| |
| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/mm/memory.c |
| * |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| */ |
| |
| /* |
| * demand-loading started 01.12.91 - seems it is high on the list of |
| * things wanted, and it should be easy to implement. - Linus |
| */ |
| |
| /* |
| * Ok, demand-loading was easy, shared pages a little bit tricker. Shared |
| * pages started 02.12.91, seems to work. - Linus. |
| * |
| * Tested sharing by executing about 30 /bin/sh: under the old kernel it |
| * would have taken more than the 6M I have free, but it worked well as |
| * far as I could see. |
| * |
| * Also corrected some "invalidate()"s - I wasn't doing enough of them. |
| */ |
| |
| /* |
| * Real VM (paging to/from disk) started 18.12.91. Much more work and |
| * thought has to go into this. Oh, well.. |
| * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. |
| * Found it. Everything seems to work now. |
| * 20.12.91 - Ok, making the swap-device changeable like the root. |
| */ |
| |
| /* |
| * 05.04.94 - Multi-page memory management added for v1.1. |
| * Idea by Alex Bligh (alex@cconcepts.co.uk) |
| * |
| * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG |
| * (Gerhard.Wichert@pdb.siemens.de) |
| * |
| * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) |
| */ |
| |
| #include <linux/kernel_stat.h> |
| #include <linux/mm.h> |
| #include <linux/mm_inline.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/coredump.h> |
| #include <linux/sched/numa_balancing.h> |
| #include <linux/sched/task.h> |
| #include <linux/hugetlb.h> |
| #include <linux/mman.h> |
| #include <linux/swap.h> |
| #include <linux/highmem.h> |
| #include <linux/pagemap.h> |
| #include <linux/memremap.h> |
| #include <linux/kmsan.h> |
| #include <linux/ksm.h> |
| #include <linux/rmap.h> |
| #include <linux/export.h> |
| #include <linux/delayacct.h> |
| #include <linux/init.h> |
| #include <linux/pfn_t.h> |
| #include <linux/writeback.h> |
| #include <linux/memcontrol.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/swapops.h> |
| #include <linux/elf.h> |
| #include <linux/gfp.h> |
| #include <linux/migrate.h> |
| #include <linux/string.h> |
| #include <linux/memory-tiers.h> |
| #include <linux/debugfs.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/dax.h> |
| #include <linux/oom.h> |
| #include <linux/numa.h> |
| #include <linux/perf_event.h> |
| #include <linux/ptrace.h> |
| #include <linux/vmalloc.h> |
| #include <linux/sched/sysctl.h> |
| |
| #include <trace/events/kmem.h> |
| |
| #include <asm/io.h> |
| #include <asm/mmu_context.h> |
| #include <asm/pgalloc.h> |
| #include <linux/uaccess.h> |
| #include <asm/tlb.h> |
| #include <asm/tlbflush.h> |
| |
| #include "pgalloc-track.h" |
| #include "internal.h" |
| #include "swap.h" |
| |
| #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST) |
| #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. |
| #endif |
| |
| #ifndef CONFIG_NUMA |
| unsigned long max_mapnr; |
| EXPORT_SYMBOL(max_mapnr); |
| |
| struct page *mem_map; |
| EXPORT_SYMBOL(mem_map); |
| #endif |
| |
| static vm_fault_t do_fault(struct vm_fault *vmf); |
| static vm_fault_t do_anonymous_page(struct vm_fault *vmf); |
| static bool vmf_pte_changed(struct vm_fault *vmf); |
| |
| /* |
| * Return true if the original pte was a uffd-wp pte marker (so the pte was |
| * wr-protected). |
| */ |
| static __always_inline bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf) |
| { |
| if (!userfaultfd_wp(vmf->vma)) |
| return false; |
| if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)) |
| return false; |
| |
| return pte_marker_uffd_wp(vmf->orig_pte); |
| } |
| |
| /* |
| * A number of key systems in x86 including ioremap() rely on the assumption |
| * that high_memory defines the upper bound on direct map memory, then end |
| * of ZONE_NORMAL. |
| */ |
| void *high_memory; |
| EXPORT_SYMBOL(high_memory); |
| |
| /* |
| * Randomize the address space (stacks, mmaps, brk, etc.). |
| * |
| * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, |
| * as ancient (libc5 based) binaries can segfault. ) |
| */ |
| int randomize_va_space __read_mostly = |
| #ifdef CONFIG_COMPAT_BRK |
| 1; |
| #else |
| 2; |
| #endif |
| |
| #ifndef arch_wants_old_prefaulted_pte |
| static inline bool arch_wants_old_prefaulted_pte(void) |
| { |
| /* |
| * Transitioning a PTE from 'old' to 'young' can be expensive on |
| * some architectures, even if it's performed in hardware. By |
| * default, "false" means prefaulted entries will be 'young'. |
| */ |
| return false; |
| } |
| #endif |
| |
| static int __init disable_randmaps(char *s) |
| { |
| randomize_va_space = 0; |
| return 1; |
| } |
| __setup("norandmaps", disable_randmaps); |
| |
| unsigned long zero_pfn __read_mostly; |
| EXPORT_SYMBOL(zero_pfn); |
| |
| unsigned long highest_memmap_pfn __read_mostly; |
| |
| /* |
| * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() |
| */ |
| static int __init init_zero_pfn(void) |
| { |
| zero_pfn = page_to_pfn(ZERO_PAGE(0)); |
| return 0; |
| } |
| early_initcall(init_zero_pfn); |
| |
| void mm_trace_rss_stat(struct mm_struct *mm, int member) |
| { |
| trace_rss_stat(mm, member); |
| } |
| |
| /* |
| * Note: this doesn't free the actual pages themselves. That |
| * has been handled earlier when unmapping all the memory regions. |
| */ |
| static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, |
| unsigned long addr) |
| { |
| pgtable_t token = pmd_pgtable(*pmd); |
| pmd_clear(pmd); |
| pte_free_tlb(tlb, token, addr); |
| mm_dec_nr_ptes(tlb->mm); |
| } |
| |
| static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| pmd = pmd_offset(pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (pmd_none_or_clear_bad(pmd)) |
| continue; |
| free_pte_range(tlb, pmd, addr); |
| } while (pmd++, addr = next, addr != end); |
| |
| start &= PUD_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= PUD_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| pmd = pmd_offset(pud, start); |
| pud_clear(pud); |
| pmd_free_tlb(tlb, pmd, start); |
| mm_dec_nr_pmds(tlb->mm); |
| } |
| |
| static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pud_t *pud; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| free_pmd_range(tlb, pud, addr, next, floor, ceiling); |
| } while (pud++, addr = next, addr != end); |
| |
| start &= P4D_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= P4D_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| pud = pud_offset(p4d, start); |
| p4d_clear(p4d); |
| pud_free_tlb(tlb, pud, start); |
| mm_dec_nr_puds(tlb->mm); |
| } |
| |
| static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| unsigned long start; |
| |
| start = addr; |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| free_pud_range(tlb, p4d, addr, next, floor, ceiling); |
| } while (p4d++, addr = next, addr != end); |
| |
| start &= PGDIR_MASK; |
| if (start < floor) |
| return; |
| if (ceiling) { |
| ceiling &= PGDIR_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| return; |
| |
| p4d = p4d_offset(pgd, start); |
| pgd_clear(pgd); |
| p4d_free_tlb(tlb, p4d, start); |
| } |
| |
| /* |
| * This function frees user-level page tables of a process. |
| */ |
| void free_pgd_range(struct mmu_gather *tlb, |
| unsigned long addr, unsigned long end, |
| unsigned long floor, unsigned long ceiling) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| |
| /* |
| * The next few lines have given us lots of grief... |
| * |
| * Why are we testing PMD* at this top level? Because often |
| * there will be no work to do at all, and we'd prefer not to |
| * go all the way down to the bottom just to discover that. |
| * |
| * Why all these "- 1"s? Because 0 represents both the bottom |
| * of the address space and the top of it (using -1 for the |
| * top wouldn't help much: the masks would do the wrong thing). |
| * The rule is that addr 0 and floor 0 refer to the bottom of |
| * the address space, but end 0 and ceiling 0 refer to the top |
| * Comparisons need to use "end - 1" and "ceiling - 1" (though |
| * that end 0 case should be mythical). |
| * |
| * Wherever addr is brought up or ceiling brought down, we must |
| * be careful to reject "the opposite 0" before it confuses the |
| * subsequent tests. But what about where end is brought down |
| * by PMD_SIZE below? no, end can't go down to 0 there. |
| * |
| * Whereas we round start (addr) and ceiling down, by different |
| * masks at different levels, in order to test whether a table |
| * now has no other vmas using it, so can be freed, we don't |
| * bother to round floor or end up - the tests don't need that. |
| */ |
| |
| addr &= PMD_MASK; |
| if (addr < floor) { |
| addr += PMD_SIZE; |
| if (!addr) |
| return; |
| } |
| if (ceiling) { |
| ceiling &= PMD_MASK; |
| if (!ceiling) |
| return; |
| } |
| if (end - 1 > ceiling - 1) |
| end -= PMD_SIZE; |
| if (addr > end - 1) |
| return; |
| /* |
| * We add page table cache pages with PAGE_SIZE, |
| * (see pte_free_tlb()), flush the tlb if we need |
| */ |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| pgd = pgd_offset(tlb->mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| free_p4d_range(tlb, pgd, addr, next, floor, ceiling); |
| } while (pgd++, addr = next, addr != end); |
| } |
| |
| void free_pgtables(struct mmu_gather *tlb, struct ma_state *mas, |
| struct vm_area_struct *vma, unsigned long floor, |
| unsigned long ceiling, bool mm_wr_locked) |
| { |
| do { |
| unsigned long addr = vma->vm_start; |
| struct vm_area_struct *next; |
| |
| /* |
| * Note: USER_PGTABLES_CEILING may be passed as ceiling and may |
| * be 0. This will underflow and is okay. |
| */ |
| next = mas_find(mas, ceiling - 1); |
| if (unlikely(xa_is_zero(next))) |
| next = NULL; |
| |
| /* |
| * Hide vma from rmap and truncate_pagecache before freeing |
| * pgtables |
| */ |
| if (mm_wr_locked) |
| vma_start_write(vma); |
| unlink_anon_vmas(vma); |
| unlink_file_vma(vma); |
| |
| if (is_vm_hugetlb_page(vma)) { |
| hugetlb_free_pgd_range(tlb, addr, vma->vm_end, |
| floor, next ? next->vm_start : ceiling); |
| } else { |
| /* |
| * Optimization: gather nearby vmas into one call down |
| */ |
| while (next && next->vm_start <= vma->vm_end + PMD_SIZE |
| && !is_vm_hugetlb_page(next)) { |
| vma = next; |
| next = mas_find(mas, ceiling - 1); |
| if (unlikely(xa_is_zero(next))) |
| next = NULL; |
| if (mm_wr_locked) |
| vma_start_write(vma); |
| unlink_anon_vmas(vma); |
| unlink_file_vma(vma); |
| } |
| free_pgd_range(tlb, addr, vma->vm_end, |
| floor, next ? next->vm_start : ceiling); |
| } |
| vma = next; |
| } while (vma); |
| } |
| |
| void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte) |
| { |
| spinlock_t *ptl = pmd_lock(mm, pmd); |
| |
| if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| mm_inc_nr_ptes(mm); |
| /* |
| * Ensure all pte setup (eg. pte page lock and page clearing) are |
