Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 9a889e4..07f42a7 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -12,6 +12,7 @@
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/err.h>
+#include <linux/interval_tree.h>
#include <linux/srcu.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
@@ -28,20 +29,277 @@
#endif
/*
+ * The mmu_notifier_subscriptions structure is allocated and installed in
+ * mm->notifier_subscriptions inside the mm_take_all_locks() protected
+ * critical section and it's released only when mm_count reaches zero
+ * in mmdrop().
+ */
+struct mmu_notifier_subscriptions {
+ /* all mmu notifiers registered in this mm are queued in this list */
+ struct hlist_head list;
+ bool has_itree;
+ /* to serialize the list modifications and hlist_unhashed */
+ spinlock_t lock;
+ unsigned long invalidate_seq;
+ unsigned long active_invalidate_ranges;
+ struct rb_root_cached itree;
+ wait_queue_head_t wq;
+ struct hlist_head deferred_list;
+};
+
+/*
+ * This is a collision-retry read-side/write-side 'lock', a lot like a
+ * seqcount, however this allows multiple write-sides to hold it at
+ * once. Conceptually the write side is protecting the values of the PTEs in
+ * this mm, such that PTES cannot be read into SPTEs (shadow PTEs) while any
+ * writer exists.
+ *
+ * Note that the core mm creates nested invalidate_range_start()/end() regions
+ * within the same thread, and runs invalidate_range_start()/end() in parallel
+ * on multiple CPUs. This is designed to not reduce concurrency or block
+ * progress on the mm side.
+ *
+ * As a secondary function, holding the full write side also serves to prevent
+ * writers for the itree, this is an optimization to avoid extra locking
+ * during invalidate_range_start/end notifiers.
+ *
+ * The write side has two states, fully excluded:
+ * - mm->active_invalidate_ranges != 0
+ * - subscriptions->invalidate_seq & 1 == True (odd)
+ * - some range on the mm_struct is being invalidated
+ * - the itree is not allowed to change
+ *
+ * And partially excluded:
+ * - mm->active_invalidate_ranges != 0
+ * - subscriptions->invalidate_seq & 1 == False (even)
+ * - some range on the mm_struct is being invalidated
+ * - the itree is allowed to change
+ *
+ * Operations on notifier_subscriptions->invalidate_seq (under spinlock):
+ * seq |= 1 # Begin writing
+ * seq++ # Release the writing state
+ * seq & 1 # True if a writer exists
+ *
+ * The later state avoids some expensive work on inv_end in the common case of
+ * no mmu_interval_notifier monitoring the VA.
+ */
+static bool
+mn_itree_is_invalidating(struct mmu_notifier_subscriptions *subscriptions)
+{
+ lockdep_assert_held(&subscriptions->lock);
+ return subscriptions->invalidate_seq & 1;
+}
+
+static struct mmu_interval_notifier *
+mn_itree_inv_start_range(struct mmu_notifier_subscriptions *subscriptions,
+ const struct mmu_notifier_range *range,
+ unsigned long *seq)
+{
+ struct interval_tree_node *node;
+ struct mmu_interval_notifier *res = NULL;
+
+ spin_lock(&subscriptions->lock);
+ subscriptions->active_invalidate_ranges++;
+ node = interval_tree_iter_first(&subscriptions->itree, range->start,
+ range->end - 1);
+ if (node) {
+ subscriptions->invalidate_seq |= 1;
+ res = container_of(node, struct mmu_interval_notifier,
+ interval_tree);
+ }
+
+ *seq = subscriptions->invalidate_seq;
+ spin_unlock(&subscriptions->lock);
+ return res;
+}
+
+static struct mmu_interval_notifier *
+mn_itree_inv_next(struct mmu_interval_notifier *interval_sub,
+ const struct mmu_notifier_range *range)
+{
+ struct interval_tree_node *node;
+
+ node = interval_tree_iter_next(&interval_sub->interval_tree,
+ range->start, range->end - 1);
+ if (!node)
+ return NULL;
+ return container_of(node, struct mmu_interval_notifier, interval_tree);
+}
+
+static void mn_itree_inv_end(struct mmu_notifier_subscriptions *subscriptions)
+{
+ struct mmu_interval_notifier *interval_sub;
+ struct hlist_node *next;
+
+ spin_lock(&subscriptions->lock);
+ if (--subscriptions->active_invalidate_ranges ||
+ !mn_itree_is_invalidating(subscriptions)) {
+ spin_unlock(&subscriptions->lock);
+ return;
+ }
+
+ /* Make invalidate_seq even */
+ subscriptions->invalidate_seq++;
+
+ /*
+ * The inv_end incorporates a deferred mechanism like rtnl_unlock().
+ * Adds and removes are queued until the final inv_end happens then
+ * they are progressed. This arrangement for tree updates is used to
+ * avoid using a blocking lock during invalidate_range_start.
