freebsd-nq/sys/compat/linux/linux_futex.c

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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("$FreeBSD$");
#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/types.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/imgact.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/sched.h>
#include <sys/sx.h>
#include <sys/malloc.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>
struct futex;
struct waiting_proc {
struct thread *wp_t;
struct futex *wp_new_futex;
TAILQ_ENTRY(waiting_proc) wp_list;
};
struct futex {
void *f_uaddr;
int f_refcount;
LIST_ENTRY(futex) f_list;
TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
};
LIST_HEAD(futex_list, futex) futex_list;
struct sx futex_sx; /* this protects the LIST of futexes */
#define FUTEX_LOCK sx_xlock(&futex_sx)
#define FUTEX_UNLOCK sx_xunlock(&futex_sx)
#define FUTEX_LOCKED 1
#define FUTEX_UNLOCKED 0
#define FUTEX_SYSTEM_LOCK mtx_lock(&Giant)
#define FUTEX_SYSTEM_UNLOCK mtx_unlock(&Giant)
static struct futex *futex_get(void *, int);
static void futex_put(struct futex *);
static int futex_sleep(struct futex *, struct thread *, unsigned long);
static int futex_wake(struct futex *, int, struct futex *, int);
static int futex_atomic_op(struct thread *td, int encoded_op, caddr_t uaddr);
/* support.s */
int futex_xchgl(int oparg, caddr_t uaddr, int *oldval);
int futex_addl(int oparg, caddr_t uaddr, int *oldval);
int futex_orl(int oparg, caddr_t uaddr, int *oldval);
int futex_andl(int oparg, caddr_t uaddr, int *oldval);
int futex_xorl(int oparg, caddr_t uaddr, int *oldval);
int
linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
{
int val;
int ret;
struct l_timespec timeout = {0, 0};
int error = 0;
struct futex *f;
struct futex *newf;
int timeout_hz;
struct timeval tv = {0, 0};
struct futex *f2;
int op_ret;
#ifdef DEBUG
if (ldebug(sys_futex))
printf(ARGS(futex, "%p, %i, %i, *, %p, %i"), args->uaddr, args->op,
args->val, args->uaddr2, args->val3);
#endif
/*
* Our implementation provides only privates futexes. Most of the apps
* should use private futexes but don't claim so. Therefore we treat
* all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works
* in most cases (ie. when futexes are not shared on file descriptor
* or between different processes.).
*/
args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG);
switch (args->op) {
case LINUX_FUTEX_WAIT:
FUTEX_SYSTEM_LOCK;
if ((error = copyin(args->uaddr,
&val, sizeof(val))) != 0) {
FUTEX_SYSTEM_UNLOCK;
return error;
}
if (val != args->val) {
FUTEX_SYSTEM_UNLOCK;
return EWOULDBLOCK;
}
if (args->timeout != NULL) {
if ((error = copyin(args->timeout,
&timeout, sizeof(timeout))) != 0) {
FUTEX_SYSTEM_UNLOCK;
return error;
}
}
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAIT %d: val = %d, uaddr = %p, "
"*uaddr = %d, timeout = %d.%09lu\n",
td->td_proc->p_pid, args->val,
args->uaddr, val, timeout.tv_sec,
(unsigned long)timeout.tv_nsec);
#endif
tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000;
timeout_hz = tvtohz(&tv);
if (timeout.tv_sec == 0 && timeout.tv_nsec == 0)
timeout_hz = 0;
/*
* If the user process requests a non null timeout,
* make sure we do not turn it into an infinite
* timeout because timeout_hz gets null.
*
* We use a minimal timeout of 1/hz. Maybe it would
* make sense to just return ETIMEDOUT without sleeping.