| * visible before the pte is made visible to other CPUs by being |
| * put into page tables. |
| * |
| * The other side of the story is the pointer chasing in the page |
| * table walking code (when walking the page table without locking; |
| * ie. most of the time). Fortunately, these data accesses consist |
| * of a chain of data-dependent loads, meaning most CPUs (alpha |
| * being the notable exception) will already guarantee loads are |
| * seen in-order. See the alpha page table accessors for the |
| * smp_rmb() barriers in page table walking code. |
| */ |
| smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ |
| pmd_populate(mm, pmd, *pte); |
| *pte = NULL; |
| } |
| spin_unlock(ptl); |
| } |
| |
| int __pte_alloc(struct mm_struct *mm, pmd_t *pmd) |
| { |
| pgtable_t new = pte_alloc_one(mm); |
| if (!new) |
| return -ENOMEM; |
| |
| pmd_install(mm, pmd, &new); |
| if (new) |
| pte_free(mm, new); |
| return 0; |
| } |
| |
| int __pte_alloc_kernel(pmd_t *pmd) |
| { |
| pte_t *new = pte_alloc_one_kernel(&init_mm); |
| if (!new) |
| return -ENOMEM; |
| |
| spin_lock(&init_mm.page_table_lock); |
| if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ |
| smp_wmb(); /* See comment in pmd_install() */ |
| pmd_populate_kernel(&init_mm, pmd, new); |
| new = NULL; |
| } |
| spin_unlock(&init_mm.page_table_lock); |
| if (new) |
| pte_free_kernel(&init_mm, new); |
| return 0; |
| } |
| |
| static inline void init_rss_vec(int *rss) |
| { |
| memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); |
| } |
| |
| static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) |
| { |
| int i; |
| |
| for (i = 0; i < NR_MM_COUNTERS; i++) |
| if (rss[i]) |
| add_mm_counter(mm, i, rss[i]); |
| } |
| |
| /* |
| * This function is called to print an error when a bad pte |
| * is found. For example, we might have a PFN-mapped pte in |
| * a region that doesn't allow it. |
| * |
| * The calling function must still handle the error. |
| */ |
| static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte, struct page *page) |
| { |
| pgd_t *pgd = pgd_offset(vma->vm_mm, addr); |
| p4d_t *p4d = p4d_offset(pgd, addr); |
| pud_t *pud = pud_offset(p4d, addr); |
| pmd_t *pmd = pmd_offset(pud, addr); |
| struct address_space *mapping; |
| pgoff_t index; |
| static unsigned long resume; |
| static unsigned long nr_shown; |
| static unsigned long nr_unshown; |
| |
| /* |
| * Allow a burst of 60 reports, then keep quiet for that minute; |
| * or allow a steady drip of one report per second. |
| */ |
| if (nr_shown == 60) { |
| if (time_before(jiffies, resume)) { |
| nr_unshown++; |
| return; |
| } |
| if (nr_unshown) { |
| pr_alert("BUG: Bad page map: %lu messages suppressed\n", |
| nr_unshown); |
| nr_unshown = 0; |
| } |
| nr_shown = 0; |
| } |
| if (nr_shown++ == 0) |
| resume = jiffies + 60 * HZ; |
| |
| mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; |
| index = linear_page_index(vma, addr); |
| |
| pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", |
| current->comm, |
| (long long)pte_val(pte), (long long)pmd_val(*pmd)); |
| if (page) |
| dump_page(page, "bad pte"); |
| pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n", |
| (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); |
| pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n", |
| vma->vm_file, |
| vma->vm_ops ? vma->vm_ops->fault : NULL, |
| vma->vm_file ? vma->vm_file->f_op->mmap : NULL, |
| mapping ? mapping->a_ops->read_folio : NULL); |
| dump_stack(); |
| add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
| } |
| |
| /* |
| * vm_normal_page -- This function gets the "struct page" associated with a pte. |
| * |
| * "Special" mappings do not wish to be associated with a "struct page" (either |
| * it doesn't exist, or it exists but they don't want to touch it). In this |
| * case, NULL is returned here. "Normal" mappings do have a struct page. |
| * |
| * There are 2 broad cases. Firstly, an architecture may define a pte_special() |
| * pte bit, in which case this function is trivial. Secondly, an architecture |
| * may not have a spare pte bit, which requires a more complicated scheme, |
| * described below. |
| * |
| * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a |
| * special mapping (even if there are underlying and valid "struct pages"). |
| * COWed pages of a VM_PFNMAP are always normal. |
| * |
| * The way we recognize COWed pages within VM_PFNMAP mappings is through the |
| * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit |
| * set, and the vm_pgoff will point to the first PFN mapped: thus every special |
| * mapping will always honor the rule |
| * |
| * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) |
| * |
| * And for normal mappings this is false. |
| * |
| * This restricts such mappings to be a linear translation from virtual address |
| * to pfn. To get around this restriction, we allow arbitrary mappings so long |
| * as the vma is not a COW mapping; in that case, we know that all ptes are |
| * special (because none can have been COWed). |
| * |
| * |
| * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. |
| * |
| * VM_MIXEDMAP mappings can likewise contain memory with or without "struct |
| * page" backing, however the difference is that _all_ pages with a struct |
| * page (that is, those where pfn_valid is true) are refcounted and considered |
| * normal pages by the VM. The disadvantage is that pages are refcounted |
| * (which can be slower and simply not an option for some PFNMAP users). The |
| * advantage is that we don't have to follow the strict linearity rule of |
| * PFNMAP mappings in order to support COWable mappings. |
| * |
| */ |
| struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte) |
| { |
| unsigned long pfn = pte_pfn(pte); |
| |
| if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { |
| if (likely(!pte_special(pte))) |
| goto check_pfn; |
| if (vma->vm_ops && vma->vm_ops->find_special_page) |
| return vma->vm_ops->find_special_page(vma, addr); |
| if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| return NULL; |
| if (is_zero_pfn(pfn)) |
| return NULL; |
| if (pte_devmap(pte)) |
| /* |
| * NOTE: New users of ZONE_DEVICE will not set pte_devmap() |
| * and will have refcounts incremented on their struct pages |
| * when they are inserted into PTEs, thus they are safe to |
| * return here. Legacy ZONE_DEVICE pages that set pte_devmap() |
| * do not have refcounts. Example of legacy ZONE_DEVICE is |
| * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers. |
| */ |
| return NULL; |
| |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ |
| |
| if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| if (vma->vm_flags & VM_MIXEDMAP) { |
| if (!pfn_valid(pfn)) |
| return NULL; |
| goto out; |
| } else { |
| unsigned long off; |
| off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| if (pfn == vma->vm_pgoff + off) |
| return NULL; |
| if (!is_cow_mapping(vma->vm_flags)) |
| return NULL; |
| } |
| } |
| |
| if (is_zero_pfn(pfn)) |
| return NULL; |
| |
| check_pfn: |
| if (unlikely(pfn > highest_memmap_pfn)) { |
| print_bad_pte(vma, addr, pte, NULL); |
| return NULL; |
| } |
| |
| /* |
| * NOTE! We still have PageReserved() pages in the page tables. |
| * eg. VDSO mappings can cause them to exist. |
| */ |
| out: |
| return pfn_to_page(pfn); |
| } |
| |
| struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr, |
| pte_t pte) |
| { |
| struct page *page = vm_normal_page(vma, addr, pte); |
| |
| if (page) |
| return page_folio(page); |
| return NULL; |
| } |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, |
| pmd_t pmd) |
| { |
| unsigned long pfn = pmd_pfn(pmd); |
| |
| /* |
| * There is no pmd_special() but there may be special pmds, e.g. |
| * in a direct-access (dax) mapping, so let's just replicate the |
| * !CONFIG_ARCH_HAS_PTE_SPECIAL case from vm_normal_page() here. |
| */ |
| if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { |
| if (vma->vm_flags & VM_MIXEDMAP) { |
| if (!pfn_valid(pfn)) |
| return NULL; |
| goto out; |
| } else { |
| unsigned long off; |
| off = (addr - vma->vm_start) >> PAGE_SHIFT; |
| if (pfn == vma->vm_pgoff + off) |
| return NULL; |
| if (!is_cow_mapping(vma->vm_flags)) |
| return NULL; |
| } |
| } |
| |
| if (pmd_devmap(pmd)) |
| return NULL; |
| if (is_huge_zero_pmd(pmd)) |
| return NULL; |
| if (unlikely(pfn > highest_memmap_pfn)) |
| return NULL; |
| |
| /* |
| * NOTE! We still have PageReserved() pages in the page tables. |
| * eg. VDSO mappings can cause them to exist. |
| */ |
| out: |
| return pfn_to_page(pfn); |
| } |
| |
| struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma, |
| unsigned long addr, pmd_t pmd) |
| { |
| struct page *page = vm_normal_page_pmd(vma, addr, pmd); |
| |
| if (page) |
| return page_folio(page); |
| return NULL; |
| } |
| #endif |
| |
| static void restore_exclusive_pte(struct vm_area_struct *vma, |
| struct page *page, unsigned long address, |
| pte_t *ptep) |
| { |
| struct folio *folio = page_folio(page); |
| pte_t orig_pte; |
| pte_t pte; |
| swp_entry_t entry; |
| |
| orig_pte = ptep_get(ptep); |
| pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot))); |
| if (pte_swp_soft_dirty(orig_pte)) |
| pte = pte_mksoft_dirty(pte); |
| |
| entry = pte_to_swp_entry(orig_pte); |
| if (pte_swp_uffd_wp(orig_pte)) |
| pte = pte_mkuffd_wp(pte); |
| else if (is_writable_device_exclusive_entry(entry)) |
| pte = maybe_mkwrite(pte_mkdirty(pte), vma); |
| |
| VM_BUG_ON_FOLIO(pte_write(pte) && (!folio_test_anon(folio) && |
| PageAnonExclusive(page)), folio); |
| |
| /* |
| * No need to take a page reference as one was already |
| * created when the swap entry was made. |
| */ |
| if (folio_test_anon(folio)) |
| folio_add_anon_rmap_pte(folio, page, vma, address, RMAP_NONE); |
| else |
| /* |
| * Currently device exclusive access only supports anonymous |
| * memory so the entry shouldn't point to a filebacked page. |
| */ |
| WARN_ON_ONCE(1); |
| |
| set_pte_at(vma->vm_mm, address, ptep, pte); |
| |
| /* |
| * No need to invalidate - it was non-present before. However |
| * secondary CPUs may have mappings that need invalidating. |
| */ |
| update_mmu_cache(vma, address, ptep); |
| } |
| |
| /* |
| * Tries to restore an exclusive pte if the page lock can be acquired without |
| * sleeping. |
| */ |
| static int |
| try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma, |
| unsigned long addr) |
| { |
| swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte)); |
| struct page *page = pfn_swap_entry_to_page(entry); |
| |
| if (trylock_page(page)) { |
| restore_exclusive_pte(vma, page, addr, src_pte); |
| unlock_page(page); |
| return 0; |
| } |
| |
| return -EBUSY; |
| } |
| |
| /* |
| * copy one vm_area from one task to the other. Assumes the page tables |
| * already present in the new task to be cleared in the whole range |
| * covered by this vma. |
| */ |
| |
| static unsigned long |
| copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, |
| pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma, |
| struct vm_area_struct *src_vma, unsigned long addr, int *rss) |
| { |
| unsigned long vm_flags = dst_vma->vm_flags; |
| pte_t orig_pte = ptep_get(src_pte); |
| pte_t pte = orig_pte; |
| struct folio *folio; |
| struct page *page; |
| swp_entry_t entry = pte_to_swp_entry(orig_pte); |
| |
| if (likely(!non_swap_entry(entry))) { |
| if (swap_duplicate(entry) < 0) |
| return -EIO; |
| |
| /* make sure dst_mm is on swapoff's mmlist. */ |
| if (unlikely(list_empty(&dst_mm->mmlist))) { |
| spin_lock(&mmlist_lock); |
| if (list_empty(&dst_mm->mmlist)) |
| list_add(&dst_mm->mmlist, |
| &src_mm->mmlist); |
| spin_unlock(&mmlist_lock); |
| } |
| /* Mark the swap entry as shared. */ |
| if (pte_swp_exclusive(orig_pte)) { |
| pte = pte_swp_clear_exclusive(orig_pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| rss[MM_SWAPENTS]++; |
| } else if (is_migration_entry(entry)) { |
| folio = pfn_swap_entry_folio(entry); |
| |
| rss[mm_counter(folio)]++; |
| |
| if (!is_readable_migration_entry(entry) && |
| is_cow_mapping(vm_flags)) { |
| /* |
| * COW mappings require pages in both parent and child |
| * to be set to read. A previously exclusive entry is |
| * now shared. |
| */ |
| entry = make_readable_migration_entry( |
| swp_offset(entry)); |
| pte = swp_entry_to_pte(entry); |
| if (pte_swp_soft_dirty(orig_pte)) |
| pte = pte_swp_mksoft_dirty(pte); |
| if (pte_swp_uffd_wp(orig_pte)) |
| pte = pte_swp_mkuffd_wp(pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| } else if (is_device_private_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| folio = page_folio(page); |
| |
| /* |
| * Update rss count even for unaddressable pages, as |
| * they should treated just like normal pages in this |
| * respect. |
| * |
| * We will likely want to have some new rss counters |
| * for unaddressable pages, at some point. But for now |
| * keep things as they are. |
| */ |
| folio_get(folio); |
| rss[mm_counter(folio)]++; |
| /* Cannot fail as these pages cannot get pinned. */ |
| folio_try_dup_anon_rmap_pte(folio, page, src_vma); |
| |
| /* |
| * We do not preserve soft-dirty information, because so |
| * far, checkpoint/restore is the only feature that |
| * requires that. And checkpoint/restore does not work |
| * when a device driver is involved (you cannot easily |
| * save and restore device driver state). |
| */ |
| if (is_writable_device_private_entry(entry) && |
| is_cow_mapping(vm_flags)) { |
| entry = make_readable_device_private_entry( |
| swp_offset(entry)); |
| pte = swp_entry_to_pte(entry); |
| if (pte_swp_uffd_wp(orig_pte)) |
| pte = pte_swp_mkuffd_wp(pte); |
| set_pte_at(src_mm, addr, src_pte, pte); |
| } |
| } else if (is_device_exclusive_entry(entry)) { |
| /* |
| * Make device exclusive entries present by restoring the |
| * original entry then copying as for a present pte. Device |
| * exclusive entries currently only support private writable |
| * (ie. COW) mappings. |
| */ |
| VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags)); |
| if (try_restore_exclusive_pte(src_pte, src_vma, addr)) |
| return -EBUSY; |
| return -ENOENT; |
| } else if (is_pte_marker_entry(entry)) { |
| pte_marker marker = copy_pte_marker(entry, dst_vma); |
| |
| if (marker) |
| set_pte_at(dst_mm, addr, dst_pte, |
| make_pte_marker(marker)); |
| return 0; |
| } |
| if (!userfaultfd_wp(dst_vma)) |
| pte = pte_swp_clear_uffd_wp(pte); |
| set_pte_at(dst_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| |
| /* |
| * Copy a present and normal page. |
| * |
| * NOTE! The usual case is that this isn't required; |
| * instead, the caller can just increase the page refcount |
| * and re-use the pte the traditional way. |
| * |
| * And if we need a pre-allocated page but don't yet have |
| * one, return a negative error to let the preallocation |
| * code know so that it can do so outside the page table |
| * lock. |
| */ |
| static inline int |
| copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss, |
| struct folio **prealloc, struct page *page) |
| { |
| struct folio *new_folio; |
| pte_t pte; |
| |
| new_folio = *prealloc; |
| if (!new_folio) |
| return -EAGAIN; |
| |
| /* |
| * We have a prealloc page, all good! Take it |
| * over and copy the page & arm it. |
| */ |
| *prealloc = NULL; |
| copy_user_highpage(&new_folio->page, page, addr, src_vma); |
| __folio_mark_uptodate(new_folio); |
| folio_add_new_anon_rmap(new_folio, dst_vma, addr); |
| folio_add_lru_vma(new_folio, dst_vma); |
| rss[MM_ANONPAGES]++; |
| |
| /* All done, just insert the new page copy in the child */ |
| pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot); |
| pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma); |
| if (userfaultfd_pte_wp(dst_vma, ptep_get(src_pte))) |
| /* Uffd-wp needs to be delivered to dest pte as well */ |
| pte = pte_mkuffd_wp(pte); |
| set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte); |
| return 0; |
| } |
| |
| static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma, |
| struct vm_area_struct *src_vma, pte_t *dst_pte, pte_t *src_pte, |
| pte_t pte, unsigned long addr, int nr) |
| { |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| |
| /* If it's a COW mapping, write protect it both processes. */ |
| if (is_cow_mapping(src_vma->vm_flags) && pte_write(pte)) { |
| wrprotect_ptes(src_mm, addr, src_pte, nr); |
| pte = pte_wrprotect(pte); |
| } |
| |
| /* If it's a shared mapping, mark it clean in the child. */ |
| if (src_vma->vm_flags & VM_SHARED) |
| pte = pte_mkclean(pte); |
| pte = pte_mkold(pte); |
| |
| if (!userfaultfd_wp(dst_vma)) |
| pte = pte_clear_uffd_wp(pte); |
| |
| set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr); |
| } |
| |
| /* |
| * Copy one present PTE, trying to batch-process subsequent PTEs that map |
| * consecutive pages of the same folio by copying them as well. |
| * |
| * Returns -EAGAIN if one preallocated page is required to copy the next PTE. |
| * Otherwise, returns the number of copied PTEs (at least 1). |
| */ |
| static inline int |
| copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pte_t *dst_pte, pte_t *src_pte, pte_t pte, unsigned long addr, |
| int max_nr, int *rss, struct folio **prealloc) |
| { |
| struct page *page; |
| struct folio *folio; |
| bool any_writable; |
| fpb_t flags = 0; |
| int err, nr; |
| |
| page = vm_normal_page(src_vma, addr, pte); |
| if (unlikely(!page)) |
| goto copy_pte; |
| |
| folio = page_folio(page); |
| |
| /* |
| * If we likely have to copy, just don't bother with batching. Make |
| * sure that the common "small folio" case is as fast as possible |
| * by keeping the batching logic separate. |
| */ |
| if (unlikely(!*prealloc && folio_test_large(folio) && max_nr != 1)) { |
| if (src_vma->vm_flags & VM_SHARED) |
| flags |= FPB_IGNORE_DIRTY; |
| if (!vma_soft_dirty_enabled(src_vma)) |
| flags |= FPB_IGNORE_SOFT_DIRTY; |
| |
| nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags, |
| &any_writable, NULL, NULL); |
| folio_ref_add(folio, nr); |
| if (folio_test_anon(folio)) { |
| if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page, |
| nr, src_vma))) { |
| folio_ref_sub(folio, nr); |
| return -EAGAIN; |
| } |
| rss[MM_ANONPAGES] += nr; |
| VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio); |
| } else { |
| folio_dup_file_rmap_ptes(folio, page, nr); |
| rss[mm_counter_file(folio)] += nr; |
| } |
| if (any_writable) |
| pte = pte_mkwrite(pte, src_vma); |
| __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, |
| addr, nr); |
| return nr; |
| } |
| |
| folio_get(folio); |
| if (folio_test_anon(folio)) { |
| /* |
| * If this page may have been pinned by the parent process, |
| * copy the page immediately for the child so that we'll always |
| * guarantee the pinned page won't be randomly replaced in the |
| * future. |
| */ |
| if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) { |
| /* Page may be pinned, we have to copy. */ |
| folio_put(folio); |
| err = copy_present_page(dst_vma, src_vma, dst_pte, src_pte, |
| addr, rss, prealloc, page); |
| return err ? err : 1; |
| } |
| rss[MM_ANONPAGES]++; |
| VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio); |
| } else { |
| folio_dup_file_rmap_pte(folio, page); |
| rss[mm_counter_file(folio)]++; |
| } |
| |
| copy_pte: |
| __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, addr, 1); |
| return 1; |
| } |
| |
| static inline struct folio *folio_prealloc(struct mm_struct *src_mm, |
| struct vm_area_struct *vma, unsigned long addr, bool need_zero) |
| { |
| struct folio *new_folio; |
| |
| if (need_zero) |
| new_folio = vma_alloc_zeroed_movable_folio(vma, addr); |
| else |
| new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, |
| addr, false); |
| |
| if (!new_folio) |
| return NULL; |
| |
| if (mem_cgroup_charge(new_folio, src_mm, GFP_KERNEL)) { |
| folio_put(new_folio); |
| return NULL; |
| } |
| folio_throttle_swaprate(new_folio, GFP_KERNEL); |
| |
| return new_folio; |
| } |
| |
| static int |
| copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pte_t *orig_src_pte, *orig_dst_pte; |
| pte_t *src_pte, *dst_pte; |
| pte_t ptent; |
| spinlock_t *src_ptl, *dst_ptl; |
| int progress, max_nr, ret = 0; |
| int rss[NR_MM_COUNTERS]; |
| swp_entry_t entry = (swp_entry_t){0}; |
| struct folio *prealloc = NULL; |
| int nr; |
| |
| again: |
| progress = 0; |
| init_rss_vec(rss); |
| |
| /* |
| * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the |
| * error handling here, assume that exclusive mmap_lock on dst and src |
| * protects anon from unexpected THP transitions; with shmem and file |
| * protected by mmap_lock-less collapse skipping areas with anon_vma |
| * (whereas vma_needs_copy() skips areas without anon_vma). A rework |
| * can remove such assumptions later, but this is good enough for now. |
| */ |
| dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); |
| if (!dst_pte) { |
| ret = -ENOMEM; |
| goto out; |
| } |
| src_pte = pte_offset_map_nolock(src_mm, src_pmd, addr, &src_ptl); |
| if (!src_pte) { |
| pte_unmap_unlock(dst_pte, dst_ptl); |
| /* ret == 0 */ |
| goto out; |
| } |
| spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); |
| orig_src_pte = src_pte; |
| orig_dst_pte = dst_pte; |
| arch_enter_lazy_mmu_mode(); |
| |
| do { |
| nr = 1; |
| |
| /* |
| * We are holding two locks at this point - either of them |
| * could generate latencies in another task on another CPU. |
| */ |
| if (progress >= 32) { |
| progress = 0; |
| if (need_resched() || |
| spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) |
| break; |
| } |
| ptent = ptep_get(src_pte); |
| if (pte_none(ptent)) { |
| progress++; |
| continue; |
| } |
| if (unlikely(!pte_present(ptent))) { |
| ret = copy_nonpresent_pte(dst_mm, src_mm, |
| dst_pte, src_pte, |
| dst_vma, src_vma, |
| addr, rss); |
| if (ret == -EIO) { |
