// SPDX-License-Identifier: GPL-2.0-only /* * Based on arch/arm/mm/mmu.c * * Copyright (C) 1995-2005 Russell King * Copyright (C) 2012 ARM Ltd. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NO_BLOCK_MAPPINGS BIT(0) #define NO_CONT_MAPPINGS BIT(1) #define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN); u64 idmap_ptrs_per_pgd = PTRS_PER_PGD; u64 __section(".mmuoff.data.write") vabits_actual; EXPORT_SYMBOL(vabits_actual); u64 kimage_voffset __ro_after_init; EXPORT_SYMBOL(kimage_voffset); /* * Empty_zero_page is a special page that is used for zero-initialized data * and COW. */ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss; EXPORT_SYMBOL(empty_zero_page); static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss; static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused; static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused; static DEFINE_SPINLOCK(swapper_pgdir_lock); static DEFINE_MUTEX(fixmap_lock); void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd) { pgd_t *fixmap_pgdp; spin_lock(&swapper_pgdir_lock); fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp)); WRITE_ONCE(*fixmap_pgdp, pgd); /* * We need dsb(ishst) here to ensure the page-table-walker sees * our new entry before set_p?d() returns. The fixmap's * flush_tlb_kernel_range() via clear_fixmap() does this for us. */ pgd_clear_fixmap(); spin_unlock(&swapper_pgdir_lock); } pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { if (!pfn_is_map_memory(pfn)) return pgprot_noncached(vma_prot); else if (file->f_flags & O_SYNC) return pgprot_writecombine(vma_prot); return vma_prot; } EXPORT_SYMBOL(phys_mem_access_prot); static phys_addr_t __init early_pgtable_alloc(int shift) { phys_addr_t phys; void *ptr; phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); if (!phys) panic("Failed to allocate page table page\n"); /* * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE * slot will be free, so we can (ab)use the FIX_PTE slot to initialise * any level of table. */ ptr = pte_set_fixmap(phys); memset(ptr, 0, PAGE_SIZE); /* * Implicit barriers also ensure the zeroed page is visible to the page * table walker */ pte_clear_fixmap(); return phys; } static bool pgattr_change_is_safe(u64 old, u64 new) { /* * The following mapping attributes may be updated in live * kernel mappings without the need for break-before-make. */ pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG; /* creating or taking down mappings is always safe */ if (old == 0 || new == 0) return true; /* live contiguous mappings may not be manipulated at all */ if ((old | new) & PTE_CONT) return false; /* Transitioning from Non-Global to Global is unsafe */ if (old & ~new & PTE_NG) return false; /* * Changing the memory type between Normal and Normal-Tagged is safe * since Tagged is considered a permission attribute from the * mismatched attribute aliases perspective. */ if (((old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) || (old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)) && ((new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) || (new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED))) mask |= PTE_ATTRINDX_MASK; return ((old ^ new) & ~mask) == 0; } static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end, phys_addr_t phys, pgprot_t prot) { pte_t *ptep; ptep = pte_set_fixmap_offset(pmdp, addr); do { pte_t old_pte = READ_ONCE(*ptep); set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); /* * After the PTE entry has been populated once, we * only allow updates to the permission attributes. */ BUG_ON(!pgattr_change_is_safe(pte_val(old_pte), READ_ONCE(pte_val(*ptep)))); phys += PAGE_SIZE; } while (ptep++, addr += PAGE_SIZE, addr != end); pte_clear_fixmap(); } static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr, unsigned long end, phys_addr_t phys, pgprot_t prot, phys_addr_t (*pgtable_alloc)(int), int flags) { unsigned long next; pmd_t pmd = READ_ONCE(*pmdp); BUG_ON(pmd_sect(pmd)); if (pmd_none(pmd)) { pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN; phys_addr_t pte_phys; if (flags & NO_EXEC_MAPPINGS) pmdval |= PMD_TABLE_PXN; BUG_ON(!pgtable_alloc); pte_phys = pgtable_alloc(PAGE_SHIFT); __pmd_populate(pmdp, pte_phys, pmdval); pmd = READ_ONCE(*pmdp); } BUG_ON(pmd_bad(pmd)); do { pgprot_t __prot = prot; next = pte_cont_addr_end(addr, end); /* use a contiguous mapping if the range is suitably aligned */ if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) && (flags & NO_CONT_MAPPINGS) == 0) __prot = __pgprot(pgprot_val(prot) | PTE_CONT); init_pte(pmdp, addr, next, phys, __prot); phys += next - addr; } while (addr = next, addr != end); } static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end, phys_addr_t phys, pgprot_t prot, phys_addr_t (*pgtable_alloc)(int), int flags) { unsigned long next; pmd_t *pmdp; pmdp = pmd_set_fixmap_offset(pudp, addr); do { pmd_t old_pmd = READ_ONCE(*pmdp); next = pmd_addr_end(addr, end); /* try section mapping first */ if (((addr | next | phys) & ~PMD_MASK) == 0 && (flags & NO_BLOCK_MAPPINGS) == 0) { pmd_set_huge(pmdp, phys, prot); /* * After