linux-kernel - [PATCH v10 3/4] arm64: Implement page table free interfaces

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 24 May 2018 19:27:29 +0530
From:   Chintan Pandya <cpandya@...eaurora.org>
To:     will.deacon@....com, catalin.marinas@....com, mark.rutland@....com,
        labbott@...hat.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 v10 3/4] arm64: Implement page table free interfaces

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@...eaurora.org>
---
 arch/arm64/mm/mmu.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index da98828..17d9282 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 +974,37 @@ 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;
+	pmd_t pmd;
+
+	pmd = READ_ONCE(*pmdp);
+	if (pmd_present(pmd)) {
+		table = __va(pmd_val(pmd));
+		pmd_clear(pmdp);
+		__flush_tlb_kernel_pgtable(addr);
+		pte_free_kernel(NULL, (pte_t *) 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;
+	pud_t pud;
+	int i = 0;
+
+	pud = READ_ONCE(*pudp);
+	if (pud_present(pud)) {
+		table = __va(pud_val(pud));
+		do {
+			pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE));
+		} while (i++, i < PTRS_PER_PMD);
+
+		pud_clear(pudp);
+		__flush_tlb_kernel_pgtable(addr);
+		pmd_free(NULL, table);
+	}
+	return 1;
 }
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project