| entry = pte_to_swp_entry(ptep_get(src_pte)); |
| break; |
| } else if (ret == -EBUSY) { |
| break; |
| } else if (!ret) { |
| progress += 8; |
| continue; |
| } |
| ptent = ptep_get(src_pte); |
| VM_WARN_ON_ONCE(!pte_present(ptent)); |
| |
| /* |
| * Device exclusive entry restored, continue by copying |
| * the now present pte. |
| */ |
| WARN_ON_ONCE(ret != -ENOENT); |
| } |
| /* copy_present_ptes() will clear `*prealloc' if consumed */ |
| max_nr = (end - addr) / PAGE_SIZE; |
| ret = copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, |
| ptent, addr, max_nr, rss, &prealloc); |
| /* |
| * If we need a pre-allocated page for this pte, drop the |
| * locks, allocate, and try again. |
| */ |
| if (unlikely(ret == -EAGAIN)) |
| break; |
| if (unlikely(prealloc)) { |
| /* |
| * pre-alloc page cannot be reused by next time so as |
| * to strictly follow mempolicy (e.g., alloc_page_vma() |
| * will allocate page according to address). This |
| * could only happen if one pinned pte changed. |
| */ |
| folio_put(prealloc); |
| prealloc = NULL; |
| } |
| nr = ret; |
| progress += 8 * nr; |
| } while (dst_pte += nr, src_pte += nr, addr += PAGE_SIZE * nr, |
| addr != end); |
| |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(orig_src_pte, src_ptl); |
| add_mm_rss_vec(dst_mm, rss); |
| pte_unmap_unlock(orig_dst_pte, dst_ptl); |
| cond_resched(); |
| |
| if (ret == -EIO) { |
| VM_WARN_ON_ONCE(!entry.val); |
| if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { |
| ret = -ENOMEM; |
| goto out; |
| } |
| entry.val = 0; |
| } else if (ret == -EBUSY) { |
| goto out; |
| } else if (ret == -EAGAIN) { |
| prealloc = folio_prealloc(src_mm, src_vma, addr, false); |
| if (!prealloc) |
| return -ENOMEM; |
| } else if (ret < 0) { |
| VM_WARN_ON_ONCE(1); |
| } |
| |
| /* We've captured and resolved the error. Reset, try again. */ |
| ret = 0; |
| |
| if (addr != end) |
| goto again; |
| out: |
| if (unlikely(prealloc)) |
| folio_put(prealloc); |
| return ret; |
| } |
| |
| static inline int |
| copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pud_t *dst_pud, pud_t *src_pud, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pmd_t *src_pmd, *dst_pmd; |
| unsigned long next; |
| |
| dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); |
| if (!dst_pmd) |
| return -ENOMEM; |
| src_pmd = pmd_offset(src_pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) |
| || pmd_devmap(*src_pmd)) { |
| int err; |
| VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma); |
| err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd, |
| addr, dst_vma, src_vma); |
| if (err == -ENOMEM) |
| return -ENOMEM; |
| if (!err) |
| continue; |
| /* fall through */ |
| } |
| if (pmd_none_or_clear_bad(src_pmd)) |
| continue; |
| if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_pmd++, src_pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int |
| copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| pud_t *src_pud, *dst_pud; |
| unsigned long next; |
| |
| dst_pud = pud_alloc(dst_mm, dst_p4d, addr); |
| if (!dst_pud) |
| return -ENOMEM; |
| src_pud = pud_offset(src_p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { |
| int err; |
| |
| VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma); |
| err = copy_huge_pud(dst_mm, src_mm, |
| dst_pud, src_pud, addr, src_vma); |
| if (err == -ENOMEM) |
| return -ENOMEM; |
| if (!err) |
| continue; |
| /* fall through */ |
| } |
| if (pud_none_or_clear_bad(src_pud)) |
| continue; |
| if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_pud++, src_pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int |
| copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, |
| pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr, |
| unsigned long end) |
| { |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| p4d_t *src_p4d, *dst_p4d; |
| unsigned long next; |
| |
| dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); |
| if (!dst_p4d) |
| return -ENOMEM; |
| src_p4d = p4d_offset(src_pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(src_p4d)) |
| continue; |
| if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d, |
| addr, next)) |
| return -ENOMEM; |
| } while (dst_p4d++, src_p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| /* |
| * Return true if the vma needs to copy the pgtable during this fork(). Return |
| * false when we can speed up fork() by allowing lazy page faults later until |
| * when the child accesses the memory range. |
| */ |
| static bool |
| vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
| { |
| /* |
| * Always copy pgtables when dst_vma has uffd-wp enabled even if it's |
| * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable |
| * contains uffd-wp protection information, that's something we can't |
| * retrieve from page cache, and skip copying will lose those info. |
| */ |
| if (userfaultfd_wp(dst_vma)) |
| return true; |
| |
| if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) |
| return true; |
| |
| if (src_vma->anon_vma) |
| return true; |
| |
| /* |
| * Don't copy ptes where a page fault will fill them correctly. Fork |
| * becomes much lighter when there are big shared or private readonly |
| * mappings. The tradeoff is that copy_page_range is more efficient |
| * than faulting. |
| */ |
| return false; |
| } |
| |
| int |
| copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) |
| { |
| pgd_t *src_pgd, *dst_pgd; |
| unsigned long next; |
| unsigned long addr = src_vma->vm_start; |
| unsigned long end = src_vma->vm_end; |
| struct mm_struct *dst_mm = dst_vma->vm_mm; |
| struct mm_struct *src_mm = src_vma->vm_mm; |
| struct mmu_notifier_range range; |
| bool is_cow; |
| int ret; |
| |
| if (!vma_needs_copy(dst_vma, src_vma)) |
| return 0; |
| |
| if (is_vm_hugetlb_page(src_vma)) |
| return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma); |
| |
| if (unlikely(src_vma->vm_flags & VM_PFNMAP)) { |
| /* |
| * We do not free on error cases below as remove_vma |
| * gets called on error from higher level routine |
| */ |
| ret = track_pfn_copy(src_vma); |
| if (ret) |
| return ret; |
| } |
| |
| /* |
| * We need to invalidate the secondary MMU mappings only when |
| * there could be a permission downgrade on the ptes of the |
| * parent mm. And a permission downgrade will only happen if |
| * is_cow_mapping() returns true. |
| */ |
| is_cow = is_cow_mapping(src_vma->vm_flags); |
| |
| if (is_cow) { |
| mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, |
| 0, src_mm, addr, end); |
| mmu_notifier_invalidate_range_start(&range); |
| /* |
| * Disabling preemption is not needed for the write side, as |
| * the read side doesn't spin, but goes to the mmap_lock. |
| * |
| * Use the raw variant of the seqcount_t write API to avoid |
| * lockdep complaining about preemptibility. |
| */ |
| vma_assert_write_locked(src_vma); |
| raw_write_seqcount_begin(&src_mm->write_protect_seq); |
| } |
| |
| ret = 0; |
| dst_pgd = pgd_offset(dst_mm, addr); |
| src_pgd = pgd_offset(src_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(src_pgd)) |
| continue; |
| if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd, |
| addr, next))) { |
| untrack_pfn_clear(dst_vma); |
| ret = -ENOMEM; |
| break; |
| } |
| } while (dst_pgd++, src_pgd++, addr = next, addr != end); |
| |
| if (is_cow) { |
| raw_write_seqcount_end(&src_mm->write_protect_seq); |
| mmu_notifier_invalidate_range_end(&range); |
| } |
| return ret; |
| } |
| |
| /* Whether we should zap all COWed (private) pages too */ |
| static inline bool should_zap_cows(struct zap_details *details) |
| { |
| /* By default, zap all pages */ |
| if (!details) |
| return true; |
| |
| /* Or, we zap COWed pages only if the caller wants to */ |
| return details->even_cows; |
| } |
| |
| /* Decides whether we should zap this folio with the folio pointer specified */ |
| static inline bool should_zap_folio(struct zap_details *details, |
| struct folio *folio) |
| { |
| /* If we can make a decision without *folio.. */ |
| if (should_zap_cows(details)) |
| return true; |
| |
| /* Otherwise we should only zap non-anon folios */ |
| return !folio_test_anon(folio); |
| } |
| |
| static inline bool zap_drop_file_uffd_wp(struct zap_details *details) |
| { |
| if (!details) |
| return false; |
| |
| return details->zap_flags & ZAP_FLAG_DROP_MARKER; |
| } |
| |
| /* |
| * This function makes sure that we'll replace the none pte with an uffd-wp |
| * swap special pte marker when necessary. Must be with the pgtable lock held. |
| */ |
| static inline void |
| zap_install_uffd_wp_if_needed(struct vm_area_struct *vma, |
| unsigned long addr, pte_t *pte, int nr, |
| struct zap_details *details, pte_t pteval) |
| { |
| /* Zap on anonymous always means dropping everything */ |
| if (vma_is_anonymous(vma)) |
| return; |
| |
| if (zap_drop_file_uffd_wp(details)) |
| return; |
| |
| for (;;) { |
| /* the PFN in the PTE is irrelevant. */ |
| pte_install_uffd_wp_if_needed(vma, addr, pte, pteval); |
| if (--nr == 0) |
| break; |
| pte++; |
| addr += PAGE_SIZE; |
| } |
| } |
| |
| static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, struct folio *folio, |
| struct page *page, pte_t *pte, pte_t ptent, unsigned int nr, |
| unsigned long addr, struct zap_details *details, int *rss, |
| bool *force_flush, bool *force_break) |
| { |
| struct mm_struct *mm = tlb->mm; |
| bool delay_rmap = false; |
| |
| if (!folio_test_anon(folio)) { |
| ptent = get_and_clear_full_ptes(mm, addr, pte, nr, tlb->fullmm); |
| if (pte_dirty(ptent)) { |
| folio_mark_dirty(folio); |
| if (tlb_delay_rmap(tlb)) { |
| delay_rmap = true; |
| *force_flush = true; |
| } |
| } |
| if (pte_young(ptent) && likely(vma_has_recency(vma))) |
| folio_mark_accessed(folio); |
| rss[mm_counter(folio)] -= nr; |
| } else { |
| /* We don't need up-to-date accessed/dirty bits. */ |
| clear_full_ptes(mm, addr, pte, nr, tlb->fullmm); |
| rss[MM_ANONPAGES] -= nr; |
| } |
| /* Checking a single PTE in a batch is sufficient. */ |
| arch_check_zapped_pte(vma, ptent); |
| tlb_remove_tlb_entries(tlb, pte, nr, addr); |
| if (unlikely(userfaultfd_pte_wp(vma, ptent))) |
| zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, |
| ptent); |
| |
| if (!delay_rmap) { |
| folio_remove_rmap_ptes(folio, page, nr, vma); |
| |
| if (unlikely(folio_mapcount(folio) < 0)) |
| print_bad_pte(vma, addr, ptent, page); |
| } |
| if (unlikely(__tlb_remove_folio_pages(tlb, page, nr, delay_rmap))) { |
| *force_flush = true; |
| *force_break = true; |
| } |
| } |
| |
| /* |
| * Zap or skip at least one present PTE, trying to batch-process subsequent |
| * PTEs that map consecutive pages of the same folio. |
| * |
| * Returns the number of processed (skipped or zapped) PTEs (at least 1). |
| */ |
| static inline int zap_present_ptes(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pte_t *pte, pte_t ptent, |
| unsigned int max_nr, unsigned long addr, |