+ */
+ hlist_for_each_entry_safe(interval_sub, next,
+ &subscriptions->deferred_list,
+ deferred_item) {
+ if (RB_EMPTY_NODE(&interval_sub->interval_tree.rb))
+ interval_tree_insert(&interval_sub->interval_tree,
+ &subscriptions->itree);
+ else
+ interval_tree_remove(&interval_sub->interval_tree,
+ &subscriptions->itree);
+ hlist_del(&interval_sub->deferred_item);
+ }
+ spin_unlock(&subscriptions->lock);
+
+ wake_up_all(&subscriptions->wq);
+}
+
+/**
+ * mmu_interval_read_begin - Begin a read side critical section against a VA
+ * range
+ * @interval_sub: The interval subscription
+ *
+ * mmu_iterval_read_begin()/mmu_iterval_read_retry() implement a
+ * collision-retry scheme similar to seqcount for the VA range under
+ * subscription. If the mm invokes invalidation during the critical section
+ * then mmu_interval_read_retry() will return true.
+ *
+ * This is useful to obtain shadow PTEs where teardown or setup of the SPTEs
+ * require a blocking context. The critical region formed by this can sleep,
+ * and the required 'user_lock' can also be a sleeping lock.
+ *
+ * The caller is required to provide a 'user_lock' to serialize both teardown
+ * and setup.
+ *
+ * The return value should be passed to mmu_interval_read_retry().
+ */
+unsigned long
+mmu_interval_read_begin(struct mmu_interval_notifier *interval_sub)
+{
+ struct mmu_notifier_subscriptions *subscriptions =
+ interval_sub->mm->notifier_subscriptions;
+ unsigned long seq;
+ bool is_invalidating;
+
+ /*
+ * If the subscription has a different seq value under the user_lock
+ * than we started with then it has collided.
+ *
+ * If the subscription currently has the same seq value as the
+ * subscriptions seq, then it is currently between
+ * invalidate_start/end and is colliding.
+ *
+ * The locking looks broadly like this:
+ * mn_tree_invalidate_start(): mmu_interval_read_begin():
+ * spin_lock
+ * seq = READ_ONCE(interval_sub->invalidate_seq);
+ * seq == subs->invalidate_seq
+ * spin_unlock
+ * spin_lock
+ * seq = ++subscriptions->invalidate_seq
+ * spin_unlock
+ * op->invalidate_range():
+ * user_lock
+ * mmu_interval_set_seq()
+ * interval_sub->invalidate_seq = seq
+ * user_unlock
+ *
+ * [Required: mmu_interval_read_retry() == true]
+ *
+ * mn_itree_inv_end():
+ * spin_lock
+ * seq = ++subscriptions->invalidate_seq
+ * spin_unlock
+ *
+ * user_lock
+ * mmu_interval_read_retry():
+ * interval_sub->invalidate_seq != seq
+ * user_unlock
+ *
+ * Barriers are not needed here as any races here are closed by an
+ * eventual mmu_interval_read_retry(), which provides a barrier via the
+ * user_lock.
+ */
+ spin_lock(&subscriptions->lock);
+ /* Pairs with the WRITE_ONCE in mmu_interval_set_seq() */
+ seq = READ_ONCE(interval_sub->invalidate_seq);
+ is_invalidating = seq == subscriptions->invalidate_seq;
+ spin_unlock(&subscriptions->lock);
+
+ /*
+ * interval_sub->invalidate_seq must always be set to an odd value via
+ * mmu_interval_set_seq() using the provided cur_seq from
+ * mn_itree_inv_start_range(). This ensures that if seq does wrap we
+ * will always clear the below sleep in some reasonable time as
+ * subscriptions->invalidate_seq is even in the idle state.
+ */
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
+ if (is_invalidating)
+ wait_event(subscriptions->wq,
+ READ_ONCE(subscriptions->invalidate_seq) != seq);
+
+ /*
+ * Notice that mmu_interval_read_retry() can already be true at this
+ * point, avoiding loops here allows the caller to provide a global
+ * time bound.
+ */
+
+ return seq;
+}
+EXPORT_SYMBOL_GPL(mmu_interval_read_begin);
+
+static void mn_itree_release(struct mmu_notifier_subscriptions *subscriptions,
+ struct mm_struct *mm)
+{
+ struct mmu_notifier_range range = {
+ .flags = MMU_NOTIFIER_RANGE_BLOCKABLE,
+ .event = MMU_NOTIFY_RELEASE,
+ .mm = mm,
+ .start = 0,
+ .end = ULONG_MAX,
+ };
+ struct mmu_interval_notifier *interval_sub;
+ unsigned long cur_seq;
+ bool ret;
+
+ for (interval_sub =
+ mn_itree_inv_start_range(subscriptions, &range, &cur_seq);
+ interval_sub;
+ interval_sub = mn_itree_inv_next(interval_sub, &range)) {
+ ret = interval_sub->ops->invalidate(interval_sub, &range,
+ cur_seq);
+ WARN_ON(!ret);
+ }
+
+ mn_itree_inv_end(subscriptions);
+}
+
+/*
* This function can't run concurrently against mmu_notifier_register
* because mm->mm_users > 0 during mmu_notifier_register and exit_mmap
* runs with mm_users == 0. Other tasks may still invoke mmu notifiers
* in parallel despite there being no task using this mm any more,
* through the vmas outside of the exit_mmap context, such as with
* vmtruncate. This serializes against mmu_notifier_unregister with
- * the mmu_notifier_mm->lock in addition to SRCU and it serializes
- * against the other mmu notifiers with SRCU. struct mmu_notifier_mm
+ * the notifier_subscriptions->lock in addition to SRCU and it serializes
+ * against the other mmu notifiers with SRCU. struct mmu_notifier_subscriptions
* can't go away from under us as exit_mmap holds an mm_count pin
* itself.
