userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation
This implements mcopy_atomic and mfill_zeropage that are the lowlevel VM methods that are invoked respectively by the UFFDIO_COPY and UFFDIO_ZEROPAGE userfaultfd commands. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Pavel Emelyanov <xemul@parallels.com> Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com> Cc: zhang.zhanghailiang@huawei.com Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Feiner <pfeiner@google.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli
Linus Torvalds
parent
1f1c6f0759
commit
c1a4de99fa
@ -30,6 +30,12 @@
|
||||
extern int handle_userfault(struct vm_area_struct *vma, unsigned long address,
|
||||
unsigned int flags, unsigned long reason);
|
||||
|
||||
extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
|
||||
unsigned long src_start, unsigned long len);
|
||||
extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
|
||||
unsigned long dst_start,
|
||||
unsigned long len);
|
||||
|
||||
/* mm helpers */
|
||||
static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
|
||||
struct vm_userfaultfd_ctx vm_ctx)
|
||||
|
||||
@ -78,3 +78,4 @@ obj-$(CONFIG_CMA) += cma.o
|
||||
obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
|
||||
obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
|
||||
obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
|
||||
obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
|
||||
|
||||
269
mm/userfaultfd.c
Normal file
269
mm/userfaultfd.c
Normal file
@ -0,0 +1,269 @@
|
||||
/*
|
||||
* mm/userfaultfd.c
|
||||
*
|
||||
* Copyright (C) 2015 Red Hat, Inc.
|
||||
*
|
||||
* This work is licensed under the terms of the GNU GPL, version 2. See
|
||||
* the COPYING file in the top-level directory.
|
||||
*/
|
||||
|
||||
#include <linux/mm.h>
|
||||
#include <linux/pagemap.h>
|
||||
#include <linux/rmap.h>
|
||||
#include <linux/swap.h>
|
||||
#include <linux/swapops.h>
|
||||
#include <linux/userfaultfd_k.h>
|
||||
#include <linux/mmu_notifier.h>
|
||||
#include <asm/tlbflush.h>
|
||||
#include "internal.h"
|
||||
|
||||
static int mcopy_atomic_pte(struct mm_struct *dst_mm,
|
||||
pmd_t *dst_pmd,
|
||||
struct vm_area_struct *dst_vma,
|
||||
unsigned long dst_addr,
|
||||
unsigned long src_addr)
|
||||
{
|
||||
struct mem_cgroup *memcg;
|
||||
pte_t _dst_pte, *dst_pte;
|
||||
spinlock_t *ptl;
|
||||
struct page *page;
|
||||
void *page_kaddr;
|
||||
int ret;
|
||||
|
||||
ret = -ENOMEM;
|
||||
page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
|
||||
if (!page)
|
||||
goto out;
|
||||
|
||||
page_kaddr = kmap(page);
|
||||
ret = -EFAULT;
|
||||
if (copy_from_user(page_kaddr, (const void __user *) src_addr,
|
||||
PAGE_SIZE))
|
||||
goto out_kunmap_release;
|
||||
kunmap(page);
|
||||
|
||||
/*
|
||||
* The memory barrier inside __SetPageUptodate makes sure that
|
||||
* preceeding stores to the page contents become visible before
|
||||
* the set_pte_at() write.
