unlock(td);
        if (P_SHOULDSTOP(p))
                newtd->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
        if (p->p_ptevents & PTRACE_LWP)
                newtd->td_dbgflags |= TDB_BORN;
 
        PROC_UNLOCK(p);
#ifdef  HWPMC_HOOKS
        if (PMC_PROC_IS_USING_PMCS(p))
                PMC_CALL_HOOK(newtd, PMC_FN_THR_CREATE, NULL);
        else if (PMC_SYSTEM_SAMPLING_ACTIVE())
                PMC_CALL_HOOK_UNLOCKED(newtd, PMC_FN_THR_CREATE_LOG, NULL);
#endif
 
        tidhash_add(newtd);
 
        /* ignore timesharing class */
        if (rtp != NULL && !(td->td_pri_class == PRI_TIMESHARE &&
            rtp->type == RTP_PRIO_NORMAL))
                rtp_to_pri(rtp, newtd);
 
        thread_lock(newtd);
        TD_SET_CAN_RUN(newtd);
        sched_add(newtd, SRQ_BORING);
 
        return (0);
 
fail:
#ifdef RACCT
        if (racct_enable) {
                PROC_LOCK(p);
                racct_sub(p, RACCT_NTHR, 1);
                PROC_UNLOCK(p);
        }
#endif
        return (error);
}
 
int
sys_thr_self(struct thread *td, struct thr_self_args *uap)
    /* long *id */
{
        int error;
 
        error = suword_lwpid(uap->id, (unsigned)td->td_tid);
        if (error == -1)
                return (EFAULT);
        return (0);
}
 
int
sys_thr_exit(struct thread *td, struct thr_exit_args *uap)
    /* long *state */
{
 
        umtx_thread_exit(td);
 
        /* Signal userland that it can free the stack. */
        if ((void *)uap->state != NULL) {
                suword_lwpid(uap->state, 1);
                kern_umtx_wake(td, uap->state, INT_MAX, 0);
        }
 
        return (kern_thr_exit(td));
}
 
int
kern_thr_exit(struct thread *td)
{
        struct proc *p;
 
        p = td->td_proc;
 
        /*
         * If all of the threads in a process call this routine to
         * exit (e.g. all threads call pthread_exit()), exactly one
         * thread should return to the caller to terminate the process
         * instead of the thread.
         *
         * Checking p_numthreads alone is not sufficient since threads
         * might be committed to terminating while the PROC_LOCK is
         * dropped in either ptracestop() or while removing this thread
         * from the tidhash.  Instead, the p_pendingexits field holds
         * the count of threads in either of those states and a thread
         * is considered the "last" thread if all of the other threads
         * in a process are already terminating.
         */
        PROC_LOCK(p);
        if (p->p_numthreads == p->p_pendingexits + 1) {
                /*
                 * Ignore attempts to shut down last thread in the
                 * proc.  This will actually call _exit(2) in the
                 * usermode trampoline when it returns.
                 */
                PROC_UNLOCK(p);
                return (0);
        }
 
        if (p->p_sysent->sv_ontdexit != NULL)
                p->p_sysent->sv_ontdexit(td);
 
        td->td_dbgflags |= TDB_EXIT;
        if (p->p_ptevents & PTRACE_LWP) {
                p->p_pendingexits++;
                ptracestop(td, SIGTRAP, NULL);
                p->p_pendingexits--;
        }
        tidhash_remove(td);
 
        /*
         * The check above should prevent all other threads from this
         * process from exiting while the PROC_LOCK is dropped, so
         * there must be at least one other thread other than the
         * current thread.
         */
        KASSERT(p->p_numthreads > 1, ("too few threads"));
        racct_sub(p, RACCT_NTHR, 1);
        tdsigcleanup(td);
 
#ifdef AUDIT
        AUDIT_SYSCALL_EXIT(0, td);
#endif
 
        PROC_SLOCK(p);
        thread_stopped(p);
        thread_exit();
        /* NOTREACHED */
}
 
int
sys_thr_kill(struct thread *td, struct thr_kill_args *uap)
    /* long id, int sig */
{
        ksiginfo_t ksi;
        struct thread *ttd;
        struct proc *p;
        int error;
 
        p = td->td_proc;
        ksiginfo_init(&ksi);
        ksi.ksi_signo = uap->sig;
        ksi.ksi_code = SI_LWP;
        ksi.ksi_pid = p->p_pid;
        ksi.ksi_uid = td->td_ucred->cr_ruid;
        if (uap->id == -1) {
                if (uap->sig != 0 && !_SIG_VALID(uap->sig)) {
                        error = EINVAL;
                } else {
                        error = ESRCH;
                        PROC_LOCK(p);
                        FOREACH_THREAD_IN_PROC(p, ttd) {
                                if (ttd != td) {
                                        error = 0;
                                        if (uap->sig == 0)
                                                break;
                                        tdksignal(ttd, uap->sig, &ksi);
                                }
                        }
                        PROC_UNLOCK(p);
                }
        } else {
                error = 0;
                ttd = tdfind((lwpid_t)uap->id, p->p_pid);
                if (ttd == NULL)
                        return (ESRCH);
                if (uap->sig == 0)
                        ;
                else if (!_SIG_VALID(uap->sig))
                        error = EINVAL;
                else 
                        tdksignal(ttd, uap->sig, &ksi);
                PROC_UNLOCK(ttd->td_proc);
        }
        return (error);
}
 
int
sys_thr_kill2(struct thread *td, struct thr_kill2_args *uap)
    /* pid_t pid, long id, int sig */
{
        ksiginfo_t ksi;
        struct thread *ttd;
        struct proc *p;
        int error;
 