*/
-void __mmu_notifier_release(struct mm_struct *mm)
+static void mn_hlist_release(struct mmu_notifier_subscriptions *subscriptions,
+ struct mm_struct *mm)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int id;
/*
@@ -49,30 +307,30 @@
* ->release returns.
*/
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist)
+ hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu))
/*
* If ->release runs before mmu_notifier_unregister it must be
* handled, as it's the only way for the driver to flush all
* existing sptes and stop the driver from establishing any more
* sptes before all the pages in the mm are freed.
*/
- if (mn->ops->release)
- mn->ops->release(mn, mm);
+ if (subscription->ops->release)
+ subscription->ops->release(subscription, mm);
- spin_lock(&mm->mmu_notifier_mm->lock);
- while (unlikely(!hlist_empty(&mm->mmu_notifier_mm->list))) {
- mn = hlist_entry(mm->mmu_notifier_mm->list.first,
- struct mmu_notifier,
- hlist);
+ spin_lock(&subscriptions->lock);
+ while (unlikely(!hlist_empty(&subscriptions->list))) {
+ subscription = hlist_entry(subscriptions->list.first,
+ struct mmu_notifier, hlist);
/*
* We arrived before mmu_notifier_unregister so
* mmu_notifier_unregister will do nothing other than to wait
* for ->release to finish and for mmu_notifier_unregister to
* return.
*/
- hlist_del_init_rcu(&mn->hlist);
+ hlist_del_init_rcu(&subscription->hlist);
}
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ spin_unlock(&subscriptions->lock);
srcu_read_unlock(&srcu, id);
/*
@@ -81,12 +339,24 @@
* until the ->release method returns, if it was invoked by
* mmu_notifier_unregister.
*
- * The mmu_notifier_mm can't go away from under us because one mm_count
- * is held by exit_mmap.
+ * The notifier_subscriptions can't go away from under us because
+ * one mm_count is held by exit_mmap.
*/
synchronize_srcu(&srcu);
}
+void __mmu_notifier_release(struct mm_struct *mm)
+{
+ struct mmu_notifier_subscriptions *subscriptions =
+ mm->notifier_subscriptions;
+
+ if (subscriptions->has_itree)
+ mn_itree_release(subscriptions, mm);
+
+ if (!hlist_empty(&subscriptions->list))
+ mn_hlist_release(subscriptions, mm);
+}
+
/*
* If no young bitflag is supported by the hardware, ->clear_flush_young can
* unmap the address and return 1 or 0 depending if the mapping previously
@@ -96,13 +366,16 @@
unsigned long start,
unsigned long end)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int young = 0, id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->clear_flush_young)
- young |= mn->ops->clear_flush_young(mn, mm, start, end);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ if (subscription->ops->clear_flush_young)
+ young |= subscription->ops->clear_flush_young(
+ subscription, mm, start, end);
}
srcu_read_unlock(&srcu, id);
@@ -113,13 +386,16 @@
unsigned long start,
unsigned long end)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int young = 0, id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->clear_young)
- young |= mn->ops->clear_young(mn, mm, start, end);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ if (subscription->ops->clear_young)
+ young |= subscription->ops->clear_young(subscription,
+ mm, start, end);
}
srcu_read_unlock(&srcu, id);
@@ -129,13 +405,16 @@
int __mmu_notifier_test_young(struct mm_struct *mm,
unsigned long address)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int young = 0, id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->test_young) {
- young = mn->ops->test_young(mn, mm, address);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ if (subscription->ops->test_young) {
+ young = subscription->ops->test_young(subscription, mm,
+ address);
if (young)
break;
}
@@ -148,57 +427,138 @@
void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address,
pte_t pte)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->change_pte)
- mn->ops->change_pte(mn, mm, address, pte);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ if (subscription->ops->change_pte)
+ subscription->ops->change_pte(subscription, mm, address,
+ pte);
}
srcu_read_unlock(&srcu, id);
}
-int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
+static int mn_itree_invalidate(struct mmu_notifier_subscriptions *subscriptions,
+ const struct mmu_notifier_range *range)
{
- struct mmu_notifier *mn;
+ struct mmu_interval_notifier *interval_sub;
+ unsigned long cur_seq;
+
+ for (interval_sub =
+ mn_itree_inv_start_range(subscriptions, range, &cur_seq);
+ interval_sub;
+ interval_sub = mn_itree_inv_next(interval_sub, range)) {
+ bool ret;
+
+ ret = interval_sub->ops->invalidate(interval_sub, range,
+ cur_seq);
+ if (!ret) {
+ if (WARN_ON(mmu_notifier_range_blockable(range)))
+ continue;
+ goto out_would_block;
+ }
+ }
+ return 0;
+
+out_would_block:
+ /*
+ * On -EAGAIN the non-blocking caller is not allowed to call
+ * invalidate_range_end()
+ */
+ mn_itree_inv_end(subscriptions);
+ return -EAGAIN;
+}
+
+static int mn_hlist_invalidate_range_start(
+ struct mmu_notifier_subscriptions *subscriptions,
+ struct mmu_notifier_range *range)
+{
+ struct mmu_notifier *subscription;
int ret = 0;
int id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &range->mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->invalidate_range_start) {
+ hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ const struct mmu_notifier_ops *ops = subscription->ops;
+
+ if (ops->invalidate_range_start) {
int _ret;
if (!mmu_notifier_range_blockable(range))
non_block_start();
- _ret = mn->ops->invalidate_range_start(mn, range);
+ _ret = ops->invalidate_range_start(subscription, range);
if (!mmu_notifier_range_blockable(range))
non_block_end();
if (_ret) {
pr_info("%pS callback failed with %d in %sblockable context.\n",
- mn->ops->invalidate_range_start, _ret,
- !mmu_notifier_range_blockable(range) ? "non-" : "");
+ ops->invalidate_range_start, _ret,
+ !mmu_notifier_range_blockable(range) ?
