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Subject[PATCH v5 05/10] arm64/mm: Add support for XPFO
Date
From: Juerg Haefliger <juerg.haefliger@hpe.com>

Enable support for eXclusive Page Frame Ownership (XPFO) for arm64 and
provide a hook for updating a single kernel page table entry (which is
required by the generic XPFO code).

At the moment, only 64k page sizes are supported.

Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Tested-by: Tycho Andersen <tycho@docker.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/mm/Makefile | 2 ++
arch/arm64/mm/xpfo.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 67 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index dfd908630631..2ddae41e0793 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -121,6 +121,7 @@ config ARM64
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
+ select ARCH_SUPPORTS_XPFO if ARM64_64K_PAGES
help
ARM 64-bit (AArch64) Linux support.

diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 9b0ba191e48e..22e5cab543d8 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -11,3 +11,5 @@ KASAN_SANITIZE_physaddr.o += n

obj-$(CONFIG_KASAN) += kasan_init.o
KASAN_SANITIZE_kasan_init.o := n
+
+obj-$(CONFIG_XPFO) += xpfo.o
diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c
new file mode 100644
index 000000000000..de03a652d48a
--- /dev/null
+++ b/arch/arm64/mm/xpfo.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P.
+ * Copyright (C) 2016 Brown University. All rights reserved.
+ *
+ * Authors:
+ * Juerg Haefliger <juerg.haefliger@hpe.com>
+ * Vasileios P. Kemerlis <vpk@cs.brown.edu>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <asm/tlbflush.h>
+
+/*
+ * Lookup the page table entry for a virtual address and return a pointer to
+ * the entry. Based on x86 tree.
+ */
+static pte_t *lookup_address(unsigned long addr)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ pgd = pgd_offset_k(addr);
+ if (pgd_none(*pgd))
+ return NULL;
+
+ BUG_ON(pgd_bad(*pgd));
+
+ pud = pud_offset(pgd, addr);
+ if (pud_none(*pud))
+ return NULL;
+
+ BUG_ON(pud_bad(*pud));
+
+ pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd))
+ return NULL;
+
+ BUG_ON(pmd_bad(*pmd));
+
+ return pte_offset_kernel(pmd, addr);
+}
+
+/* Update a single kernel page table entry */
+inline void set_kpte(void *kaddr, struct page *page, pgprot_t prot)
+{
+ pte_t *pte = lookup_address((unsigned long)kaddr);
+
+ set_pte(pte, pfn_pte(page_to_pfn(page), prot));
+}
+
+inline void xpfo_flush_kernel_page(struct page *page, int order)
+{
+ unsigned long kaddr = (unsigned long)page_address(page);
+ unsigned long size = PAGE_SIZE;
+
+ flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size);
+}
--
2.11.0
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