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/* $NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $ */
/*-
* Copyright (c) 2005 Emmanuel Dreyfus, 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, 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Emmanuel Dreyfus
* 4. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/sys/compat/linux/linux_futex.c 219460 2011-03-10 19:50:12Z jhb $");
#if 0
__KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $");
#endif
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/imgact.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/umtx.h>
#ifdef COMPAT_LINUX32
#include <machine/../linux32/linux.h>
#include <machine/../linux32/linux32_proto.h>
#else
#include <machine/../linux/linux.h>
#include <machine/../linux/linux_proto.h>
#endif
#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_futex.h>
#include <compat/linux/linux_util.h>
MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes");
MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp");
struct futex;
struct waiting_proc {
uint32_t wp_flags;
struct futex *wp_futex;
TAILQ_ENTRY(waiting_proc) wp_list;
};
struct futex {
struct sx f_lck;
uint32_t *f_uaddr; /* user-supplied value, for debug */
struct umtx_key f_key;
uint32_t f_refcount;
uint32_t f_bitset;
LIST_ENTRY(futex) f_list;
TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
};
struct futex_list futex_list;
#define FUTEX_LOCK(f) sx_xlock(&(f)->f_lck)
#define FUTEX_UNLOCK(f) sx_xunlock(&(f)->f_lck)
#define FUTEX_INIT(f) sx_init_flags(&(f)->f_lck, "ftlk", SX_DUPOK)
#define FUTEX_DESTROY(f) sx_destroy(&(f)->f_lck)
#define FUTEX_ASSERT_LOCKED(f) sx_assert(&(f)->f_lck, SA_XLOCKED)
struct mtx futex_mtx; /* protects the futex list */
#define FUTEXES_LOCK mtx_lock(&futex_mtx)
#define FUTEXES_UNLOCK mtx_unlock(&futex_mtx)
/* flags for futex_get() */
#define FUTEX_CREATE_WP 0x1 /* create waiting_proc */
#define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */
#define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */
#define FUTEX_SHARED 0x8 /* shared futex */
/* wp_flags */
#define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list
* of futex where thread sleep to wp_list
* of another futex.
*/
#define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex
* wp_list to prevent double wakeup.
*/
/* support.s */
int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
static void
futex_put(struct futex *f, struct waiting_proc *wp)
{
FUTEX_ASSERT_LOCKED(f);
if (wp != NULL) {
if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
free(wp, M_FUTEX_WP);
}
FUTEXES_LOCK;
if (--f->f_refcount == 0) {
LIST_REMOVE(f, f_list);
FUTEXES_UNLOCK;
FUTEX_UNLOCK(f);
LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
"shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
umtx_key_release(&f->f_key);
FUTEX_DESTROY(f);
free(f, M_FUTEX);
return;
}
LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
f->f_uaddr, f->f_refcount, f->f_key.shared);
FUTEXES_UNLOCK;
FUTEX_UNLOCK(f);
}
static int
futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
{
struct futex *f, *tmpf;
struct umtx_key key;
int error;
*newf = tmpf = NULL;
error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
AUTO_SHARE : THREAD_SHARE, &key);
if (error)
return (error);
retry:
FUTEXES_LOCK;
LIST_FOREACH(f, &futex_list, f_list) {
if (umtx_key_match(&f->f_key, &key)) {
if (tmpf != NULL) {
FUTEX_UNLOCK(tmpf);
FUTEX_DESTROY(tmpf);
free(tmpf, M_FUTEX);
}
if (flags & FUTEX_DONTEXISTS) {
FUTEXES_UNLOCK;
umtx_key_release(&key);
return (EINVAL);
}
/*
* Increment refcount of the found futex to
* prevent it from deallocation before FUTEX_LOCK()
*/
++f->f_refcount;
FUTEXES_UNLOCK;
umtx_key_release(&key);
FUTEX_LOCK(f);
*newf = f;
LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
uaddr, f->f_refcount, f->f_key.shared);
return (0);
}
}
if (flags & FUTEX_DONTCREATE) {
FUTEXES_UNLOCK;
umtx_key_release(&key);
LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
return (0);
}
if (tmpf == NULL) {
FUTEXES_UNLOCK;
tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
tmpf->f_uaddr = uaddr;
tmpf->f_key = key;
tmpf->f_refcount = 1;
tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
FUTEX_INIT(tmpf);
TAILQ_INIT(&tmpf->f_waiting_proc);
/*
* Lock the new futex before an insert into the futex_list
* to prevent futex usage by other.