+ "non-" :
+ "");
WARN_ON(mmu_notifier_range_blockable(range) ||
_ret != -EAGAIN);
+ /*
+ * We call all the notifiers on any EAGAIN,
+ * there is no way for a notifier to know if
+ * its start method failed, thus a start that
+ * does EAGAIN can't also do end.
+ */
+ WARN_ON(ops->invalidate_range_end);
ret = _ret;
}
}
}
+
+ if (ret) {
+ /*
+ * Must be non-blocking to get here. If there are multiple
+ * notifiers and one or more failed start, any that succeeded
+ * start are expecting their end to be called. Do so now.
+ */
+ hlist_for_each_entry_rcu(subscription, &subscriptions->list,
+ hlist, srcu_read_lock_held(&srcu)) {
+ if (!subscription->ops->invalidate_range_end)
+ continue;
+
+ subscription->ops->invalidate_range_end(subscription,
+ range);
+ }
+ }
srcu_read_unlock(&srcu, id);
return ret;
}
-void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
- bool only_end)
+int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier_subscriptions *subscriptions =
+ range->mm->notifier_subscriptions;
+ int ret;
+
+ if (subscriptions->has_itree) {
+ ret = mn_itree_invalidate(subscriptions, range);
+ if (ret)
+ return ret;
+ }
+ if (!hlist_empty(&subscriptions->list))
+ return mn_hlist_invalidate_range_start(subscriptions, range);
+ return 0;
+}
+
+static void
+mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions,
+ struct mmu_notifier_range *range, bool only_end)
+{
+ struct mmu_notifier *subscription;
int id;
- lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &range->mm->mmu_notifier_mm->list, hlist) {
+ hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
/*
* Call invalidate_range here too to avoid the need for the
* subsystem of having to register an invalidate_range_end
@@ -212,46 +572,67 @@
* is safe to do when we know that a call to invalidate_range()
* already happen under page table lock.
*/
- if (!only_end && mn->ops->invalidate_range)
- mn->ops->invalidate_range(mn, range->mm,
- range->start,
- range->end);
- if (mn->ops->invalidate_range_end) {
+ if (!only_end && subscription->ops->invalidate_range)
+ subscription->ops->invalidate_range(subscription,
+ range->mm,
+ range->start,
+ range->end);
+ if (subscription->ops->invalidate_range_end) {
if (!mmu_notifier_range_blockable(range))
non_block_start();
- mn->ops->invalidate_range_end(mn, range);
+ subscription->ops->invalidate_range_end(subscription,
+ range);
if (!mmu_notifier_range_blockable(range))
non_block_end();
}
}
srcu_read_unlock(&srcu, id);
+}
+
+void __mmu_notifier_invalidate_range_end(struct mmu_notifier_range *range,
+ bool only_end)
+{
+ struct mmu_notifier_subscriptions *subscriptions =
+ range->mm->notifier_subscriptions;
+
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
+ if (subscriptions->has_itree)
+ mn_itree_inv_end(subscriptions);
+
+ if (!hlist_empty(&subscriptions->list))
+ mn_hlist_invalidate_end(subscriptions, range, only_end);
lock_map_release(&__mmu_notifier_invalidate_range_start_map);
}
void __mmu_notifier_invalidate_range(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int id;
id = srcu_read_lock(&srcu);
- hlist_for_each_entry_rcu(mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops->invalidate_range)
- mn->ops->invalidate_range(mn, mm, start, end);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ srcu_read_lock_held(&srcu)) {
+ if (subscription->ops->invalidate_range)
+ subscription->ops->invalidate_range(subscription, mm,
+ start, end);
}
srcu_read_unlock(&srcu, id);
}
/*
- * Same as mmu_notifier_register but here the caller must hold the
- * mmap_sem in write mode.
