// SPDX-License-Identifier: GPL-2.0-or-later /* * This file contains common routines for dealing with free of page tables * Along with common page table handling code * * Derived from arch/powerpc/mm/tlb_64.c: * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) * * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au) * and Cort Dougan (PReP) (cort@cs.nmt.edu) * Copyright (C) 1996 Paul Mackerras * * Derived from "arch/i386/mm/init.c" * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * * Dave Engebretsen * Rework for PPC64 port. */ #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_PPC64 #define PGD_ALIGN (sizeof(pgd_t) * MAX_PTRS_PER_PGD) #else #define PGD_ALIGN PAGE_SIZE #endif pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __section(".bss..page_aligned") __aligned(PGD_ALIGN); static inline int is_exec_fault(void) { return current->thread.regs && TRAP(current->thread.regs) == 0x400; } /* We only try to do i/d cache coherency on stuff that looks like * reasonably "normal" PTEs. We currently require a PTE to be present * and we avoid _PAGE_SPECIAL and cache inhibited pte. We also only do that * on userspace PTEs */ static inline int pte_looks_normal(pte_t pte, unsigned long addr) { if (pte_present(pte) && !pte_special(pte)) { if (pte_ci(pte)) return 0; if (!is_kernel_addr(addr)) return 1; } return 0; } static struct folio *maybe_pte_to_folio(pte_t pte) { unsigned long pfn = pte_pfn(pte); struct page *page; if (unlikely(!pfn_valid(pfn))) return NULL; page = pfn_to_page(pfn); if (PageReserved(page)) return NULL; return page_folio(page); } #ifdef CONFIG_PPC_BOOK3S /* Server-style MMU handles coherency when hashing if HW exec permission * is supposed per page (currently 64-bit only). If not, then, we always * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec * support falls into the same category. */ static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr) { pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS); if (pte_looks_normal(pte, addr) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) || cpu_has_feature(CPU_FTR_NOEXECUTE))) { struct folio *folio = maybe_pte_to_folio(pte); if (!folio) return pte; if (!test_bit(PG_dcache_clean, &folio->flags)) { flush_dcache_icache_folio(folio); set_bit(PG_dcache_clean, &folio->flags); } } return pte; } #else /* CONFIG_PPC_BOOK3S */ static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr) { return pte; } #endif /* CONFIG_PPC_BOOK3S */ /* Embedded type MMU with HW exec support. This is a bit more complicated * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so * instead we "filter out" the exec permission for non clean pages. * * This is also called once for the folio. So only work with folio->flags here. */ static inline pte_t set_pte_filter(pte_t pte, unsigned long addr) { struct folio *folio; if (radix_enabled()) return pte; if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) return set_pte_filter_hash(pte, addr); /* No exec permission in the first place, move on */ if (!pte_exec(pte) || !pte_looks_normal(pte, addr)) return pte; /* If you set _PAGE_EXEC on weird pages you're on your own */ folio = maybe_pte_to_folio(pte); if (unlikely(!folio)) return pte; /* If the page clean, we move on */ if (test_bit(PG_dcache_clean, &folio->flags)) return pte; /* If it's an exec fault, we flush the cache and make it clean */ if (is_exec_fault()) { flush_dcache_icache_folio(folio); set_bit(PG_dcache_clean, &folio->flags); return pte; } /* Else, we filter out _PAGE_EXEC */ return pte_exprotect(pte); } static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma, int dirty) { struct folio *folio; if (IS_ENABLED(CONFIG_PPC_BOOK3S_64)) return pte; if (mmu_has_feature(MMU_FTR_HPTE_TABLE)) return pte; /* So here, we only care about exec faults, as we use them * to recover lost _PAGE_EXEC and perform I$/D$ coherency * if necessary. Also if _PAGE_EXEC is already set, same deal, * we just bail out */ if (dirty || pte_exec(pte) || !is_exec_fault()) return pte; #ifdef CONFIG_DEBUG_VM /* So this is an exec fault, _PAGE_EXEC is not set. If it was * an error we would have bailed out earlier in do_page_fault() * but let's make sure of it */ if (WARN_ON(!