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From:   Chintan Pandya <cpandya@codeaurora.org>
To:     catalin.marinas@arm.com, will.deacon@arm.com, mark.rutland@arm.com,
        toshi.kani@hpe.com
Cc:     arnd@arndb.de, ard.biesheuvel@linaro.org, marc.zyngier@arm.com,
        james.morse@arm.com, kristina.martsenko@arm.com,
        takahiro.akashi@linaro.org, gregkh@linuxfoundation.org,
        tglx@linutronix.de, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        akpm@linux-foundation.org, Chintan Pandya <cpandya@codeaurora.org>
Subject: [PATCH v6 1/2] arm64: Implement page table free interfaces
Date:   Wed, 28 Mar 2018 16:28:50 +0530
Message-Id: <1522234731-27397-4-git-send-email-cpandya@codeaurora.org>
In-Reply-To: <1522234731-27397-1-git-send-email-cpandya@codeaurora.org>
References: <1522234731-27397-1-git-send-email-cpandya@codeaurora.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Implement pud_free_pmd_page() and pmd_free_pte_page().

Implementation requires,
 1) Clearing off the current pud/pmd entry
 2) Invalidate TLB which could have previously
    valid but not stale entry
 3) Freeing of the un-used next level page tables

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
---
From V5->V6:
 - Removed extra bool parameter 'tlb_inv'
 - Doing pmd/pud TLB invalidation with __flush_tlb_kernel_pgtable()

 arch/arm64/mm/mmu.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index da98828..0f651db 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -45,6 +45,7 @@
 #include <asm/memblock.h>
 #include <asm/mmu_context.h>
 #include <asm/ptdump.h>
+#include <asm/tlbflush.h>
 
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)
@@ -973,12 +974,32 @@ int pmd_clear_huge(pmd_t *pmdp)
 	return 1;
 }
 
-int pud_free_pmd_page(pud_t *pud, unsigned long addr)
+int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
 {
-	return pud_none(*pud);
+	pmd_t *table;
+
+	if (pmd_present(READ_ONCE(*pmdp))) {
+		table = __va(pmd_val(*pmdp));
+		pmd_clear(pmdp);
+		__flush_tlb_kernel_pgtable(addr);
+		free_page((unsigned long) table);
+	}
+	return 1;
 }
 
-int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
+int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
 {
-	return pmd_none(*pmd);
+	pmd_t *table;
+	int i;
+
+	if (pud_present(READ_ONCE(*pudp))) {
+		table = __va(pud_val(*pudp));
+		for (i = 0; i < PTRS_PER_PMD; i++)
+			pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE));
+
+		pud_clear(pudp);
+		__flush_tlb_kernel_pgtable(addr);
+		free_page((unsigned long) table);
+	}
+	return 1;
 }
-- 
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