| struct zap_details *details, int *rss, bool *force_flush, |
| bool *force_break) |
| { |
| const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; |
| struct mm_struct *mm = tlb->mm; |
| struct folio *folio; |
| struct page *page; |
| int nr; |
| |
| page = vm_normal_page(vma, addr, ptent); |
| if (!page) { |
| /* We don't need up-to-date accessed/dirty bits. */ |
| ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm); |
| arch_check_zapped_pte(vma, ptent); |
| tlb_remove_tlb_entry(tlb, pte, addr); |
| if (userfaultfd_pte_wp(vma, ptent)) |
| zap_install_uffd_wp_if_needed(vma, addr, pte, 1, |
| details, ptent); |
| ksm_might_unmap_zero_page(mm, ptent); |
| return 1; |
| } |
| |
| folio = page_folio(page); |
| if (unlikely(!should_zap_folio(details, folio))) |
| return 1; |
| |
| /* |
| * Make sure that the common "small folio" case is as fast as possible |
| * by keeping the batching logic separate. |
| */ |
| if (unlikely(folio_test_large(folio) && max_nr != 1)) { |
| nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, fpb_flags, |
| NULL, NULL, NULL); |
| |
| zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr, |
| addr, details, rss, force_flush, |
| force_break); |
| return nr; |
| } |
| zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, 1, addr, |
| details, rss, force_flush, force_break); |
| return 1; |
| } |
| |
| static unsigned long zap_pte_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| bool force_flush = false, force_break = false; |
| struct mm_struct *mm = tlb->mm; |
| int rss[NR_MM_COUNTERS]; |
| spinlock_t *ptl; |
| pte_t *start_pte; |
| pte_t *pte; |
| swp_entry_t entry; |
| int nr; |
| |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| init_rss_vec(rss); |
| start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return addr; |
| |
| flush_tlb_batched_pending(mm); |
| arch_enter_lazy_mmu_mode(); |
| do { |
| pte_t ptent = ptep_get(pte); |
| struct folio *folio; |
| struct page *page; |
| int max_nr; |
| |
| nr = 1; |
| if (pte_none(ptent)) |
| continue; |
| |
| if (need_resched()) |
| break; |
| |
| if (pte_present(ptent)) { |
| max_nr = (end - addr) / PAGE_SIZE; |
| nr = zap_present_ptes(tlb, vma, pte, ptent, max_nr, |
| addr, details, rss, &force_flush, |
| &force_break); |
| if (unlikely(force_break)) { |
| addr += nr * PAGE_SIZE; |
| break; |
| } |
| continue; |
| } |
| |
| entry = pte_to_swp_entry(ptent); |
| if (is_device_private_entry(entry) || |
| is_device_exclusive_entry(entry)) { |
| page = pfn_swap_entry_to_page(entry); |
| folio = page_folio(page); |
| if (unlikely(!should_zap_folio(details, folio))) |
| continue; |
| /* |
| * Both device private/exclusive mappings should only |
| * work with anonymous page so far, so we don't need to |
| * consider uffd-wp bit when zap. For more information, |
| * see zap_install_uffd_wp_if_needed(). |
| */ |
| WARN_ON_ONCE(!vma_is_anonymous(vma)); |
| rss[mm_counter(folio)]--; |
| if (is_device_private_entry(entry)) |
| folio_remove_rmap_pte(folio, page, vma); |
| folio_put(folio); |
| } else if (!non_swap_entry(entry)) { |
| max_nr = (end - addr) / PAGE_SIZE; |
| nr = swap_pte_batch(pte, max_nr, ptent); |
| /* Genuine swap entries, hence a private anon pages */ |
| if (!should_zap_cows(details)) |
| continue; |
| rss[MM_SWAPENTS] -= nr; |
| free_swap_and_cache_nr(entry, nr); |
| } else if (is_migration_entry(entry)) { |
| folio = pfn_swap_entry_folio(entry); |
| if (!should_zap_folio(details, folio)) |
| continue; |
| rss[mm_counter(folio)]--; |
| } else if (pte_marker_entry_uffd_wp(entry)) { |
| /* |
| * For anon: always drop the marker; for file: only |
| * drop the marker if explicitly requested. |
| */ |
| if (!vma_is_anonymous(vma) && |
| !zap_drop_file_uffd_wp(details)) |
| continue; |
| } else if (is_hwpoison_entry(entry) || |
| is_poisoned_swp_entry(entry)) { |
| if (!should_zap_cows(details)) |
| continue; |
| } else { |
| /* We should have covered all the swap entry types */ |
| pr_alert("unrecognized swap entry 0x%lx\n", entry.val); |
| WARN_ON_ONCE(1); |
| } |
| clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm); |
| zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent); |
| } while (pte += nr, addr += PAGE_SIZE * nr, addr != end); |
| |
| add_mm_rss_vec(mm, rss); |
| arch_leave_lazy_mmu_mode(); |
| |
| /* Do the actual TLB flush before dropping ptl */ |
| if (force_flush) { |
| tlb_flush_mmu_tlbonly(tlb); |
| tlb_flush_rmaps(tlb, vma); |
| } |
| pte_unmap_unlock(start_pte, ptl); |
| |
| /* |
| * If we forced a TLB flush (either due to running out of |
| * batch buffers or because we needed to flush dirty TLB |
| * entries before releasing the ptl), free the batched |
| * memory too. Come back again if we didn't do everything. |
| */ |
| if (force_flush) |
| tlb_flush_mmu(tlb); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { |
| if (next - addr != HPAGE_PMD_SIZE) |
| __split_huge_pmd(vma, pmd, addr, false, NULL); |
| else if (zap_huge_pmd(tlb, vma, pmd, addr)) { |
| addr = next; |
| continue; |
| } |
| /* fall through */ |
| } else if (details && details->single_folio && |
| folio_test_pmd_mappable(details->single_folio) && |
| next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) { |
| spinlock_t *ptl = pmd_lock(tlb->mm, pmd); |
| /* |
| * Take and drop THP pmd lock so that we cannot return |
| * prematurely, while zap_huge_pmd() has cleared *pmd, |
| * but not yet decremented compound_mapcount(). |
| */ |
| spin_unlock(ptl); |
| } |
| if (pmd_none(*pmd)) { |
| addr = next; |
| continue; |
| } |
| addr = zap_pte_range(tlb, vma, pmd, addr, next, details); |
| if (addr != next) |
| pmd--; |
| } while (pmd++, cond_resched(), addr != end); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_pud_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pud_t *pud; |
| unsigned long next; |
| |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_trans_huge(*pud) || pud_devmap(*pud)) { |
| if (next - addr != HPAGE_PUD_SIZE) { |
| mmap_assert_locked(tlb->mm); |
| split_huge_pud(vma, pud, addr); |
| } else if (zap_huge_pud(tlb, vma, pud, addr)) |
| goto next; |
| /* fall through */ |
| } |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| next = zap_pmd_range(tlb, vma, pud, addr, next, details); |
| next: |
| cond_resched(); |
| } while (pud++, addr = next, addr != end); |
| |
| return addr; |
| } |
| |
| static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| next = zap_pud_range(tlb, vma, p4d, addr, next, details); |
| } while (p4d++, addr = next, addr != end); |
| |
| return addr; |
| } |
| |
| void unmap_page_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end, |
| struct zap_details *details) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| |
| BUG_ON(addr >= end); |
| tlb_start_vma(tlb, vma); |
| pgd = pgd_offset(vma->vm_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| next = zap_p4d_range(tlb, vma, pgd, addr, next, details); |
| } while (pgd++, addr = next, addr != end); |
| tlb_end_vma(tlb, vma); |
| } |
| |
| |
| static void unmap_single_vma(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, unsigned long start_addr, |
| unsigned long end_addr, |
| struct zap_details *details, bool mm_wr_locked) |
| { |
| unsigned long start = max(vma->vm_start, start_addr); |
| unsigned long end; |
| |
| if (start >= vma->vm_end) |
| return; |
| end = min(vma->vm_end, end_addr); |
| if (end <= vma->vm_start) |
| return; |
| |
| if (vma->vm_file) |
| uprobe_munmap(vma, start, end); |
| |
| if (unlikely(vma->vm_flags & VM_PFNMAP)) |
| untrack_pfn(vma, 0, 0, mm_wr_locked); |
| |
| if (start != end) { |
| if (unlikely(is_vm_hugetlb_page(vma))) { |
| /* |
| * It is undesirable to test vma->vm_file as it |
| * should be non-null for valid hugetlb area. |
| * However, vm_file will be NULL in the error |
| * cleanup path of mmap_region. When |
| * hugetlbfs ->mmap method fails, |
| * mmap_region() nullifies vma->vm_file |
| * before calling this function to clean up. |
| * Since no pte has actually been setup, it is |
| * safe to do nothing in this case. |
| */ |
| if (vma->vm_file) { |
| zap_flags_t zap_flags = details ? |
| details->zap_flags : 0; |
| __unmap_hugepage_range(tlb, vma, start, end, |
| NULL, zap_flags); |
| } |
| } else |
| unmap_page_range(tlb, vma, start, end, details); |
| } |
| } |
| |
| /** |
| * unmap_vmas - unmap a range of memory covered by a list of vma's |
| * @tlb: address of the caller's struct mmu_gather |
| * @mas: the maple state |
| * @vma: the starting vma |
| * @start_addr: virtual address at which to start unmapping |
| * @end_addr: virtual address at which to end unmapping |
| * @tree_end: The maximum index to check |
| * @mm_wr_locked: lock flag |
| * |
| * Unmap all pages in the vma list. |
| * |
| * Only addresses between `start' and `end' will be unmapped. |
| * |
| * The VMA list must be sorted in ascending virtual address order. |
| * |
| * unmap_vmas() assumes that the caller will flush the whole unmapped address |
| * range after unmap_vmas() returns. So the only responsibility here is to |
| * ensure that any thus-far unmapped pages are flushed before unmap_vmas() |
| * drops the lock and schedules. |
| */ |
| void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas, |
| struct vm_area_struct *vma, unsigned long start_addr, |
| unsigned long end_addr, unsigned long tree_end, |
| bool mm_wr_locked) |
| { |
| struct mmu_notifier_range range; |
| struct zap_details details = { |
| .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP, |
| /* Careful - we need to zap private pages too! */ |
| .even_cows = true, |
| }; |
| |
| mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm, |
| start_addr, end_addr); |
| mmu_notifier_invalidate_range_start(&range); |
| do { |
| unsigned long start = start_addr; |
| unsigned long end = end_addr; |
| hugetlb_zap_begin(vma, &start, &end); |
| unmap_single_vma(tlb, vma, start, end, &details, |
| mm_wr_locked); |
| hugetlb_zap_end(vma, &details); |
| vma = mas_find(mas, tree_end - 1); |
| } while (vma && likely(!xa_is_zero(vma))); |
| mmu_notifier_invalidate_range_end(&range); |
| } |
| |
| /** |
| * zap_page_range_single - remove user pages in a given range |
| * @vma: vm_area_struct holding the applicable pages |
| * @address: starting address of pages to zap |
| * @size: number of bytes to zap |
| * @details: details of shared cache invalidation |
| * |
| * The range must fit into one VMA. |
| */ |
| void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, |
| unsigned long size, struct zap_details *details) |
| { |
| const unsigned long end = address + size; |
| struct mmu_notifier_range range; |
| struct mmu_gather tlb; |
| |
| lru_add_drain(); |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, |
| address, end); |
| hugetlb_zap_begin(vma, &range.start, &range.end); |
| tlb_gather_mmu(&tlb, vma->vm_mm); |
| update_hiwater_rss(vma->vm_mm); |
| mmu_notifier_invalidate_range_start(&range); |