*/
FUTEX_LOCK(tmpf);
goto retry;
}
LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
FUTEXES_UNLOCK;
LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
uaddr, tmpf->f_refcount, tmpf->f_key.shared);
*newf = tmpf;
return (0);
}
static int
futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
uint32_t flags)
{
int error;
if (flags & FUTEX_CREATE_WP) {
*wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
(*wp)->wp_flags = 0;
}
error = futex_get0(uaddr, f, flags);
if (error) {
if (flags & FUTEX_CREATE_WP)
free(*wp, M_FUTEX_WP);
return (error);
}
if (flags & FUTEX_CREATE_WP) {
TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
(*wp)->wp_futex = *f;
}
return (error);
}
static int
futex_sleep(struct futex *f, struct waiting_proc *wp, int timeout)
{
int error;
FUTEX_ASSERT_LOCKED(f);
LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d ref %d",
f->f_uaddr, wp, timeout, f->f_refcount);
error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
if (wp->wp_flags & FUTEX_WP_REQUEUED) {
KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w"
" %p requeued uaddr %p ref %d",
error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
wp->wp_futex->f_refcount);
futex_put(f, NULL);
f = wp->wp_futex;
FUTEX_LOCK(f);
} else
LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
error, f->f_uaddr, wp);
futex_put(f, wp);
return (error);
}
static int
futex_wake(struct futex *f, int n, uint32_t bitset)
{
struct waiting_proc *wp, *wpt;
int count = 0;
if (bitset == 0)
return (EINVAL);
FUTEX_ASSERT_LOCKED(f);
TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
f->f_uaddr, wp, f->f_refcount);
/*
* Unless we find a matching bit in
* the bitset, continue searching.
*/
if (!(wp->wp_futex->f_bitset & bitset))
continue;
wp->wp_flags |= FUTEX_WP_REMOVED;
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
wakeup_one(wp);
if (++count == n)
break;
}
return (count);
}
static int
futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
{
struct waiting_proc *wp, *wpt;
int count = 0;
FUTEX_ASSERT_LOCKED(f);
FUTEX_ASSERT_LOCKED(f2);
TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
if (++count <= n) {
LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
f->f_uaddr, wp);
wp->wp_flags |= FUTEX_WP_REMOVED;
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
wakeup_one(wp);
} else {
LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
f->f_uaddr, wp, f2->f_uaddr);
wp->wp_flags |= FUTEX_WP_REQUEUED;
/* Move wp to wp_list of f2 futex */
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
/*
* Thread which sleeps on wp after waking should
* acquire f2 lock, so increment refcount of f2 to
* prevent it from premature deallocation.