the PMD entry has been populated once, we * only allow updates to the permission attributes. */ BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd), READ_ONCE(pmd_val(*pmdp)))); } else { alloc_init_cont_pte(pmdp, addr, next, phys, prot, pgtable_alloc, flags); BUG_ON(pmd_val(old_pmd) != 0 && pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp))); } phys += next - addr; } while (pmdp++, addr = next, addr != end); pmd_clear_fixmap(); } static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr, unsigned long end, phys_addr_t phys, pgprot_t prot, phys_addr_t (*pgtable_alloc)(int), int flags) { unsigned long next; pud_t pud = READ_ONCE(*pudp); /* * Check for initial section mappings in the pgd/pud. */ BUG_ON(pud_sect(pud)); if (pud_none(pud)) { pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN; phys_addr_t pmd_phys; if (flags & NO_EXEC_MAPPINGS) pudval |= PUD_TABLE_PXN; BUG_ON(!pgtable_alloc); pmd_phys = pgtable_alloc(PMD_SHIFT); __pud_populate(pudp, pmd_phys, pudval); pud = READ_ONCE(*pudp); } BUG_ON(pud_bad(pud)); do { pgprot_t __prot = prot; next = pmd_cont_addr_end(addr, end); /* use a contiguous mapping if the range is suitably aligned */ if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) && (flags & NO_CONT_MAPPINGS) == 0) __prot = __pgprot(pgprot_val(prot) | PTE_CONT); init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags); phys += next - addr; } while (addr = next, addr != end); } static inline bool use_1G_block(unsigned long addr, unsigned long next, unsigned long phys) { if (PAGE_SHIFT != 12) return false; if (((addr | next | phys) & ~PUD_MASK) != 0) return false; return true; } static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end, phys_addr_t phys, pgprot_t prot, phys_addr_t (*pgtable_alloc)(int), int flags) { unsigned long next; pud_t *pudp; p4d_t *p4dp = p4d_offset(pgdp, addr); p4d_t p4d = READ_ONCE(*p4dp); if (p4d_none(p4d)) { p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN; phys_addr_t pud_phys; if (flags & NO_EXEC_MAPPINGS) p4dval |= P4D_TABLE_PXN; BUG_ON(!pgtable_alloc); pud_phys = pgtable_alloc(PUD_SHIFT); __p4d_populate(p4dp, pud_phys, p4dval); p4d = READ_ONCE(*p4dp); } BUG_ON(p4d_bad(p4d)); /* * No need for locking during early boot. And it doesn't work as * expected with KASLR enabled. */ if (system_state != SYSTEM_BOOTING) mutex_lock(&fixmap_lock); pudp = pud_set_fixmap_offset(p4dp, addr); do { pud_t old_pud = READ_ONCE(*pudp); next = pud_addr_end(addr, end); /* * For 4K granule only, attempt to put down a 1GB block */ if (use_1G_block(addr, next, phys) && (flags & NO_BLOCK_MAPPINGS) == 0) { pud_set_huge(pudp, phys, prot); /* * After the PUD entry has been populated once, we * only allow updates to the permission attributes. */ BUG_ON(!pgattr_change_is_safe(pud_val(old_pud), READ_ONCE(pud_val(*pudp)))); } else { alloc_init_cont_pmd(pudp, addr, next, phys, prot, pgtable_alloc, flags); BUG_ON(pud_val(old_pud) != 0 && pud_val(old_pud) != READ_ONCE(pud_val(*pudp))); } phys += next - addr; } while (pudp++, addr = next, addr != end); pud_clear_fixmap(); if (system_state != SYSTEM_BOOTING) mutex_unlock(&fixmap_lock); } static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot, phys_addr_t (*pgtable_alloc)(int), int flags) { unsigned long addr, end, next; pgd_t *pgdp = pgd_offset_pgd(pgdir, virt); /* * If the virtual and physical address don't have the same offset * within a page, we cannot map the region as the caller expects. */ if (WARN_ON((phys ^ virt) & ~PAGE_MASK)) return; phys &= PAGE_MASK; addr = virt & PAGE_MASK; end = PAGE_ALIGN(virt + size); do { next = pgd_addr_end(addr, end); alloc_init_pud(pgdp, addr, next, phys, prot, pgtable_alloc, flags); phys += next - addr; } while (pgdp++, addr = next, addr != end); } static phys_addr_t __pgd_pgtable_alloc(int shift) { void *ptr = (void *)__get_free_page(GFP_PGTABLE_KERNEL); BUG_ON(!ptr); /* Ensure the zeroed page is visible to the page table walker */ dsb(ishst); return __pa(ptr); } static phys_addr_t pgd_pgtable_alloc(int shift) { phys_addr_t pa = __pgd_pgtable_alloc(shift); /* * Call proper page table ctor in case later we need to * call core mm functions like apply_to_page_range() on * this pre-allocated page table. * * We don't select ARCH_ENABLE_SPLIT_PMD_PTLOCK if pmd is * folded, and if so pgtable_pmd_page_ctor() becomes nop. */ if (shift == PAGE_SHIFT) BUG_ON(!pgtable_pte_page_ctor(phys_to_page(pa))); else if (shift == PMD_SHIFT) BUG_ON(!pgtable_pmd_page_ctor(phys_to_page(pa))); return pa; } /* * This function can only be used to modify existing table entries, * without allocating new levels of table. Note that this permits the * creation of new section or page entries. */ static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot) { if ((virt >= PAGE_END) && (virt < VMALLOC_START)) { pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", &phys, virt); return; } __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, NO_CONT_MAPPINGS); } void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot, bool page_mappings_only) { int flags = 0; BUG_ON(mm == &init_mm); if (page_mappings_only) flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(mm->pgd, phys, virt, size, prot, pgd_pgtable_alloc, flags); } static void update_mapping_prot(phys_addr_t phys, unsigned long virt, phys_addr_t size, pgprot_t prot) { if ((virt >= PAGE_END) && (virt < VMALLOC_START)) { pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n", &phys, virt); return; } __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL, NO_CONT_MAPPINGS); /* flush the TLBs after updating live kernel mappings */ flush_tlb_kernel_range(virt, virt + size); } static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start, phys_addr_t end, pgprot_t prot, int flags) { __create_pgd_mapping(pgdp, start, __phys_to_virt(start), end - start, prot, early_pgtable_alloc, flags); } void __init mark_linear_text_alias_ro(void) { /* * Remove the write permissions from the linear alias of .text/.rodata */ update_mapping_prot(__pa_symbol(_stext), (unsigned long)lm_alias(_stext), (unsigned long)__init_begin - (unsigned long)_stext, PAGE_KERNEL_RO); } static bool crash_mem_map __initdata; static int __init enable_crash_mem_map(char *arg) { /* * Proper parameter parsing is done by reserve_crashkernel(). We only * need to know if the linear map has to avoid block mappings so that * the crashkernel reservations can be unmapped later. */ crash_mem_map = true; return 0; } early_param("crashkernel", enable_crash_mem_map); static void __init map_mem(pgd_t *pgdp) { static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN); phys_addr_t kernel_start = __pa_symbol(_stext); phys_addr_t kernel_end = __pa_symbol(__init_begin); phys_addr_t start, end; int flags = NO_EXEC_MAPPINGS; u64 i; /* * Setting hierarchical PXNTable attributes on table entries covering * the linear region is only possible if it is guaranteed that no table * entries at any level are being shared between the linear region and * the vmalloc region. Check whether this is true for the PGD level, in * which case it is guaranteed to be true for all other levels as well. */ BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; /* * Take care not to create a writable alias for the * read-only text and rodata sections of the kernel image. * So temporarily mark them as NOMAP to skip mappings in * the following for-loop */ memblock_mark_nomap(kernel_start, kernel_end - kernel_start); #ifdef CONFIG_KEXEC_CORE if (crash_mem_map) { if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; else if (crashk_res.end) memblock_mark_nomap(crashk_res.start, resource_size(&crashk_res)); } #endif /* map all the memory banks */ for_each_mem_range(i, &start, &end) { if (start >= end) break; /* * The linear map must allow allocation tags reading/writing * if MTE is present. Otherwise, it has the same attributes as * PAGE_KERNEL. */ __map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL), flags); } /* * Map the linear alias of the [_stext, __init_begin) interval * as non-executable now, and remove the write permission in * mark_linear_text_alias_ro() below (which will be called after * alternative patching has completed). This makes the contents * of the region accessible to subsystems such as hibernate, * but protects it from inadvertent modification or execution. * Note that contiguous mappings cannot be remapped in this way, * so we should avoid them here. */ __map_memblock(pgdp, kernel_start, kernel_end, PAGE_KERNEL, NO_CONT_MAPPINGS); memblock_clear_nomap(kernel_start, kernel_end - kernel_start); /* * Use page-level mappings here so that we can shrink the region * in page granularity and put back unused memory to buddy system * through /sys/kernel/kexec_crash_size interface. */ #ifdef CONFIG_KEXEC_CORE if (crash_mem_map && !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) { if (crashk_res.end) { __map_memblock(pgdp, crashk_res.start, crashk_res.end + 1, PAGE_KERNEL, NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); memblock_clear_nomap(crashk_res.start, resource_size(&crashk_res)); } } #endif } void mark_rodata_ro(void) { unsigned long section_size; /* * mark .rodata as read only. Use __init_begin rather than __end_rodata * to cover NOTES and EXCEPTION_TABLE. */ section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata; update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata, section_size, PAGE_KERNEL_RO); debug_checkwx(); } static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end, pgprot_t prot, struct vm_struct *vma, int flags, unsigned long vm_flags) { phys_addr_t pa_start = __pa_symbol(va_start); unsigned long size = va_end - va_start; BUG_ON(!PAGE_ALIGNED(pa_start)); BUG_ON(!PAGE_ALIGNED(size)); __create_pgd_mapping(pgdp, pa_start, (unsigned long)va_start, size, prot, early_pgtable_alloc, flags); if (!