2019-01-11 20:50:20

by Souptick Joarder

Subject: [PATCH 9/9] xen/privcmd-buf.c: Convert to use vm_insert_range_buggy

Convert to use vm_insert_range_buggy() to map range of kernel
memory to user vma.

This driver has ignored vm_pgoff. We could later "fix" these drivers
to behave according to the normal vm_pgoff offsetting simply by
removing the _buggy suffix on the function name and if that causes
regressions, it gives us an easy way to revert.

Signed-off-by: Souptick Joarder <[email protected]>
---
drivers/xen/privcmd-buf.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/privcmd-buf.c b/drivers/xen/privcmd-buf.c
index de01a6d..a9d7e97 100644
--- a/drivers/xen/privcmd-buf.c
+++ b/drivers/xen/privcmd-buf.c
@@ -166,12 +166,8 @@ static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
if (vma_priv->n_pages != count)
ret = -ENOMEM;
else
- for (i = 0; i < vma_priv->n_pages; i++) {
- ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE,
- vma_priv->pages[i]);
- if (ret)
- break;
- }
+ ret = vm_insert_range_buggy(vma, vma_priv->pages,
+ vma_priv->n_pages);

if (ret)
privcmd_buf_vmapriv_free(vma_priv);
--
1.9.1

2019-01-14 23:33:14

by Boris Ostrovsky

Subject: Re: [PATCH 9/9] xen/privcmd-buf.c: Convert to use vm_insert_range_buggy

On 1/11/19 10:13 AM, Souptick Joarder wrote:
> Convert to use vm_insert_range_buggy() to map range of kernel
> memory to user vma.
>
> This driver has ignored vm_pgoff. We could later "fix" these drivers
> to behave according to the normal vm_pgoff offsetting simply by
> removing the _buggy suffix on the function name and if that causes
> regressions, it gives us an easy way to revert.
>
> Signed-off-by: Souptick Joarder <[email protected]>
> ---
> drivers/xen/privcmd-buf.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/xen/privcmd-buf.c b/drivers/xen/privcmd-buf.c
> index de01a6d..a9d7e97 100644
> --- a/drivers/xen/privcmd-buf.c
> +++ b/drivers/xen/privcmd-buf.c
> @@ -166,12 +166,8 @@ static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
> if (vma_priv->n_pages != count)
> ret = -ENOMEM;
> else
> - for (i = 0; i < vma_priv->n_pages; i++) {
> - ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE,
> - vma_priv->pages[i]);
> - if (ret)
> - break;
> - }
> + ret = vm_insert_range_buggy(vma, vma_priv->pages,
> + vma_priv->n_pages);

This can use the non-buggy version. But since the original code was
indeed buggy in this respect I can submit this as a separate patch later.

So

Reviewed-by: Boris Ostrovsky <[email protected]>


>
> if (ret)
> privcmd_buf_vmapriv_free(vma_priv);

2019-01-15 06:34:15

by Souptick Joarder

Subject: Re: [PATCH 9/9] xen/privcmd-buf.c: Convert to use vm_insert_range_buggy

On Tue, Jan 15, 2019 at 5:01 AM Boris Ostrovsky
<[email protected]> wrote:
>
> On 1/11/19 10:13 AM, Souptick Joarder wrote:
> > Convert to use vm_insert_range_buggy() to map range of kernel
> > memory to user vma.
> >
> > This driver has ignored vm_pgoff. We could later "fix" these drivers
> > to behave according to the normal vm_pgoff offsetting simply by
> > removing the _buggy suffix on the function name and if that causes
> > regressions, it gives us an easy way to revert.
> >
> > Signed-off-by: Souptick Joarder <[email protected]>
> > ---
> > drivers/xen/privcmd-buf.c | 8 ++------
> > 1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/xen/privcmd-buf.c b/drivers/xen/privcmd-buf.c
> > index de01a6d..a9d7e97 100644
> > --- a/drivers/xen/privcmd-buf.c
> > +++ b/drivers/xen/privcmd-buf.c
> > @@ -166,12 +166,8 @@ static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma)
> > if (vma_priv->n_pages != count)
> > ret = -ENOMEM;
> > else
> > - for (i = 0; i < vma_priv->n_pages; i++) {
> > - ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE,
> > - vma_priv->pages[i]);
> > - if (ret)
> > - break;
> > - }
> > + ret = vm_insert_range_buggy(vma, vma_priv->pages,
> > + vma_priv->n_pages);
>
> This can use the non-buggy version. But since the original code was
> indeed buggy in this respect I can submit this as a separate patch later.
>
> So
>
> Reviewed-by: Boris Ostrovsky <[email protected]>

Thanks Boris.
>
>
> >
> > if (ret)
> > privcmd_buf_vmapriv_free(vma_priv);
>