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t=1777997287; bh=PHibZSTZ+M49JBQ4ek0CSdAJ2no6ww2ow8catbJRkbA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=pJt30ocTXb7hE3yyXbYT/nSgcR9UGUgOhCrLw1N3ELE9tv7VKn9yqPIGkenp5OBxD lj0a0EN2vzEyemi5amPKyxEWoByxWzuAMzvvvnb+vE2s+djQKhWqcy4M5gk+WT+l6y KErmv1Lg62LAOWaupMVBcFI2wyMSxZAv2SJS9BaA= From: Kevin Brodsky Date: Tue, 05 May 2026 17:06:03 +0100 Subject: [PATCH RFC v7 14/24] mm: kpkeys: Protect vmemmap page tables MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260505-kpkeys-v7-14-20c0bdd97197@arm.com> References: <20260505-kpkeys-v7-0-20c0bdd97197@arm.com> In-Reply-To: <20260505-kpkeys-v7-0-20c0bdd97197@arm.com> To: linux-hardening@vger.kernel.org Cc: Kevin Brodsky , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , Ryan Roberts , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Lorenzo Stoakes , Thomas Gleixner , Vlastimil Babka X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1777997220; l=3365; i=kevin.brodsky@arm.com; s=20260427; h=from:subject:message-id; bh=PHibZSTZ+M49JBQ4ek0CSdAJ2no6ww2ow8catbJRkbA=; b=tgzTvZYCgZKHtLvh8bIbz88J3Sv+Gfhv63Gz+41QPPK0ecs+LDqfcfVQJszRcWPf09gQS/R2H Qy0ZIBKMqBXAfXZvmpbDux3ogpELrzjrv18rcm/SClO23PGIj/3dmFA X-Developer-Key: i=kevin.brodsky@arm.com; a=ed25519; pk=N2QG+eJKrvkNovwhhwJhnJ4+ScVfsGCHldmqLfcMTFs= X-Rspam-User: X-Rspamd-Queue-Id: 35145180005 X-Rspamd-Server: rspam04 X-Stat-Signature: bkoqsj43awbdn871mfumb3cya8qhpqwq X-HE-Tag: 1777997287-808771 X-HE-Meta: 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 Ho/H7MkE VqkiHAAHREHeOUmrzYInBVeuB+u7N1kjw/22n0waYMbopPYy3Pzq4whF/BP7OGm/DI/pXlVAX5dwKMSAhWxE4l5V7M5PalcZMvHsn8l7mpuWjqUindv/qjzM/UoLf9sLsQOL/+PTHofhyJjL+C+WBd6mRUAPLZvzRcmjtBofuKpfWKO6281dlGJuCPAXyVR332XTQLHZ4aItzUwK8+NhRMSmxxqru/OG+hwyAfi5Sfx8SR0UU+xJ410cYHCfEqxMt25dx Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When the kpkeys_hardened_pgtables feature is enabled, make sure that vmemmap page tables are protected by using: * The standard pagetable_alloc() if the buddy allocator is available, as it already allocates protected memory. * The memblock-based kpkeys allocator for early allocations. These allocators are not NUMA-aware, so the page tables may be allocated on any node. This could potentially incur some overhead on large NUMA systems. Signed-off-by: Kevin Brodsky --- This is a minimal patch to protect vmemmmap page tables. More work may be needed here: * Restoring NUMA awareness * General refactoring of how these page tables are allocated: since we are not using the standard per-level functions (e.g. pmd_alloc()), we are not calling pagetable_*_ctor() or ptdesc_set_kernel(). [Maybe that doesn't matter because these page tables can only be freed via vmemmap_free()?] --- mm/sparse-vmemmap.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index 6eadb9d116e4..0c0d3b1e356c 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -184,13 +184,28 @@ pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node, return pte; } -static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node) +static void * __meminit vmemmap_alloc_pgtable(int node) { - void *p = vmemmap_alloc_block(size, node); + void *p; + + if (slab_is_available()) { + struct ptdesc *ptdesc = pagetable_alloc(GFP_PGTABLE_KERNEL, 0); + + return ptdesc ? ptdesc_address(ptdesc) : NULL; + } + + if (kpkeys_hardened_pgtables_early_enabled()) { + phys_addr_t phys = kpkeys_physmem_pgtable_alloc(); + + p = phys ? phys_to_virt(phys) : NULL; + } else { + p = __earlyonly_bootmem_alloc(node, PAGE_SIZE, PAGE_SIZE, + __pa(MAX_DMA_ADDRESS)); + } if (!p) return NULL; - memset(p, 0, size); + memset(p, 0, PAGE_SIZE); return p; } @@ -199,7 +214,7 @@ pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) { pmd_t *pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) { - void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); + void *p = vmemmap_alloc_pgtable(node); if (!p) return NULL; kernel_pte_init(p); @@ -212,7 +227,7 @@ pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node) { pud_t *pud = pud_offset(p4d, addr); if (pud_none(*pud)) { - void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); + void *p = vmemmap_alloc_pgtable(node); if (!p) return NULL; pmd_init(p); @@ -225,7 +240,7 @@ p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node) { p4d_t *p4d = p4d_offset(pgd, addr); if (p4d_none(*p4d)) { - void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); + void *p = vmemmap_alloc_pgtable(node); if (!p) return NULL; pud_init(p); @@ -238,7 +253,7 @@ pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) { pgd_t *pgd = pgd_offset_k(addr); if (pgd_none(*pgd)) { - void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); + void *p = vmemmap_alloc_pgtable(node); if (!p) return NULL; pgd_populate_kernel(addr, pgd, p); -- 2.51.2