| /* |
| * unmap 'address-end' not 'range.start-range.end' as range |
| * could have been expanded for hugetlb pmd sharing. |
| */ |
| unmap_single_vma(&tlb, vma, address, end, details, false); |
| mmu_notifier_invalidate_range_end(&range); |
| tlb_finish_mmu(&tlb); |
| hugetlb_zap_end(vma, details); |
| } |
| |
| /** |
| * zap_vma_ptes - remove ptes mapping the vma |
| * @vma: vm_area_struct holding ptes to be zapped |
| * @address: starting address of pages to zap |
| * @size: number of bytes to zap |
| * |
| * This function only unmaps ptes assigned to VM_PFNMAP vmas. |
| * |
| * The entire address range must be fully contained within the vma. |
| * |
| */ |
| void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, |
| unsigned long size) |
| { |
| if (!range_in_vma(vma, address, address + size) || |
| !(vma->vm_flags & VM_PFNMAP)) |
| return; |
| |
| zap_page_range_single(vma, address, size, NULL); |
| } |
| EXPORT_SYMBOL_GPL(zap_vma_ptes); |
| |
| static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr) |
| { |
| pgd_t *pgd; |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| pgd = pgd_offset(mm, addr); |
| p4d = p4d_alloc(mm, pgd, addr); |
| if (!p4d) |
| return NULL; |
| pud = pud_alloc(mm, p4d, addr); |
| if (!pud) |
| return NULL; |
| pmd = pmd_alloc(mm, pud, addr); |
| if (!pmd) |
| return NULL; |
| |
| VM_BUG_ON(pmd_trans_huge(*pmd)); |
| return pmd; |
| } |
| |
| pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, |
| spinlock_t **ptl) |
| { |
| pmd_t *pmd = walk_to_pmd(mm, addr); |
| |
| if (!pmd) |
| return NULL; |
| return pte_alloc_map_lock(mm, pmd, addr, ptl); |
| } |
| |
| static int validate_page_before_insert(struct page *page) |
| { |
| struct folio *folio = page_folio(page); |
| |
| if (folio_test_anon(folio) || folio_test_slab(folio) || |
| page_has_type(page)) |
| return -EINVAL; |
| flush_dcache_folio(folio); |
| return 0; |
| } |
| |
| static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte, |
| unsigned long addr, struct page *page, pgprot_t prot) |
| { |
| struct folio *folio = page_folio(page); |
| |
| if (!pte_none(ptep_get(pte))) |
| return -EBUSY; |
| /* Ok, finally just insert the thing.. */ |
| folio_get(folio); |
| inc_mm_counter(vma->vm_mm, mm_counter_file(folio)); |
| folio_add_file_rmap_pte(folio, page, vma); |
| set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot)); |
| return 0; |
| } |
| |
| /* |
| * This is the old fallback for page remapping. |
| * |
| * For historical reasons, it only allows reserved pages. Only |
| * old drivers should use this, and they needed to mark their |
| * pages reserved for the old functions anyway. |
| */ |
| static int insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page, pgprot_t prot) |
| { |
| int retval; |
| pte_t *pte; |
| spinlock_t *ptl; |
| |
| retval = validate_page_before_insert(page); |
| if (retval) |
| goto out; |
| retval = -ENOMEM; |
| pte = get_locked_pte(vma->vm_mm, addr, &ptl); |
| if (!pte) |
| goto out; |
| retval = insert_page_into_pte_locked(vma, pte, addr, page, prot); |
| pte_unmap_unlock(pte, ptl); |
| out: |
| return retval; |
| } |
| |
| static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte, |
| unsigned long addr, struct page *page, pgprot_t prot) |
| { |
| int err; |
| |
| if (!page_count(page)) |
| return -EINVAL; |
| err = validate_page_before_insert(page); |
| if (err) |
| return err; |
| return insert_page_into_pte_locked(vma, pte, addr, page, prot); |
| } |
| |
| /* insert_pages() amortizes the cost of spinlock operations |
| * when inserting pages in a loop. |
| */ |
| static int insert_pages(struct vm_area_struct *vma, unsigned long addr, |
| struct page **pages, unsigned long *num, pgprot_t prot) |
| { |
| pmd_t *pmd = NULL; |
| pte_t *start_pte, *pte; |
| spinlock_t *pte_lock; |
| struct mm_struct *const mm = vma->vm_mm; |
| unsigned long curr_page_idx = 0; |
| unsigned long remaining_pages_total = *num; |
| unsigned long pages_to_write_in_pmd; |
| int ret; |
| more: |
| ret = -EFAULT; |
| pmd = walk_to_pmd(mm, addr); |
| if (!pmd) |
| goto out; |
| |
| pages_to_write_in_pmd = min_t(unsigned long, |
| remaining_pages_total, PTRS_PER_PTE - pte_index(addr)); |
| |
| /* Allocate the PTE if necessary; takes PMD lock once only. */ |
| ret = -ENOMEM; |
| if (pte_alloc(mm, pmd)) |
| goto out; |
| |
| while (pages_to_write_in_pmd) { |
| int pte_idx = 0; |
| const int batch_size = min_t(int, pages_to_write_in_pmd, 8); |
| |
| start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock); |
| if (!start_pte) { |
| ret = -EFAULT; |
| goto out; |
| } |
| for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { |
| int err = insert_page_in_batch_locked(vma, pte, |
| addr, pages[curr_page_idx], prot); |
| if (unlikely(err)) { |
| pte_unmap_unlock(start_pte, pte_lock); |
| ret = err; |
| remaining_pages_total -= pte_idx; |
| goto out; |
| } |
| addr += PAGE_SIZE; |
| ++curr_page_idx; |
| } |
| pte_unmap_unlock(start_pte, pte_lock); |
| pages_to_write_in_pmd -= batch_size; |
| remaining_pages_total -= batch_size; |
| } |
| if (remaining_pages_total) |
| goto more; |
| ret = 0; |
| out: |
| *num = remaining_pages_total; |
| return ret; |
| } |
| |
| /** |
| * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock. |
| * @vma: user vma to map to |
| * @addr: target start user address of these pages |
| * @pages: source kernel pages |
| * @num: in: number of pages to map. out: number of pages that were *not* |
| * mapped. (0 means all pages were successfully mapped). |
| * |
| * Preferred over vm_insert_page() when inserting multiple pages. |
| * |
| * In case of error, we may have mapped a subset of the provided |
| * pages. It is the caller's responsibility to account for this case. |
| * |
| * The same restrictions apply as in vm_insert_page(). |
| */ |
| int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, |
| struct page **pages, unsigned long *num) |
| { |
| const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1; |
| |
| if (addr < vma->vm_start || end_addr >= vma->vm_end) |
| return -EFAULT; |
| if (!(vma->vm_flags & VM_MIXEDMAP)) { |
| BUG_ON(mmap_read_trylock(vma->vm_mm)); |
| BUG_ON(vma->vm_flags & VM_PFNMAP); |
| vm_flags_set(vma, VM_MIXEDMAP); |
| } |
| /* Defer page refcount checking till we're about to map that page. */ |
| return insert_pages(vma, addr, pages, num, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_insert_pages); |
| |
| /** |
| * vm_insert_page - insert single page into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @page: source kernel page |
| * |
| * This allows drivers to insert individual pages they've allocated |
| * into a user vma. |
| * |
| * The page has to be a nice clean _individual_ kernel allocation. |
| * If you allocate a compound page, you need to have marked it as |
| * such (__GFP_COMP), or manually just split the page up yourself |
| * (see split_page()). |
| * |
| * NOTE! Traditionally this was done with "remap_pfn_range()" which |
| * took an arbitrary page protection parameter. This doesn't allow |
| * that. Your vma protection will have to be set up correctly, which |
| * means that if you want a shared writable mapping, you'd better |
| * ask for a shared writable mapping! |
| * |
| * The page does not need to be reserved. |
| * |
| * Usually this function is called from f_op->mmap() handler |
| * under mm->mmap_lock write-lock, so it can change vma->vm_flags. |
| * Caller must set VM_MIXEDMAP on vma if it wants to call this |
| * function from other places, for example from page-fault handler. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
| struct page *page) |
| { |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return -EFAULT; |
| if (!page_count(page)) |
| return -EINVAL; |
| if (!(vma->vm_flags & VM_MIXEDMAP)) { |
| BUG_ON(mmap_read_trylock(vma->vm_mm)); |
| BUG_ON(vma->vm_flags & VM_PFNMAP); |
| vm_flags_set(vma, VM_MIXEDMAP); |
| } |
| return insert_page(vma, addr, page, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_insert_page); |
| |
| /* |
| * __vm_map_pages - maps range of kernel pages into user vma |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * @offset: user's requested vm_pgoff |
| * |
| * This allows drivers to map range of kernel pages into a user vma. |
| * |
| * Return: 0 on success and error code otherwise. |
| */ |
| static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num, unsigned long offset) |
| { |
| unsigned long count = vma_pages(vma); |
| unsigned long uaddr = vma->vm_start; |
| int ret, i; |
| |
| /* Fail if the user requested offset is beyond the end of the object */ |
| if (offset >= num) |
| return -ENXIO; |
| |
| /* Fail if the user requested size exceeds available object size */ |
| if (count > num - offset) |
| return -ENXIO; |
| |
| for (i = 0; i < count; i++) { |
| ret = vm_insert_page(vma, uaddr, pages[offset + i]); |
| if (ret < 0) |
| return ret; |
| uaddr += PAGE_SIZE; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * vm_map_pages - maps range of kernel pages starts with non zero offset |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * |
| * Maps an object consisting of @num pages, catering for the user's |
| * requested vm_pgoff |
| * |
| * If we fail to insert any page into the vma, the function will return |
| * immediately leaving any previously inserted pages present. Callers |
| * from the mmap handler may immediately return the error as their caller |
| * will destroy the vma, removing any successfully inserted pages. Other |
| * callers should make their own arrangements for calling unmap_region(). |
| * |
| * Context: Process context. Called by mmap handlers. |
| * Return: 0 on success and error code otherwise. |
| */ |
| int vm_map_pages(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num) |
| { |
| return __vm_map_pages(vma, pages, num, vma->vm_pgoff); |
| } |
| EXPORT_SYMBOL(vm_map_pages); |
| |
| /** |
| * vm_map_pages_zero - map range of kernel pages starts with zero offset |
| * @vma: user vma to map to |
| * @pages: pointer to array of source kernel pages |
| * @num: number of pages in page array |
| * |
| * Similar to vm_map_pages(), except that it explicitly sets the offset |
| * to 0. This function is intended for the drivers that did not consider |
| * vm_pgoff. |
| * |
| * Context: Process context. Called by mmap handlers. |
| * Return: 0 on success and error code otherwise. |
| */ |
| int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, |
| unsigned long num) |
| { |
| return __vm_map_pages(vma, pages, num, 0); |
| } |
| EXPORT_SYMBOL(vm_map_pages_zero); |
| |
| static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| pfn_t pfn, pgprot_t prot, bool mkwrite) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pte_t *pte, entry; |
| spinlock_t *ptl; |
| |
| pte = get_locked_pte(mm, addr, &ptl); |
| if (!pte) |
| return VM_FAULT_OOM; |
| entry = ptep_get(pte); |