(vm_flags & VM_NO_GUARD)) size += PAGE_SIZE; vma->addr = va_start; vma->phys_addr = pa_start; vma->size = size; vma->flags = VM_MAP | vm_flags; vma->caller = __builtin_return_address(0); vm_area_add_early(vma); } static int __init parse_rodata(char *arg) { int ret = strtobool(arg, &rodata_enabled); if (!ret) { rodata_full = false; return 0; } /* permit 'full' in addition to boolean options */ if (strcmp(arg, "full")) return -EINVAL; rodata_enabled = true; rodata_full = true; return 0; } early_param("rodata", parse_rodata); #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static int __init map_entry_trampoline(void) { int i; pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start); /* The trampoline is always mapped and can therefore be global */ pgprot_val(prot) &= ~PTE_NG; /* Map only the text into the trampoline page table */ memset(tramp_pg_dir, 0, PGD_SIZE); __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, entry_tramp_text_size(), prot, __pgd_pgtable_alloc, NO_BLOCK_MAPPINGS); /* Map both the text and data into the kernel page table */ for (i = 0; i < DIV_ROUND_UP(entry_tramp_text_size(), PAGE_SIZE); i++) __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i, pa_start + i * PAGE_SIZE, prot); if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { extern char __entry_tramp_data_start[]; __set_fixmap(FIX_ENTRY_TRAMP_DATA, __pa_symbol(__entry_tramp_data_start), PAGE_KERNEL_RO); } return 0; } core_initcall(map_entry_trampoline); #endif /* * Open coded check for BTI, only for use to determine configuration * for early mappings for before the cpufeature code has run. */ static bool arm64_early_this_cpu_has_bti(void) { u64 pfr1; if (!IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)) return false; pfr1 = __read_sysreg_by_encoding(SYS_ID_AA64PFR1_EL1); return cpuid_feature_extract_unsigned_field(pfr1, ID_AA64PFR1_BT_SHIFT); } /* * Create fine-grained mappings for the kernel. */ static void __init map_kernel(pgd_t *pgdp) { static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext, vmlinux_initdata, vmlinux_data; /* * External debuggers may need to write directly to the text * mapping to install SW breakpoints. Allow this (only) when * explicitly requested with rodata=off. */ pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; /* * If we have a CPU that supports BTI and a kernel built for * BTI then mark the kernel executable text as guarded pages * now so we don't have to rewrite the page tables later. */ if (arm64_early_this_cpu_has_bti()) text_prot = __pgprot_modify(text_prot, PTE_GP, PTE_GP); /* * Only rodata will be remapped with different permissions later on, * all other segments are allowed to use contiguous mappings. */ map_kernel_segment(pgdp, _stext, _etext, text_prot, &vmlinux_text, 0, VM_NO_GUARD); map_kernel_segment(pgdp, __start_rodata, __inittext_begin, PAGE_KERNEL, &vmlinux_rodata, NO_CONT_MAPPINGS, VM_NO_GUARD); map_kernel_segment(pgdp, __inittext_begin, __inittext_end, text_prot, &vmlinux_inittext, 0, VM_NO_GUARD); map_kernel_segment(pgdp, __initdata_begin, __initdata_end, PAGE_KERNEL, &vmlinux_initdata, 0, VM_NO_GUARD); map_kernel_segment(pgdp, _data, _end, PAGE_KERNEL, &vmlinux_data, 0, 0); if (!READ_ONCE(pgd_val(*pgd_offset_pgd(pgdp, FIXADDR_START)))) { /* * The fixmap falls in a separate pgd to the kernel, and doesn't * live in the carveout for the swapper_pg_dir. We can simply * re-use the existing dir for the fixmap. */ set_pgd(pgd_offset_pgd(pgdp, FIXADDR_START), READ_ONCE(*pgd_offset_k(FIXADDR_START))); } else if (CONFIG_PGTABLE_LEVELS > 3) { pgd_t *bm_pgdp; p4d_t *bm_p4dp; pud_t *bm_pudp; /* * The fixmap shares its top level pgd entry with the kernel * mapping. This can really only occur when we are running * with 16k/4 levels, so we can simply reuse the pud level * entry instead. */ BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES)); bm_pgdp = pgd_offset_pgd(pgdp, FIXADDR_START); bm_p4dp = p4d_offset(bm_pgdp, FIXADDR_START); bm_pudp = pud_set_fixmap_offset(bm_p4dp, FIXADDR_START); pud_populate(&init_mm, bm_pudp, lm_alias(bm_pmd)); pud_clear_fixmap(); } else { BUG(); } kasan_copy_shadow(pgdp); } void __init paging_init(void) { pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir)); map_kernel(pgdp); map_mem(pgdp); pgd_clear_fixmap(); cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); init_mm.pgd = swapper_pg_dir; memblock_free(__pa_symbol(init_pg_dir), __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir)); memblock_allow_resize(); } /* * Check whether a kernel address is valid (derived from arch/x86/). */ int kern_addr_valid(unsigned long addr) { pgd_t *pgdp; p4d_t *p4dp; pud_t *pudp, pud; pmd_t *pmdp, pmd; pte_t *ptep, pte; addr = arch_kasan_reset_tag(addr); if ((((long)addr) >> VA_BITS) != -1UL) return 0; pgdp = pgd_offset_k(addr); if (pgd_none(READ_ONCE(*pgdp))) return 0; p4dp = p4d_offset(pgdp, addr); if (p4d_none(READ_ONCE(*p4dp))) return 0; pudp = pud_offset(p4dp, addr); pud = READ_ONCE(*pudp); if (pud_none(pud)) return 0; if (pud_sect(pud)) return pfn_valid(pud_pfn(pud)); pmdp = pmd_offset(pudp, addr); pmd = READ_ONCE(*pmdp); if (pmd_none(pmd)) return 0; if (pmd_sect(pmd)) return pfn_valid(pmd_pfn(pmd)); ptep = pte_offset_kernel(pmdp, addr); pte = READ_ONCE(*ptep); if (pte_none(pte)) return 0; return pfn_valid(pte_pfn(pte)); } #ifdef CONFIG_MEMORY_HOTPLUG static void free_hotplug_page_range(struct page *page, size_t size, struct