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userfaultfd: hugetlbfs: add __mcopy_atomic_hugetlb for huge page UFFDIO_COPY 

__mcopy_atomic_hugetlb performs the UFFDIO_COPY operation for huge
pages.  It is based on the existing __mcopy_atomic routine for normal
pages.  Unlike normal pages, there is no huge page support for the
UFFDIO_ZEROPAGE operation.

Link: http://lkml.kernel.org/r/20161216144821.5183-19-aarcange@redhat.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2017-02-22 15:42:55 -08:00 committed by Linus Torvalds
parent 8fb5debc5f
commit 60d4d2d2b4
1 changed files with 186 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

186
mm/userfaultfd.c
View File

@ -14,6 +14,8 @@
#include <linux/swapops.h>
#include <linux/userfaultfd_k.h>
#include <linux/mmu_notifier.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <asm/tlbflush.h>
#include "internal.h"
@ -139,6 +141,183 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
return pmd;
}
#ifdef CONFIG_HUGETLB_PAGE
/*
* __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
* called with mmap_sem held, it will release mmap_sem before returning.
*/
static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
struct vm_area_struct *dst_vma,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
bool zeropage)
{
ssize_t err;
pte_t *dst_pte;
unsigned long src_addr, dst_addr;
long copied;
struct page *page;
struct hstate *h;
unsigned long vma_hpagesize;
pgoff_t idx;
u32 hash;
struct address_space *mapping;
/*
* There is no default zero huge page for all huge page sizes as
* supported by hugetlb. A PMD_SIZE huge pages may exist as used
* by THP. Since we can not reliably insert a zero page, this
* feature is not supported.
*/
if (zeropage) {
up_read(&dst_mm->mmap_sem);
return -EINVAL;
}
src_addr = src_start;
dst_addr = dst_start;
copied = 0;
page = NULL;
vma_hpagesize = vma_kernel_pagesize(dst_vma);
/*
* Validate alignment based on huge page size
*/
err = -EINVAL;
if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
goto out_unlock;
retry:
/*
* On routine entry dst_vma is set. If we had to drop mmap_sem and
* retry, dst_vma will be set to NULL and we must lookup again.
*/
if (!dst_vma) {
err = -EINVAL;
dst_vma = find_vma(dst_mm, dst_start);
if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
goto out_unlock;
if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
goto out_unlock;
/*
* Make sure the vma is not shared, that the remaining dst
* range is both valid and fully within a single existing vma.
*/
if (dst_vma->vm_flags & VM_SHARED)
goto out_unlock;
if (dst_start < dst_vma->vm_start ||
dst_start + len > dst_vma->vm_end)
goto out_unlock;
}
if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
(len - copied) & (vma_hpagesize - 1)))
goto out_unlock;
/*
* Only allow __mcopy_atomic_hugetlb on userfaultfd registered ranges.
*/
if (!dst_vma->vm_userfaultfd_ctx.ctx)
goto out_unlock;
/*
* Ensure the dst_vma has a anon_vma.
*/
err = -ENOMEM;
if (unlikely(anon_vma_prepare(dst_vma)))
goto out_unlock;
h = hstate_vma(dst_vma);
while (src_addr < src_start + len) {
pte_t dst_pteval;
BUG_ON(dst_addr >= dst_start + len);
VM_BUG_ON(dst_addr & ~huge_page_mask(h));
/*
* Serialize via hugetlb_fault_mutex
*/
idx = linear_page_index(dst_vma, dst_addr);
mapping = dst_vma->vm_file->f_mapping;
hash = hugetlb_fault_mutex_hash(h, dst_mm, dst_vma, mapping,
idx, dst_addr);
mutex_lock(&hugetlb_fault_mutex_table[hash]);
err = -ENOMEM;
dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h));
if (!dst_pte) {
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
goto out_unlock;
}
err = -EEXIST;
dst_pteval = huge_ptep_get(dst_pte);
if (!huge_pte_none(dst_pteval)) {
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
goto out_unlock;
}
err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
dst_addr, src_addr, &page);
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
cond_resched();
if (unlikely(err == -EFAULT)) {
up_read(&dst_mm->mmap_sem);
BUG_ON(!page);
err = copy_huge_page_from_user(page,
(const void __user *)src_addr,
pages_per_huge_page(h));
if (unlikely(err)) {
err = -EFAULT;
goto out;
}
down_read(&dst_mm->mmap_sem);
dst_vma = NULL;
goto retry;
} else
BUG_ON(page);
if (!err) {
dst_addr += vma_hpagesize;
src_addr += vma_hpagesize;
copied += vma_hpagesize;
if (fatal_signal_pending(current))
err = -EINTR;
}
if (err)
break;
}
out_unlock:
up_read(&dst_mm->mmap_sem);
out:
if (page)
put_page(page);
BUG_ON(copied < 0);
BUG_ON(err > 0);
BUG_ON(!copied && !err);
return copied ? copied : err;
}
#else /* !CONFIG_HUGETLB_PAGE */
/* fail at build time if gcc attempts to use this */
extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
struct vm_area_struct *dst_vma,
unsigned long dst_start,
unsigned long src_start,
unsigned long len,
bool zeropage);
#endif /* CONFIG_HUGETLB_PAGE */
static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
unsigned long dst_start,
unsigned long src_start,
@ -181,6 +360,13 @@ retry:
dst_start + len > dst_vma->vm_end)
goto out_unlock;
/*
* If this is a HUGETLB vma, pass off to appropriate routine
*/
if (is_vm_hugetlb_page(dst_vma))
return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
src_start, len, zeropage);
/*
* Be strict and only allow __mcopy_atomic on userfaultfd
* registered ranges to prevent userland errors going