        AUDIT_ARG_SIGNUM(uap->sig);
 
        ksiginfo_init(&ksi);
        ksi.ksi_signo = uap->sig;
        ksi.ksi_code = SI_LWP;
        ksi.ksi_pid = td->td_proc->p_pid;
        ksi.ksi_uid = td->td_ucred->cr_ruid;
        if (uap->id == -1) {
                if ((p = pfind(uap->pid)) == NULL)
                        return (ESRCH);
                AUDIT_ARG_PROCESS(p);
                error = p_cansignal(td, p, uap->sig);
                if (error) {
                        PROC_UNLOCK(p);
                        return (error);
                }
                if (uap->sig != 0 && !_SIG_VALID(uap->sig)) {
                        error = EINVAL;
                } else {
                        error = ESRCH;
                        FOREACH_THREAD_IN_PROC(p, ttd) {
                                if (ttd != td) {
                                        error = 0;
                                        if (uap->sig == 0)
                                                break;
                                        tdksignal(ttd, uap->sig, &ksi);
                                }
                        }
                }
                PROC_UNLOCK(p);
        } else {
                ttd = tdfind((lwpid_t)uap->id, uap->pid);
                if (ttd == NULL)
                        return (ESRCH);
                p = ttd->td_proc;
                AUDIT_ARG_PROCESS(p);
                error = p_cansignal(td, p, uap->sig);
                if (uap->sig == 0)
                        ;
                else if (!_SIG_VALID(uap->sig))
                        error = EINVAL;
                else
                        tdksignal(ttd, uap->sig, &ksi);
                PROC_UNLOCK(p);
        }
        return (error);
}
 
int
sys_thr_suspend(struct thread *td, struct thr_suspend_args *uap)
        /* const struct timespec *timeout */
{
        struct timespec ts, *tsp;
        int error;
 
        tsp = NULL;
        if (uap->timeout != NULL) {
                error = umtx_copyin_timeout(uap->timeout, &ts);
                if (error != 0)
                        return (error);
                tsp = &ts;
        }
 
        return (kern_thr_suspend(td, tsp));
}
 
int
kern_thr_suspend(struct thread *td, struct timespec *tsp)
{
        struct proc *p = td->td_proc;
        struct timeval tv;
        int error = 0;
        int timo = 0;
 
        if (td->td_pflags & TDP_WAKEUP) {
                td->td_pflags &= ~TDP_WAKEUP;
                return (0);
        }
 
        if (tsp != NULL) {
                if (tsp->tv_sec == 0 && tsp->tv_nsec == 0)
                        error = EWOULDBLOCK;
                else {
                        TIMESPEC_TO_TIMEVAL(&tv, tsp);
                        timo = tvtohz(&tv);
                }
        }
 
        PROC_LOCK(p);
        if (error == 0 && (td->td_flags & TDF_THRWAKEUP) == 0)
                error = msleep((void *)td, &p->p_mtx,
                         PCATCH, "lthr", timo);
 
        if (td->td_flags & TDF_THRWAKEUP) {
                thread_lock(td);
                td->td_flags &= ~TDF_THRWAKEUP;
                thread_unlock(td);
                PROC_UNLOCK(p);
                return (0);
        }
        PROC_UNLOCK(p);
        if (error == EWOULDBLOCK)
                error = ETIMEDOUT;
        else if (error == ERESTART) {
                if (timo != 0)
                        error = EINTR;
        }
        return (error);
}
 
int
sys_thr_wake(struct thread *td, struct thr_wake_args *uap)
        /* long id */
{
        struct proc *p;
        struct thread *ttd;
 
        if (uap->id == td->td_tid) {
                td->td_pflags |= TDP_WAKEUP;
                return (0);
        } 
 
        p = td->td_proc;
        ttd = tdfind((lwpid_t)uap->id, p->p_pid);
        if (ttd == NULL)
                return (ESRCH);
        thread_lock(ttd);
        ttd->td_flags |= TDF_THRWAKEUP;
        thread_unlock(ttd);
        wakeup((void *)ttd);
        PROC_UNLOCK(p);
        return (0);
}
 
int
sys_thr_set_name(struct thread *td, struct thr_set_name_args *uap)
{
        struct proc *p;
        char name[MAXCOMLEN + 1];
        struct thread *ttd;
        int error;
 
        error = 0;
        name[0] = '\0';
        if (uap->name != NULL) {
                error = copyinstr(uap->name, name, sizeof(name), NULL);
                if (error == ENAMETOOLONG) {
                        error = copyin(uap->name, name, sizeof(name) - 1);
                        name[sizeof(name) - 1] = '\0';
                }
                if (error)
                        return (error);
        }
        p = td->td_proc;
        ttd = tdfind((lwpid_t)uap->id, p->p_pid);
        if (ttd == NULL)
                return (ESRCH);
        strcpy(ttd->td_name, name);
#ifdef HWPMC_HOOKS
        if (PMC_PROC_IS_USING_PMCS(p) || PMC_SYSTEM_SAMPLING_ACTIVE())
                PMC_CALL_HOOK_UNLOCKED(ttd, PMC_FN_THR_CREATE_LOG, NULL);
#endif
#ifdef KTR
        sched_clear_tdname(ttd);
#endif
        PROC_UNLOCK(p);
        return (error);
}
 
int
kern_thr_alloc(struct proc *p, int pages, struct thread **ntd)
{
 
        /* Have race condition but it is cheap. */
        if (p->p_numthreads >= max_threads_per_proc) {
                ++max_threads_hits;
                return (EPROCLIM);
        }
 
        *ntd = thread_alloc(pages);
        if (*ntd == NULL)
                return (ENOMEM);
 
        return (0);
}