Re: [PATCH] nommu: remap_pfn_range: fix addr parameter check
I was using 3.3 linux kernel. I will again check if videobuf2 in 3.5 has already fixed this issue. [snip..] Ok I just checked the vb2_dma_contig allocator and it has no major changes from my version, http://lxr.linux.no/linux+v3.5.3/drivers/media/video/videobuf2-dma-contig.c#L37 So, I am not sure if this issue has been fixed in the videobuf2 (or if any patch is in the pipeline which fixes the issue). I run my test on our blackfin platform, and all addresses in remap_pfn_range is aligned for 3.5 branch. -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] nommu: remap_pfn_range: fix addr parameter check
Yes, the MMU version of remap_pfn_range() does permit non-page-aligned `addr' (at least, if the userspace maaping is a non-COW one). But I suspect that was an implementation accident - it is a nonsensical thing to do, isn't it? The MMU cannot map a bunch of kernel pages onto a non-page-aligned userspace address. So I'm thinking that we should declare ((addr ~PAGE_MASK) != 0) to be a caller bug, and fix up this regrettably unidentified v4l driver? I agree. This should be fixed in videobuf. Hi sharma, what's your kernel version? It seems videobuf2 already fixed this bug in 3.5. -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [PATCH] nommu: remap_pfn_range: fix addr parameter check
-Original Message- From: Scott Jiang [mailto:scott.jiang.li...@gmail.com] Sent: Friday, September 14, 2012 2:53 PM To: Andrew Morton Cc: Bob Liu; linux...@kvack.org; Bhupesh SHARMA; laurent.pinch...@ideasonboard.com; uclinux-dist- de...@blackfin.uclinux.org; linux-media@vger.kernel.org; dhowe...@redhat.com; ge...@linux-m68k.org; g...@uclinux.org; sta...@kernel.org; gre...@linuxfoundation.org; Hugh Dickins Subject: Re: [PATCH] nommu: remap_pfn_range: fix addr parameter check Yes, the MMU version of remap_pfn_range() does permit non-page- aligned `addr' (at least, if the userspace maaping is a non-COW one). But I suspect that was an implementation accident - it is a nonsensical thing to do, isn't it? The MMU cannot map a bunch of kernel pages onto a non-page-aligned userspace address. So I'm thinking that we should declare ((addr ~PAGE_MASK) != 0) to be a caller bug, and fix up this regrettably unidentified v4l driver? I agree. This should be fixed in videobuf. Hi sharma, what's your kernel version? It seems videobuf2 already fixed this bug in 3.5. Hi Scott, I was using 3.3 linux kernel. I will again check if videobuf2 in 3.5 has already fixed this issue. Regards, Bhupesh -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [PATCH] nommu: remap_pfn_range: fix addr parameter check
-Original Message-
From: Bhupesh SHARMA
Sent: Friday, September 14, 2012 3:45 PM
To: 'Scott Jiang'; Andrew Morton
Cc: Bob Liu; linux...@kvack.org; laurent.pinch...@ideasonboard.com;
uclinux-dist-de...@blackfin.uclinux.org; linux-media@vger.kernel.org;
dhowe...@redhat.com; ge...@linux-m68k.org; g...@uclinux.org;
sta...@kernel.org; gre...@linuxfoundation.org; Hugh Dickins
Subject: RE: [PATCH] nommu: remap_pfn_range: fix addr parameter check
-Original Message-
From: Scott Jiang [mailto:scott.jiang.li...@gmail.com]
Sent: Friday, September 14, 2012 2:53 PM
To: Andrew Morton
Cc: Bob Liu; linux...@kvack.org; Bhupesh SHARMA;
laurent.pinch...@ideasonboard.com; uclinux-dist-
de...@blackfin.uclinux.org; linux-media@vger.kernel.org;
dhowe...@redhat.com; ge...@linux-m68k.org; g...@uclinux.org;
sta...@kernel.org; gre...@linuxfoundation.org; Hugh Dickins
Subject: Re: [PATCH] nommu: remap_pfn_range: fix addr parameter check
Yes, the MMU version of remap_pfn_range() does permit non-page-
aligned
`addr' (at least, if the userspace maaping is a non-COW one). But I
suspect that was an implementation accident - it is a nonsensical
thing to do, isn't it? The MMU cannot map a bunch of kernel pages
onto a non-page-aligned userspace address.
So I'm thinking that we should declare ((addr ~PAGE_MASK) != 0) to
be a caller bug, and fix up this regrettably unidentified v4l driver?
I agree. This should be fixed in videobuf.
Hi sharma, what's your kernel version? It seems videobuf2 already
fixed this bug in 3.5.
[snip..]
I was using 3.3 linux kernel. I will again check if videobuf2 in 3.5 has
already
fixed this issue.
[snip..]
Ok I just checked the vb2_dma_contig allocator and it has no major changes from
my version,
http://lxr.linux.no/linux+v3.5.3/drivers/media/video/videobuf2-dma-contig.c#L37
So, I am not sure if this issue has been fixed in the videobuf2 (or if any
patch is in the pipeline
which fixes the issue).
