linux-kernel - [RFC PATCH for 4.21 05/16] mm: Provide is_vma

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Date:   Thu,  1 Nov 2018 10:58:33 +0100
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Dave Watson <davejwatson@...com>, Paul Turner <pjt@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Russell King <linux@....linux.org.uk>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>,
        Ben Maurer <bmaurer@...com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Josh Triplett <josh@...htriplett.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-mm@...ck.org
Subject: [RFC PATCH for 4.21 05/16] mm: Provide is_vma_noncached

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@...icios.com>
CC: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
CC: Peter Zijlstra <peterz@...radead.org>
CC: Paul Turner <pjt@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Andy Lutomirski <luto@...capital.net>
CC: Andi Kleen <andi@...stfloor.org>
CC: Dave Watson <davejwatson@...com>
CC: Chris Lameter <cl@...ux.com>
CC: Ingo Molnar <mingo@...hat.com>
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Ben Maurer <bmaurer@...com>
CC: Steven Rostedt <rostedt@...dmis.org>
CC: Josh Triplett <josh@...htriplett.org>
CC: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: Russell King <linux@....linux.org.uk>
CC: Catalin Marinas <catalin.marinas@....com>
CC: Will Deacon <will.deacon@....com>
CC: Michael Kerrisk <mtk.manpages@...il.com>
CC: Boqun Feng <boqun.feng@...il.com>
CC: linux-mm@...ck.org
---
 include/linux/mm.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0416a7204be3..18acf4f339f8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2551,6 +2551,30 @@ 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