[RFC PATCH 10/18] arm64: enable per-NUMA node kernel text and rodata replication
From: Nikita Panov
Date: Thu Aug 27 2026 - 12:29:25 EST
During boot memory for replicas is allocated,
local translation tables are created,
original text and rodata are copied to replicas,
and replicas are mapped to local tables.
On startup of the secondary CPUs, after minimal initialization,
the local pgtable is loaded to ttbr1.
Acked-by: Artem Kuzin <artem.kuzin@xxxxxxxxxx>
Acked-by: Alexander Grubnikov <alexander.grubnikov@xxxxxxxxxx>
Acked-by: Ilya Hanov <ilya.hanov@xxxxxxxxxxxxxxxxxxx>
Acked-by: Denis Darvish <darvish.denis@xxxxxxxxxx>
Signed-off-by: Nikita Panov <panov.nikita@xxxxxxxxxx>
---
arch/arm64/include/asm/pgtable.h | 4 +++
arch/arm64/kernel/smp.c | 8 ++++++
arch/arm64/mm/context.c | 1 +
arch/arm64/mm/init.c | 49 ++++++++++++++++++++++++++++++++
arch/arm64/mm/kasan_init.c | 2 ++
arch/arm64/mm/mmu.c | 38 ++++++++++++++++++++++++-
6 files changed, 101 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 6000905a2e86..f11d77829890 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -20,7 +20,11 @@
* VMALLOC_START: beginning of the kernel vmalloc space
* VMALLOC_END: extends to the available space below vmemmap
*/
+#ifdef CONFIG_KERNEL_REPLICATION
+#define VMALLOC_START ((MODULES_END & PGDIR_MASK) + PGDIR_SIZE)
+#else /* !CONFIG_KERNEL_REPLICATION */
#define VMALLOC_START (MODULES_END)
+#endif /* CONFIG_KERNEL_REPLICATION */
#if VA_BITS == VA_BITS_MIN
#define VMALLOC_END (VMEMMAP_START - SZ_8M)
#else
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index a61dc3016a11..4832a89ba992 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -36,6 +36,7 @@
#include <linux/kprobes.h>
#include <linux/kvm_host.h>
#include <linux/nmi.h>
+#include <linux/numa_kernel_replication.h>
#include <asm/alternative.h>
#include <asm/atomic.h>
@@ -208,6 +209,13 @@ asmlinkage notrace void secondary_start_kernel(void)
mmgrab(mm);
current->active_mm = mm;
+ /*
+ * Setup per-NUMA node page table if kernel
+ * replication is enabled. Option supported
+ * only for 64-bit mode.
+ */
+ numa_setup_pgd();
+
/*
* TTBR0 is only used for the identity mapping at this stage. Make it
* point to zero page to avoid speculatively fetching new entries.
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 0f4a28b87469..3afdae62784e 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -11,6 +11,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
+#include <linux/numa_kernel_replication.h>
#include <asm/cpufeature.h>
#include <asm/mmu_context.h>
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index fbf215ecc7d0..3c2394b20c03 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -331,6 +331,47 @@ void __init bootmem_init(void)
memblock_dump_all();
}
+#ifdef CONFIG_KERNEL_REPLICATION
+/*
+ * It is necessary to preallocate vmalloc pages in advance,
+ * otherwise the replicated page-tables can be incomplete.
+ */
+void __init preallocate_vmalloc_pages(void)
+{
+ unsigned long addr;
+
+ for (addr = MODULES_VADDR; addr <= VMALLOC_END && addr != 0UL;
+ addr = ALIGN(addr + 1, PGDIR_SIZE)) {
+ pgd_t *pgd = pgd_offset_k(addr);
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+ int pte;
+
+ p4d = p4d_alloc(&init_mm, pgd, addr);
+ /*
+ * No need to check p4d here due to
+ * only 4-stage page table is possible
+ */
+ pud = pud_alloc(&init_mm, p4d, addr);
+ if (!pud)
+ panic("Failed to pre-allocate pud pages for vmalloc area\n");
+ if (!mm_pud_folded(&init_mm))
+ continue;
+
+ pmd = pmd_alloc(&init_mm, pud, addr);
+ if (!pmd)
+ panic("Failed to pre-allocate pmd pages for vmalloc area\n");
+ if (!mm_pmd_folded(&init_mm))
+ continue;
+
+ pte = pte_alloc(&init_mm, pmd);
+ if (pte)
+ panic("Failed to pre-allocate pte pages for vmalloc area\n");
+ }
+}
+#endif /* CONFIG_KERNEL_REPLICATION */
+
void __init arch_setup_zero_pages(void)
{
__zero_page = phys_to_page(__pa_symbol(empty_zero_page));
@@ -401,7 +442,15 @@ void free_initmem(void)
* prevents the region from being reused for kernel modules, which
* is not supported by kallsyms.
