linux-kernel - [PATCH V17 1/2] x86/mm: Define mm_p4d

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Date:   Tue, 21 Apr 2020 08:04:54 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-mm@...ck.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill@...temov.name>
Subject: [PATCH V17 1/2] x86/mm: Define mm_p4d_folded()

This just defines mm_p4d_folded() to check whether P4D page table level is
folded at runtime.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org

Signed-off-by: Kirill A. Shutemov <kirill@...temov.name>
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
 arch/x86/include/asm/pgtable_64.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index df1373415f11..8d03ffd43794 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -53,6 +53,12 @@ static inline void sync_initial_page_table(void) { }
 
 struct mm_struct;
 
+#define mm_p4d_folded mm_p4d_folded
+static inline bool mm_p4d_folded(struct mm_struct *mm)
+{
+	return !pgtable_l5_enabled();
+}
+
 void set_pte_vaddr_p4d(p4d_t *p4d_page, unsigned long vaddr, pte_t new_pte);
 void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte);
 
-- 
2.20.1