+ * Same as mmu_notifier_register but here the caller must hold the mmap_lock in
+ * write mode. A NULL mn signals the notifier is being registered for itree
+ * mode.
*/
-int __mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+int __mmu_notifier_register(struct mmu_notifier *subscription,
+ struct mm_struct *mm)
{
- struct mmu_notifier_mm *mmu_notifier_mm = NULL;
+ struct mmu_notifier_subscriptions *subscriptions = NULL;
int ret;
- lockdep_assert_held_write(&mm->mmap_sem);
+ mmap_assert_write_locked(mm);
BUG_ON(atomic_read(&mm->mm_users) <= 0);
if (IS_ENABLED(CONFIG_LOCKDEP)) {
@@ -261,31 +642,29 @@
fs_reclaim_release(GFP_KERNEL);
}
- mn->mm = mm;
- mn->users = 1;
-
- if (!mm->mmu_notifier_mm) {
+ if (!mm->notifier_subscriptions) {
/*
* kmalloc cannot be called under mm_take_all_locks(), but we
- * know that mm->mmu_notifier_mm can't change while we hold
- * the write side of the mmap_sem.
+ * know that mm->notifier_subscriptions can't change while we
+ * hold the write side of the mmap_lock.
*/
- mmu_notifier_mm =
- kmalloc(sizeof(struct mmu_notifier_mm), GFP_KERNEL);
- if (!mmu_notifier_mm)
+ subscriptions = kzalloc(
+ sizeof(struct mmu_notifier_subscriptions), GFP_KERNEL);
+ if (!subscriptions)
return -ENOMEM;
- INIT_HLIST_HEAD(&mmu_notifier_mm->list);
- spin_lock_init(&mmu_notifier_mm->lock);
+ INIT_HLIST_HEAD(&subscriptions->list);
+ spin_lock_init(&subscriptions->lock);
+ subscriptions->invalidate_seq = 2;
+ subscriptions->itree = RB_ROOT_CACHED;
+ init_waitqueue_head(&subscriptions->wq);
+ INIT_HLIST_HEAD(&subscriptions->deferred_list);
}
ret = mm_take_all_locks(mm);
if (unlikely(ret))
goto out_clean;
- /* Pairs with the mmdrop in mmu_notifier_unregister_* */
- mmgrab(mm);
-
/*
* Serialize the update against mmu_notifier_unregister. A
* side note: mmu_notifier_release can't run concurrently with
@@ -293,30 +672,47 @@
* current->mm or explicitly with get_task_mm() or similar).
* We can't race against any other mmu notifier method either
* thanks to mm_take_all_locks().
+ *
+ * release semantics on the initialization of the
+ * mmu_notifier_subscriptions's contents are provided for unlocked
+ * readers. acquire can only be used while holding the mmgrab or
+ * mmget, and is safe because once created the
+ * mmu_notifier_subscriptions is not freed until the mm is destroyed.
+ * As above, users holding the mmap_lock or one of the
+ * mm_take_all_locks() do not need to use acquire semantics.
*/
- if (mmu_notifier_mm)
- mm->mmu_notifier_mm = mmu_notifier_mm;
+ if (subscriptions)
+ smp_store_release(&mm->notifier_subscriptions, subscriptions);
- spin_lock(&mm->mmu_notifier_mm->lock);
- hlist_add_head_rcu(&mn->hlist, &mm->mmu_notifier_mm->list);
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ if (subscription) {
+ /* Pairs with the mmdrop in mmu_notifier_unregister_* */
+ mmgrab(mm);
+ subscription->mm = mm;
+ subscription->users = 1;
+
+ spin_lock(&mm->notifier_subscriptions->lock);
+ hlist_add_head_rcu(&subscription->hlist,
+ &mm->notifier_subscriptions->list);
+ spin_unlock(&mm->notifier_subscriptions->lock);
+ } else
+ mm->notifier_subscriptions->has_itree = true;
mm_drop_all_locks(mm);
BUG_ON(atomic_read(&mm->mm_users) <= 0);
return 0;
out_clean:
- kfree(mmu_notifier_mm);
+ kfree(subscriptions);
return ret;
}
EXPORT_SYMBOL_GPL(__mmu_notifier_register);
/**
* mmu_notifier_register - Register a notifier on a mm
- * @mn: The notifier to attach
+ * @subscription: The notifier to attach
* @mm: The mm to attach the notifier to
*
- * Must not hold mmap_sem nor any other VM related lock when calling
+ * Must not hold mmap_lock nor any other VM related lock when calling
* this registration function. Must also ensure mm_users can't go down
* to zero while this runs to avoid races with mmu_notifier_release,
* so mm has to be current->mm or the mm should be pinned safely such
@@ -327,16 +723,17 @@
* mmu_notifier_unregister() or mmu_notifier_put() must be always called to
* unregister the notifier.
