linux-kernel - [PATCH v12 3/4] x86/mm: implement arch_faults_on_old

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Message-Id: <20191011140939.6115-4-justin.he@arm.com>
Date:   Fri, 11 Oct 2019 22:09:38 +0800
From:   Jia He <justin.he@....com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Marc Zyngier <maz@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Suzuki Poulose <Suzuki.Poulose@....com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>, hejianet@...il.com,
        Kaly Xin <Kaly.Xin@....com>, nd@....com,
        Jia He <justin.he@....com>
Subject: [PATCH v12 3/4] x86/mm: implement arch_faults_on_old_pte() stub on x86

arch_faults_on_old_pte is a helper to indicate that it might cause page
fault when accessing old pte. But on x86, there is feature to setting
pte access flag by hardware. Hence implement an overriding stub which
always returns false.

Signed-off-by: Jia He <justin.he@....com>
Suggested-by: Will Deacon <will@...nel.org>
---
 arch/x86/include/asm/pgtable.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 0bc530c4eb13..ad97dc155195 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1463,6 +1463,12 @@ static inline bool arch_has_pfn_modify_check(void)
 	return boot_cpu_has_bug(X86_BUG_L1TF);
 }
 
+#define arch_faults_on_old_pte arch_faults_on_old_pte
+static inline bool arch_faults_on_old_pte(void)
+{
+	return false;
+}
+
 #include <asm-generic/pgtable.h>
 #endif	/* __ASSEMBLY__ */
 
-- 
2.17.1