Re: [PATCH v13 17/20] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get
On Mon, Mar 25, 2019 at 3:08 PM Kevin Brodsky wrote:
>
> On 22/03/2019 16:07, Catalin Marinas wrote:
> > On Wed, Mar 20, 2019 at 03:51:31PM +0100, Andrey Konovalov wrote:
> >> This patch is a part of a series that extends arm64 kernel ABI to allow to
> >> pass tagged user pointers (with the top byte set to something else other
> >> than 0x00) as syscall arguments.
> >>
> >> videobuf_dma_contig_user_get() uses provided user pointers for vma
> >> lookups, which can only by done with untagged pointers.
> >>
> >> Untag the pointers in this function.
> >>
> >> Signed-off-by: Andrey Konovalov
> >> ---
> >> drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +
> >> 1 file changed, 5 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c
> >> b/drivers/media/v4l2-core/videobuf-dma-contig.c
> >> index e1bf50df4c70..8a1ddd146b17 100644
> >> --- a/drivers/media/v4l2-core/videobuf-dma-contig.c
> >> +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
> >> @@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct
> >> videobuf_dma_contig_memory *mem)
> >> static int videobuf_dma_contig_user_get(struct
> >> videobuf_dma_contig_memory *mem,
> >> struct videobuf_buffer *vb)
> >> {
> >> +unsigned long untagged_baddr = untagged_addr(vb->baddr);
> >> struct mm_struct *mm = current->mm;
> >> struct vm_area_struct *vma;
> >> unsigned long prev_pfn, this_pfn;
> >> @@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct
> >> videobuf_dma_contig_memory *mem,
> >> unsigned int offset;
> >> int ret;
> >>
> >> -offset = vb->baddr & ~PAGE_MASK;
> >> +offset = untagged_baddr & ~PAGE_MASK;
> >> mem->size = PAGE_ALIGN(vb->size + offset);
> >> ret = -EINVAL;
> >>
> >> down_read(&mm->mmap_sem);
> >>
> >> -vma = find_vma(mm, vb->baddr);
> >> +vma = find_vma(mm, untagged_baddr);
> >> if (!vma)
> >> goto out_up;
> >>
> >> -if ((vb->baddr + mem->size) > vma->vm_end)
> >> +if ((untagged_baddr + mem->size) > vma->vm_end)
> >> goto out_up;
> >>
> >> pages_done = 0;
> >> prev_pfn = 0; /* kill warning */
> >> -user_address = vb->baddr;
> >> +user_address = untagged_baddr;
> >>
> >> while (pages_done < (mem->size >> PAGE_SHIFT)) {
> >> ret = follow_pfn(vma, user_address, &this_pfn);
> > I don't think vb->baddr here is anonymous mmap() but worth checking the
> > call paths.
The call path is
__videobuf_iolock()->videobuf_dma_contig_user_get()->find_vma().
>
> I spent some time on this, I didn't find any restriction on the kind of
> mapping
> that's allowed here. The API regarding V4L2_MEMORY_USERPTR doesn't seem to say
> anything about that either [0] [1]. It's probably best to ask the V4L2
> maintainers.
Mauro, could you comment on whether the vb->baddr argument for the
V4L2_MEMORY_USERPTR API can come from an anonymous memory mapping?
>
> Kevin
>
> [0] https://www.kernel.org/doc/html/latest/media/uapi/v4l/vidioc-qbuf.html
> [1] https://www.kernel.org/doc/html/latest/media/uapi/v4l/userp.html
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Re: [PATCH v13 17/20] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get
On 22/03/2019 16:07, Catalin Marinas wrote:
On Wed, Mar 20, 2019 at 03:51:31PM +0100, Andrey Konovalov wrote:
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.
videobuf_dma_contig_user_get() uses provided user pointers for vma
lookups, which can only by done with untagged pointers.
Untag the pointers in this function.
Signed-off-by: Andrey Konovalov
---
drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c
b/drivers/media/v4l2-core/videobuf-dma-contig.c
index e1bf50df4c70..8a1ddd146b17 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct
videobuf_dma_contig_memory *mem)
static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory
*mem,
struct videobuf_buffer *vb)
{
+ unsigned long untagged_baddr = untagged_addr(vb->baddr);
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long prev_pfn, this_pfn;
@@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct
videobuf_dma_contig_memory *mem,
unsigned int offset;
int ret;
- offset = vb->baddr & ~PAGE_MASK;
+ offset = untagged_baddr & ~PAGE_MASK;
mem->size = PAGE_ALIGN(vb->size + offset);
ret = -EINVAL;
down_read(&mm->mmap_sem);
- vma = find_vma(mm, vb->baddr);
+ vma = find_vma(mm, untagged_baddr);
if (!vma)
goto out_up;
- if ((vb->baddr + mem->size) > vma->vm_end)
+ if ((untagged_baddr + mem->size) > vma->vm_end)
goto out_up;
pages_done = 0;
prev_pfn = 0; /* kill warning */
- user_address = vb->baddr;
+ user_address = untagged_baddr;
while (pages_done < (mem->size >> PAGE_SHIFT)) {
ret = follow_pfn(vma, user_address, &this_pfn);
I don't think vb->baddr here is anonymous mmap() but worth checking the
call paths.