*
- * While the caller has a mmu_notifier get the mn->mm pointer will remain
+ * While the caller has a mmu_notifier get the subscription->mm pointer will remain
* valid, and can be converted to an active mm pointer via mmget_not_zero().
*/
-int mmu_notifier_register(struct mmu_notifier *mn, struct mm_struct *mm)
+int mmu_notifier_register(struct mmu_notifier *subscription,
+ struct mm_struct *mm)
{
int ret;
- down_write(&mm->mmap_sem);
- ret = __mmu_notifier_register(mn, mm);
- up_write(&mm->mmap_sem);
+ mmap_write_lock(mm);
+ ret = __mmu_notifier_register(subscription, mm);
+ mmap_write_unlock(mm);
return ret;
}
EXPORT_SYMBOL_GPL(mmu_notifier_register);
@@ -344,21 +741,23 @@
static struct mmu_notifier *
find_get_mmu_notifier(struct mm_struct *mm, const struct mmu_notifier_ops *ops)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
- spin_lock(&mm->mmu_notifier_mm->lock);
- hlist_for_each_entry_rcu (mn, &mm->mmu_notifier_mm->list, hlist) {
- if (mn->ops != ops)
+ spin_lock(&mm->notifier_subscriptions->lock);
+ hlist_for_each_entry_rcu(subscription,
+ &mm->notifier_subscriptions->list, hlist,
+ lockdep_is_held(&mm->notifier_subscriptions->lock)) {
+ if (subscription->ops != ops)
continue;
- if (likely(mn->users != UINT_MAX))
- mn->users++;
+ if (likely(subscription->users != UINT_MAX))
+ subscription->users++;
else
- mn = ERR_PTR(-EOVERFLOW);
- spin_unlock(&mm->mmu_notifier_mm->lock);
- return mn;
+ subscription = ERR_PTR(-EOVERFLOW);
+ spin_unlock(&mm->notifier_subscriptions->lock);
+ return subscription;
}
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ spin_unlock(&mm->notifier_subscriptions->lock);
return NULL;
}
@@ -374,7 +773,7 @@
* are the same.
*
* Each call to mmu_notifier_get() must be paired with a call to
- * mmu_notifier_put(). The caller must hold the write side of mm->mmap_sem.
+ * mmu_notifier_put(). The caller must hold the write side of mm->mmap_lock.
*
* While the caller has a mmu_notifier get the mm pointer will remain valid,
* and can be converted to an active mm pointer via mmget_not_zero().
@@ -382,37 +781,37 @@
struct mmu_notifier *mmu_notifier_get_locked(const struct mmu_notifier_ops *ops,
struct mm_struct *mm)
{
- struct mmu_notifier *mn;
+ struct mmu_notifier *subscription;
int ret;
- lockdep_assert_held_write(&mm->mmap_sem);
+ mmap_assert_write_locked(mm);
- if (mm->mmu_notifier_mm) {
- mn = find_get_mmu_notifier(mm, ops);
- if (mn)
- return mn;
+ if (mm->notifier_subscriptions) {
+ subscription = find_get_mmu_notifier(mm, ops);
+ if (subscription)
+ return subscription;
}
- mn = ops->alloc_notifier(mm);
- if (IS_ERR(mn))
- return mn;
- mn->ops = ops;
- ret = __mmu_notifier_register(mn, mm);
+ subscription = ops->alloc_notifier(mm);
+ if (IS_ERR(subscription))
+ return subscription;
+ subscription->ops = ops;
+ ret = __mmu_notifier_register(subscription, mm);
if (ret)
goto out_free;
- return mn;
+ return subscription;
out_free:
- mn->ops->free_notifier(mn);
+ subscription->ops->free_notifier(subscription);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(mmu_notifier_get_locked);
/* this is called after the last mmu_notifier_unregister() returned */
-void __mmu_notifier_mm_destroy(struct mm_struct *mm)
+void __mmu_notifier_subscriptions_destroy(struct mm_struct *mm)
{
- BUG_ON(!hlist_empty(&mm->mmu_notifier_mm->list));
- kfree(mm->mmu_notifier_mm);
- mm->mmu_notifier_mm = LIST_POISON1; /* debug */
+ BUG_ON(!hlist_empty(&mm->notifier_subscriptions->list));
+ kfree(mm->notifier_subscriptions);
+ mm->notifier_subscriptions = LIST_POISON1; /* debug */
}
/*
@@ -425,11 +824,12 @@
* and only after mmu_notifier_unregister returned we're guaranteed
* that ->release or any other method can't run anymore.
*/
-void mmu_notifier_unregister(struct mmu_notifier *mn, struct mm_struct *mm)
+void mmu_notifier_unregister(struct mmu_notifier *subscription,
+ struct mm_struct *mm)
{
BUG_ON(atomic_read(&mm->mm_count) <= 0);
- if (!hlist_unhashed(&mn->hlist)) {
+ if (!hlist_unhashed(&subscription->hlist)) {
/*
* SRCU here will force exit_mmap to wait for ->release to
* finish before freeing the pages.
