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00833b56d8
commit
c08decaa1b
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Load Diff
@ -0,0 +1,502 @@
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# Calculate format=diff merge(sys-kernel/calculate-sources[fsync])!=
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From 7229895c1a6432219d05b02c8702189ab65570b3 Mon Sep 17 00:00:00 2001
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From: Piotr Gorski <lucjan.lucjanov@gmail.com>
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Date: Tue, 13 Apr 2021 16:06:05 +0200
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Subject: [PATCH] futex: resync from gitlab.collabora.com
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Signed-off-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
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---
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include/uapi/linux/futex.h | 20 +++
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kernel/futex.c | 357 ++++++++++++++++++++++++++++++++++++-
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2 files changed, 373 insertions(+), 4 deletions(-)
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diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h
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index a89eb0acc..a3e760886 100644
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--- a/include/uapi/linux/futex.h
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+++ b/include/uapi/linux/futex.h
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@@ -21,6 +21,7 @@
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#define FUTEX_WAKE_BITSET 10
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#define FUTEX_WAIT_REQUEUE_PI 11
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#define FUTEX_CMP_REQUEUE_PI 12
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+#define FUTEX_WAIT_MULTIPLE 31
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#define FUTEX_PRIVATE_FLAG 128
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#define FUTEX_CLOCK_REALTIME 256
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@@ -40,6 +41,8 @@
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FUTEX_PRIVATE_FLAG)
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#define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \
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FUTEX_PRIVATE_FLAG)
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+#define FUTEX_WAIT_MULTIPLE_PRIVATE (FUTEX_WAIT_MULTIPLE | \
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+ FUTEX_PRIVATE_FLAG)
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/*
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* Support for robust futexes: the kernel cleans up held futexes at
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@@ -150,4 +153,21 @@ struct robust_list_head {
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(((op & 0xf) << 28) | ((cmp & 0xf) << 24) \
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| ((oparg & 0xfff) << 12) | (cmparg & 0xfff))
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+/*
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+ * Maximum number of multiple futexes to wait for
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+ */
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+#define FUTEX_MULTIPLE_MAX_COUNT 128
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+
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+/**
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+ * struct futex_wait_block - Block of futexes to be waited for
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+ * @uaddr: User address of the futex
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+ * @val: Futex value expected by userspace
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+ * @bitset: Bitset for the optional bitmasked wakeup
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+ */
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+struct futex_wait_block {
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+ __u32 __user *uaddr;
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+ __u32 val;
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+ __u32 bitset;
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+};
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+
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#endif /* _UAPI_LINUX_FUTEX_H */
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diff --git a/kernel/futex.c b/kernel/futex.c
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index 00febd6de..6859dd7ca 100644
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--- a/kernel/futex.c
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+++ b/kernel/futex.c
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@@ -198,6 +198,8 @@ struct futex_pi_state {
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* @rt_waiter: rt_waiter storage for use with requeue_pi
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* @requeue_pi_key: the requeue_pi target futex key
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* @bitset: bitset for the optional bitmasked wakeup
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+ * @uaddr: userspace address of futex
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+ * @uval: expected futex's value
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*
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* We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so
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* we can wake only the relevant ones (hashed queues may be shared).
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@@ -220,6 +222,8 @@ struct futex_q {
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struct rt_mutex_waiter *rt_waiter;
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union futex_key *requeue_pi_key;
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u32 bitset;
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+ u32 __user *uaddr;
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+ u32 uval;
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} __randomize_layout;
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static const struct futex_q futex_q_init = {
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@@ -2313,6 +2317,29 @@ static int unqueue_me(struct futex_q *q)
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return ret;
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}
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+/**
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+ * unqueue_multiple() - Remove several futexes from their futex_hash_bucket
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+ * @q: The list of futexes to unqueue
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+ * @count: Number of futexes in the list
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+ *
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+ * Helper to unqueue a list of futexes. This can't fail.
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+ *
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+ * Return:
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+ * - >=0 - Index of the last futex that was awoken;
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+ * - -1 - If no futex was awoken
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+ */
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+static int unqueue_multiple(struct futex_q *q, int count)
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+{
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+ int ret = -1;
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+ int i;
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+
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+ for (i = 0; i < count; i++) {
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+ if (!unqueue_me(&q[i]))
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+ ret = i;
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+ }
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+ return ret;
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+}
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+
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/*
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* PI futexes can not be requeued and must remove themself from the
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* hash bucket. The hash bucket lock (i.e. lock_ptr) is held on entry
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@@ -2680,6 +2707,205 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
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return ret;
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}
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+/**
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+ * futex_wait_multiple_setup() - Prepare to wait and enqueue multiple futexes
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+ * @qs: The corresponding futex list
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+ * @count: The size of the lists
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+ * @flags: Futex flags (FLAGS_SHARED, etc.)
