diff options
Diffstat (limited to 'drivers/android/node.rs')
| -rw-r--r-- | drivers/android/node.rs | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/drivers/android/node.rs b/drivers/android/node.rs new file mode 100644 index 000000000000..ce4367a78436 --- /dev/null +++ b/drivers/android/node.rs @@ -0,0 +1,476 @@ +// SPDX-License-Identifier: GPL-2.0 + +use core::sync::atomic::{AtomicU64, Ordering}; +use kernel::{ + io_buffer::IoBufferWriter, + linked_list::{GetLinks, Links, List}, + prelude::*, + sync::{Arc, Guard, LockedBy, Mutex, SpinLock}, + user_ptr::UserSlicePtrWriter, +}; + +use crate::{ + defs::*, + process::{Process, ProcessInner}, + thread::{BinderError, BinderResult, Thread}, + DeliverToRead, +}; + +struct CountState { + count: usize, + has_count: bool, + is_biased: bool, +} + +impl CountState { + fn new() -> Self { + Self { + count: 0, + has_count: false, + is_biased: false, + } + } + + fn add_bias(&mut self) { + self.count += 1; + self.is_biased = true; + } +} + +struct NodeInner { + strong: CountState, + weak: CountState, + death_list: List<Arc<NodeDeath>>, +} + +struct NodeDeathInner { + dead: bool, + cleared: bool, + notification_done: bool, + + /// Indicates whether the normal flow was interrupted by removing the handle. In this case, we + /// need behave as if the death notification didn't exist (i.e., we don't deliver anything to + /// the user. + aborted: bool, +} + +pub(crate) struct NodeDeath { + node: Arc<Node>, + process: Arc<Process>, + // TODO: Make this private. + pub(crate) cookie: usize, + work_links: Links<dyn DeliverToRead>, + // TODO: Add the moment we're using this for two lists, which isn't safe because we want to + // remove from the list without knowing the list it's in. We need to separate this out. + death_links: Links<NodeDeath>, + inner: SpinLock<NodeDeathInner>, +} + +impl NodeDeath { + /// Constructs a new node death notification object. + /// + /// # Safety + /// + /// The caller must call `NodeDeath::init` before using the notification object. + pub(crate) unsafe fn new(node: Arc<Node>, process: Arc<Process>, cookie: usize) -> Self { + Self { + node, + process, + cookie, + work_links: Links::new(), + death_links: Links::new(), + inner: unsafe { + SpinLock::new(NodeDeathInner { + dead: false, + cleared: false, + notification_done: false, + aborted: false, + }) + }, + } + } + + pub(crate) fn init(self: Pin<&mut Self>) { + // SAFETY: `inner` is pinned when `self` is. + let inner = unsafe { self.map_unchecked_mut(|n| &mut n.inner) }; + kernel::spinlock_init!(inner, "NodeDeath::inner"); + } + + /// Sets the cleared flag to `true`. + /// + /// It removes `self` from the node's death notification list if needed. It must only be called + /// once. + /// + /// Returns whether it needs to be queued. + pub(crate) fn set_cleared(self: &Arc<Self>, abort: bool) -> bool { + let (needs_removal, needs_queueing) = { + // Update state and determine if we need to queue a work item. We only need to do it + // when the node is not dead or if the user already completed the death notification. + let mut inner = self.inner.lock(); + inner.cleared = true; + if abort { + inner.aborted = true; + } + (!inner.dead, !inner.dead || inner.notification_done) + }; + + // Remove death notification from node. + if needs_removal { + let mut owner_inner = self.node.owner.inner.lock(); + let node_inner = self.node.inner.access_mut(&mut owner_inner); + unsafe { node_inner.death_list.remove(self) }; + } + + needs_queueing + } + + /// Sets the 'notification done' flag to `true`. + /// + /// Returns whether it needs to be queued. + pub(crate) fn set_notification_done(self: Arc<Self>, thread: &Thread) { + let needs_queueing = { + let mut inner = self.inner.lock(); + inner.notification_done = true; + inner.cleared + }; + + if needs_queueing { + let _ = thread.push_work_if_looper(self); + } + } + + /// Sets the 'dead' flag to `true` and