(vma->vm_flags & VM_EXEC))) return pte; #endif /* CONFIG_DEBUG_VM */ /* If you set _PAGE_EXEC on weird pages you're on your own */ folio = maybe_pte_to_folio(pte); if (unlikely(!folio)) goto bail; /* If the page is already clean, we move on */ if (test_bit(PG_dcache_clean, &folio->flags)) goto bail; /* Clean the page and set PG_dcache_clean */ flush_dcache_icache_folio(folio); set_bit(PG_dcache_clean, &folio->flags); bail: return pte_mkexec(pte); } /* * set_pte stores a linux PTE into the linux page table. */ void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte, unsigned int nr) { /* Note: mm->context.id might not yet have been assigned as * this context might not have been activated yet when this * is called. Filter the pte value and use the filtered value * to setup all the ptes in the range. */ pte = set_pte_filter(pte, addr); /* * We don't need to call arch_enter/leave_lazy_mmu_mode() * because we expect set_ptes to be only be used on not present * and not hw_valid ptes. Hence there is no translation cache flush * involved that need to be batched. */ for (;;) { /* * Make sure hardware valid bit is not set. We don't do * tlb flush for this update. */ VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); /* Perform the setting of the PTE */ __set_pte_at(mm, addr, ptep, pte, 0); if (--nr == 0) break; ptep++; addr += PAGE_SIZE; pte = pte_next_pfn(pte); } } void unmap_kernel_page(unsigned long va) { pmd_t *pmdp = pmd_off_k(va); pte_t *ptep = pte_offset_kernel(pmdp, va); pte_clear(&init_mm, va, ptep); flush_tlb_kernel_range(va, va + PAGE_SIZE); } /* * This is called when relaxing access to a PTE. It's also called in the page * fault path when we don't hit any of the major fault cases, ie, a minor * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have * handled those two for us, we additionally deal with missing execute * permission here on some processors */ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty) { int changed; entry = set_access_flags_filter(entry, vma, dirty); changed = !pte_same(*(ptep), entry); if (changed) { assert_pte_locked(vma->vm_mm, address); __ptep_set_access_flags(vma, ptep, entry, address, mmu_virtual_psize); } return changed; } #ifdef CONFIG_HUGETLB_PAGE int huge_ptep_set_access_flags(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, pte_t pte, int dirty) { #ifdef HUGETLB_NEED_PRELOAD /* * The "return 1" forces a call of update_mmu_cache, which will write a * TLB entry. Without this, platforms that don't do a write of the TLB * entry in the TLB miss handler asm will fault ad infinitum. */ ptep_set_access_flags(vma, addr, ptep, pte, dirty); return 1; #else int changed, psize; pte = set_access_flags_filter(pte, vma, dirty); changed = !pte_same(*(ptep), pte); if (changed) { #ifdef CONFIG_PPC_BOOK3S_64 struct hstate *h = hstate_vma(vma); psize = hstate_get_psize(h); #ifdef CONFIG_DEBUG_VM assert_spin_locked(huge_pte_lockptr(h, vma->vm_mm, ptep)); #endif #else /* * Not used on non book3s64 platforms. * 8xx compares it with mmu_virtual_psize to * know if it is a huge page or not. */ psize = MMU_PAGE_COUNT; #endif __ptep_set_access_flags(vma, ptep, pte, addr, psize); } return changed; #endif } #if defined(CONFIG_PPC_8xx) #if defined(CONFIG_SPLIT_PTE_PTLOCKS) || defined(CONFIG_SPLIT_PMD_PTLOCKS) /* We need the same lock to protect the PMD table and the two PTE tables. */ #error "8M hugetlb folios are incompatible with split page table locks" #endif static void __set_huge_pte_at(pmd_t *pmd, pte_t *ptep, pte_basic_t val) { pte_basic_t *entry = (pte_basic_t *)ptep; int num, i; /* * Make sure hardware valid bit is not set. We don't do * tlb flush for this update. */ VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); num = number_of_cells_per_pte(pmd, val, 1); for (i = 0; i < num; i++, entry++, val += SZ_4K) *entry = val; } void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte, unsigned long sz) { pmd_t *pmdp = pmd_off(mm, addr); pte = set_pte_filter(pte, addr); if (sz == SZ_8M) { /* Flag both PMD entries as 8M and fill both page tables */ *pmdp = __pmd(pmd_val(*pmdp) | _PMD_PAGE_8M); *(pmdp + 1) = __pmd(pmd_val(*(pmdp + 1)) | _PMD_PAGE_8M); __set_huge_pte_at(pmdp, pte_offset_kernel(pmdp, 0), pte_val(pte)); __set_huge_pte_at(pmdp, pte_offset_kernel(pmdp + 1, 0), pte_val(pte) + SZ_4M); } else { __set_huge_pte_at(pmdp, ptep, pte_val(pte)); } } #else void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte, unsigned long sz) { unsigned long pdsize; int i; pte = set_pte_filter(pte, addr); /* * Make sure hardware valid bit is not set. We don't do * tlb flush for this update. */ VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); if (sz < PMD_SIZE) pdsize = PAGE_SIZE; else if (sz < PUD_SIZE) pdsize = PMD_SIZE; else if (sz < P4D_SIZE) pdsize = PUD_SIZE; else if (sz < PGDIR_SIZE) pdsize = P4D_SIZE; else pdsize = PGDIR_SIZE; for (i = 0; i < sz / pdsize; i++, ptep++, addr += pdsize) { __set_pte_at(mm, addr, ptep, pte, 0); pte = __pte(pte_val(pte) + ((unsigned long long)pdsize / PAGE_SIZE << PFN_PTE_SHIFT)); } } #endif #endif /* CONFIG_HUGETLB_PAGE */ #ifdef CONFIG_DEBUG_VM void assert_pte_locked(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; p4d_t *p4d; pud_t *pud; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; if (mm == &init_mm) return; pgd = mm->pgd + pgd_index(addr); BUG_ON(pgd_none(*pgd)); p4d = p4d_offset(pgd, addr); BUG_ON(p4d_none(*p4d)); pud = pud_offset(p4d, addr); BUG_ON(pud_none(*pud)); pmd = pmd_offset(pud, addr); /* * khugepaged to collapse normal pages to hugepage, first set * pmd to none to force page fault/gup to take mmap_lock. After * pmd is set to none, we do a pte_clear which does this assertion * so if we find pmd none, return. */ if (pmd_none(*pmd)) return; pte = pte_offset_map_nolock(mm, pmd, addr, &ptl); BUG_ON(!pte); assert_spin_locked(ptl); pte_unmap(pte); } #endif /* CONFIG_DEBUG_VM */ unsigned long vmalloc_to_phys(void *va) { unsigned long pfn = vmalloc_to_pfn(va); BUG_ON(!pfn); return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va); } EXPORT_SYMBOL_GPL(vmalloc_to_phys); /* * We have 3 cases for pgds and pmds: * (1) invalid (all zeroes) * (2) pointer to next table, as normal; bottom 6 bits == 0 * (3) leaf pte for huge page _PAGE_PTE set * * So long as we atomically load page table pointers we are safe against teardown, * we can follow the address down to the page and take a ref on it. * This function need to be called with interrupts disabled. We use this variant * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED */ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, bool *is_thp, unsigned *hpage_shift) { pgd_t *pgdp; #ifdef CONFIG_PPC64 p4d_t p4d, *p4dp; pud_t pud, *pudp; #endif pmd_t pmd, *pmdp; pte_t *ret_pte; unsigned pdshift; if (hpage_shift) *hpage_shift = 0; if (is_thp) *is_thp = false; /* * Always operate on the local stack value. This make sure the * value don't get updated by a parallel THP split/collapse, * page fault or a page unmap. The return pte_t * is still not * stable. So should be checked there for above conditions. * Top level is an exception because it is folded into p4d. * * On PPC32, P4D/PUD/PMD are folded into PGD so go straight to * PMD level. */ pgdp = pgdir + pgd_index(ea); #ifdef CONFIG_PPC64 p4dp = p4d_offset(pgdp, ea); p4d = READ_ONCE(*p4dp); pdshift = P4D_SHIFT; if (p4d_none(p4d)) return NULL; if (p4d_leaf(p4d)) { ret_pte = (pte_t *)p4dp; goto out; } /* * Even if we end up with an unmap, the pgtable will not * be freed, because we do an rcu free and here we are * irq disabled */ pdshift = PUD_SHIFT; pudp = pud_offset(&p4d, ea); pud = READ_ONCE(*pudp); if (pud_none(pud)) return NULL; if (pud_leaf(pud)) { ret_pte = (pte_t *)pudp; goto out; } pmdp = pmd_offset(&pud, ea); #else pmdp = pmd_offset(pud_offset(p4d_offset(pgdp, ea), ea), ea); #endif pdshift = PMD_SHIFT; pmd = READ_ONCE(*pmdp); /* * A hugepage collapse is captured by this condition, see * pmdp_collapse_flush. */ if (pmd_none(pmd)) return NULL; #ifdef CONFIG_PPC_BOOK3S_64 /* * A hugepage split is captured by this condition, see * pmdp_invalidate. * * Huge page modification can be caught here too. */ if (pmd_is_serializing(pmd)) return NULL; #endif if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) { if (is_thp) *is_thp = true; ret_pte = (pte_t *)pmdp; goto out; } if (pmd_leaf(pmd)) { ret_pte = (pte_t *)pmdp; goto out; } return pte_offset_kernel(&pmd, ea); out: if (hpage_shift) *hpage_shift = pdshift; return ret_pte; } EXPORT_SYMBOL_GPL(__find_linux_pte); /* Note due to the way vm flags are laid out, the bits are XWR */ const pgprot_t protection_map[16] = { [VM_NONE] = PAGE_NONE, [VM_READ] = PAGE_READONLY, [VM_WRITE] = PAGE_COPY, [VM_WRITE | VM_READ] = PAGE_COPY, [VM_EXEC] = PAGE_EXECONLY_X, [VM_EXEC | VM_READ] = PAGE_READONLY_X, [VM_EXEC | VM_WRITE] = PAGE_COPY_X, [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X, [VM_SHARED] = PAGE_NONE, [VM_SHARED | VM_READ] = PAGE_READONLY, [VM_SHARED | VM_WRITE] = PAGE_SHARED, [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED, [VM_SHARED | VM_EXEC] = PAGE_EXECONLY_X, [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X, [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X, [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X }; #ifndef CONFIG_PPC_BOOK3S_64 DECLARE_VM_GET_PAGE_PROT #endif