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+ * @awaken: Index of the last awoken futex
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+ *
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+ * Prepare multiple futexes in a single step and enqueue them. This may fail if
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+ * the futex list is invalid or if any futex was already awoken. On success the
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+ * task is ready to interruptible sleep.
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+ *
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+ * Return:
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+ * - 1 - One of the futexes was awaken by another thread
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+ * - 0 - Success
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+ * - <0 - -EFAULT, -EWOULDBLOCK or -EINVAL
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+ */
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+static int futex_wait_multiple_setup(struct futex_q *qs, int count,
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+ unsigned int flags, int *awaken)
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+{
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+ struct futex_hash_bucket *hb;
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+ int ret, i;
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+ u32 uval;
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+
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+ /*
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+ * Enqueuing multiple futexes is tricky, because we need to
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+ * enqueue each futex in the list before dealing with the next
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+ * one to avoid deadlocking on the hash bucket. But, before
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+ * enqueuing, we need to make sure that current->state is
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+ * TASK_INTERRUPTIBLE, so we don't absorb any awake events, which
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+ * cannot be done before the get_futex_key of the next key,
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+ * because it calls get_user_pages, which can sleep. Thus, we
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+ * fetch the list of futexes keys in two steps, by first pinning
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+ * all the memory keys in the futex key, and only then we read
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+ * each key and queue the corresponding futex.
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+ */
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+retry:
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+ for (i = 0; i < count; i++) {
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+ qs[i].key = FUTEX_KEY_INIT;
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+ ret = get_futex_key(qs[i].uaddr, flags & FLAGS_SHARED,
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+ &qs[i].key, FUTEX_READ);
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+ if (unlikely(ret)) {
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+ return ret;
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+ }
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+ }
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+
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+ set_current_state(TASK_INTERRUPTIBLE);
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+
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+ for (i = 0; i < count; i++) {
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+ struct futex_q *q = &qs[i];
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+
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+ hb = queue_lock(q);
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+
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+ ret = get_futex_value_locked(&uval, q->uaddr);
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+ if (ret) {
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+ /*
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+ * We need to try to handle the fault, which
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+ * cannot be done without sleep, so we need to
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+ * undo all the work already done, to make sure
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+ * we don't miss any wake ups. Therefore, clean
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+ * up, handle the fault and retry from the
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+ * beginning.
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+ */
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+ queue_unlock(hb);
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+
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+ /*
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+ * Keys 0..(i-1) are implicitly put
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+ * on unqueue_multiple.
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+ */
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+ *awaken = unqueue_multiple(qs, i);
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+
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+ __set_current_state(TASK_RUNNING);
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+
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+ /*
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+ * On a real fault, prioritize the error even if
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+ * some other futex was awoken. Userspace gave
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+ * us a bad address, -EFAULT them.
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+ */
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+ ret = get_user(uval, q->uaddr);
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+ if (ret)
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+ return ret;
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+
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+ /*
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+ * Even if the page fault was handled, If
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+ * something was already awaken, we can safely
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+ * give up and succeed to give a hint for userspace to
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+ * acquire the right futex faster.
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+ */
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+ if (*awaken >= 0)
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+ return 1;
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+
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+ goto retry;
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+ }
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+
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+ if (uval != q->uval) {
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+ queue_unlock(hb);
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+
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+ /*
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+ * If something was already awaken, we can
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+ * safely ignore the error and succeed.
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+ */
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+ *awaken = unqueue_multiple(qs, i);
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+ __set_current_state(TASK_RUNNING);
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+ if (*awaken >= 0)
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+ return 1;
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+
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+ return -EWOULDBLOCK;
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+ }
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+
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+ /*
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+ * The bucket lock can't be held while dealing with the
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+ * next futex. Queue each futex at this moment so hb can
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+ * be unlocked.
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+ */
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+ queue_me(&qs[i], hb);
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+ }
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+ return 0;
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+}
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+
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+/**
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+ * futex_wait_multiple() - Prepare to wait on and enqueue several futexes
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+ * @qs: The list of futexes to wait on
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+ * @op: Operation code from futex's syscall
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+ * @count: The number of objects
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+ * @abs_time: Timeout before giving up and returning to userspace
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+ *
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+ * Entry point for the FUTEX_WAIT_MULTIPLE futex operation, this function
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+ * sleeps on a group of futexes and returns on the first futex that
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+ * triggered, or after the timeout has elapsed.