vmem_altmap *altmap) { if (altmap) { vmem_altmap_free(altmap, size >> PAGE_SHIFT); } else { WARN_ON(PageReserved(page)); free_pages((unsigned long)page_address(page), get_order(size)); } } static void free_hotplug_pgtable_page(struct page *page) { free_hotplug_page_range(page, PAGE_SIZE, NULL); } static bool pgtable_range_aligned(unsigned long start, unsigned long end, unsigned long floor, unsigned long ceiling, unsigned long mask) { start &= mask; if (start < floor) return false; if (ceiling) { ceiling &= mask; if (!ceiling) return false; } if (end - 1 > ceiling - 1) return false; return true; } static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr, unsigned long end, bool free_mapped, struct vmem_altmap *altmap) { pte_t *ptep, pte; do { ptep = pte_offset_kernel(pmdp, addr); pte = READ_ONCE(*ptep); if (pte_none(pte)) continue; WARN_ON(!pte_present(pte)); pte_clear(&init_mm, addr, ptep); flush_tlb_kernel_range(addr, addr + PAGE_SIZE); if (free_mapped) free_hotplug_page_range(pte_page(pte), PAGE_SIZE, altmap); } while (addr += PAGE_SIZE, addr < end); } static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr, unsigned long end, bool free_mapped, struct vmem_altmap *altmap) { unsigned long next; pmd_t *pmdp, pmd; do { next = pmd_addr_end(addr, end); pmdp = pmd_offset(pudp, addr); pmd = READ_ONCE(*pmdp); if (pmd_none(pmd)) continue; WARN_ON(!pmd_present(pmd)); if (pmd_sect(pmd)) { pmd_clear(pmdp); /* * One TLBI should be sufficient here as the PMD_SIZE * range is mapped with a single block entry. */ flush_tlb_kernel_range(addr, addr + PAGE_SIZE); if (free_mapped) free_hotplug_page_range(pmd_page(pmd), PMD_SIZE, altmap); continue; } WARN_ON(!pmd_table(pmd)); unmap_hotplug_pte_range(pmdp, addr, next, free_mapped, altmap); } while (addr = next, addr < end); } static void unmap_hotplug_pud_range(p4d_t *p4dp, unsigned long addr, unsigned long end, bool free_mapped, struct vmem_altmap *altmap) { unsigned long next; pud_t *pudp, pud; do { next = pud_addr_end(addr, end); pudp = pud_offset(p4dp, addr); pud = READ_ONCE(*pudp); if (pud_none(pud)) continue; WARN_ON(!pud_present(pud)); if (pud_sect(pud)) { pud_clear(pudp); /* * One TLBI should be sufficient here as the PUD_SIZE * range is mapped with a single block entry. */ flush_tlb_kernel_range(addr, addr + PAGE_SIZE); if (free_mapped) free_hotplug_page_range(pud_page(pud), PUD_SIZE, altmap); continue; } WARN_ON(!pud_table(pud)); unmap_hotplug_pmd_range(pudp, addr, next, free_mapped, altmap); } while (addr = next, addr < end); } static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr, unsigned long end, bool free_mapped, struct vmem_altmap *altmap) { unsigned long next; p4d_t *p4dp, p4d; do { next = p4d_addr_end(addr, end); p4dp = p4d_offset(pgdp, addr); p4d = READ_ONCE(*p4dp); if (p4d_none(p4d)) continue; WARN_ON(!p4d_present(p4d)); unmap_hotplug_pud_range(p4dp, addr, next, free_mapped, altmap); } while (addr = next, addr < end); } static void unmap_hotplug_range(unsigned long addr, unsigned long end, bool free_mapped, struct vmem_altmap *altmap) { unsigned long next; pgd_t *pgdp, pgd; /* * altmap can only be used as vmemmap mapping backing memory. * In case the backing memory itself is not being freed, then * altmap is irrelevant. Warn about this inconsistency when * encountered. */ WARN_ON(!free_mapped && altmap); do { next = pgd_addr_end(addr, end); pgdp = pgd_offset_k(addr); pgd = READ_ONCE(*pgdp); if (pgd_none(pgd)) continue; WARN_ON(!pgd_present(pgd)); unmap_hotplug_p4d_range(pgdp, addr, next, free_mapped, altmap); } while (addr = next, addr < end); } static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pte_t *ptep, pte; unsigned long i, start = addr; do { ptep = pte_offset_kernel(pmdp, addr); pte = READ_ONCE(*ptep); /* * This is just a sanity check here which verifies that * pte clearing has been done by earlier unmap loops. */ WARN_ON(!pte_none(pte)); } while (addr += PAGE_SIZE, addr < end); if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK)) return; /* * Check whether we can free the pte page if the rest of the * entries are empty. Overlap with other regions have been * handled by the floor/ceiling check. */ ptep = pte_offset_kernel(pmdp, 0UL); for (i = 0; i < PTRS_PER_PTE; i++) { if (!pte_none(READ_ONCE(ptep[i]))) return; } pmd_clear(pmdp); __flush_tlb_kernel_pgtable(start); free_hotplug_pgtable_page(virt_to_page(ptep)); } static void free_empty_pmd_table(pud_t *pudp, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pmd_t *pmdp, pmd; unsigned long i, next, start = addr; do { next = pmd_addr_end(addr, end); pmdp = pmd_offset(pudp, addr); pmd = READ_ONCE(*pmdp); if (pmd_none(pmd)) continue; WARN_ON(!pmd_present(pmd) || !pmd_table(pmd) || pmd_sect(pmd)); free_empty_pte_table(pmdp, addr, next, floor, ceiling); } while (addr = next, addr < end); if (CONFIG_PGTABLE_LEVELS <= 2) return; if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK)) return; /* * Check whether we can free the pmd page if the rest of the * entries are empty. Overlap with other regions have been * handled by the floor/ceiling check. */ pmdp = pmd_offset(pudp, 