queues work item if needed. + pub(crate) fn set_dead(self: Arc<Self>) { + let needs_queueing = { + let mut inner = self.inner.lock(); + if inner.cleared { + false + } else { + inner.dead = true; + true + } + }; + + if needs_queueing { + // Push the death notification to the target process. There is nothing else to do if + // it's already dead. + let process = self.process.clone(); + let _ = process.push_work(self); + } + } +} + +impl GetLinks for NodeDeath { + type EntryType = NodeDeath; + fn get_links(data: &NodeDeath) -> &Links<NodeDeath> { + &data.death_links + } +} + +impl DeliverToRead for NodeDeath { + fn do_work(self: Arc<Self>, _thread: &Thread, writer: &mut UserSlicePtrWriter) -> Result<bool> { + let done = { + let inner = self.inner.lock(); + if inner.aborted { + return Ok(true); + } + inner.cleared && (!inner.dead || inner.notification_done) + }; + + let cookie = self.cookie; + let cmd = if done { + BR_CLEAR_DEATH_NOTIFICATION_DONE + } else { + let process = self.process.clone(); + let mut process_inner = process.inner.lock(); + let inner = self.inner.lock(); + if inner.aborted { + return Ok(true); + } + // We're still holding the inner lock, so it cannot be aborted while we insert it into + // the delivered list. + process_inner.death_delivered(self.clone()); + BR_DEAD_BINDER + }; + + writer.write(&cmd)?; + writer.write(&cookie)?; + + // Mimic the original code: we stop processing work items when we get to a death + // notification. + Ok(cmd != BR_DEAD_BINDER) + } + + fn get_links(&self) -> &Links<dyn DeliverToRead> { + &self.work_links + } +} + +pub(crate) struct Node { + pub(crate) global_id: u64, + ptr: usize, + cookie: usize, + pub(crate) flags: u32, + pub(crate) owner: Arc<Process>, + inner: LockedBy<NodeInner, Mutex<ProcessInner>>, + links: Links<dyn DeliverToRead>, +} + +impl Node { + pub(crate) fn new(ptr: usize, cookie: usize, flags: u32, owner: Arc<Process>) -> Self { + static NEXT_ID: AtomicU64 = AtomicU64::new(1); + let inner = LockedBy::new( + &owner.inner, + NodeInner { + strong: CountState::new(), + weak: CountState::new(), + death_list: List::new(), + }, + ); + Self { + global_id: NEXT_ID.fetch_add(1, Ordering::Relaxed), + ptr, + cookie, + flags, + owner, + inner, + links: Links::new(), + } + } + + pub(crate) fn get_id(&self) -> (usize, usize) { + (self.ptr, self.cookie) + } + + pub(crate) fn next_death( + &self, + guard: &mut Guard<'_, Mutex<ProcessInner>>, + ) -> Option<Arc<NodeDeath>> { + self.inner.access_mut(guard).death_list.pop_front() + } + + pub(crate) fn add_death( + &self, + death: Arc<NodeDeath>, + guard: &mut Guard<'_, Mutex<ProcessInner>>, + ) { + self.inner.access_mut(guard).death_list.push_back(death); + } + + pub(crate) fn update_refcount_locked( + &self, + inc: bool, + strong: bool, + biased: bool, + owner_inner: &mut ProcessInner, + ) -> bool { + let inner = self.inner.access_from_mut(owner_inner); + + // Get a reference to the state we'll update. + let state = if strong { + &mut inner.strong + } else { + &mut inner.weak + }; + + // Update biased state: if the count is not biased, there is nothing to do; otherwise, + // we're removing the bias, so mark the state as such. + if biased { + if !state.is_biased { + return false; + } + + state.is_biased = false; + } + + // Update the count and determine whether we need to push work. + // TODO: Here we may want to check the weak count being zero but the strong count being 1, + // because in such cases, we won't deliver anything to userspace, so we shouldn't queue + // either. + if inc { + state.count += 1; + !state.has_count + } else { + state.count -= 1; + state.count == 0 && state.has_count + } + } + + pub(crate) fn update_refcount(self: &Arc<Self>, inc: bool, strong: bool) { + self.owner + .inner + .lock() + .update_node_refcount(self, inc, strong, false, None); + } + + pub(crate) fn populate_counts( + &self, + out: &mut BinderNodeInfoForRef, + guard: &Guard<'_, Mutex<ProcessInner>>, + ) { + let inner = self.inner.access(guard); + out.strong_count = inner.strong.count as _; + out.weak_count = inner.weak.count as _; + } + + pub(crate) fn populate_debug_info( + &self, + out: &mut BinderNodeDebugInfo, + guard: &Guard<'_, Mutex<ProcessInner>>, + ) { + out.ptr = self.ptr as _; + out.cookie = self.cookie as _; + let inner = self.inner.access(guard); + if inner.strong.has_count { + out.has_strong_ref = 1; + } + if inner.weak.has_count { + out.has_weak_ref = 1; + } + } + + pub(crate) fn force_has_count(&self, guard: &mut Guard<'_, Mutex<ProcessInner>>) { + let inner = self.inner.access_mut(guard); + inner.strong.has_count = true; + inner.weak.has_count = true; + } + + fn write(&self, writer: &mut UserSlicePtrWriter, code: u32) -> Result { + writer.write(&code)?; + writer.write(&self.ptr)?; + writer.write(&self.cookie)?; + Ok(()) + } +} + +impl DeliverToRead for Node { + fn do_work(self: Arc<Self>, _thread: &Thread, writer: &mut UserSlicePtrWriter) -> Result<bool> { + let mut owner_inner = self.owner.inner.lock(); + let inner = self.inner.access_mut(&mut owner_inner); + let strong = inner.strong.count > 0; + let has_strong = inner.strong.has_count; + let weak = strong || inner.weak.count > 0; + let has_weak = inner.weak.has_count; + inner.weak.has_count = weak; + inner.strong.has_count = strong; + + if !weak { + // Remove the node if there are no references to it. + owner_inner.remove_node(self.ptr); + } else { + if !has_weak { + inner.weak.add_bias(); + } + + if !has_strong && strong { + inner.strong.add_bias(); + } + } + + drop(owner_inner); + + // This could be done more compactly but we write out all the posibilities for + // compatibility with the original implementation wrt the order of events. + if weak && !has_weak { + self.write(writer, BR_INCREFS)?; + } + + if strong && !has_strong { + self.write(writer, BR_ACQUIRE)?; + } + + if !strong && has_strong { + self.write(writer, BR_RELEASE)?; + } + + if !weak && has_weak { + self.write(writer, BR_DECREFS)?; + } + + Ok(true) + } + + fn get_links(&self) -> &Links<dyn DeliverToRead> { + &self.links + } +} + +pub(crate) struct NodeRef { + pub(crate) node: Arc<Node>, + strong_count: usize, + weak_count: usize, +} + +impl NodeRef { + pub(crate) fn new(node: Arc<Node>, strong_count: usize, weak_count: usize) -> Self { + Self { + node, + strong_count, + weak_count, + } + } + + pub(crate) fn absorb(&mut self, mut other: Self) { + self.strong_count += other.strong_count; + self.weak_count += other.weak_count; + other.strong_count = 0; + other.weak_count = 0; + } + + pub(crate) fn clone(&self, strong: bool) -> BinderResult<NodeRef> { + if strong && self.strong_count == 0 { + return Err(BinderError::new_failed()); + } + + Ok(self + .node + .owner + .inner + .lock() + .new_node_ref(self.node.clone(), strong, None)) + } + + /// Updates (increments or decrements) the number of references held against the node. If the + /// count being updated transitions from 0 to 1 or from 1 to 0, the node is notified by having + /// its `update_refcount` function called. + /// + /// Returns whether `self` should be removed (when both counts are zero). + pub(crate) fn update(&mut self, inc: bool, strong: bool) -> bool { + if strong && self.strong_count == 0 { + return false; + } + + let (count, other_count) = if strong { + (&mut self.strong_count, self.weak_count) + } else { + (&mut self.weak_count, self.strong_count) + }; + + if inc { + if *count == 0 { + self.node.update_refcount(true, strong); + } + *count += 1; + } else { + *count -= 1; + if *count == 0 { + self.node.update_refcount(false, strong); + return other_count == 0; + } + } + + false + } +} + +impl Drop for NodeRef { + fn drop(&mut self) { + if self.strong_count > 0 { + self.node.update_refcount(false, true); + } + + if self.weak_count > 0 { + self.node.update_refcount(false, false); + } + } +} |