|
||||
*/
|
||||
__SetPageUptodate(page);
|
||||
|
||||
ret = -ENOMEM;
|
||||
if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg))
|
||||
goto out_release;
|
||||
|
||||
_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
|
||||
if (dst_vma->vm_flags & VM_WRITE)
|
||||
_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
|
||||
|
||||
ret = -EEXIST;
|
||||
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
|
||||
if (!pte_none(*dst_pte))
|
||||
goto out_release_uncharge_unlock;
|
||||
|
||||
inc_mm_counter(dst_mm, MM_ANONPAGES);
|
||||
page_add_new_anon_rmap(page, dst_vma, dst_addr);
|
||||
mem_cgroup_commit_charge(page, memcg, false);
|
||||
lru_cache_add_active_or_unevictable(page, dst_vma);
|
||||
|
||||
set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
|
||||
|
||||
/* No need to invalidate - it was non-present before */
|
||||
update_mmu_cache(dst_vma, dst_addr, dst_pte);
|
||||
|
||||
pte_unmap_unlock(dst_pte, ptl);
|
||||
ret = 0;
|
||||
out:
|
||||
return ret;
|
||||
out_release_uncharge_unlock:
|
||||
pte_unmap_unlock(dst_pte, ptl);
|
||||
mem_cgroup_cancel_charge(page, memcg);
|
||||
out_release:
|
||||
page_cache_release(page);
|
||||
goto out;
|
||||
out_kunmap_release:
|
||||
kunmap(page);
|
||||
goto out_release;
|
||||
}
|
||||
|
||||
static int mfill_zeropage_pte(struct mm_struct *dst_mm,
|
||||
pmd_t *dst_pmd,
|
||||
struct vm_area_struct *dst_vma,
|
||||
unsigned long dst_addr)
|
||||
{
|
||||
pte_t _dst_pte, *dst_pte;
|
||||
spinlock_t *ptl;
|
||||
int ret;
|
||||
|
||||
_dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
|
||||
dst_vma->vm_page_prot));
|
||||
ret = -EEXIST;
|
||||
dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
|
||||
if (!pte_none(*dst_pte))
|
||||
goto out_unlock;
|
||||
set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
|
||||
/* No need to invalidate - it was non-present before */
|
||||
update_mmu_cache(dst_vma, dst_addr, dst_pte);
|
||||
ret = 0;
|
||||
out_unlock:
|
||||
pte_unmap_unlock(dst_pte, ptl);
|
||||
return ret;
|
||||
}
|
||||
|
||||
static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
|
||||
{
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
pmd_t *pmd = NULL;
|
||||
|
||||
pgd = pgd_offset(mm, address);
|
||||
pud = pud_alloc(mm, pgd, address);
|
||||
if (pud)
|
||||
/*
|
||||
* Note that we didn't run this because the pmd was
|
||||
* missing, the *pmd may be already established and in
|
||||
* turn it may also be a trans_huge_pmd.
|
||||
*/
|
||||
pmd = pmd_alloc(mm, pud, address);
|
||||
return pmd;
|
||||
}
|
||||
|
||||
static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
|
||||
unsigned long dst_start,
|
||||
unsigned long src_start,
|
||||
unsigned long len,
|
||||
bool zeropage)
|
||||
{
|
||||
struct vm_area_struct *dst_vma;
|
||||
ssize_t err;
|
||||
pmd_t *dst_pmd;
|
||||
unsigned long src_addr, dst_addr;
|
||||
long copied = 0;
|
||||
|
||||
/*
|
||||
* Sanitize the command parameters:
|
||||
*/
|
||||
BUG_ON(dst_start & ~PAGE_MASK);
|
||||
BUG_ON(len & ~PAGE_MASK);
|
||||
|
||||
/* Does the address range wrap, or is the span zero-sized? */
|
||||
BUG_ON(src_start + len <= src_start);
|
||||
BUG_ON(dst_start + len <= dst_start);
|
||||
|
||||
down_read(&dst_mm->mmap_sem);
|
||||
|
||||
/*
|
||||
* Make sure the vma is not shared, that the dst range is
|
||||
* both valid and fully within a single existing vma.