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+ *
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+ * Return:
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+ * - >=0 - Hint to the futex that was awoken
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+ * - <0 - On error
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+ */
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+static int futex_wait_multiple(struct futex_q *qs, int op,
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+ u32 count, ktime_t *abs_time)
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+{
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+ struct hrtimer_sleeper timeout, *to;
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+ int ret, flags = 0, hint = 0;
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+ unsigned int i;
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+
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+ if (!(op & FUTEX_PRIVATE_FLAG))
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+ flags |= FLAGS_SHARED;
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+
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+ if (op & FUTEX_CLOCK_REALTIME)
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+ flags |= FLAGS_CLOCKRT;
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+
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+ to = futex_setup_timer(abs_time, &timeout, flags, 0);
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+ while (1) {
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+ ret = futex_wait_multiple_setup(qs, count, flags, &hint);
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+ if (ret) {
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+ if (ret > 0) {
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+ /* A futex was awaken during setup */
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+ ret = hint;
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+ }
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+ break;
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+ }
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+
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+ if (to)
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+ hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS);
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+
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+ /*
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+ * Avoid sleeping if another thread already tried to
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+ * wake us.
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+ */
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+ for (i = 0; i < count; i++) {
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+ if (plist_node_empty(&qs[i].list))
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+ break;
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+ }
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+
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+ if (i == count && (!to || to->task))
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+ freezable_schedule();
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+
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+ ret = unqueue_multiple(qs, count);
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+
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+ __set_current_state(TASK_RUNNING);
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+
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+ if (ret >= 0)
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+ break;
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+ if (to && !to->task) {
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+ ret = -ETIMEDOUT;
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+ break;
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+ } else if (signal_pending(current)) {
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+ ret = -ERESTARTSYS;
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+ break;
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+ }
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+ /*
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+ * The final case is a spurious wakeup, for
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+ * which just retry.
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+ */
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+ }
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+
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+ if (to) {
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+ hrtimer_cancel(&to->timer);
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+ destroy_hrtimer_on_stack(&to->timer);
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+ }
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+
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+ return ret;
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+}
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+
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static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
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ktime_t *abs_time, u32 bitset)
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{
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@@ -3759,6 +3985,43 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
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return -ENOSYS;
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}
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+/**
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+ * futex_read_wait_block - Read an array of futex_wait_block from userspace
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+ * @uaddr: Userspace address of the block
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+ * @count: Number of blocks to be read
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+ *
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+ * This function creates and allocate an array of futex_q (we zero it to
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+ * initialize the fields) and then, for each futex_wait_block element from
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+ * userspace, fill a futex_q element with proper values.
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+ */
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+inline struct futex_q *futex_read_wait_block(u32 __user *uaddr, u32 count)
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+{
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+ unsigned int i;
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+ struct futex_q *qs;
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+ struct futex_wait_block fwb;
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+ struct futex_wait_block __user *entry =
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+ (struct futex_wait_block __user *)uaddr;
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+
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+ if (!count || count > FUTEX_MULTIPLE_MAX_COUNT)
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+ return ERR_PTR(-EINVAL);
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+
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+ qs = kcalloc(count, sizeof(*qs), GFP_KERNEL);
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+ if (!qs)
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+ return ERR_PTR(-ENOMEM);
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+
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+ for (i = 0; i < count; i++) {
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+ if (copy_from_user(&fwb, &entry[i], sizeof(fwb))) {
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+ kfree(qs);
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+ return ERR_PTR(-EFAULT);
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+ }
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+
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+ qs[i].uaddr = fwb.uaddr;
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+ qs[i].uval = fwb.val;
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+ qs[i].bitset = fwb.bitset;
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+ }
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+
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+ return qs;
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+}
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SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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const struct __kernel_timespec __user *, utime,
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@@ -3771,7 +4034,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
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cmd == FUTEX_WAIT_BITSET ||
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- cmd == FUTEX_WAIT_REQUEUE_PI)) {
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+ cmd == FUTEX_WAIT_REQUEUE_PI ||
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+ cmd == FUTEX_WAIT_MULTIPLE)) {
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if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
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return -EFAULT;
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if (get_timespec64(&ts, utime))
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@@ -3780,7 +4044,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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return -EINVAL;
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t = timespec64_to_ktime(ts);
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- if (cmd == FUTEX_WAIT)
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+ if (cmd == FUTEX_WAIT || cmd == FUTEX_WAIT_MULTIPLE)
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t = ktime_add_safe(ktime_get(), t);
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else if (!(op & FUTEX_CLOCK_REALTIME))
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t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
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@@ -3794,6 +4058,25 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
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val2 = (u32) (unsigned long) utime;
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+ if (cmd == FUTEX_WAIT_MULTIPLE) {
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+ int ret;
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+ struct futex_q *qs;
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+
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+#ifdef CONFIG_X86_X32
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+ if (unlikely(in_x32_syscall()))
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+ return -ENOSYS;
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+#endif
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+ qs = futex_read_wait_block(uaddr, val);
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+
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+ if (IS_ERR(qs))
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+ return PTR_ERR(qs);
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+
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+ ret = futex_wait_multiple(qs, op, val, tp);
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+ kfree(qs);
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+
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+ return ret;
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+ }
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+
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return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
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}
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@@ -3956,6 +4239,58 @@ COMPAT_SYSCALL_DEFINE3(get_robust_list, int, pid,
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#endif /* CONFIG_COMPAT */
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#ifdef CONFIG_COMPAT_32BIT_TIME
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+/**
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+ * struct compat_futex_wait_block - Block of futexes to be waited for
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+ * @uaddr: User address of the futex (compatible pointer)
|
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+ * @val: Futex value expected by userspace
|
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+ * @bitset: Bitset for the optional bitmasked wakeup
|
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+ */
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+struct compat_futex_wait_block {
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+ compat_uptr_t uaddr;
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+ __u32 pad;
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+ __u32 val;
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+ __u32 bitset;
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+};
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+
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+/**
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+ * compat_futex_read_wait_block - Read an array of futex_wait_block from
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+ * userspace
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+ * @uaddr: Userspace address of the block
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+ * @count: Number of blocks to be read
|
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+ *
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+ * This function does the same as futex_read_wait_block(), except that it
|
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+ * converts the pointer to the futex from the compat version to the regular one.