*/
+#ifdef CONFIG_KERNEL_REPLICATION
+ /*
+ * In case of replicated kernel the per-NUMA node vmalloc
+ * memory should be released.
+ */
+ vunmap_range_replicas((u64)__init_begin, (u64)__init_end);
+#else
vunmap_range((u64)__init_begin, (u64)__init_end);
+#endif /* CONFIG_KERNEL_REPLICATION */
}
void dump_mem_limit(void)
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 45fbdce684c8..37eb408830f0 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -345,7 +345,9 @@ static void __init kasan_init_shadow(void)
kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
(void *)mod_shadow_start);
+#ifndef CONFIG_KERNEL_REPLICATION
BUILD_BUG_ON(VMALLOC_START != MODULES_END);
+#endif
kasan_populate_early_shadow((void *)vmalloc_shadow_end,
(void *)KASAN_SHADOW_END);
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 79d90226fd5d..fa12461c0d8e 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -30,6 +30,7 @@
#include <linux/mm_inline.h>
#include <linux/pagewalk.h>
#include <linux/stop_machine.h>
+#include <linux/numa_kernel_replication.h>
#include <asm/barrier.h>
#include <asm/cputype.h>
@@ -1039,6 +1040,22 @@ void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
pgd_pgtable_alloc_special_mm, flags);
}
+static void populate_mappings_prot(phys_addr_t phys, unsigned long virt,
+ phys_addr_t size, pgprot_t prot)
+{
+#ifdef CONFIG_KERNEL_REPLICATION
+ int nid;
+
+ for_each_memory_node(nid) {
+ early_create_pgd_mapping(per_node_pgd(&init_mm, nid),
+ page_to_phys(walk_to_page_node(nid, (void *)virt)),
+ virt, size, prot, NULL, 0);
+ }
+#else
+ early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, 0);
+#endif /* CONFIG_KERNEL_REPLICATION */
+}
+
static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
phys_addr_t size, pgprot_t prot)
{
@@ -1048,7 +1065,7 @@ static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
return;
}
- early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, 0);
+ populate_mappings_prot(phys, virt, size, prot);
/* flush the TLBs after updating live kernel mappings */
flush_tlb_kernel_range(virt, virt + size);
@@ -1390,6 +1407,21 @@ static pgprot_t __init kernel_exec_prot(void)
return rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
}
+#ifdef CONFIG_KERNEL_REPLICATION
+static void __init populate_trampoline_mappings(void)
+{
+ int nid;
+
+ /* Copy trampoline mappings in replicated tables */
+ for_each_memory_node(nid) {
+ memcpy(per_node_pgd(&init_mm, nid) - (PAGE_SIZE * 2 / sizeof(pgd_t)),
+ tramp_pg_dir, PGD_SIZE);
+ }
+ /* Be sure that replicated page table can be observed properly */
+ dsb(ishst);
+}
+#endif /* CONFIG_KERNEL_REPLICATION */
+
static int __init map_entry_trampoline(void)
{
int i;
@@ -1418,6 +1450,10 @@ static int __init map_entry_trampoline(void)
__set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
pa_start + i * PAGE_SIZE, PAGE_KERNEL_RO);
+#ifdef CONFIG_KERNEL_REPLICATION
+ populate_trampoline_mappings();
+#endif /* CONFIG_KERNEL_REPLICATION */
+
return 0;
}
core_initcall(map_entry_trampoline);
--
2.34.1