linux-kernel - [PATCH 06/10] powerpc/hugetlb: Split the function 'huge_pte

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Date:	Thu,  7 Apr 2016 11:07:40 +0530
From:	Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Cc:	hughd@...gle.com, kirill@...temov.name, n-horiguchi@...jp.nec.com,
	akpm@...ux-foundation.org, mgorman@...hsingularity.net,
	dave.hansen@...el.com, aneesh.kumar@...ux.vnet.ibm.com,
	mpe@...erman.id.au
Subject: [PATCH 06/10] powerpc/hugetlb: Split the function 'huge_pte_offset'

Currently the function 'huge_pte_offset' has just got one version for all
possible configurations and platforms. This change splits that function
into two versions, first one for ARCH_WANT_GENERAL_HUGETLB implementation
and the other one for everything else. This change is again one of the
prerequisites towards enabling ARCH_WANT_GENERAL_ HUGETLB config option
on POWER platform.

Signed-off-by: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/hugetlbpage.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index e453918..8fc6d23 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -53,11 +53,46 @@ static unsigned nr_gpages;
 
 #define hugepd_none(hpd)	((hpd).pd == 0)
 
+#ifndef CONFIG_ARCH_WANT_GENERAL_HUGETLB
 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 {
 	/* Only called for hugetlbfs pages, hence can ignore THP */
 	return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL, NULL);
 }
+#else /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
+pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
+{
+	pgd_t pgd, *pgdp;
+	pud_t pud, *pudp;
+	pmd_t pmd, *pmdp;
+
+	pgdp = mm->pgd + pgd_index(addr);
+	pgd  = READ_ONCE(*pgdp);
+
+	if (pgd_none(pgd))
+		return NULL;
+
+	if (pgd_huge(pgd))
+		return (pte_t *)pgdp;
+
+	pudp = pud_offset(&pgd, addr);
+	pud  = READ_ONCE(*pudp);
+	if (pud_none(pud))
+		return NULL;
+
+	if (pud_huge(pud))
+		return (pte_t *)pudp;
+
+	pmdp = pmd_offset(&pud, addr);
+	pmd  = READ_ONCE(*pmdp);
+	if (pmd_none(pmd))
+		return NULL;
+
+	if (pmd_huge(pmd))
+		return (pte_t *)pmdp;
+	return NULL;
+}
+#endif /* !CONFIG_ARCH_WANT_GENERAL_HUGETLB */
 
 #ifndef CONFIG_ARCH_WANT_GENERAL_HUGETLB
 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
-- 
2.1.0