From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu, linux-hardening@vger.kernel.org,
Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
Marc Zyngier <maz@kernel.org>, Fuad Tabba <tabba@google.com>,
Quentin Perret <qperret@google.com>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: [RFC PATCH 08/12] arm64: mm: remap kernel PTE level page tables r/o in the linear region
Date: Wed, 26 Jan 2022 18:30:07 +0100 [thread overview]
Message-ID: <20220126173011.3476262-9-ardb@kernel.org> (raw)
In-Reply-To: <20220126173011.3476262-1-ardb@kernel.org>
Now that all kernel page table manipulations are routed through the
fixmap API if r/o page tables are enabled, we can remove write access
from the linear mapping of those pages.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/arm64/include/asm/pgalloc.h | 6 +++++
arch/arm64/mm/mmu.c | 24 +++++++++++++++++++-
2 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 18a5bb0c9ee4..073482634e74 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -20,6 +20,9 @@
#define __HAVE_ARCH_PMD_FREE
#define __HAVE_ARCH_PTE_ALLOC_ONE
#define __HAVE_ARCH_PTE_FREE
+#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
+#define __HAVE_ARCH_PTE_FREE_KERNEL
+
#include <asm-generic/pgalloc.h>
#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
@@ -27,6 +30,9 @@
pgtable_t pte_alloc_one(struct mm_struct *mm);
void pte_free(struct mm_struct *mm, struct page *pte_page);
+pte_t *pte_alloc_one_kernel(struct mm_struct *mm);
+void pte_free_kernel(struct mm_struct *mm, pte_t *pte);
+
#if CONFIG_PGTABLE_LEVELS > 2
pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr);
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 949846654797..971501535757 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1402,7 +1402,7 @@ int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
table = pte_offset_kernel(pmdp, addr);
pmd_clear(pmdp);
__flush_tlb_kernel_pgtable(addr);
- pte_free_kernel(NULL, table);
+ pte_free_kernel(&init_mm, table);
return 1;
}
@@ -1709,3 +1709,25 @@ void pte_free(struct mm_struct *mm, struct page *pte_page)
pgtable_pte_page_dtor(pte_page);
__free_page(pte_page);
}
+
+pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
+{
+ pte_t *pte = __pte_alloc_one_kernel(mm);
+
+ VM_BUG_ON(mm != &init_mm);
+
+ if (!pte)
+ return NULL;
+ if (page_tables_are_ro())
+ set_pgtable_ro(pte);
+ return pte;
+}
+
+void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+ VM_BUG_ON(mm != &init_mm);
+
+ if (page_tables_are_ro())
+ set_pgtable_rw(pte);
+ free_page((u64)pte);
+}
--
2.30.2
next prev parent reply other threads:[~2022-01-26 17:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 17:29 [RFC PATCH 00/12] arm64: implement read-only page tables Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 01/12] asm-generic/pgalloc: allow arch to override PMD alloc/free routines Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 02/12] arm64: mm: add helpers to remap page tables read-only/read-write Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 03/12] arm64: mm: use a fixmap slot for user page table modifications Ard Biesheuvel
2022-01-28 16:08 ` Steven Price
2022-01-26 17:30 ` [RFC PATCH 04/12] arm64: mm: remap PGD pages r/o in the linear region after allocation Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 05/12] arm64: mm: remap PUD pages r/o in linear region Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 06/12] arm64: mm: remap PMD " Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 07/12] arm64: mm: remap PTE level user page tables r/o in the " Ard Biesheuvel
2022-01-26 17:30 ` Ard Biesheuvel [this message]
2022-01-26 17:30 ` [RFC PATCH 09/12] arm64: mm: remap kernel page tables read-only at end of init Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 10/12] mm: add default definition of p4d_index() Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 11/12] arm64: efi: use set_pte_at() not set_pte() in order to pass mm pointer Ard Biesheuvel
2022-01-26 17:30 ` [RFC PATCH 12/12] arm64: hugetlb: use set_pte_at() not set_pte() to provide " Ard Biesheuvel
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