*/
if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) &&
(timeout_hz == 0))
timeout_hz = 1;
f = futex_get(args->uaddr, FUTEX_UNLOCKED);
ret = futex_sleep(f, td, timeout_hz);
futex_put(f);
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAIT %d: uaddr = %p, "
"ret = %d\n", td->td_proc->p_pid, args->uaddr, ret);
#endif
FUTEX_SYSTEM_UNLOCK;
switch (ret) {
case EWOULDBLOCK: /* timeout */
return ETIMEDOUT;
break;
case EINTR: /* signal */
return EINTR;
break;
case 0: /* FUTEX_WAKE received */
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAIT %d: uaddr = %p, "
"got FUTEX_WAKE\n",
td->td_proc->p_pid, args->uaddr);
#endif
return 0;
break;
default:
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAIT: unexpected ret = %d\n",
ret);
#endif
break;
}
/* NOTREACHED */
break;
case LINUX_FUTEX_WAKE:
FUTEX_SYSTEM_LOCK;
/*
* XXX: Linux is able to cope with different addresses
* corresponding to the same mapped memory in the sleeping
* and waker process(es).
*/
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAKE %d: uaddr = %p, val = %d\n",
td->td_proc->p_pid, args->uaddr, args->val);
#endif
f = futex_get(args->uaddr, FUTEX_UNLOCKED);
td->td_retval[0] = futex_wake(f, args->val, NULL, 0);
futex_put(f);
FUTEX_SYSTEM_UNLOCK;
break;
case LINUX_FUTEX_CMP_REQUEUE:
FUTEX_SYSTEM_LOCK;
if ((error = copyin(args->uaddr,
&val, sizeof(val))) != 0) {
FUTEX_SYSTEM_UNLOCK;
return error;
}
if (val != args->val3) {
FUTEX_SYSTEM_UNLOCK;
return EAGAIN;
}
f = futex_get(args->uaddr, FUTEX_UNLOCKED);
newf = futex_get(args->uaddr2, FUTEX_UNLOCKED);
td->td_retval[0] = futex_wake(f, args->val, newf,
(int)(unsigned long)args->timeout);
futex_put(f);
futex_put(newf);
FUTEX_SYSTEM_UNLOCK;
break;
case LINUX_FUTEX_REQUEUE:
FUTEX_SYSTEM_LOCK;
f = futex_get(args->uaddr, FUTEX_UNLOCKED);
newf = futex_get(args->uaddr2, FUTEX_UNLOCKED);
td->td_retval[0] = futex_wake(f, args->val, newf,
(int)(unsigned long)args->timeout);
futex_put(f);
futex_put(newf);
FUTEX_SYSTEM_UNLOCK;
break;
case LINUX_FUTEX_FD:
#ifdef DEBUG
printf("linux_sys_futex: unimplemented op %d\n",
args->op);
#endif
return (ENOSYS);
case LINUX_FUTEX_WAKE_OP:
FUTEX_SYSTEM_LOCK;
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX_WAKE_OP: %d: uaddr = %p, op = %d, "
"val = %x, uaddr2 = %p, val3 = %x\n",
td->td_proc->p_pid, args->uaddr, args->op,
args->val, args->uaddr2, args->val3);
#endif
f = futex_get(args->uaddr, FUTEX_UNLOCKED);
f2 = futex_get(args->uaddr2, FUTEX_UNLOCKED);
/*
* This function returns positive number as results and
* negative as errors
*/
op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
#ifdef DEBUG
if (ldebug(sys_futex))
printf("futex_atomic_op ret %d\n", op_ret);
#endif
if (op_ret < 0) {
/* XXX: We don't handle the EFAULT yet. */
if (op_ret != -EFAULT) {
futex_put(f);
futex_put(f2);
FUTEX_SYSTEM_UNLOCK;
return (-op_ret);
}
futex_put(f);
futex_put(f2);
FUTEX_SYSTEM_UNLOCK;
return (EFAULT);
}
ret = futex_wake(f, args->val, NULL, 0);
futex_put(f);
if (op_ret > 0) {
op_ret = 0;
/*
* Linux abuses the address of the timespec parameter
* as the number of retries.
