linux-kernel - [PATCH 04/21] userfaultfd: linux/userfaultfd

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Date:	Thu,  5 Mar 2015 18:17:47 +0100
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	qemu-devel@...gnu.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-api@...r.kernel.org,
	Android Kernel Team <kernel-team@...roid.com>
Cc:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Pavel Emelyanov <xemul@...allels.com>,
	Sanidhya Kashyap <sanidhya.gatech@...il.com>,
	zhang.zhanghailiang@...wei.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Dave Hansen <dave@...1.net>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Andy Lutomirski <luto@...capital.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Peter Feiner <pfeiner@...gle.com>,
	"Dr. David Alan Gilbert" <dgilbert@...hat.com>,
	Christopher Covington <cov@...eaurora.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Robert Love <rlove@...gle.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Neil Brown <neilb@...e.de>, Mike Hommey <mh@...ndium.org>,
	Taras Glek <tglek@...illa.com>, Jan Kara <jack@...e.cz>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Michel Lespinasse <walken@...gle.com>,
	Minchan Kim <minchan@...nel.org>,
	Keith Packard <keithp@...thp.com>,
	"Huangpeng (Peter)" <peter.huangpeng@...wei.com>,
	Anthony Liguori <anthony@...emonkey.ws>,
	Stefan Hajnoczi <stefanha@...il.com>,
	Wenchao Xia <wenchaoqemu@...il.com>,
	Andrew Jones <drjones@...hat.com>,
	Juan Quintela <quintela@...hat.com>
Subject: [PATCH 04/21] userfaultfd: linux/userfaultfd_k.h

Kernel header defining the methods needed by the VM common code to
interact with the userfaultfd.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 include/linux/userfaultfd_k.h | 79 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 include/linux/userfaultfd_k.h

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
new file mode 100644
index 0000000..e1e4360
--- /dev/null
+++ b/include/linux/userfaultfd_k.h
@@ -0,0 +1,79 @@
+/*
+ *  include/linux/userfaultfd_k.h
+ *
+ *  Copyright (C) 2015  Red Hat, Inc.
+ *
+ */
+
+#ifndef _LINUX_USERFAULTFD_K_H
+#define _LINUX_USERFAULTFD_K_H
+
+#ifdef CONFIG_USERFAULTFD
+
+#include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
+
+#include <linux/fcntl.h>
+
+/*
+ * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
+ * new flags, since they might collide with O_* ones. We want
+ * to re-use O_* flags that couldn't possibly have a meaning
+ * from userfaultfd, in order to leave a free define-space for
+ * shared O_* flags.
+ */
+#define UFFD_CLOEXEC O_CLOEXEC
+#define UFFD_NONBLOCK O_NONBLOCK
+
+#define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
+#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
+
+extern int handle_userfault(struct vm_area_struct *vma, unsigned long address,
+			    unsigned int flags, unsigned long reason);
+
+/* mm helpers */
+static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
+					struct vm_userfaultfd_ctx vm_ctx)
+{
+	return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
+}
+
+static inline bool userfaultfd_missing(struct vm_area_struct *vma)
+{
+	return vma->vm_flags & VM_UFFD_MISSING;
+}
+
+static inline bool userfaultfd_armed(struct vm_area_struct *vma)
+{
+	return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
+}
+
+#else /* CONFIG_USERFAULTFD */
+
+/* mm helpers */
+static inline int handle_userfault(struct vm_area_struct *vma,
+				   unsigned long address,
+				   unsigned int flags,
+				   unsigned long reason)
+{
+	return VM_FAULT_SIGBUS;
+}
+
+static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
+					struct vm_userfaultfd_ctx vm_ctx)
+{
+	return true;
+}
+
+static inline bool userfaultfd_missing(struct vm_area_struct *vma)
+{
+	return false;
+}
+
+static inline bool userfaultfd_armed(struct vm_area_struct *vma)
+{
+	return false;
+}
+
+#endif /* CONFIG_USERFAULTFD */
+
+#endif /* _LINUX_USERFAULTFD_K_H */
--
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