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Date: Tue, 9 Aug 2022 20:00:48 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Peter Collingbourne <pcc@...gle.com>, Will Deacon <will@...nel.org>, Ard Biesheuvel <ardb@...nel.org>, Catalin Marinas <catalin.marinas@....com> Subject: [PATCH 5.18 19/35] arm64: set UXN on swapper page tables From: Peter Collingbourne <pcc@...gle.com> [ This issue was fixed upstream by accident in c3cee924bd85 ("arm64: head: cover entire kernel image in initial ID map") as part of a large refactoring of the arm64 boot flow. This simple fix is therefore preferred for -stable backporting ] On a system that implements FEAT_EPAN, read/write access to the idmap is denied because UXN is not set on the swapper PTEs. As a result, idmap_kpti_install_ng_mappings panics the kernel when accessing __idmap_kpti_flag. Fix it by setting UXN on these PTEs. Fixes: 18107f8a2df6 ("arm64: Support execute-only permissions with Enhanced PAN") Cc: <stable@...r.kernel.org> # 5.15 Link: https://linux-review.googlesource.com/id/Ic452fa4b4f74753e54f71e61027e7222a0fae1b1 Signed-off-by: Peter Collingbourne <pcc@...gle.com> Acked-by: Will Deacon <will@...nel.org> Cc: Ard Biesheuvel <ardb@...nel.org> Cc: Catalin Marinas <catalin.marinas@....com> Link: https://lore.kernel.org/r/20220719234909.1398992-1-pcc@google.com Signed-off-by: Will Deacon <will@...nel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- arch/arm64/include/asm/kernel-pgtable.h | 4 ++-- arch/arm64/kernel/head.S | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) --- a/arch/arm64/include/asm/kernel-pgtable.h +++ b/arch/arm64/include/asm/kernel-pgtable.h @@ -103,8 +103,8 @@ /* * Initial memory map attributes. */ -#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED) -#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S) +#define SWAPPER_PTE_FLAGS (PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN) +#define SWAPPER_PMD_FLAGS (PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PMD_SECT_UXN) #if ARM64_KERNEL_USES_PMD_MAPS #define SWAPPER_MM_MMUFLAGS (PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS) --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -285,7 +285,7 @@ SYM_FUNC_START_LOCAL(__create_page_table subs x1, x1, #64 b.ne 1b - mov x7, SWAPPER_MM_MMUFLAGS + mov_q x7, SWAPPER_MM_MMUFLAGS /* * Create the identity mapping.
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