@@ -441,17 +841,17 @@
* exit_mmap will block in mmu_notifier_release to guarantee
* that ->release is called before freeing the pages.
*/
- if (mn->ops->release)
- mn->ops->release(mn, mm);
+ if (subscription->ops->release)
+ subscription->ops->release(subscription, mm);
srcu_read_unlock(&srcu, id);
- spin_lock(&mm->mmu_notifier_mm->lock);
+ spin_lock(&mm->notifier_subscriptions->lock);
/*
* Can not use list_del_rcu() since __mmu_notifier_release
* can delete it before we hold the lock.
*/
- hlist_del_init_rcu(&mn->hlist);
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ hlist_del_init_rcu(&subscription->hlist);
+ spin_unlock(&mm->notifier_subscriptions->lock);
}
/*
@@ -468,17 +868,18 @@
static void mmu_notifier_free_rcu(struct rcu_head *rcu)
{
- struct mmu_notifier *mn = container_of(rcu, struct mmu_notifier, rcu);
- struct mm_struct *mm = mn->mm;
+ struct mmu_notifier *subscription =
+ container_of(rcu, struct mmu_notifier, rcu);
+ struct mm_struct *mm = subscription->mm;
- mn->ops->free_notifier(mn);
+ subscription->ops->free_notifier(subscription);
/* Pairs with the get in __mmu_notifier_register() */
mmdrop(mm);
}
/**
* mmu_notifier_put - Release the reference on the notifier
- * @mn: The notifier to act on
+ * @subscription: The notifier to act on
*
* This function must be paired with each mmu_notifier_get(), it releases the
* reference obtained by the get. If this is the last reference then process
@@ -498,24 +899,204 @@
* Modules calling this function must call mmu_notifier_synchronize() in
* their __exit functions to ensure the async work is completed.
*/
-void mmu_notifier_put(struct mmu_notifier *mn)
+void mmu_notifier_put(struct mmu_notifier *subscription)
{
- struct mm_struct *mm = mn->mm;
+ struct mm_struct *mm = subscription->mm;
- spin_lock(&mm->mmu_notifier_mm->lock);
- if (WARN_ON(!mn->users) || --mn->users)
+ spin_lock(&mm->notifier_subscriptions->lock);
+ if (WARN_ON(!subscription->users) || --subscription->users)
goto out_unlock;
- hlist_del_init_rcu(&mn->hlist);
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ hlist_del_init_rcu(&subscription->hlist);
+ spin_unlock(&mm->notifier_subscriptions->lock);
- call_srcu(&srcu, &mn->rcu, mmu_notifier_free_rcu);
+ call_srcu(&srcu, &subscription->rcu, mmu_notifier_free_rcu);
return;
out_unlock:
- spin_unlock(&mm->mmu_notifier_mm->lock);
+ spin_unlock(&mm->notifier_subscriptions->lock);
}
EXPORT_SYMBOL_GPL(mmu_notifier_put);
+static int __mmu_interval_notifier_insert(
+ struct mmu_interval_notifier *interval_sub, struct mm_struct *mm,
+ struct mmu_notifier_subscriptions *subscriptions, unsigned long start,
+ unsigned long length, const struct mmu_interval_notifier_ops *ops)
+{
+ interval_sub->mm = mm;
+ interval_sub->ops = ops;
+ RB_CLEAR_NODE(&interval_sub->interval_tree.rb);
+ interval_sub->interval_tree.start = start;
+ /*
+ * Note that the representation of the intervals in the interval tree
+ * considers the ending point as contained in the interval.
+ */
+ if (length == 0 ||
+ check_add_overflow(start, length - 1,
+ &interval_sub->interval_tree.last))
+ return -EOVERFLOW;
+
+ /* Must call with a mmget() held */
+ if (WARN_ON(atomic_read(&mm->mm_users) <= 0))
+ return -EINVAL;
+
+ /* pairs with mmdrop in mmu_interval_notifier_remove() */
+ mmgrab(mm);
+
+ /*
+ * If some invalidate_range_start/end region is going on in parallel
+ * we don't know what VA ranges are affected, so we must assume this
+ * new range is included.
+ *
+ * If the itree is invalidating then we are not allowed to change
+ * it. Retrying until invalidation is done is tricky due to the
+ * possibility for live lock, instead defer the add to
+ * mn_itree_inv_end() so this algorithm is deterministic.
+ *
+ * In all cases the value for the interval_sub->invalidate_seq should be
+ * odd, see mmu_interval_read_begin()
+ */
+ spin_lock(&subscriptions->lock);
+ if (subscriptions->active_invalidate_ranges) {
+ if (mn_itree_is_invalidating(subscriptions))
+ hlist_add_head(&interval_sub->deferred_item,
+ &subscriptions->deferred_list);
+ else {
+ subscriptions->invalidate_seq |= 1;
+ interval_tree_insert(&interval_sub->interval_tree,
+ &subscriptions->itree);
+ }
+ interval_sub->invalidate_seq = subscriptions->invalidate_seq;
+ } else {
+ WARN_ON(mn_itree_is_invalidating(subscriptions));
+ /*
+ * The starting seq for a subscription not under invalidation
+ * should be odd, not equal to the current invalidate_seq and
+ * invalidate_seq should not 'wrap' to the new seq any time
+ * soon.