0UL); for (i = 0; i < PTRS_PER_PMD; i++) { if (!pmd_none(READ_ONCE(pmdp[i]))) return; } pud_clear(pudp); __flush_tlb_kernel_pgtable(start); free_hotplug_pgtable_page(virt_to_page(pmdp)); } static void free_empty_pud_table(p4d_t *p4dp, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { pud_t *pudp, pud; unsigned long i, next, start = addr; do { next = pud_addr_end(addr, end); pudp = pud_offset(p4dp, addr); pud = READ_ONCE(*pudp); if (pud_none(pud)) continue; WARN_ON(!pud_present(pud) || !pud_table(pud) || pud_sect(pud)); free_empty_pmd_table(pudp, addr, next, floor, ceiling); } while (addr = next, addr < end); if (CONFIG_PGTABLE_LEVELS <= 3) return; if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK)) return; /* * Check whether we can free the pud page if the rest of the * entries are empty. Overlap with other regions have been * handled by the floor/ceiling check. */ pudp = pud_offset(p4dp, 0UL); for (i = 0; i < PTRS_PER_PUD; i++) { if (!pud_none(READ_ONCE(pudp[i]))) return; } p4d_clear(p4dp); __flush_tlb_kernel_pgtable(start); free_hotplug_pgtable_page(virt_to_page(pudp)); } static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { unsigned long next; p4d_t *p4dp, p4d; do { next = p4d_addr_end(addr, end); p4dp = p4d_offset(pgdp, addr); p4d = READ_ONCE(*p4dp); if (p4d_none(p4d)) continue; WARN_ON(!p4d_present(p4d)); free_empty_pud_table(p4dp, addr, next, floor, ceiling); } while (addr = next, addr < end); } static void free_empty_tables(unsigned long addr, unsigned long end, unsigned long floor, unsigned long ceiling) { unsigned long next; pgd_t *pgdp, pgd; do { next = pgd_addr_end(addr, end); pgdp = pgd_offset_k(addr); pgd = READ_ONCE(*pgdp); if (pgd_none(pgd)) continue; WARN_ON(!pgd_present(pgd)); free_empty_p4d_table(pgdp, addr, next, floor, ceiling); } while (addr = next, addr < end); } #endif #if !ARM64_KERNEL_USES_PMD_MAPS int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, struct vmem_altmap *altmap) { WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); return vmemmap_populate_basepages(start, end, node, altmap); } #else /* !ARM64_KERNEL_USES_PMD_MAPS */ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node, struct vmem_altmap *altmap) { unsigned long addr = start; unsigned long next; pgd_t *pgdp; p4d_t *p4dp; pud_t *pudp; pmd_t *pmdp; WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); do { next = pmd_addr_end(addr, end); pgdp = vmemmap_pgd_populate(addr, node); if (!pgdp) return -ENOMEM; p4dp = vmemmap_p4d_populate(pgdp, addr, node); if (!p4dp) return -ENOMEM; pudp = vmemmap_pud_populate(p4dp, addr, node); if (!pudp) return -ENOMEM; pmdp = pmd_offset(pudp, addr); if (pmd_none(READ_ONCE(*pmdp))) { void *p = NULL; p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); if (!p) { if (vmemmap_populate_basepages(addr, next, node, altmap)) return -ENOMEM; continue; } pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); } else vmemmap_verify((pte_t *)pmdp, node, addr, next); } while (addr = next, addr != end); return 0; } #endif /* !ARM64_KERNEL_USES_PMD_MAPS */ #ifdef CONFIG_MEMORY_HOTPLUG void vmemmap_free(unsigned long start, unsigned long end, struct vmem_altmap *altmap) { WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END)); unmap_hotplug_range(start, end, true, altmap); free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END); } #endif /* CONFIG_MEMORY_HOTPLUG */ static inline pud_t *fixmap_pud(unsigned long addr) { pgd_t *pgdp = pgd_offset_k(addr); p4d_t *p4dp = p4d_offset(pgdp, addr); p4d_t p4d = READ_ONCE(*p4dp); BUG_ON(p4d_none(p4d) || p4d_bad(p4d)); return pud_offset_kimg(p4dp, addr); } static inline pmd_t *fixmap_pmd(unsigned long addr) { pud_t *pudp = fixmap_pud(addr); pud_t pud = READ_ONCE(*pudp); BUG_ON(pud_none(pud) || pud_bad(pud)); return pmd_offset_kimg(pudp, addr); } static inline pte_t *fixmap_pte(unsigned long addr) { return &bm_pte[pte_index(addr)]; } /* * The p*d_populate functions call virt_to_phys implicitly so they can't be used * directly on kernel symbols (bm_p*d). This function is called too early to use * lm_alias so __p*d_populate functions must be used to populate with the * physical address from __pa_symbol. */ void __init early_fixmap_init(void) { pgd_t *pgdp; p4d_t *p4dp, p4d; pud_t *pudp; pmd_t *pmdp; unsigned long addr = FIXADDR_START; pgdp = pgd_offset_k(addr); p4dp = p4d_offset(pgdp, addr); p4d = READ_ONCE(*p4dp); if (CONFIG_PGTABLE_LEVELS > 3 && !(p4d_none(p4d) || p4d_page_paddr(p4d) == __pa_symbol(bm_pud))) { /* * We only end up here if the kernel mapping and the fixmap * share the top level pgd entry, which should only happen on * 16k/4 levels configurations. */ BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES)); pudp = pud_offset_kimg(p4dp, addr); } else { if (p4d_none(p4d)) __p4d_populate(p4dp, __pa_symbol(bm_pud), P4D_TYPE_TABLE); pudp = fixmap_pud(addr); } if (pud_none(READ_ONCE(*pudp))) __pud_populate(pudp, __pa_symbol(bm_pmd), PUD_TYPE_TABLE); pmdp = fixmap_pmd(addr); __pmd_populate(pmdp, __pa_symbol(bm_pte), PMD_TYPE_TABLE); /* * The boot-ioremap range spans multiple pmds, for which * we are not prepared: */ BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); if ((pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) || pmdp != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) { WARN_ON(1); pr_warn("pmdp %p != %p, %p\n", pmdp, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)), fixmap_pmd(fix_to_virt(FIX_BTMAP_END))); pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n", fix_to_virt(FIX_BTMAP_BEGIN)); pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n", fix_to_virt(FIX_BTMAP_END)); pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END); pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN); } } /* * Unusually, this is also called in IRQ context (ghes_iounmap_irq) so if we * ever need to use IPIs for TLB broadcasting, then we're in trouble here. */ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags) { unsigned long addr = __fix_to_virt(idx); pte_t *ptep; BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses); ptep = fixmap_pte(addr); if (pgprot_val(flags)) { set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags)); } else { pte_clear(&init_mm, addr, ptep); flush_tlb_kernel_range(addr, addr+PAGE_SIZE); } } void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot) { const u64 dt_virt_base = __fix_to_virt(FIX_FDT); int offset; void *dt_virt; /* * Check whether the physical FDT address is set and meets the minimum * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be * at least 8 bytes so that we can always access the magic and size * fields of the FDT header after mapping the first chunk, double check * here if that is indeed the case. */ BUILD_BUG_ON(MIN_FDT_ALIGN < 8); if (!dt_phys || dt_phys % MIN_FDT_ALIGN) return NULL; /* * Make sure that the FDT region can be mapped without the need to * allocate additional translation table pages, so that it is safe * to call create_mapping_noalloc() this early. * * On 64k pages, the FDT will be mapped using PTEs, so we need to * be in the same PMD as the rest of the fixmap. * On 4k pages, we'll use section mappings for the FDT so we only * have to be in the same PUD. */ BUILD_BUG_ON(dt_virt_base % SZ_2M); BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); offset = dt_phys % SWAPPER_BLOCK_SIZE; dt_virt = (void *)dt_virt_base + offset; /* map the first chunk so we can read the size from the header */ create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base, SWAPPER_BLOCK_SIZE, prot); if (fdt_magic(dt_virt) != FDT_MAGIC) return NULL; *size = fdt_totalsize(dt_virt); if (*size > MAX_FDT_SIZE) return NULL; if (offset + *size > SWAPPER_BLOCK_SIZE) create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base, round_up(offset + *size, SWAPPER_BLOCK_SIZE), prot); return dt_virt; } int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot) { pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot)); /* Only allow permission changes for now */ if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)), pud_val(new_pud))) return 0; VM_BUG_ON(phys & ~PUD_MASK); set_pud(pudp, new_pud); return 1; } int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot) { pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot)); /* Only allow permission changes for now */ if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)), pmd_val(new_pmd))) return 0; VM_BUG_ON(phys & ~PMD_MASK); set_pmd(pmdp, new_pmd); return 1; } int pud_clear_huge(pud_t *pudp) { if (!pud_sect(READ_ONCE(*pudp))) return 0; pud_clear(pudp); return 1; } int pmd_clear_huge(pmd_t *pmdp) { if (!pmd_sect(READ_ONCE(*pmdp))) return 0; pmd_clear(pmdp); return 1; } int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr) { pte_t *table; pmd_t pmd; pmd = READ_ONCE(*pmdp); if (!pmd_table(pmd)) { VM_WARN_ON(1); return 1; } table = pte_offset_kernel(pmdp, addr); pmd_clear(pmdp); __flush_tlb_kernel_pgtable(addr); pte_free_kernel(NULL, table); return 1; } int pud_free_pmd_page(pud_t *pudp, unsigned long addr) { pmd_t *table; pmd_t *pmdp; pud_t pud; unsigned long next, end; pud = READ_ONCE(*pudp); if (!pud_table(pud)) { VM_WARN_ON(1); return 1; } table = pmd_offset(pudp, addr); pmdp = table; next = addr; end = addr + PUD_SIZE; do { pmd_free_pte_page(pmdp, next); } while (pmdp++, next += PMD_SIZE, next != end); pud_clear(pudp); __flush_tlb_kernel_pgtable(addr); pmd_free(NULL, table); return 1; } #ifdef CONFIG_MEMORY_HOTPLUG static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) { unsigned long end = start + size; WARN_ON(pgdir != init_mm.pgd); WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END)); unmap_hotplug_range(start, end, false, NULL); free_empty_tables(start, end, PAGE_OFFSET, PAGE_END); } struct range arch_get_mappable_range(void) { struct range mhp_range; u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual)); u64 end_linear_pa = __pa(PAGE_END - 1); if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { /* * Check for a wrap, it is possible because of randomized linear * mapping the start physical address is actually bigger than * the end physical address. In this case set start to zero * because [0, end_linear_pa] range must still be able to cover * all addressable physical addresses. */ if (start_linear_pa > end_linear_pa) start_linear_pa = 0; } WARN_ON(start_linear_pa > end_linear_pa); /* * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] * accommodating both its ends but excluding PAGE_END. Max physical * range which can be mapped inside this linear mapping range, must * also be derived from its end points. */ mhp_range.start = start_linear_pa; mhp_range.end = end_linear_pa; return mhp_range; } int arch_add_memory(int nid, u64 start, u64 size, struct mhp_params *params) { int ret, flags = NO_EXEC_MAPPINGS; VM_BUG_ON(!mhp_range_allowed(start, size, true)); /* * KFENCE requires linear map to be mapped at page granularity, so that * it is possible to protect/unprotect single pages in the KFENCE pool. */ if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE)) flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), size, params->pgprot, __pgd_pgtable_alloc, flags); memblock_clear_nomap(start, size); ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT, params); if (ret) __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); else { max_pfn = PFN_UP(start + size); max_low_pfn = max_pfn; } return ret; } void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap) { unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; __remove_pages(start_pfn, nr_pages, altmap); __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size); } /* * This memory hotplug notifier helps prevent boot memory from being * inadvertently removed as it blocks pfn range offlining process in * __offline_pages(). Hence this prevents both offlining as well as * removal process for boot memory which is initially always online. * In future if and when boot memory could be removed, this notifier * should be dropped and free_hotplug_page_range() should handle any * reserved pages allocated during boot. */ static int prevent_bootmem_remove_notifier(struct notifier_block *nb, unsigned long action, void *data) { struct mem_section *ms; struct memory_notify *arg = data; unsigned long end_pfn = arg->start_pfn + arg->nr_pages; unsigned long pfn = arg->start_pfn; if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE)) return NOTIFY_OK; for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { unsigned long start = PFN_PHYS(pfn); unsigned long end = start + (1UL << PA_SECTION_SHIFT); ms = __pfn_to_section(pfn); if (!early_section(ms)) continue; if (action == MEM_GOING_OFFLINE) { /* * Boot memory removal is not supported. Prevent * it via blocking any attempted offline request * for the boot memory and just report it. */ pr_warn("Boot memory [%lx %lx] offlining attempted\n", start, end); return NOTIFY_BAD; } else if (action == MEM_OFFLINE) { /* * This should have never happened. Boot memory * offlining should have been prevented by this * very notifier. Probably some memory removal * procedure might have changed which would then * require further debug. */ pr_err("Boot memory [%lx %lx] offlined\n", start, end); /* * Core memory hotplug does not process a return * code from the notifier for MEM_OFFLINE events. * The error condition has been reported. Return * from here as if ignored. */ return NOTIFY_DONE; } } return NOTIFY_OK; } static struct notifier_block prevent_bootmem_remove_nb = { .notifier_call = prevent_bootmem_remove_notifier, }; /* * This ensures that boot memory sections on the platform are online * from early boot. Memory sections could not be prevented from being * offlined, unless for some reason they are not online to begin with. * This helps validate the basic assumption on which the above memory * event notifier works to prevent boot memory section offlining and * its possible removal. */ static void validate_bootmem_online(void) { phys_addr_t start, end, addr; struct mem_section *ms; u64 i; /* * Scanning across all memblock might be expensive * on some big memory systems. Hence enable this * validation only with DEBUG_VM. */ if (!IS_ENABLED(CONFIG_DEBUG_VM)) return; for_each_mem_range(i, &start, &end) { for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) { ms = __pfn_to_section(PHYS_PFN(addr)); /* * All memory ranges in the system at this point * should have been marked as early sections. */ WARN_ON(!early_section(ms)); /* * Memory notifier mechanism here to prevent boot * memory offlining depends on the fact that each * early section memory on the system is initially * online. Otherwise a given memory section which * is already offline will be overlooked and can * be removed completely. Call out such sections. */ if (!online_section(ms)) pr_err("Boot memory [%llx %llx] is offline, can be removed\n", addr, addr + (1UL << PA_SECTION_SHIFT)); } } } static int __init prevent_bootmem_remove_init(void) { int ret = 0; if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE)) return ret; validate_bootmem_online(); ret = register_memory_notifier(&prevent_bootmem_remove_nb); if (ret) pr_err("%s: Notifier registration failed %d\n", __func__, ret); return ret; } early_initcall(prevent_bootmem_remove_init); #endif