ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation
sys_oabi_semtimedop() is one of the last users of set_fs() on Arm. To
remove this one, expose the internal code of the actual implementation
that operates on a kernel pointer and call it directly after copying.
There should be no measurable impact on the normal execution of this
function, and it makes the overly long function a little shorter, which
may help readability.
While reworking the oabi version, make it behave a little more like
the native one, using kvmalloc_array() and restructure the code
flow in a similar way.
The naming of __do_semtimedop() is not very good, I hope someone can
come up with a better name.
One regression was spotted by kernel test robot <rong.a.chen@intel.com>
and fixed before the first mailing list submission.
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
diff --git a/ipc/sem.c b/ipc/sem.c
index 971e75d..ae8d910 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1984,46 +1984,34 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
return un;
}
-static long do_semtimedop(int semid, struct sembuf __user *tsops,
- unsigned nsops, const struct timespec64 *timeout)
+long __do_semtimedop(int semid, struct sembuf *sops,
+ unsigned nsops, const struct timespec64 *timeout,
+ struct ipc_namespace *ns)
{
int error = -EINVAL;
struct sem_array *sma;
- struct sembuf fast_sops[SEMOPM_FAST];
- struct sembuf *sops = fast_sops, *sop;
+ struct sembuf *sop;
struct sem_undo *un;
int max, locknum;
bool undos = false, alter = false, dupsop = false;
struct sem_queue queue;
unsigned long dup = 0, jiffies_left = 0;
- struct ipc_namespace *ns;
-
- ns = current->nsproxy->ipc_ns;
if (nsops < 1 || semid < 0)
return -EINVAL;
if (nsops > ns->sc_semopm)
return -E2BIG;
- if (nsops > SEMOPM_FAST) {
- sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
- if (sops == NULL)
- return -ENOMEM;
- }
-
- if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
- error = -EFAULT;
- goto out_free;
- }
if (timeout) {
if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
timeout->tv_nsec >= 1000000000L) {
error = -EINVAL;
- goto out_free;
+ goto out;
}
jiffies_left = timespec64_to_jiffies(timeout);
}
+
max = 0;
for (sop = sops; sop < sops + nsops; sop++) {
unsigned long mask = 1ULL << ((sop->sem_num) % BITS_PER_LONG);
@@ -2052,7 +2040,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
un = find_alloc_undo(ns, semid);
if (IS_ERR(un)) {
error = PTR_ERR(un);
- goto out_free;
+ goto out;
}
} else {
un = NULL;
@@ -2063,25 +2051,25 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
if (IS_ERR(sma)) {
rcu_read_unlock();
error = PTR_ERR(sma);
- goto out_free;
+ goto out;
}
error = -EFBIG;
if (max >= sma->sem_nsems) {
rcu_read_unlock();
- goto out_free;
+ goto out;
}
error = -EACCES;
if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
rcu_read_unlock();
- goto out_free;
+ goto out;
}
error = security_sem_semop(&sma->sem_perm, sops, nsops, alter);
if (error) {
rcu_read_unlock();
- goto out_free;
+ goto out;
}
error = -EIDRM;
@@ -2095,7 +2083,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* entangled here and why it's RMID race safe on comments at sem_lock()
*/
if (!ipc_valid_object(&sma->sem_perm))
- goto out_unlock_free;
+ goto out_unlock;
/*
* semid identifiers are not unique - find_alloc_undo may have
* allocated an undo structure, it was invalidated by an RMID
@@ -2104,7 +2092,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* "un" itself is guaranteed by rcu.
*/
if (un && un->semid == -1)
- goto out_unlock_free;
+ goto out_unlock;
queue.sops = sops;
queue.nsops = nsops;
@@ -2130,10 +2118,10 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
rcu_read_unlock();
wake_up_q(&wake_q);
- goto out_free;
+ goto out;
}
if (error < 0) /* non-blocking error path */
- goto out_unlock_free;
+ goto out_unlock;
/*
* We need to sleep on this operation, so we put the current
@@ -2198,14 +2186,14 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
if (error != -EINTR) {
/* see SEM_BARRIER_2 for purpose/pairing */
smp_acquire__after_ctrl_dep();
- goto out_free;
+ goto out;
}
rcu_read_lock();
locknum = sem_lock(sma, sops, nsops);
if (!ipc_valid_object(&sma->sem_perm))
- goto out_unlock_free;
+ goto out_unlock;
/*
* No necessity for any barrier: We are protect by sem_lock()
@@ -2217,7 +2205,7 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
* Leave without unlink_queue(), but with sem_unlock().
*/
if (error != -EINTR)
- goto out_unlock_free;
+ goto out_unlock;
/*
* If an interrupt occurred we have to clean up the queue.
@@ -2228,13 +2216,45 @@ static long do_semtimedop(int semid, struct sembuf __user *tsops,
unlink_queue(sma, &queue);
-out_unlock_free:
+out_unlock:
sem_unlock(sma, locknum);
rcu_read_unlock();
+out:
+ return error;
+}
+
+static long do_semtimedop(int semid, struct sembuf __user *tsops,
+ unsigned nsops, const struct timespec64 *timeout)
+{
+ struct sembuf fast_sops[SEMOPM_FAST];
+ struct sembuf *sops = fast_sops;
+ struct ipc_namespace *ns;
+ int ret;
+
+ ns = current->nsproxy->ipc_ns;
+ if (nsops > ns->sc_semopm)
+ return -E2BIG;
+ if (nsops < 1)
+ return -EINVAL;
+
+ if (nsops > SEMOPM_FAST) {
+ sops = kvmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
+ if (sops == NULL)
+ return -ENOMEM;
+ }
+
+ if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) {
+ ret = -EFAULT;
+ goto out_free;
+ }
+
+ ret = __do_semtimedop(semid, sops, nsops, timeout, ns);
+
out_free:
if (sops != fast_sops)
kvfree(sops);
- return error;
+
+ return ret;
}
long ksys_semtimedop(int semid, struct sembuf __user *tsops,