*/
wp->wp_futex = f2;
FUTEXES_LOCK;
++f2->f_refcount;
FUTEXES_UNLOCK;
if (count - n >= n2)
break;
}
}
return (count);
}
static int
futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts,
uint32_t bitset)
{
struct l_timespec timeout;
struct timeval tv;
int timeout_hz;
int error;
if (bitset == 0)
return (EINVAL);
f->f_bitset = bitset;
if (ts != NULL) {
error = copyin(ts, &timeout, sizeof(timeout));
if (error)
return (error);
TIMESPEC_TO_TIMEVAL(&tv, &timeout);
error = itimerfix(&tv);
if (error)
return (error);
timeout_hz = tvtohz(&tv);
} else
timeout_hz = 0;
error = futex_sleep(f, wp, timeout_hz);
if (error == EWOULDBLOCK)
error = ETIMEDOUT;
return (error);
}
static int
futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
{
int op = (encoded_op >> 28) & 7;
int cmp = (encoded_op >> 24) & 15;
int oparg = (encoded_op << 8) >> 20;
int cmparg = (encoded_op << 20) >> 20;
int oldval = 0, ret;
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
oparg = 1 << oparg;
#ifdef DEBUG
if (ldebug(sys_futex))
printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
"cmparg = %x, uaddr = %p\n",
op, cmp, oparg, cmparg, uaddr);
#endif
/* XXX: Linux verifies access here and returns EFAULT */
switch (op) {
case FUTEX_OP_SET:
ret = futex_xchgl(oparg, uaddr, &oldval);
break;
case FUTEX_OP_ADD:
ret = futex_addl(oparg, uaddr, &oldval);
break;
case FUTEX_OP_OR:
ret = futex_orl(oparg, uaddr, &oldval);
break;
case FUTEX_OP_ANDN:
ret = futex_andl(~oparg, uaddr, &oldval);
break;
case FUTEX_OP_XOR:
ret = futex_xorl(oparg, uaddr, &oldval);
break;
default:
ret = -ENOSYS;
break;
}
if (ret)
return (ret);
switch (cmp) {
case FUTEX_OP_CMP_EQ:
return (oldval == cmparg);
case FUTEX_OP_CMP_NE:
return (oldval != cmparg);
case FUTEX_OP_CMP_LT:
return (oldval < cmparg);
case FUTEX_OP_CMP_GE:
return (oldval >= cmparg);
case FUTEX_OP_CMP_LE:
return (oldval <= cmparg);
case FUTEX_OP_CMP_GT:
return (oldval > cmparg);
default:
return (-ENOSYS);
}
}
int
linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
{
int clockrt, nrwake, op_ret, ret, val;
struct linux_emuldata *em;
struct waiting_proc *wp;
struct futex *f, *f2;
int error;
uint32_t flags;
if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
flags = 0;
args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
} else
flags = FUTEX_SHARED;
/*
* Currently support for switching between CLOCK_MONOTONIC and
* CLOCK_REALTIME is not present. However Linux forbids the use of
* FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
* FUTEX_WAIT_REQUEUE_PI.
*/
clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
args->op != LINUX_FUTEX_WAIT_REQUEUE_PI)
return (ENOSYS);
error = 0;
f = f2 = NULL;
switch (args->op) {
case LINUX_FUTEX_WAIT:
args->val3 = FUTEX_BITSET_MATCH_ANY;
/* FALLTHROUGH */
case LINUX_FUTEX_WAIT_BITSET:
LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d val3 %d",
args->uaddr, args->val, args->val3);
#ifdef DEBUG
if (ldebug(sys_futex))
printf(ARGS(sys_futex,
"futex_wait uaddr %p val %d val3 %d"),
args->uaddr, args->val, args->val3);
#endif
error = futex_get(args->uaddr, &wp, &f,
flags | FUTEX_CREATE_WP);
if (error)
return (error);
error = copyin(args->uaddr, &val, sizeof(val));
if (error) {
LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
error);
futex_put(f, wp);
return (error);
}
if (val != args->val) {
LINUX_CTR4(sys_futex,
"WAIT uaddr %p val %d != uval %d val3 %d",
args->uaddr, args->val, val, args->val3);
futex_put(f, wp);
return (EWOULDBLOCK);
}
error = futex_wait(f, wp, args->timeout, args->val3);
break;
case LINUX_FUTEX_WAKE:
args->val3 = FUTEX_BITSET_MATCH_ANY;
/* FALLTHROUGH */
case LINUX_FUTEX_WAKE_BITSET:
LINUX_CTR3(sys_futex, "WAKE uaddr %p val % d val3 %d",
args->uaddr, args->val, args->val3);
#ifdef DEBUG
if (ldebug(sys_futex))
printf(ARGS(sys_futex, "futex_wake uaddr %p val %d val3 %d"),
args->uaddr, args->val, args->val3);
#endif
error = futex_get(args->uaddr, NULL, &f,
flags | FUTEX_DONTCREATE);
if (error)
return (error);
if (f == NULL) {
td->td_retval[0] = 0;
return (error);
}
td->td_retval[0] = futex_wake(f, args->val, args->val3);
futex_put(f, NULL);
break;
case LINUX_FUTEX_CMP_REQUEUE:
LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
"val %d val3 %d uaddr2 %p val2 %d",
args->uaddr, args->val, args->val3, args->uaddr2,
(int)(unsigned long)args->timeout);
#ifdef DEBUG
if (ldebug(sys_futex))
printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
"val %d val3 %d uaddr2 %p val2 %d"),
args->uaddr, args->val, args->val3, args->uaddr2,
(int)(unsigned long)args->timeout);
#endif
/*
* Linux allows this, we would not, it is an incorrect
* usage of declared ABI, so return EINVAL.
