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freebsd/sys/kern/kern_thr.c
Konstantin Belousov 74d5b4af82 Clean up confusing comment. Move it to the place of code which is
talked about.  Explain where the mentioned trampoline located
(usermode), and the fact that attempt to exit last thread is denied in
kernel (by delegating the work to usermode).

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2014-11-03 11:29:08 +00:00

558 lines
12 KiB
C

/*-
* 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_compat.h"
#include "opt_posix.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/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/umtx.h>
#include <sys/limits.h>
#include <machine/frame.h>
#include <security/audit/audit.h>
static SYSCTL_NODE(_kern, OID_AUTO, threads, CTLFLAG_RW, 0,
"thread allocation");
static 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
static int create_thread(struct thread *td, mcontext_t *ctx,
void (*start_func)(void *), void *arg,
char *stack_base, size_t stack_size,
char *tls_base,
long *child_tid, long *parent_tid,
int flags, struct rtprio *rtp);
/*
* System call interface.
*/
int
sys_thr_create(struct thread *td, struct thr_create_args *uap)
/* ucontext_t *ctx, long *id, int flags */
{
ucontext_t ctx;
int error;
if ((error = copyin(uap->ctx, &ctx, sizeof(ctx))))
return (error);
error = create_thread(td, &ctx.uc_mcontext, NULL, NULL,
NULL, 0, NULL, uap->id, NULL, uap->flags, NULL);
return (error);
}
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));
}
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;
}
error = create_thread(td, NULL, param->start_func, param->arg,
param->stack_base, param->stack_size, param->tls_base,
param->child_tid, param->parent_tid, param->flags,
rtpp);
return (error);
}
static int
create_thread(struct thread *td, mcontext_t *ctx,
void (*start_func)(void *), void *arg,
char *stack_base, size_t stack_size,
char *tls_base,
long *child_tid, long *parent_tid,
int flags, struct rtprio *rtp)
{
stack_t stack;
struct thread *newtd;
struct proc *p;
int error;
p = td->td_proc;
/* Have race condition but it is cheap. */
if (p->p_numthreads >= max_threads_per_proc) {
++max_threads_hits;
return (EPROCLIM);
}
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
PROC_LOCK(td->td_proc);
error = racct_add(p, RACCT_NTHR, 1);
PROC_UNLOCK(td->td_proc);
if (error != 0)
return (EPROCLIM);
#endif
/* Initialize our td */
newtd = thread_alloc(0);
if (newtd == NULL) {
error = ENOMEM;
goto fail;
}
cpu_set_upcall(newtd, td);
/*
* Try the copyout as soon as we allocate the td so we don't
* have to tear things down in a failure case below.
* 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.
*/
if ((child_tid != NULL &&
suword_lwpid(child_tid, newtd->td_tid)) ||
(parent_tid != NULL &&
suword_lwpid(parent_tid, newtd->td_tid))) {
thread_free(newtd);
error = EFAULT;
goto fail;
}
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_ucred = crhold(td->td_ucred);
if (ctx != NULL) { /* old way to set user context */
error = set_mcontext(newtd, ctx);
if (error != 0) {
thread_free(newtd);
crfree(td->td_ucred);
goto fail;
}
} else {
/* Set up our machine context. */
stack.ss_sp = stack_base;
stack.ss_size = stack_size;
/* Set upcall address to user thread entry function. */
cpu_set_upcall_kse(newtd, start_func, arg, &stack);
/* Setup user TLS address and TLS pointer register. */
error = cpu_set_user_tls(newtd, tls_base);
if (error != 0) {
thread_free(newtd);
crfree(td->td_ucred);
goto fail;
}
}
PROC_LOCK(td->td_proc);
td->td_proc->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;
PROC_UNLOCK(p);
tidhash_add(newtd);
thread_lock(newtd);
if (rtp != NULL) {
if (!(td->td_pri_class == PRI_TIMESHARE &&
rtp->type == RTP_PRIO_NORMAL)) {
rtp_to_pri(rtp, newtd);
sched_prio(newtd, newtd->td_user_pri);
} /* ignore timesharing class */
}
TD_SET_CAN_RUN(newtd);
sched_add(newtd, SRQ_BORING);
thread_unlock(newtd);
return (0);
fail:
#ifdef RACCT
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 */
{
struct proc *p;
p = td->td_proc;
/* 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);
}
rw_wlock(&tidhash_lock);
PROC_LOCK(p);
if (p->p_numthreads != 1) {
racct_sub(p, RACCT_NTHR, 1);
LIST_REMOVE(td, td_hash);
rw_wunlock(&tidhash_lock);
tdsigcleanup(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();
/* NOTREACHED */
}
/*
* 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);
rw_wunlock(&tidhash_lock);
return (0);
}
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)
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 KTR
sched_clear_tdname(ttd);
#endif
PROC_UNLOCK(p);
return (error);
}