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From:   Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Dave Watson <davejwatson@fb.com>
Cc:     linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Paul Turner <pjt@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Russell King <linux@arm.linux.org.uk>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>, Andrew Hunter <ahh@google.com>,
        Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
        Ben Maurer <bmaurer@fb.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-mm@kvack.org
Subject: [RFC PATCH for 4.18 11/23] mm: Provide is_vma_noncached
Date:   Thu, 12 Apr 2018 15:27:48 -0400
Message-Id: <20180412192800.15708-12-mathieu.desnoyers@efficios.com>
In-Reply-To: <20180412192800.15708-1-mathieu.desnoyers@efficios.com>
References: <20180412192800.15708-1-mathieu.desnoyers@efficios.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Provide is_vma_noncached() static inline to allow generic code to
check whether the given vma consists of noncached memory.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Paul Turner <pjt@google.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Andrew Hunter <ahh@google.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andi Kleen <andi@firstfloor.org>
CC: Dave Watson <davejwatson@fb.com>
CC: Chris Lameter <cl@linux.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Ben Maurer <bmaurer@fb.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Russell King <linux@arm.linux.org.uk>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Michael Kerrisk <mtk.manpages@gmail.com>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: linux-mm@kvack.org
---
 include/linux/mm.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ad06d42adb1a..1f93a061a43b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2425,6 +2425,30 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
 	return follow_page_mask(vma, address, foll_flags, &unused_page_mask);
 }
 
+static inline bool pgprot_same(pgprot_t a, pgprot_t b)
+{
+	return pgprot_val(a) == pgprot_val(b);
+}
+
+#ifdef pgprot_noncached
+static inline bool is_vma_noncached(struct vm_area_struct *vma)
+{
+	pgprot_t pgprot = vma->vm_page_prot;
+
+	/* Check whether architecture implements noncached pages. */
+	if (pgprot_same(pgprot_noncached(PAGE_KERNEL), PAGE_KERNEL))
+		return false;
+	if (!pgprot_same(pgprot, pgprot_noncached(pgprot)))
+		return false;
+	return true;
+}
+#else
+static inline bool is_vma_noncached(struct vm_area_struct *vma)
+{
+	return false;
+}
+#endif
+
 #define FOLL_WRITE	0x01	/* check pte is writable */
 #define FOLL_TOUCH	0x02	/* mark page accessed */
 #define FOLL_GET	0x04	/* do get_page on page */
-- 
2.11.0