From af7249b317e4d0b3d5a0ebbb7ee7a0f336ca7bca Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 11 Jan 2023 11:22:32 +0100 Subject: arm64: kernel: move identity map out of .text mapping Reorganize the ID map slightly so that only code that is executed with the MMU off or via the 1:1 mapping remains. This allows us to move the identity map out of the .text segment, as it will no longer need executable permissions via the kernel mapping. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20230111102236.1430401-3-ardb@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/mm/proc.S | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/arm64/mm') diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 066fa60b93d2..91410f488090 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -110,7 +110,6 @@ SYM_FUNC_END(cpu_do_suspend) * * x0: Address of context pointer */ - .pushsection ".idmap.text", "awx" SYM_FUNC_START(cpu_do_resume) ldp x2, x3, [x0] ldp x4, x5, [x0, #16] @@ -166,7 +165,6 @@ alternative_else_nop_endif isb ret SYM_FUNC_END(cpu_do_resume) - .popsection #endif .pushsection ".idmap.text", "awx" -- cgit From 61786170383093908e9f5f8fd8c5c3ff0c3bbe03 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 11 Jan 2023 11:22:36 +0100 Subject: efi: arm64: enter with MMU and caches enabled Instead of cleaning the entire loaded kernel image to the PoC and disabling the MMU and caches before branching to the kernel's bare metal entry point, we can leave the MMU and caches enabled, and rely on EFI's cacheable 1:1 mapping of all of system RAM (which is mandated by the spec) to populate the initial page tables. This removes the need for managing coherency in software, which is tedious and error prone. Note that we still need to clean the executable region of the image to the PoU if this is required for I/D coherency, but only if we actually decided to move the image in memory, as otherwise, this will have been taken care of by the loader. This change affects both the builtin EFI stub as well as the zboot decompressor, which now carries the entire EFI stub along with the decompression code and the compressed image. Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20230111102236.1430401-7-ardb@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/mm/cache.S | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm64/mm') diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S index 081058d4e436..503567c864fd 100644 --- a/arch/arm64/mm/cache.S +++ b/arch/arm64/mm/cache.S @@ -56,6 +56,7 @@ SYM_FUNC_START(caches_clean_inval_pou) caches_clean_inval_pou_macro ret SYM_FUNC_END(caches_clean_inval_pou) +SYM_FUNC_ALIAS(__pi_caches_clean_inval_pou, caches_clean_inval_pou) /* * caches_clean_inval_user_pou(start,end) -- cgit From 004fc58f917cfea5d7190139e3ed1b7a13e39c25 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Mon, 30 Jan 2023 17:44:57 +0530 Subject: arm64/mm: Intercept pfn changes in set_pte_at() Changing pfn on a user page table mapped entry, without first going through break-before-make (BBM) procedure is unsafe. This just updates set_pte_at() to intercept such changes, via an updated pgattr_change_is_safe(). This new check happens via __check_racy_pte_update(), which has now been renamed as __check_safe_pte_update(). Cc: Will Deacon Cc: Mark Rutland Cc: Andrew Morton Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Acked-by: Mark Rutland Signed-off-by: Anshuman Khandual Link: https://lore.kernel.org/r/20230130121457.1607675-1-anshuman.khandual@arm.com Signed-off-by: Catalin Marinas --- arch/arm64/mm/mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/arm64/mm') diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 14c87e8d69d8..34d5f7c4c64e 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -133,7 +133,7 @@ static phys_addr_t __init early_pgtable_alloc(int shift) return phys; } -static bool pgattr_change_is_safe(u64 old, u64 new) +bool pgattr_change_is_safe(u64 old, u64 new) { /* * The following mapping attributes may be updated in live @@ -142,9 +142,13 @@ static bool pgattr_change_is_safe(u64 old, u64 new) pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG; /* creating or taking down mappings is always safe */ - if (old == 0 || new == 0) + if (!pte_valid(__pte(old)) || !pte_valid(__pte(new))) return true; + /* A live entry's pfn should not change */ + if (pte_pfn(__pte(old)) != pte_pfn(__pte(new))) + return false; + /* live contiguous mappings may not be manipulated at all */ if ((old | new) & PTE_CONT) return false; -- cgit