+ */
+ interval_sub->invalidate_seq =
+ subscriptions->invalidate_seq - 1;
+ interval_tree_insert(&interval_sub->interval_tree,
+ &subscriptions->itree);
+ }
+ spin_unlock(&subscriptions->lock);
+ return 0;
+}
+
+/**
+ * mmu_interval_notifier_insert - Insert an interval notifier
+ * @interval_sub: Interval subscription to register
+ * @start: Starting virtual address to monitor
+ * @length: Length of the range to monitor
+ * @mm: mm_struct to attach to
+ * @ops: Interval notifier operations to be called on matching events
+ *
+ * This function subscribes the interval notifier for notifications from the
+ * mm. Upon return the ops related to mmu_interval_notifier will be called
+ * whenever an event that intersects with the given range occurs.
+ *
+ * Upon return the range_notifier may not be present in the interval tree yet.
+ * The caller must use the normal interval notifier read flow via
+ * mmu_interval_read_begin() to establish SPTEs for this range.
+ */
+int mmu_interval_notifier_insert(struct mmu_interval_notifier *interval_sub,
+ struct mm_struct *mm, unsigned long start,
+ unsigned long length,
+ const struct mmu_interval_notifier_ops *ops)
+{
+ struct mmu_notifier_subscriptions *subscriptions;
+ int ret;
+
+ might_lock(&mm->mmap_lock);
+
+ subscriptions = smp_load_acquire(&mm->notifier_subscriptions);
+ if (!subscriptions || !subscriptions->has_itree) {
+ ret = mmu_notifier_register(NULL, mm);
+ if (ret)
+ return ret;
+ subscriptions = mm->notifier_subscriptions;
+ }
+ return __mmu_interval_notifier_insert(interval_sub, mm, subscriptions,
+ start, length, ops);
+}
+EXPORT_SYMBOL_GPL(mmu_interval_notifier_insert);
+
+int mmu_interval_notifier_insert_locked(
+ struct mmu_interval_notifier *interval_sub, struct mm_struct *mm,
+ unsigned long start, unsigned long length,
+ const struct mmu_interval_notifier_ops *ops)
+{
+ struct mmu_notifier_subscriptions *subscriptions =
+ mm->notifier_subscriptions;
+ int ret;
+
+ mmap_assert_write_locked(mm);
+
+ if (!subscriptions || !subscriptions->has_itree) {
+ ret = __mmu_notifier_register(NULL, mm);
+ if (ret)
+ return ret;
+ subscriptions = mm->notifier_subscriptions;
+ }
+ return __mmu_interval_notifier_insert(interval_sub, mm, subscriptions,
+ start, length, ops);
+}
+EXPORT_SYMBOL_GPL(mmu_interval_notifier_insert_locked);
+
+/**
+ * mmu_interval_notifier_remove - Remove a interval notifier
+ * @interval_sub: Interval subscription to unregister
+ *
+ * This function must be paired with mmu_interval_notifier_insert(). It cannot
+ * be called from any ops callback.
+ *
+ * Once this returns ops callbacks are no longer running on other CPUs and
+ * will not be called in future.
+ */
+void mmu_interval_notifier_remove(struct mmu_interval_notifier *interval_sub)
+{
+ struct mm_struct *mm = interval_sub->mm;
+ struct mmu_notifier_subscriptions *subscriptions =
+ mm->notifier_subscriptions;
+ unsigned long seq = 0;
+
+ might_sleep();
+
+ spin_lock(&subscriptions->lock);
+ if (mn_itree_is_invalidating(subscriptions)) {
+ /*
+ * remove is being called after insert put this on the
+ * deferred list, but before the deferred list was processed.
+ */
+ if (RB_EMPTY_NODE(&interval_sub->interval_tree.rb)) {
+ hlist_del(&interval_sub->deferred_item);
+ } else {
+ hlist_add_head(&interval_sub->deferred_item,
+ &subscriptions->deferred_list);
+ seq = subscriptions->invalidate_seq;
+ }
+ } else {
+ WARN_ON(RB_EMPTY_NODE(&interval_sub->interval_tree.rb));
+ interval_tree_remove(&interval_sub->interval_tree,
+ &subscriptions->itree);
+ }
+ spin_unlock(&subscriptions->lock);
+
+ /*
+ * The possible sleep on progress in the invalidation requires the
+ * caller not hold any locks held by invalidation callbacks.
+ */
+ lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
+ lock_map_release(&__mmu_notifier_invalidate_range_start_map);
+ if (seq)
+ wait_event(subscriptions->wq,
+ READ_ONCE(subscriptions->invalidate_seq) != seq);
+
+ /* pairs with mmgrab in mmu_interval_notifier_insert() */
+ mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmu_interval_notifier_remove);
+
/**
* mmu_notifier_synchronize - Ensure all mmu_notifiers are freed
*