I spent some time on this, I didn't find any restriction on the kind of mapping
that's allowed here. The API regarding V4L2_MEMORY_USERPTR doesn't seem to say
anything about that either [0] [1]. It's probably best to ask the V4L2 maintainers.
Kevin
[0] https://www.kernel.org/doc/html/latest/media/uapi/v4l/vidioc-qbuf.html
[1] https://www.kernel.org/doc/html/latest/media/uapi/v4l/userp.html
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Re: [PATCH v13 17/20] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get
On Wed, Mar 20, 2019 at 03:51:31PM +0100, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> videobuf_dma_contig_user_get() uses provided user pointers for vma
> lookups, which can only by done with untagged pointers.
>
> Untag the pointers in this function.
>
> Signed-off-by: Andrey Konovalov
> ---
> drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c
> b/drivers/media/v4l2-core/videobuf-dma-contig.c
> index e1bf50df4c70..8a1ddd146b17 100644
> --- a/drivers/media/v4l2-core/videobuf-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
> @@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct
> videobuf_dma_contig_memory *mem)
> static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory
> *mem,
> struct videobuf_buffer *vb)
> {
> + unsigned long untagged_baddr = untagged_addr(vb->baddr);
> struct mm_struct *mm = current->mm;
> struct vm_area_struct *vma;
> unsigned long prev_pfn, this_pfn;
> @@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct
> videobuf_dma_contig_memory *mem,
> unsigned int offset;
> int ret;
>
> - offset = vb->baddr & ~PAGE_MASK;
> + offset = untagged_baddr & ~PAGE_MASK;
> mem->size = PAGE_ALIGN(vb->size + offset);
> ret = -EINVAL;
>
> down_read(&mm->mmap_sem);
>
> - vma = find_vma(mm, vb->baddr);
> + vma = find_vma(mm, untagged_baddr);
> if (!vma)
> goto out_up;
>
> - if ((vb->baddr + mem->size) > vma->vm_end)
> + if ((untagged_baddr + mem->size) > vma->vm_end)
> goto out_up;
>
> pages_done = 0;
> prev_pfn = 0; /* kill warning */
> - user_address = vb->baddr;
> + user_address = untagged_baddr;
>
> while (pages_done < (mem->size >> PAGE_SHIFT)) {
> ret = follow_pfn(vma, user_address, &this_pfn);
I don't think vb->baddr here is anonymous mmap() but worth checking the
call paths.
--
Catalin
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[PATCH v13 17/20] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.
videobuf_dma_contig_user_get() uses provided user pointers for vma
lookups, which can only by done with untagged pointers.
Untag the pointers in this function.
Signed-off-by: Andrey Konovalov
---
drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c
b/drivers/media/v4l2-core/videobuf-dma-contig.c
index e1bf50df4c70..8a1ddd146b17 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct
videobuf_dma_contig_memory *mem)
static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
struct videobuf_buffer *vb)
{
+ unsigned long untagged_baddr = untagged_addr(vb->baddr);
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long prev_pfn, this_pfn;
@@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct
videobuf_dma_contig_memory *mem,
unsigned int offset;
int ret;
- offset = vb->baddr & ~PAGE_MASK;
+ offset = untagged_baddr & ~PAGE_MASK;
mem->size = PAGE_ALIGN(vb->size + offset);
ret = -EINVAL;
down_read(&mm->mmap_sem);
- vma = find_vma(mm, vb->baddr);
+ vma = find_vma(mm, untagged_baddr);
if (!vma)
goto out_up;
- if ((vb->baddr + mem->size) > vma->vm_end)
+ if ((untagged_baddr + mem->size) > vma->vm_end)
goto out_up;
pages_done = 0;
prev_pfn = 0; /* kill warning */
- user_address = vb->baddr;
+ user_address = untagged_baddr;
while (pages_done < (mem->size >> PAGE_SHIFT)) {
ret = follow_pfn(vma, user_address, &this_pfn);
--
2.21.0.225.g810b269d1ac-goog
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