From: Juerg Haefliger <juerg.haefli...@canonical.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).
XPFO doesn't support section/contiguous mappings yet, so let's disable
it if XPFO is turned on.
Thanks to Laura Abbot for the simplification from v5, and Mark Rutland
for pointing out we need NO_CONT_MAPPINGS too.
CC: linux-arm-ker...@lists.infradead.org
Signed-off-by: Juerg Haefliger <juerg.haefli...@canonical.com>
Signed-off-by: Tycho Andersen <ty...@tycho.ws>
Signed-off-by: Khalid Aziz <khalid.a...@oracle.com>
Cc: Khalid Aziz <kha...@gonehiking.org>
---
.../admin-guide/kernel-parameters.txt | 2 +-
arch/arm64/Kconfig | 1 +
arch/arm64/mm/Makefile | 2 +
arch/arm64/mm/mmu.c | 2 +-
arch/arm64/mm/xpfo.c | 66 +++++++++++++++++++
5 files changed, 71 insertions(+), 2 deletions(-)
create mode 100644 arch/arm64/mm/xpfo.c
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index e65e3bc1efe0..9fcf8c83031a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2997,7 +2997,7 @@
nox2apic [X86-64,APIC] Do not enable x2APIC mode.
- noxpfo [XPFO,X86-64] Disable eXclusive Page Frame
+ noxpfo [XPFO,X86-64,ARM64] Disable eXclusive Page Frame
Ownership (XPFO) when CONFIG_XPFO is on. Physical
pages mapped into user applications will also be
mapped in the kernel's address space as if
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a4168d366127..9a8d8e649cf8 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -174,6 +174,7 @@ config ARM64
select SWIOTLB
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
+ select ARCH_SUPPORTS_XPFO
help
ARM 64-bit (AArch64) Linux support.
diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 849c1df3d214..cca3808d9776 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -12,3 +12,5 @@ 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/mmu.c b/arch/arm64/mm/mmu.c
index b6f5aa52ac67..1673f7443d62 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -453,7 +453,7 @@ static void __init map_mem(pgd_t *pgdp)
struct memblock_region *reg;
int flags = 0;
- if (rodata_full || debug_pagealloc_enabled())
+ if (rodata_full || debug_pagealloc_enabled() || xpfo_enabled())
flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
/*
diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c
new file mode 100644
index 000000000000..7866c5acfffb
--- /dev/null
+++ b/arch/arm64/mm/xpfo.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Hewlett Packard Enterprise Development, L.P.
+ * Copyright (C) 2016 Brown University. All rights reserved.
+ *
+ * Authors:
+ * Juerg Haefliger <juerg.haefli...@hpe.com>
+ * Vasileios P. Kemerlis <v...@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;
+
+ pud = pud_offset(pgd, addr);
+ if (pud_none(*pud))
+ return NULL;
+
+ pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd))
+ return NULL;
+
+ 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);
+
+ if (unlikely(!pte)) {
+ WARN(1, "xpfo: invalid address %p\n", kaddr);
+ return;
+ }
+
+ set_pte(pte, pfn_pte(page_to_pfn(page), prot));
+}
+EXPORT_SYMBOL_GPL(set_kpte);
+
+inline void xpfo_flush_kernel_tlb(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);
+}
+EXPORT_SYMBOL_GPL(xpfo_flush_kernel_tlb);
--
2.17.1
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