|
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+ */
|
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+inline struct futex_q *compat_futex_read_wait_block(u32 __user *uaddr,
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+ u32 count)
|
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+{
|
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+ unsigned int i;
|
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+ struct futex_q *qs;
|
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+ struct compat_futex_wait_block fwb;
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+ struct compat_futex_wait_block __user *entry =
|
||||
+ (struct compat_futex_wait_block __user *)uaddr;
|
||||
+
|
||||
+ if (!count || count > FUTEX_MULTIPLE_MAX_COUNT)
|
||||
+ return ERR_PTR(-EINVAL);
|
||||
+
|
||||
+ qs = kcalloc(count, sizeof(*qs), GFP_KERNEL);
|
||||
+ if (!qs)
|
||||
+ return ERR_PTR(-ENOMEM);
|
||||
+
|
||||
+ for (i = 0; i < count; i++) {
|
||||
+ if (copy_from_user(&fwb, &entry[i], sizeof(fwb))) {
|
||||
+ kfree(qs);
|
||||
+ return ERR_PTR(-EFAULT);
|
||||
+ }
|
||||
+
|
||||
+ qs[i].uaddr = compat_ptr(fwb.uaddr);
|
||||
+ qs[i].uval = fwb.val;
|
||||
+ qs[i].bitset = fwb.bitset;
|
||||
+ }
|
||||
+
|
||||
+ return qs;
|
||||
+}
|
||||
+
|
||||
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
|
||||
const struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
|
||||
u32, val3)
|
||||
@@ -3967,14 +4302,15 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
|
||||
|
||||
if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
|
||||
cmd == FUTEX_WAIT_BITSET ||
|
||||
- cmd == FUTEX_WAIT_REQUEUE_PI)) {
|
||||
+ cmd == FUTEX_WAIT_REQUEUE_PI ||
|
||||
+ cmd == FUTEX_WAIT_MULTIPLE)) {
|
||||
if (get_old_timespec32(&ts, utime))
|
||||
return -EFAULT;
|
||||
if (!timespec64_valid(&ts))
|
||||
return -EINVAL;
|
||||
|
||||
t = timespec64_to_ktime(ts);
|
||||
- if (cmd == FUTEX_WAIT)
|
||||
+ if (cmd == FUTEX_WAIT || cmd == FUTEX_WAIT_MULTIPLE)
|
||||
t = ktime_add_safe(ktime_get(), t);
|
||||
else if (!(op & FUTEX_CLOCK_REALTIME))
|
||||
t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
|
||||
@@ -3984,6 +4320,19 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
|
||||
cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
|
||||
val2 = (int) (unsigned long) utime;
|
||||
|
||||
+ if (cmd == FUTEX_WAIT_MULTIPLE) {
|
||||
+ int ret;
|
||||
+ struct futex_q *qs = compat_futex_read_wait_block(uaddr, val);
|
||||
+
|
||||
+ if (IS_ERR(qs))
|
||||
+ return PTR_ERR(qs);
|
||||
+
|
||||
+ ret = futex_wait_multiple(qs, op, val, tp);
|
||||
+ kfree(qs);
|
||||
+
|
||||
+ return ret;
|
||||
+ }
|
||||
+
|
||||
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
|
||||
}
|
||||
#endif /* CONFIG_COMPAT_32BIT_TIME */
|
||||
--
|
||||
2.31.1.305.gd1b10fc6d8
|
||||
|
||||
Loading…
Reference in new issue