linux-kernel - [PATCH v12 5/5] arm64: Allow huge io mappings again

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Date:   Fri,  1 Jun 2018 18:09:18 +0530
From:   Chintan Pandya <cpandya@...eaurora.org>
To:     will.deacon@....com, catalin.marinas@....com, mark.rutland@....com,
        akpm@...ux-foundation.org
Cc:     toshi.kani@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Chintan Pandya <cpandya@...eaurora.org>
Subject: [PATCH v12 5/5] arm64: Allow huge io mappings again

Huge mappings have had stability issues due to stale
TLB entry and memory leak issues. Since, those are
addressed in this series of patches, it is now safe
to allow huge mappings.

Signed-off-by: Chintan Pandya <cpandya@...eaurora.org>
---
 arch/arm64/mm/mmu.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6e7e16c..c65abc4 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -934,15 +934,8 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
 {
 	pgprot_t sect_prot = __pgprot(PUD_TYPE_SECT |
 					pgprot_val(mk_sect_prot(prot)));
-	pud_t new_pud = pfn_pud(__phys_to_pfn(phys), sect_prot);
-
-	/* Only allow permission changes for now */
-	if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
-				   pud_val(new_pud)))
-		return 0;
-
 	BUG_ON(phys & ~PUD_MASK);
-	set_pud(pudp, new_pud);
+	set_pud(pudp, pfn_pud(__phys_to_pfn(phys), sect_prot));
 	return 1;
 }
 
@@ -950,15 +943,8 @@ int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
 {
 	pgprot_t sect_prot = __pgprot(PMD_TYPE_SECT |
 					pgprot_val(mk_sect_prot(prot)));
-	pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), sect_prot);
-
-	/* Only allow permission changes for now */
-	if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)),
-				   pmd_val(new_pmd)))
-		return 0;
-
 	BUG_ON(phys & ~PMD_MASK);
-	set_pmd(pmdp, new_pmd);
+	set_pmd(pmdp, pfn_pmd(__phys_to_pfn(phys), sect_prot));
 	return 1;
 }
 
-- 
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