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Fri, 20 Mar 2026 08:00:07 -0700 (PDT) Date: Fri, 20 Mar 2026 15:59:43 +0100 In-Reply-To: <20260320145934.2349881-15-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260320145934.2349881-15-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=3121; i=ardb@kernel.org; h=from:subject; bh=VnAD88hkLu5Up6Du4sjF1AveOX8gYjjnmNe0JbrOG+0=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIXNvwqMIO70jyYE/p2/KNi920Lz0X/ugW5nOKo/Md52XA 26Hz1vaUcrCIMbFICumyCIw+++7nacnStU6z5KFmcPKBDKEgYtTACZiO5WR4d+tzgX3g9Jerc87 E3eRxd664Iji4VvFHa9cJBU57ZbkBzMyPChvTPatULg0M6nmzqWtzAf+Zx1N+sL29ENg1lJm71n 5nAA= X-Mailer: git-send-email 2.53.0.959.g497ff81fa9-goog Message-ID: <20260320145934.2349881-23-ardb+git@google.com> Subject: [PATCH v3 08/13] arm64: kfence: Avoid NOMAP tricks when mapping the early pool From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, Ard Biesheuvel , Ryan Roberts , Anshuman Khandual , Liz Prucka , Seth Jenkins , Kees Cook , linux-hardening@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Ard Biesheuvel Now that the map_mem() routines respect existing page mappings and contiguous granule sized blocks with the contiguous bit cleared, there is no longer a reason to play tricks with the memblock NOMAP attribute. Instead, the kfence pool can be allocated and mapped with page granularity first, and this granularity will be respected when the rest of DRAM is mapped later, even if block and contiguous mappings are allowed for the remainder of those mappings. Signed-off-by: Ard Biesheuvel --- arch/arm64/mm/mmu.c | 25 ++++---------------- 1 file changed, 5 insertions(+), 20 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 6780236b6cf8..1c434c242641 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1047,36 +1047,24 @@ static int __init parse_kfence_early_init(char *arg) } early_param("kfence.sample_interval", parse_kfence_early_init); =20 -static phys_addr_t __init arm64_kfence_alloc_pool(void) +static void __init arm64_kfence_map_pool(void) { phys_addr_t kfence_pool; =20 if (!kfence_early_init) - return 0; + return; =20 kfence_pool =3D memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); if (!kfence_pool) { pr_err("failed to allocate kfence pool\n"); kfence_early_init =3D false; - return 0; - } - - /* Temporarily mark as NOMAP. */ - memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE); - - return kfence_pool; -} - -static void __init arm64_kfence_map_pool(phys_addr_t kfence_pool) -{ - if (!kfence_pool) return; + } =20 /* KFENCE pool needs page-level mapping. */ __map_memblock(kfence_pool, kfence_pool + KFENCE_POOL_SIZE, pgprot_tagged(PAGE_KERNEL), NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); - memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE); __kfence_pool =3D phys_to_virt(kfence_pool); } =20 @@ -1108,8 +1096,7 @@ bool arch_kfence_init_pool(void) } #else /* CONFIG_KFENCE */ =20 -static inline phys_addr_t arm64_kfence_alloc_pool(void) { return 0; } -static inline void arm64_kfence_map_pool(phys_addr_t kfence_pool) { } +static inline void arm64_kfence_map_pool(void) { } =20 #endif /* CONFIG_KFENCE */ =20 @@ -1119,7 +1106,6 @@ static void __init map_mem(void) phys_addr_t kernel_start =3D __pa_symbol(_text); phys_addr_t kernel_end =3D __pa_symbol(__init_begin); phys_addr_t start, end; - phys_addr_t early_kfence_pool; int flags =3D NO_EXEC_MAPPINGS; u64 i; =20 @@ -1136,7 +1122,7 @@ static void __init map_mem(void) BUILD_BUG_ON(pgd_index(direct_map_end - 1) =3D=3D pgd_index(direct_map_en= d) && pgd_index(_PAGE_OFFSET(VA_BITS_MIN)) !=3D PTRS_PER_PGD - 1); =20 - early_kfence_pool =3D arm64_kfence_alloc_pool(); + arm64_kfence_map_pool(); =20 linear_map_requires_bbml2 =3D !force_pte_mapping() && can_set_direct_map(= ); =20 @@ -1174,7 +1160,6 @@ static void __init map_mem(void) */ __map_memblock(kernel_start, kernel_end, PAGE_KERNEL, NO_CONT_MAPPINGS); memblock_clear_nomap(kernel_start, kernel_end - kernel_start); - arm64_kfence_map_pool(early_kfence_pool); } =20 void mark_rodata_ro(void) --=20 2.53.0.959.g497ff81fa9-goog