*/
if (args->uaddr == args->uaddr2)
return (EINVAL);
error = futex_get(args->uaddr, NULL, &f, flags);
if (error)
return (error);
/*
* To avoid deadlocks return EINVAL if second futex
* exists at this time.
*
* Glibc fall back to FUTEX_WAKE in case of any error
* returned by FUTEX_CMP_REQUEUE.
*/
error = futex_get(args->uaddr2, NULL, &f2,
flags | FUTEX_DONTEXISTS);
if (error) {
futex_put(f, NULL);
return (error);
}
error = copyin(args->uaddr, &val, sizeof(val));
if (error) {
LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
error);
futex_put(f2, NULL);
futex_put(f, NULL);
return (error);
}
if (val != args->val3) {
LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
args->val, val);
futex_put(f2, NULL);
futex_put(f, NULL);
return (EAGAIN);
}
nrwake = (int)(unsigned long)args->timeout;
td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
futex_put(f2, NULL);
futex_put(f, NULL);
break;
case LINUX_FUTEX_WAKE_OP:
LINUX_CTR5(sys_futex, "WAKE_OP "
"uaddr %p op %d val %x uaddr2 %p val3 %x",
args->uaddr, args->op, args->val,
args->uaddr2, args->val3);
#ifdef DEBUG
if (ldebug(sys_futex))
printf(ARGS(sys_futex, "futex_wake_op "
"uaddr %p op %d val %x uaddr2 %p val3 %x"),
args->uaddr, args->op, args->val,
args->uaddr2, args->val3);
#endif
error = futex_get(args->uaddr, NULL, &f, flags);
if (error)
return (error);
if (args->uaddr != args->uaddr2)
error = futex_get(args->uaddr2, NULL, &f2, flags);
if (error) {
futex_put(f, NULL);
return (error);
}
/*
* This function returns positive number as results and
* negative as errors
*/
op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
if (op_ret < 0) {
/* XXX: We don't handle the EFAULT yet. */
if (op_ret != -EFAULT) {
if (f2 != NULL)
futex_put(f2, NULL);
futex_put(f, NULL);
return (-op_ret);
}
if (f2 != NULL)
futex_put(f2, NULL);
futex_put(f, NULL);
return (EFAULT);
}
ret = futex_wake(f, args->val, args->val3);
if (op_ret > 0) {
op_ret = 0;
nrwake = (int)(unsigned long)args->timeout;
if (f2 != NULL)
op_ret += futex_wake(f2, nrwake, args->val3);
else
op_ret += futex_wake(f, nrwake, args->val3);
ret += op_ret;
}
if (f2 != NULL)
futex_put(f2, NULL);
futex_put(f, NULL);
td->td_retval[0] = ret;
break;
case LINUX_FUTEX_LOCK_PI:
/* not yet implemented */
linux_msg(td,
"linux_sys_futex: "
"op LINUX_FUTEX_LOCK_PI not implemented\n");
return (ENOSYS);
case LINUX_FUTEX_UNLOCK_PI:
/* not yet implemented */
linux_msg(td,
"linux_sys_futex: "
"op LINUX_FUTEX_UNLOCK_PI not implemented\n");
return (ENOSYS);
case LINUX_FUTEX_TRYLOCK_PI:
/* not yet implemented */
linux_msg(td,
"linux_sys_futex: "
"op LINUX_FUTEX_TRYLOCK_PI not implemented\n");
return (ENOSYS);
case LINUX_FUTEX_REQUEUE:
/*
* Glibc does not use this operation since version 2.3.3,
* as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
* Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
* FUTEX_REQUEUE returned EINVAL.