BTW I paste my original mail on the subject below to help everyone understand
the complete setup
and the issue I faced.
Regards,
Bhupesh
-
Hi,
I have been trying recently to make a usb-based-webcam device to work with
Linux. The entire scheme is a bit complex:
UVC gadget --User Pointer-- User-Space Daemon -- MMAP -- V4L2 capture
device.
The UVC gadget is internally a v4l2 based device supporting VB2_VMALLOC
operations, whereas the V4L2 capture device supports VB2_DMA_CONTIG operations.
The application (user-space daemon), is responsible for getting memory
allocated from the V4L2 capture device via REQBUF calls. The V4L2 capture side
exposes a
MMAP IO method, whereas the UVC gadget can get a USERPTR to the buffer filled
with video data from the V4L2 capture device and then send the same on a USB
bus.
This scheme works absolutely fine on an architecture having a MMU, but when I
try the same on a NOMMU arch, I see MMAP calls from the user-space daemon
failing.
I have implemented a .get_unmapped_area callback in my V4L2 capture driver
using the blackfin video capture driver as a reference (see [1]).
I make a MMAP call from the user-space application in a sequence like this
(pretty similar to the standard capture.c example, see[2]):
static void init_mmap (void)
{
struct v4l2_requestbuffers req;
CLEAR (req);
req.count = 4;
req.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
if (-1 == xioctl (fd, VIDIOC_REQBUFS, req))
{
if (EINVAL == errno)
{
fprintf (stderr, %s does not support memory
mapping\n, dev_name);
exit (EXIT_FAILURE);
}
else
{
errno_exit (VIDIOC_REQBUFS);
}
}
if (req.count 2)
{
fprintf (stderr, Insufficient buffer memory on %s\n,dev_name);
exit (EXIT_FAILURE);
}
buffers = (buffer*) calloc (req.count, sizeof (*buffers));
if (!buffers)
{
fprintf (stderr, Out of memory\n);
exit (EXIT_FAILURE);
}
for (n_buffers = 0; n_buffers req.count; ++n_buffers)
{
struct v4l2_buffer buf;
CLEAR (buf);
buf.type= V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = n_buffers;
if (-1 == xioctl (fd, VIDIOC_QUERYBUF, buf))
errno_exit (VIDIOC_QUERYBUF);
buffers[n_buffers].length = buf.length;
buffers[n_buffers].start =
mmap (NULL /* start anywhere */,
buf.length
Re: [PATCH] nommu: remap_pfn_range: fix addr parameter check
On Thu, 13 Sep 2012 10:40:57 +0800
Bob Liu lliu...@gmail.com wrote:
The addr parameter may not page aligned eg. when it's come from
vfb_mmap():vma-vm_start in video driver.
This patch fix the check in remap_pfn_range() else some driver like v4l2 will
fail in this function while calling mmap() on nommu arch like blackfin and st.
Reported-by: Bhupesh SHARMA bhupesh.sha...@st.com
Reported-by: Scott Jiang scott.jiang.li...@gmail.com
Signed-off-by: Bob Liu lliu...@gmail.com
---
mm/nommu.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/nommu.c b/mm/nommu.c
index d4b0c10..5d6068b 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1819,7 +1819,7 @@ struct page *follow_page(struct vm_area_struct *vma,
unsigned long address,
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t prot)
{
- if (addr != (pfn PAGE_SHIFT))
+ if ((addr PAGE_MASK) != (pfn PAGE_SHIFT))
return -EINVAL;
vma-vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
hm, what is the right thing to do here?
Yes, the MMU version of remap_pfn_range() does permit non-page-aligned
`addr' (at least, if the userspace maaping is a non-COW one). But I
suspect that was an implementation accident - it is a nonsensical thing
to do, isn't it? The MMU cannot map a bunch of kernel pages onto a
non-page-aligned userspace address.
So I'm thinking that we should declare ((addr ~PAGE_MASK) != 0) to be
a caller bug, and fix up this regrettably unidentified v4l driver?
--
To unsubscribe from this list: send the line unsubscribe linux-media in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] nommu: remap_pfn_range: fix addr parameter check
The addr parameter may not page aligned eg. when it's come from
vfb_mmap():vma-vm_start in video driver.
This patch fix the check in remap_pfn_range() else some driver like v4l2 will
fail in this function while calling mmap() on nommu arch like blackfin and st.
Reported-by: Bhupesh SHARMA bhupesh.sha...@st.com
Reported-by: Scott Jiang scott.jiang.li...@gmail.com
Signed-off-by: Bob Liu lliu...@gmail.com
---
mm/nommu.c |2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/nommu.c b/mm/nommu.c
index d4b0c10..5d6068b 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1819,7 +1819,7 @@ struct page *follow_page(struct vm_area_struct *vma,
unsigned long address,
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t prot)
{
- if (addr != (pfn PAGE_SHIFT))
+ if ((addr PAGE_MASK) != (pfn PAGE_SHIFT))
return -EINVAL;
vma-vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
--
1.7.9.5
--
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