*/
op_ret += futex_wake(f2,
(int)(unsigned long)args->timeout, NULL, 0);
ret += op_ret;
}
futex_put(f2);
td->td_retval[0] = ret;
FUTEX_SYSTEM_UNLOCK;
break;
case LINUX_FUTEX_LOCK_PI:
/* not yet implemented */
return (ENOSYS);
case LINUX_FUTEX_UNLOCK_PI:
/* not yet implemented */
return (ENOSYS);
case LINUX_FUTEX_TRYLOCK_PI:
/* not yet implemented */
return (ENOSYS);
default:
printf("linux_sys_futex: unknown op %d\n",
args->op);
return (ENOSYS);
}
return (0);
}
static struct futex *
futex_get(void *uaddr, int locked)
{
struct futex *f;
if (locked == FUTEX_UNLOCKED)
FUTEX_LOCK;
LIST_FOREACH(f, &futex_list, f_list) {
if (f->f_uaddr == uaddr) {
f->f_refcount++;
if (locked == FUTEX_UNLOCKED)
FUTEX_UNLOCK;
return f;
}
}
f = malloc(sizeof(*f), M_LINUX, M_WAITOK);
f->f_uaddr = uaddr;
f->f_refcount = 1;
TAILQ_INIT(&f->f_waiting_proc);
LIST_INSERT_HEAD(&futex_list, f, f_list);
if (locked == FUTEX_UNLOCKED)
FUTEX_UNLOCK;
return f;
}
static void
futex_put(f)
struct futex *f;
{
FUTEX_LOCK;
f->f_refcount--;
if (f->f_refcount == 0) {
LIST_REMOVE(f, f_list);
free(f, M_LINUX);
}
FUTEX_UNLOCK;
return;
}
static int
futex_sleep(struct futex *f, struct thread *td, unsigned long timeout)
{
struct waiting_proc *wp;
int ret;
wp = malloc(sizeof(*wp), M_LINUX, M_WAITOK);
wp->wp_t = td;
wp->wp_new_futex = NULL;
FUTEX_LOCK;
TAILQ_INSERT_TAIL(&f->f_waiting_proc, wp, wp_list);
FUTEX_UNLOCK;
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX --> %d tlseep timeout = %ld\n",
td->td_proc->p_pid, timeout);
#endif
ret = tsleep(wp, PCATCH | PZERO, "linuxfutex", timeout);
#ifdef DEBUG
if (ldebug(sys_futex))
printf("FUTEX -> %d tsleep returns %d\n",
td->td_proc->p_pid, ret);
#endif
FUTEX_LOCK;
TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
FUTEX_UNLOCK;
/* if we got woken up in futex_wake */
if ((ret == 0) && (wp->wp_new_futex != NULL)) {
/* suspend us on the new futex */
ret = futex_sleep(wp->wp_new_futex, td, timeout);
/* and release the old one */
futex_put(wp->wp_new_futex);
}
free(wp, M_LINUX);
return ret;
}
static int
futex_wake(struct futex *f, int n, struct futex *newf, int n2)
{
struct waiting_proc *wp;
int count;
/*
* Linux is very strange it wakes up N threads for
* all operations BUT requeue ones where its N+1
* mimic this.
*/
count = newf ? 0 : 1;
FUTEX_LOCK;
TAILQ_FOREACH(wp, &f->f_waiting_proc, wp_list) {
if (count <= n) {
wakeup_one(wp);
count++;
} else {
if (newf != NULL) {
/* futex_put called after tsleep */
wp->wp_new_futex = futex_get(newf->f_uaddr,
FUTEX_LOCKED);
wakeup_one(wp);
if (count - n >= n2)
break;
}
}
}
FUTEX_UNLOCK;
return count;
}
static int
futex_atomic_op(struct thread *td, int encoded_op, caddr_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_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, ""));
#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))
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(void *uaddr, pid_t pid, int pi)
{
int uval, nval, mval;
struct futex *f;
retry:
if (copyin(uaddr, &uval, 4))
return (EFAULT);
if ((uval & FUTEX_TID_MASK) == 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)) {
f = futex_get(uaddr, FUTEX_UNLOCKED);
futex_wake(f, 1, NULL, 0);
}
}
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_ulong 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(l_ulong)))
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((char *)entry + futex_offset,
p->p_pid, pi))
return;
if (rc)
return;
entry = next_entry;
pi = next_pi;
if (!--limit)
break;
sched_relinquish(curthread);
}
if (pending)
handle_futex_death((char *) pending + futex_offset,
p->p_pid, pip);
}