*/
em = em_find(td->td_proc, EMUL_DONTLOCK);
if ((em->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
linux_msg(td,
"linux_sys_futex: "
"unsupported futex_requeue op\n");
em->flags |= LINUX_XDEPR_REQUEUEOP;
}
return (EINVAL);
case LINUX_FUTEX_WAIT_REQUEUE_PI:
/* not yet implemented */
linux_msg(td,
"linux_sys_futex: "
"op FUTEX_WAIT_REQUEUE_PI not implemented\n");
return (ENOSYS);
case LINUX_FUTEX_CMP_REQUEUE_PI:
/* not yet implemented */
linux_msg(td,
"linux_sys_futex: "
"op LINUX_FUTEX_CMP_REQUEUE_PI not implemented\n");
return (ENOSYS);
default:
linux_msg(td,
"linux_sys_futex: unknown op %d\n", args->op);
return (ENOSYS);
}
return (error);
}
int
linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
{
struct linux_emuldata *em;
#ifdef DEBUG
if (ldebug(set_robust_list))
printf(ARGS(set_robust_list, "head %p len %d"),
args->head, args->len);
#endif
if (args->len != sizeof(struct linux_robust_list_head))
return (EINVAL);
em = em_find(td->td_proc, EMUL_DOLOCK);
em->robust_futexes = args->head;
EMUL_UNLOCK(&emul_lock);
return (0);
}
int
linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
{
struct linux_emuldata *em;
struct linux_robust_list_head *head;
l_size_t len = sizeof(struct linux_robust_list_head);
int error = 0;
#ifdef DEBUG
if (ldebug(get_robust_list))
printf(ARGS(get_robust_list, ""));
#endif
if (!args->pid) {
em = em_find(td->td_proc, EMUL_DONTLOCK);
head = em->robust_futexes;
} else {
struct proc *p;
p = pfind(args->pid);
if (p == NULL)
return (ESRCH);
em = em_find(p, EMUL_DONTLOCK);
/* XXX: ptrace? */
if (priv_check(td, PRIV_CRED_SETUID) ||
priv_check(td, PRIV_CRED_SETEUID) ||
p_candebug(td, p)) {
PROC_UNLOCK(p);
return (EPERM);
}
head = em->robust_futexes;
PROC_UNLOCK(p);
}
error = copyout(&len, args->len, sizeof(l_size_t));
if (error)
return (EFAULT);
error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
return (error);
}
static int
handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
{
uint32_t uval, nval, mval;
struct futex *f;
int error;
retry:
if (copyin(uaddr, &uval, 4))
return (EFAULT);
if ((uval & FUTEX_TID_MASK) == p->p_pid) {
mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
nval = casuword32(uaddr, uval, mval);
if (nval == -1)
return (EFAULT);
if (nval != uval)
goto retry;
if (!pi && (uval & FUTEX_WAITERS)) {
error = futex_get(uaddr, NULL, &f,
FUTEX_DONTCREATE | FUTEX_SHARED);
if (error)
return (error);
if (f != NULL) {
futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
futex_put(f, NULL);
}
}
}
return (0);
}
static int
fetch_robust_entry(struct linux_robust_list **entry,
struct linux_robust_list **head, int *pi)
{
l_ulong uentry;
if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
return (EFAULT);
*entry = (void *)(uentry & ~1UL);
*pi = uentry & 1;
return (0);
}
/* This walks the list of robust futexes releasing them. */
void
release_futexes(struct proc *p)
{
struct linux_robust_list_head *head = NULL;
struct linux_robust_list *entry, *next_entry, *pending;
unsigned int limit = 2048, pi, next_pi, pip;
struct linux_emuldata *em;
l_long futex_offset;
int rc;
em = em_find(p, EMUL_DONTLOCK);
head = em->robust_futexes;
if (head == NULL)
return;
if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
return;
if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
return;
if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
return;
while (entry != &head->list) {
rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
if (entry != pending)
if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
return;
if (rc)
return;
entry = next_entry;
pi = next_pi;
if (!--limit)
break;
sched_relinquish(curthread);
}
if (pending)
handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
}