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Date: Wed, 26 Jan 2022 18:30:01 +0100 From: Ard Biesheuvel <ardb@...nel.org> To: linux-arm-kernel@...ts.infradead.org Cc: kvmarm@...ts.cs.columbia.edu, linux-hardening@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Fuad Tabba <tabba@...gle.com>, Quentin Perret <qperret@...gle.com>, Mark Rutland <mark.rutland@....com>, James Morse <james.morse@....com>, Catalin Marinas <catalin.marinas@....com> Subject: [RFC PATCH 02/12] arm64: mm: add helpers to remap page tables read-only/read-write Add a couple of helpers to remap a single page read-only or read-write via its linear address. This will be used for mappings of page table pages in the linear region. Note that set_memory_ro/set_memory_rw operate on addresses in the vmalloc space only, so they cannot be used here. Signed-off-by: Ard Biesheuvel <ardb@...nel.org> --- arch/arm64/include/asm/pgtable.h | 3 +++ arch/arm64/mm/pageattr.c | 14 ++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index c4ba047a82d2..8d3806c68687 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -34,6 +34,9 @@ #include <linux/mm_types.h> #include <linux/sched.h> +int set_pgtable_ro(void *addr); +int set_pgtable_rw(void *addr); + #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index a3bacd79507a..61f4aca08b95 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -153,6 +153,20 @@ int set_memory_valid(unsigned long addr, int numpages, int enable) __pgprot(PTE_VALID)); } +int set_pgtable_ro(void *addr) +{ + return __change_memory_common((u64)addr, PAGE_SIZE, + __pgprot(PTE_RDONLY), + __pgprot(PTE_WRITE)); +} + +int set_pgtable_rw(void *addr) +{ + return __change_memory_common((u64)addr, PAGE_SIZE, + __pgprot(PTE_WRITE), + __pgprot(PTE_RDONLY)); +} + int set_direct_map_invalid_noflush(struct page *page) { struct page_change_data data = { -- 2.30.2
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