|
||||
*/
|
||||
err = -EINVAL;
|
||||
dst_vma = find_vma(dst_mm, dst_start);
|
||||
if (!dst_vma || (dst_vma->vm_flags & VM_SHARED))
|
||||
goto out;
|
||||
if (dst_start < dst_vma->vm_start ||
|
||||
dst_start + len > dst_vma->vm_end)
|
||||
goto out;
|
||||
|
||||
/*
|
||||
* Be strict and only allow __mcopy_atomic on userfaultfd
|
||||
* registered ranges to prevent userland errors going
|
||||
* unnoticed. As far as the VM consistency is concerned, it
|
||||
* would be perfectly safe to remove this check, but there's
|
||||
* no useful usage for __mcopy_atomic ouside of userfaultfd
|
||||
* registered ranges. This is after all why these are ioctls
|
||||
* belonging to the userfaultfd and not syscalls.
|
||||
*/
|
||||
if (!dst_vma->vm_userfaultfd_ctx.ctx)
|
||||
goto out;
|
||||
|
||||
/*
|
||||
* FIXME: only allow copying on anonymous vmas, tmpfs should
|
||||
* be added.
|
||||
*/
|
||||
if (dst_vma->vm_ops)
|
||||
goto out;
|
||||
|
||||
/*
|
||||
* Ensure the dst_vma has a anon_vma or this page
|
||||
* would get a NULL anon_vma when moved in the
|
||||
* dst_vma.
|
||||
*/
|
||||
err = -ENOMEM;
|
||||
if (unlikely(anon_vma_prepare(dst_vma)))
|
||||
goto out;
|
||||
|
||||
for (src_addr = src_start, dst_addr = dst_start;
|
||||
src_addr < src_start + len; ) {
|
||||
pmd_t dst_pmdval;
|
||||
BUG_ON(dst_addr >= dst_start + len);
|
||||
dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
|
||||
if (unlikely(!dst_pmd)) {
|
||||
err = -ENOMEM;
|
||||
break;
|
||||
}
|
||||
|
||||
dst_pmdval = pmd_read_atomic(dst_pmd);
|
||||
/*
|
||||
* If the dst_pmd is mapped as THP don't
|
||||
* override it and just be strict.
|
||||
*/
|
||||
if (unlikely(pmd_trans_huge(dst_pmdval))) {
|
||||
err = -EEXIST;
|
||||
break;
|
||||
}
|
||||
if (unlikely(pmd_none(dst_pmdval)) &&
|
||||
unlikely(__pte_alloc(dst_mm, dst_vma, dst_pmd,
|
||||
dst_addr))) {
|
||||
err = -ENOMEM;
|
||||
break;
|
||||
}
|
||||
/* If an huge pmd materialized from under us fail */
|
||||
if (unlikely(pmd_trans_huge(*dst_pmd))) {
|
||||
err = -EFAULT;
|
||||
break;
|
||||
}
|
||||
|
||||
BUG_ON(pmd_none(*dst_pmd));
|
||||
BUG_ON(pmd_trans_huge(*dst_pmd));
|
||||
|
||||
if (!zeropage)
|
||||
err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
|
||||
dst_addr, src_addr);
|
||||
else
|
||||
err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma,
|
||||
dst_addr);
|
||||
|
||||
cond_resched();
|
||||
|
||||
if (!err) {
|
||||
dst_addr += PAGE_SIZE;
|
||||
src_addr += PAGE_SIZE;
|
||||
copied += PAGE_SIZE;
|
||||
|
||||
if (fatal_signal_pending(current))
|
||||
err = -EINTR;
|
||||
}
|
||||
if (err)
|
||||
break;
|
||||
}
|
||||
|
||||
out:
|
||||
up_read(&dst_mm->mmap_sem);
|
||||
BUG_ON(copied < 0);
|
||||
BUG_ON(err > 0);
|
||||
BUG_ON(!copied && !err);
|
||||
return copied ? copied : err;
|
||||
}
|
||||
|
||||
ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
|
||||
unsigned long src_start, unsigned long len)
|
||||
{
|
||||
return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
|
||||
}
|
||||
|
||||
ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
|
||||
unsigned long len)
|
||||
{
|
||||
return __mcopy_atomic(dst_mm, start, 0, len, true);
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user