167 lines
4.8 KiB
Diff
167 lines
4.8 KiB
Diff
From b70e738f08403950aa3053c36b98c6b0eeb0eb90 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Andr=C3=A9=20Almeida?= <andrealmeid@collabora.com>
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Date: Mon, 25 Oct 2021 09:49:42 -0300
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Subject: [PATCH] futex: Add entry point for FUTEX_WAIT_MULTIPLE (opcode 31)
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Add an option to wait on multiple futexes using the old interface, that
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uses opcode 31 through futex() syscall. Do that by just translation the
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old interface to use the new code. This allows old and stable versions
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of Proton to still use fsync in new kernel releases.
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Signed-off-by: André Almeida <andrealmeid@collabora.com>
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---
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include/uapi/linux/futex.h | 13 +++++++
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kernel/futex/syscalls.c | 75 +++++++++++++++++++++++++++++++++++++-
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2 files changed, 87 insertions(+), 1 deletion(-)
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diff --git a/include/uapi/linux/futex.h b/include/uapi/linux/futex.h
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index 71a5df8d2689..d375ab21cbf8 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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@@ -22,6 +22,7 @@
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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_LOCK_PI2 13
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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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@@ -68,6 +69,18 @@ struct futex_waitv {
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__u32 __reserved;
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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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/*
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* Support for robust futexes: the kernel cleans up held futexes at
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* thread exit time.
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diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c
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index 6f91a07a6a83..2f4d4c04ede2 100644
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--- a/kernel/futex/syscalls.c
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+++ b/kernel/futex/syscalls.c
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@@ -158,6 +158,7 @@ static __always_inline bool futex_cmd_has_timeout(u32 cmd)
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case FUTEX_LOCK_PI2:
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case FUTEX_WAIT_BITSET:
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case FUTEX_WAIT_REQUEUE_PI:
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+ case FUTEX_WAIT_MULTIPLE:
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return true;
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}
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return false;
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@@ -170,13 +171,79 @@ futex_init_timeout(u32 cmd, u32 op, struct timespec64 *ts, ktime_t *t)
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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 (cmd != FUTEX_LOCK_PI && !(op & FUTEX_CLOCK_REALTIME))
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*t = timens_ktime_to_host(CLOCK_MONOTONIC, *t);
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return 0;
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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_vector *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_vector *futexv;
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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_WAITV_MAX)
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+ return ERR_PTR(-EINVAL);
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+
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+ futexv = kcalloc(count, sizeof(*futexv), GFP_KERNEL);
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+ if (!futexv)
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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(futexv);
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+ return ERR_PTR(-EFAULT);
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+ }
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+
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+ futexv[i].w.flags = FUTEX_32;
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+ futexv[i].w.val = fwb.val;
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+ futexv[i].w.uaddr = (uintptr_t) (fwb.uaddr);
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+ futexv[i].q = futex_q_init;
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+ }
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+
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+ return futexv;
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+}
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+
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+int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
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+ struct hrtimer_sleeper *to);
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+
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+int futex_opcode_31(ktime_t *abs_time, u32 __user *uaddr, int count)
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+{
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+ int ret;
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+ struct futex_vector *vs;
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+ struct hrtimer_sleeper *to = NULL, timeout;
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+
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+ to = futex_setup_timer(abs_time, &timeout, 0, 0);
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+
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+ vs = futex_read_wait_block(uaddr, count);
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+
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+ if (IS_ERR(vs))
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+ return PTR_ERR(vs);
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+
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+ ret = futex_wait_multiple(vs, count, abs_time ? to : NULL);
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+ kfree(vs);
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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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SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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const struct __kernel_timespec __user *, utime,
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u32 __user *, uaddr2, u32, val3)
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@@ -196,6 +263,9 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
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tp = &t;
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}
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+ if (cmd == FUTEX_WAIT_MULTIPLE)
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+ return futex_opcode_31(tp, uaddr, val);
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+
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return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
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}
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@@ -392,6 +462,9 @@ SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
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tp = &t;
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}
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+ if (cmd == FUTEX_WAIT_MULTIPLE)
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+ return futex_opcode_31(tp, uaddr, val);
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+
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return do_futex(uaddr, op, val, tp, uaddr2, (unsigned long)utime, val3);
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}
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#endif /* CONFIG_COMPAT_32BIT_TIME */
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--
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2.33.1
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