// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright 2007-2008 Paul Mackerras, IBM Corp. */ #include <linux/errno.h> #include <linux/kernel.h> #include <linux/gfp.h> #include <linux/types.h> #include <linux/pagewalk.h> #include <linux/hugetlb.h> #include <linux/syscalls.h> #include <linux/pgtable.h> #include <linux/uaccess.h> /* * Free all pages allocated for subpage protection maps and pointers. * Also makes sure that the subpage_prot_table structure is * reinitialized for the next user. */ void subpage_prot_free(struct mm_struct *mm) { struct subpage_prot_table *spt = mm_ctx_subpage_prot(&mm->context); unsigned long i, j, addr; u32 **p; if (!spt) return; for (i = 0; i < 4; ++i) { if (spt->low_prot[i]) { free_page((unsigned long)spt->low_prot[i]); spt->low_prot[i] = NULL; } } addr = 0; for (i = 0; i < (TASK_SIZE_USER64 >> 43); ++i) { p = spt->protptrs[i]; if (!p) continue; spt->protptrs[i] = NULL; for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr; ++j, addr += PAGE_SIZE) if (p[j]) free_page((unsigned long)p[j]); free_page((unsigned long)p); } spt->maxaddr = 0; kfree(spt); } static void hpte_flush_range(struct mm_struct *mm, unsigned long addr, int npages) { pgd_t *pgd; p4d_t *p4d; pud_t *pud; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; pgd = pgd_offset(mm, addr); p4d = p4d_offset(pgd, addr); if (p4d_none(*p4d)) return; pud = pud_offset(p4d, addr); if (pud_none(*pud)) return; pmd = pmd_offset(pud, addr); if (pmd_none(*pmd)) return; pte = pte_offset_map_lock(mm, pmd, addr, &ptl); arch_enter_lazy_mmu_mode(); for (; npages > 0; --npages) { pte_update(mm, addr, pte, 0, 0, 0); addr += PAGE_SIZE; ++pte; } arch_leave_lazy_mmu_mode(); pte_unmap_unlock(pte - 1, ptl); } /* * Clear the subpage protection map for an address range, allowing * all accesses that are allowed by the pte permissions. */ static void subpage_prot_clear(unsigned long addr, unsigned long len) { struct mm_struct *mm = current->mm; struct subpage_prot_table *spt; u32 **spm, *spp; unsigned long i; size_t nw; unsigned long next, limit; mmap_write_lock(mm); spt = mm_ctx_subpage_prot(&mm->context); if (!spt) goto err_out; limit = addr + len; if (limit > spt->maxaddr) limit = spt->maxaddr; for (; addr < limit; addr = next) { next = pmd_addr_end(addr, limit); if (addr < 0x100000000UL) { spm = spt->low_prot; } else { spm = spt->protptrs[addr >> SBP_L3_SHIFT]; if (!spm) continue; } spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)]; if (!spp) continue; spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); nw = PTRS_PER_PTE - i; if (addr + (nw << PAGE_SHIFT) > next) nw = (next - addr) >> PAGE_SHIFT; memset(spp, 0, nw * sizeof(u32)); /* now flush any existing HPTEs for the range */ hpte_flush_range(mm, addr, nw); } err_out: mmap_write_unlock(mm); } #ifdef CONFIG_TRANSPARENT_HUGEPAGE static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) { struct vm_area_struct *vma = walk->vma; split_huge_pmd(vma, pmd, addr); return 0; } static const struct mm_walk_ops subpage_walk_ops = { .pmd_entry = subpage_walk_pmd_entry, }; static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr, unsigned long len) { struct vm_area_struct *vma; VMA_ITERATOR(vmi, mm, addr); /* * We don't try too hard, we just mark all the vma in that range * VM_NOHUGEPAGE and split them. */ for_each_vma_range(vmi, vma, addr + len) { vm_flags_set(vma, VM_NOHUGEPAGE); walk_page_vma(vma, &subpage_walk_ops, NULL); } } #else static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr, unsigned long len) { return; } #endif /* * Copy in a subpage protection map for an address range. * The map has 2 bits per 4k subpage, so 32 bits per 64k page. * Each 2-bit field is 0 to allow any access, 1 to prevent writes, * 2 or 3 to prevent all accesses. * Note that the normal page protections also apply; the subpage * protection mechanism is an additional constraint, so putting 0 * in a 2-bit field won't allow writes to a page that is otherwise * write-protected. */ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr, unsigned long, len, u32 __user *, map) { struct mm_struct *mm = current->mm; struct subpage_prot_table *spt; u32 **spm, *spp; unsigned long i; size_t nw; unsigned long next, limit; int err; if (radix_enabled()) return -ENOENT; /* Check parameters */ if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) || addr >= mm->task_size || len >= mm->task_size || addr + len > mm->task_size) return -EINVAL; if (is_hugepage_only_range(mm, addr, len)) return -EINVAL; if (!map) { /* Clear out the protection map for the address range */ subpage_prot_clear(addr, len); return 0; } if (!access_ok(map, (len >> PAGE_SHIFT) * sizeof(u32))) return -EFAULT; mmap_write_lock(mm); spt = mm_ctx_subpage_prot(&mm->context); if (!spt) { /* * Allocate subpage prot table if not already done. * Do this with mmap_lock held */ spt = kzalloc(sizeof(struct subpage_prot_table), GFP_KERNEL); if (!spt) { err = -ENOMEM; goto out; } mm->context.hash_context->spt = spt; } subpage_mark_vma_nohuge(mm, addr, len); for (limit = addr + len; addr < limit; addr = next) { next = pmd_addr_end(addr, limit); err = -ENOMEM; if (addr < 0x100000000UL) { spm = spt->low_prot; } else { spm = spt->protptrs[addr >> SBP_L3_SHIFT]; if (!spm) { spm = (u32 **)get_zeroed_page(GFP_KERNEL); if (!spm) goto out; spt->protptrs[addr >> SBP_L3_SHIFT] = spm; } } spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1); spp = *spm; if (!spp) { spp = (u32 *)get_zeroed_page(GFP_KERNEL); if (!spp) goto out; *spm = spp; } spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); local_irq_disable(); demote_segment_4k(mm, addr); local_irq_enable(); i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); nw = PTRS_PER_PTE - i; if (addr + (nw << PAGE_SHIFT) > next) nw = (next - addr) >> PAGE_SHIFT; mmap_write_unlock(mm); if (__copy_from_user(spp, map, nw * sizeof(u32))) return -EFAULT; map += nw; mmap_write_lock(mm); /* now flush any existing HPTEs for the range */ hpte_flush_range(mm, addr, nw); } if (limit > spt->maxaddr) spt->maxaddr = limit; err = 0; out: mmap_write_unlock(mm); return err; }