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[Qemu-devel] [PATCH 23/23] userfaultfd: UFFDIO_COPY and UFFDIO_ZEROPAGE
From: |
Andrea Arcangeli |
Subject: |
[Qemu-devel] [PATCH 23/23] userfaultfd: UFFDIO_COPY and UFFDIO_ZEROPAGE |
Date: |
Thu, 14 May 2015 19:31:20 +0200 |
These two ioctl allows to either atomically copy or to map zeropages
into the virtual address space. This is used by the thread that opened
the userfaultfd to resolve the userfaults.
Signed-off-by: Andrea Arcangeli <address@hidden>
---
fs/userfaultfd.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 96 insertions(+)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 6772c22..65704cb 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -942,6 +942,96 @@ out:
return ret;
}
+static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
+ unsigned long arg)
+{
+ __s64 ret;
+ struct uffdio_copy uffdio_copy;
+ struct uffdio_copy __user *user_uffdio_copy;
+ struct userfaultfd_wake_range range;
+
+ user_uffdio_copy = (struct uffdio_copy __user *) arg;
+
+ ret = -EFAULT;
+ if (copy_from_user(&uffdio_copy, user_uffdio_copy,
+ /* don't copy "copy" last field */
+ sizeof(uffdio_copy)-sizeof(__s64)))
+ goto out;
+
+ ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
+ if (ret)
+ goto out;
+ /*
+ * double check for wraparound just in case. copy_from_user()
+ * will later check uffdio_copy.src + uffdio_copy.len to fit
+ * in the userland range.
+ */
+ ret = -EINVAL;
+ if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src)
+ goto out;
+ if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE)
+ goto out;
+
+ ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,
+ uffdio_copy.len);
+ if (unlikely(put_user(ret, &user_uffdio_copy->copy)))
+ return -EFAULT;
+ if (ret < 0)
+ goto out;
+ BUG_ON(!ret);
+ /* len == 0 would wake all */
+ range.len = ret;
+ if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) {
+ range.start = uffdio_copy.dst;
+ wake_userfault(ctx, &range);
+ }
+ ret = range.len == uffdio_copy.len ? 0 : -EAGAIN;
+out:
+ return ret;
+}
+
+static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
+ unsigned long arg)
+{
+ __s64 ret;
+ struct uffdio_zeropage uffdio_zeropage;
+ struct uffdio_zeropage __user *user_uffdio_zeropage;
+ struct userfaultfd_wake_range range;
+
+ user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg;
+
+ ret = -EFAULT;
+ if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage,
+ /* don't copy "zeropage" last field */
+ sizeof(uffdio_zeropage)-sizeof(__s64)))
+ goto out;
+
+ ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
+ uffdio_zeropage.range.len);
+ if (ret)
+ goto out;
+ ret = -EINVAL;
+ if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE)
+ goto out;
+
+ ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
+ uffdio_zeropage.range.len);
+ if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage)))
+ return -EFAULT;
+ if (ret < 0)
+ goto out;
+ /* len == 0 would wake all */
+ BUG_ON(!ret);
+ range.len = ret;
+ if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) {
+ range.start = uffdio_zeropage.range.start;
+ wake_userfault(ctx, &range);
+ }
+ ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN;
+out:
+ return ret;
+}
+
/*
* userland asks for a certain API version and we return which bits
* and ioctl commands are implemented in this kernel for such API
@@ -997,6 +1087,12 @@ static long userfaultfd_ioctl(struct file *file, unsigned
cmd,
case UFFDIO_WAKE:
ret = userfaultfd_wake(ctx, arg);
break;
+ case UFFDIO_COPY:
+ ret = userfaultfd_copy(ctx, arg);
+ break;
+ case UFFDIO_ZEROPAGE:
+ ret = userfaultfd_zeropage(ctx, arg);
+ break;
}
return ret;
}
- [Qemu-devel] [PATCH 04/23] userfaultfd: linux/userfaultfd_k.h, (continued)
- [Qemu-devel] [PATCH 04/23] userfaultfd: linux/userfaultfd_k.h, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 12/23] userfaultfd: Rename uffd_api.bits into .features fixup, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 11/23] userfaultfd: Rename uffd_api.bits into .features, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 09/23] userfaultfd: prevent khugepaged to merge if userfaultfd is armed, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 22/23] userfaultfd: avoid mmap_sem read recursion in mcopy_atomic, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 14/23] userfaultfd: wake pending userfaults, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 02/23] userfaultfd: waitqueue: add nr wake parameter to __wake_up_locked_key, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 08/23] userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 07/23] userfaultfd: call handle_userfault() for userfaultfd_missing() faults, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 13/23] userfaultfd: change the read API to return a uffd_msg, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 23/23] userfaultfd: UFFDIO_COPY and UFFDIO_ZEROPAGE,
Andrea Arcangeli <=
- [Qemu-devel] [PATCH 01/23] userfaultfd: linux/Documentation/vm/userfaultfd.txt, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 16/23] userfaultfd: allocate the userfaultfd_ctx cacheline aligned, Andrea Arcangeli, 2015/05/14
- [Qemu-devel] [PATCH 10/23] userfaultfd: add new syscall to provide memory externalization, Andrea Arcangeli, 2015/05/14
- Re: [Qemu-devel] [PATCH 00/23] userfaultfd v4, Pavel Emelyanov, 2015/05/18
- Re: [Qemu-devel] [PATCH 00/23] userfaultfd v4, Andrew Morton, 2015/05/19