| if (!pte_none(entry)) { |
| if (mkwrite) { |
| /* |
| * For read faults on private mappings the PFN passed |
| * in may not match the PFN we have mapped if the |
| * mapped PFN is a writeable COW page. In the mkwrite |
| * case we are creating a writable PTE for a shared |
| * mapping and we expect the PFNs to match. If they |
| * don't match, we are likely racing with block |
| * allocation and mapping invalidation so just skip the |
| * update. |
| */ |
| if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) { |
| WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry))); |
| goto out_unlock; |
| } |
| entry = pte_mkyoung(entry); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| if (ptep_set_access_flags(vma, addr, pte, entry, 1)) |
| update_mmu_cache(vma, addr, pte); |
| } |
| goto out_unlock; |
| } |
| |
| /* Ok, finally just insert the thing.. */ |
| if (pfn_t_devmap(pfn)) |
| entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); |
| else |
| entry = pte_mkspecial(pfn_t_pte(pfn, prot)); |
| |
| if (mkwrite) { |
| entry = pte_mkyoung(entry); |
| entry = maybe_mkwrite(pte_mkdirty(entry), vma); |
| } |
| |
| set_pte_at(mm, addr, pte, entry); |
| update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ |
| |
| out_unlock: |
| pte_unmap_unlock(pte, ptl); |
| return VM_FAULT_NOPAGE; |
| } |
| |
| /** |
| * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * @pgprot: pgprot flags for the inserted page |
| * |
| * This is exactly like vmf_insert_pfn(), except that it allows drivers |
| * to override pgprot on a per-page basis. |
| * |
| * This only makes sense for IO mappings, and it makes no sense for |
| * COW mappings. In general, using multiple vmas is preferable; |
| * vmf_insert_pfn_prot should only be used if using multiple VMAs is |
| * impractical. |
| * |
| * pgprot typically only differs from @vma->vm_page_prot when drivers set |
| * caching- and encryption bits different than those of @vma->vm_page_prot, |
| * because the caching- or encryption mode may not be known at mmap() time. |
| * |
| * This is ok as long as @vma->vm_page_prot is not used by the core vm |
| * to set caching and encryption bits for those vmas (except for COW pages). |
| * This is ensured by core vm only modifying these page table entries using |
| * functions that don't touch caching- or encryption bits, using pte_modify() |
| * if needed. (See for example mprotect()). |
| * |
| * Also when new page-table entries are created, this is only done using the |
| * fault() callback, and never using the value of vma->vm_page_prot, |
| * except for page-table entries that point to anonymous pages as the result |
| * of COW. |
| * |
| * Context: Process context. May allocate using %GFP_KERNEL. |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, pgprot_t pgprot) |
| { |
| /* |
| * Technically, architectures with pte_special can avoid all these |
| * restrictions (same for remap_pfn_range). However we would like |
| * consistency in testing and feature parity among all, so we should |
| * try to keep these invariants in place for everybody. |
| */ |
| BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); |
| BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == |
| (VM_PFNMAP|VM_MIXEDMAP)); |
| BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); |
| BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return VM_FAULT_SIGBUS; |
| |
| if (!pfn_modify_allowed(pfn, pgprot)) |
| return VM_FAULT_SIGBUS; |
| |
| track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); |
| |
| return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, |
| false); |
| } |
| EXPORT_SYMBOL(vmf_insert_pfn_prot); |
| |
| /** |
| * vmf_insert_pfn - insert single pfn into user vma |
| * @vma: user vma to map to |
| * @addr: target user address of this page |
| * @pfn: source kernel pfn |
| * |
| * Similar to vm_insert_page, this allows drivers to insert individual pages |
| * they've allocated into a user vma. Same comments apply. |
| * |
| * This function should only be called from a vm_ops->fault handler, and |
| * in that case the handler should return the result of this function. |
| * |
| * vma cannot be a COW mapping. |
| * |
| * As this is called only for pages that do not currently exist, we |
| * do not need to flush old virtual caches or the TLB. |
| * |
| * Context: Process context. May allocate using %GFP_KERNEL. |
| * Return: vm_fault_t value. |
| */ |
| vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn) |
| { |
| return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vmf_insert_pfn); |
| |
| static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) |
| { |
| /* these checks mirror the abort conditions in vm_normal_page */ |
| if (vma->vm_flags & VM_MIXEDMAP) |
| return true; |
| if (pfn_t_devmap(pfn)) |
| return true; |
| if (pfn_t_special(pfn)) |
| return true; |
| if (is_zero_pfn(pfn_t_to_pfn(pfn))) |
| return true; |
| return false; |
| } |
| |
| static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, |
| unsigned long addr, pfn_t pfn, bool mkwrite) |
| { |
| pgprot_t pgprot = vma->vm_page_prot; |
| int err; |
| |
| BUG_ON(!vm_mixed_ok(vma, pfn)); |
| |
| if (addr < vma->vm_start || addr >= vma->vm_end) |
| return VM_FAULT_SIGBUS; |
| |
| track_pfn_insert(vma, &pgprot, pfn); |
| |
| if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot)) |
| return VM_FAULT_SIGBUS; |
| |
| /* |
| * If we don't have pte special, then we have to use the pfn_valid() |
| * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* |
| * refcount the page if pfn_valid is true (hence insert_page rather |
| * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP |
| * without pte special, it would there be refcounted as a normal page. |
| */ |
| if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && |
| !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { |
| struct page *page; |
| |
| /* |
| * At this point we are committed to insert_page() |
| * regardless of whether the caller specified flags that |
| * result in pfn_t_has_page() == false. |
| */ |
| page = pfn_to_page(pfn_t_to_pfn(pfn)); |
| err = insert_page(vma, addr, page, pgprot); |
| } else { |
| return insert_pfn(vma, addr, pfn, pgprot, mkwrite); |
| } |
| |
| if (err == -ENOMEM) |
| return VM_FAULT_OOM; |
| if (err < 0 && err != -EBUSY) |
| return VM_FAULT_SIGBUS; |
| |
| return VM_FAULT_NOPAGE; |
| } |
| |
| vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr, |
| pfn_t pfn) |
| { |
| return __vm_insert_mixed(vma, addr, pfn, false); |
| } |
| EXPORT_SYMBOL(vmf_insert_mixed); |
| |
| /* |
| * If the insertion of PTE failed because someone else already added a |
| * different entry in the mean time, we treat that as success as we assume |
| * the same entry was actually inserted. |
| */ |
| vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma, |
| unsigned long addr, pfn_t pfn) |
| { |
| return __vm_insert_mixed(vma, addr, pfn, true); |
| } |
| EXPORT_SYMBOL(vmf_insert_mixed_mkwrite); |
| |
| /* |
| * maps a range of physical memory into the requested pages. the old |
| * mappings are removed. any references to nonexistent pages results |
| * in null mappings (currently treated as "copy-on-access") |
| */ |
| static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pte_t *pte, *mapped_pte; |
| spinlock_t *ptl; |
| int err = 0; |
| |
| mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| arch_enter_lazy_mmu_mode(); |
| do { |
| BUG_ON(!pte_none(ptep_get(pte))); |
| if (!pfn_modify_allowed(pfn, prot)) { |
| err = -EACCES; |
| break; |
| } |
| set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); |
| pfn++; |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(mapped_pte, ptl); |
| return err; |
| } |
| |
| static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| pmd = pmd_alloc(mm, pud, addr); |
| if (!pmd) |
| return -ENOMEM; |
| VM_BUG_ON(pmd_trans_huge(*pmd)); |
| do { |
| next = pmd_addr_end(addr, end); |
| err = remap_pte_range(mm, pmd, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| pud = pud_alloc(mm, p4d, addr); |
| if (!pud) |
| return -ENOMEM; |
| do { |
| next = pud_addr_end(addr, end); |
| err = remap_pmd_range(mm, pud, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned long pfn, pgprot_t prot) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int err; |
| |
| pfn -= addr >> PAGE_SHIFT; |
| p4d = p4d_alloc(mm, pgd, addr); |
| if (!p4d) |
| return -ENOMEM; |
| do { |
| next = p4d_addr_end(addr, end); |
| err = remap_pud_range(mm, p4d, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| /* |
| * Variant of remap_pfn_range that does not call track_pfn_remap. The caller |
| * must have pre-validated the caching bits of the pgprot_t. |
| */ |
| int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, unsigned long size, pgprot_t prot) |
| { |
| pgd_t *pgd; |
| unsigned long next; |
| unsigned long end = addr + PAGE_ALIGN(size); |
| struct mm_struct *mm = vma->vm_mm; |
| int err; |
| |
| if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) |
| return -EINVAL; |
| |
| /* |
| * Physically remapped pages are special. Tell the |
| * rest of the world about it: |
| * VM_IO tells people not to look at these pages |
| * (accesses can have side effects). |
| * VM_PFNMAP tells the core MM that the base pages are just |
| * raw PFN mappings, and do not have a "struct page" associated |
| * with them. |
| * VM_DONTEXPAND |
| * Disable vma merging and expanding with mremap(). |
| * VM_DONTDUMP |
| * Omit vma from core dump, even when VM_IO turned off. |
| * |
| * There's a horrible special case to handle copy-on-write |
| * behaviour that some programs depend on. We mark the "original" |
| * un-COW'ed pages by matching them up with "vma->vm_pgoff". |
| * See vm_normal_page() for details. |
| */ |
| if (is_cow_mapping(vma->vm_flags)) { |
| if (addr != vma->vm_start || end != vma->vm_end) |
| return -EINVAL; |
| vma->vm_pgoff = pfn; |
| } |
| |
| vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); |
| |
| BUG_ON(addr >= end); |
| pfn -= addr >> PAGE_SHIFT; |
| pgd = pgd_offset(mm, addr); |
| flush_cache_range(vma, addr, end); |
| do { |
| next = pgd_addr_end(addr, end); |
| err = remap_p4d_range(mm, pgd, addr, next, |
| pfn + (addr >> PAGE_SHIFT), prot); |
| if (err) |
| return err; |
| } while (pgd++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| /** |
| * remap_pfn_range - remap kernel memory to userspace |
| * @vma: user vma to map to |
| * @addr: target page aligned user address to start at |
| * @pfn: page frame number of kernel physical memory address |
| * @size: size of mapping area |
| * @prot: page protection flags for this mapping |
| * |
| * Note: this is only safe if the mm semaphore is held when called. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
| unsigned long pfn, unsigned long size, pgprot_t prot) |
| { |
| int err; |
| |
| err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); |
| if (err) |
| return -EINVAL; |
| |
| err = remap_pfn_range_notrack(vma, addr, pfn, size, prot); |
| if (err) |
| untrack_pfn(vma, pfn, PAGE_ALIGN(size), true); |
| return err; |
| } |
| EXPORT_SYMBOL(remap_pfn_range); |
| |
| /** |
| * vm_iomap_memory - remap memory to userspace |
| * @vma: user vma to map to |
| * @start: start of the physical memory to be mapped |
| * @len: size of area |
| * |
| * This is a simplified io_remap_pfn_range() for common driver use. The |
| * driver just needs to give us the physical memory range to be mapped, |
| * we'll figure out the rest from the vma information. |
| * |
| * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get |
| * whatever write-combining details or similar. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
| { |
| unsigned long vm_len, pfn, pages; |
| |
| /* Check that the physical memory area passed in looks valid */ |
| if (start + len < start) |
| return -EINVAL; |
| /* |
| * You *really* shouldn't map things that aren't page-aligned, |
| * but we've historically allowed it because IO memory might |
| * just have smaller alignment. |
| */ |
| len += start & ~PAGE_MASK; |
| pfn = start >> PAGE_SHIFT; |
| pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; |
| if (pfn + pages < pfn) |
| return -EINVAL; |
| |
| /* We start the mapping 'vm_pgoff' pages into the area */ |
| if (vma->vm_pgoff > pages) |
| return -EINVAL; |
| pfn += vma->vm_pgoff; |
| pages -= vma->vm_pgoff; |
| |
| /* Can we fit all of the mapping? */ |
| vm_len = vma->vm_end - vma->vm_start; |
| if (vm_len >> PAGE_SHIFT > pages) |
| return -EINVAL; |
| |
| /* Ok, let it rip */ |
| return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
| } |
| EXPORT_SYMBOL(vm_iomap_memory); |
| |
| static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pte_t *pte, *mapped_pte; |
| int err = 0; |
| spinlock_t *ptl; |
| |
| if (create) { |
| mapped_pte = pte = (mm == &init_mm) ? |
| pte_alloc_kernel_track(pmd, addr, mask) : |
| pte_alloc_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -ENOMEM; |
| } else { |
| mapped_pte = pte = (mm == &init_mm) ? |
| pte_offset_kernel(pmd, addr) : |
| pte_offset_map_lock(mm, pmd, addr, &ptl); |
| if (!pte) |
| return -EINVAL; |
| } |
| |
| arch_enter_lazy_mmu_mode(); |
| |
| if (fn) { |
| do { |
| if (create || !pte_none(ptep_get(pte))) { |
| err = fn(pte++, addr, data); |
| if (err) |
| break; |
| } |
| } while (addr += PAGE_SIZE, addr != end); |
| } |
| *mask |= PGTBL_PTE_MODIFIED; |
| |
| arch_leave_lazy_mmu_mode(); |
| |
| if (mm != &init_mm) |
| pte_unmap_unlock(mapped_pte, ptl); |
| return err; |
| } |
| |
| static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int err = 0; |
| |
| BUG_ON(pud_leaf(*pud)); |
| |
| if (create) { |
| pmd = pmd_alloc_track(mm, pud, addr, mask); |
| if (!pmd) |
| return -ENOMEM; |
| } else { |
| pmd = pmd_offset(pud, addr); |
| } |
| do { |
| next = pmd_addr_end(addr, end); |
| if (pmd_none(*pmd) && !create) |
| continue; |
| if (WARN_ON_ONCE(pmd_leaf(*pmd))) |
| return -EINVAL; |
| if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) { |
| if (!create) |
| continue; |
| pmd_clear_bad(pmd); |
| } |
| err = apply_to_pte_range(mm, pmd, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (pmd++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int err = 0; |
| |
| if (create) { |
| pud = pud_alloc_track(mm, p4d, addr, mask); |
| if (!pud) |
| return -ENOMEM; |
| } else { |
| pud = pud_offset(p4d, addr); |
| } |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none(*pud) && !create) |
| continue; |
| if (WARN_ON_ONCE(pud_leaf(*pud))) |
| return -EINVAL; |
| if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) { |
| if (!create) |
| continue; |
| pud_clear_bad(pud); |
| } |
| err = apply_to_pmd_range(mm, pud, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (pud++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| pte_fn_t fn, void *data, bool create, |
| pgtbl_mod_mask *mask) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int err = 0; |
| |
| if (create) { |
| p4d = p4d_alloc_track(mm, pgd, addr, mask); |
| if (!p4d) |
| return -ENOMEM; |
| } else { |
| p4d = p4d_offset(pgd, addr); |
| } |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none(*p4d) && !create) |
| continue; |
| if (WARN_ON_ONCE(p4d_leaf(*p4d))) |
| return -EINVAL; |
| if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) { |
| if (!create) |
| continue; |
| p4d_clear_bad(p4d); |
| } |
| err = apply_to_pud_range(mm, p4d, addr, next, |
| fn, data, create, mask); |
| if (err) |
| break; |
| } while (p4d++, addr = next, addr != end); |
| |
| return err; |
| } |
| |
| static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, |
| void *data, bool create) |
| { |
| pgd_t *pgd; |
| unsigned long start = addr, next; |
| unsigned long end = addr + size; |
| pgtbl_mod_mask mask = 0; |
| int err = 0; |
| |
| if (WARN_ON(addr >= end)) |
| return -EINVAL; |
| |
| pgd = pgd_offset(mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none(*pgd) && !create) |
| continue; |
| if (WARN_ON_ONCE(pgd_leaf(*pgd))) |
| return -EINVAL; |
| if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) { |
| if (!create) |
| continue; |
| pgd_clear_bad(pgd); |
| } |
| err = apply_to_p4d_range(mm, pgd, addr, next, |
| fn, data, create, &mask); |
| if (err) |
| break; |
| } while (pgd++, addr = next, addr != end); |
| |
| if (mask & ARCH_PAGE_TABLE_SYNC_MASK) |
| arch_sync_kernel_mappings(start, start + size); |
| |
| return err; |
| } |
| |
| /* |
| * Scan a region of virtual memory, filling in page tables as necessary |
| * and calling a provided function on each leaf page table. |
| */ |
| int apply_to_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, void *data) |
| { |
| return __apply_to_page_range(mm, addr, size, fn, data, true); |
| } |
| EXPORT_SYMBOL_GPL(apply_to_page_range); |
| |
| /* |
| * Scan a region of virtual memory, calling a provided function on |
| * each leaf page table where it exists. |
| * |
| * Unlike apply_to_page_range, this does _not_ fill in page tables |
| * where they are absent. |
| */ |
| int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr, |
| unsigned long size, pte_fn_t fn, void *data) |
| { |
| return __apply_to_page_range(mm, addr, size, fn, data, false); |
| } |
| EXPORT_SYMBOL_GPL(apply_to_existing_page_range); |
| |
| /* |
| * handle_pte_fault chooses page fault handler according to an entry which was |
| * read non-atomically. Before making any commitment, on those architectures |
| * or configurations (e.g. i386 with PAE) which might give a mix of unmatched |
| * parts, do_swap_page must check under lock before unmapping the pte and |
| * proceeding (but do_wp_page is only called after already making such a check; |
| * and do_anonymous_page can safely check later on). |
| */ |
| static inline int pte_unmap_same(struct vm_fault *vmf) |
| { |
| int same = 1; |
| #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION) |
| if (sizeof(pte_t) > sizeof(unsigned long)) { |
| spin_lock(vmf->ptl); |
| same = pte_same(ptep_get(vmf->pte), vmf->orig_pte); |
| spin_unlock(vmf->ptl); |
| } |
| #endif |
| pte_unmap(vmf->pte); |
| vmf->pte = NULL; |
| return same; |
| } |
| |
| /* |
| * Return: |
| * 0: copied succeeded |
| * -EHWPOISON: copy failed due to hwpoison in source page |
| * -EAGAIN: copied failed (some other reason) |
| */ |
| static inline int __wp_page_copy_user(struct page *dst, struct page *src, |
| struct vm_fault *vmf) |
| { |
| int ret; |
| void *kaddr; |
| void __user *uaddr; |
| struct vm_area_struct *vma = vmf->vma; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long addr = vmf->address; |
| |
| if (likely(src)) { |
| if (copy_mc_user_highpage(dst, src, addr, vma)) { |
| memory_failure_queue(page_to_pfn(src), 0); |
| return -EHWPOISON; |
| } |
| return 0; |
| } |
| |
| /* |
| * If the source page was a PFN mapping, we don't have |
| * a "struct page" for it. We do a best-effort copy by |
| * just copying from the original user address. If that |
| * fails, we just zero-fill it. Live with it. |
| */ |
| kaddr = kmap_local_page(dst); |
| pagefault_disable(); |
| uaddr = (void __user *)(addr & PAGE_MASK); |
| |
| /* |
| * On architectures with software "accessed" bits, we would |
| * take a double page fault, so mark it accessed here. |
| */ |
| vmf->pte = NULL; |
| if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) { |
| pte_t entry; |
| |
| vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); |
| if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
| /* |
| * Other thread has already handled the fault |
| * and update local tlb only |
| */ |
| if (vmf->pte) |
| update_mmu_tlb(vma, addr, vmf->pte); |
| ret = -EAGAIN; |
| goto pte_unlock; |
| } |
| |
| entry = pte_mkyoung(vmf->orig_pte); |
| if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0)) |
| update_mmu_cache_range(vmf, vma, addr, vmf->pte, 1); |
| } |
| |
| /* |
| * This really shouldn't fail, because the page is there |
| * in the page tables. But it might just be unreadable, |
| * in which case we just give up and fill the result with |
| * zeroes. |
| */ |
| if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { |
| if (vmf->pte) |
| goto warn; |
| |
| /* Re-validate under PTL if the page is still mapped */ |
| vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl); |
| if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) { |
| /* The PTE changed under us, update local tlb */ |
| if (vmf->pte) |
| update_mmu_tlb(vma, addr, vmf->pte); |
| ret = -EAGAIN; |
| goto pte_unlock; |
| } |
| |
| /* |
| * The same page can be mapped back since last copy attempt. |
| * Try to copy again under PTL. |
| */ |
| if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) { |
| /* |
| * Give a warn in case there can be some obscure |
| * use-case |
| */ |
| warn: |
| WARN_ON_ONCE(1); |
| clear_page(kaddr); |
| } |
| } |
| |
| ret = 0; |
| |
| pte_unlock: |
| if (vmf->pte) |
| pte_unmap_unlock(vmf->pte, vmf->ptl); |
| pagefault_enable(); |
| kunmap_local(kaddr); |
| flush_dcache_page(dst); |
| |
| return ret; |
| } |
| |
| static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) |
| { |
| struct file *vm_file = vma->vm_file; |
| |
| if (vm_file) |
| return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; |
| |
| /* |
| * Special mappings (e.g. VDSO) do not have any file so fake |
| * a default GFP_KERNEL for them. |
| */ |
| return GFP_KERNEL; |
| } |
| |
| /* |
| * Notify the address space that the page is about to become writable so that |
| * it can prohibit this or wait for the page to get into an appropriate state. |
| * |
| * We do this without the lock held, so that it can sleep if it needs to. |
| */ |
| static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio) |
| { |
| vm_fault_t ret; |
| unsigned int old_flags = vmf->flags; |
| |
| vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; |
| |
| if (v
|