On 08.12.2013 01:49, Steven Luo wrote:
This patch causes problems with DSP codecs on OMAP3 devices running
Android -- specifically, when the decoder is cleaning up after itself,
munmap() of the mapped area fails, leading to a memory leak which
eventually crashes the system.
As far as I can tell, the code with this patch applied reduces to
(ignoring checks and such)
remap_pfn_range(vma, vma->vm_start,
(pdata->phys_mempool_base >> PAGE_SHIFT) + vma->vm_pgoff,
vma->vm_end - vma->vm_start,
vma->vm_page_prot);
whereas the original was
- status = remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
- vma->vm_end - vma->vm_start,
- vma->vm_page_prot);
We're subtracting (pdata->phys_mempool_base >> PAGE_SHIFT) from
vma->vm_pgoff before calling vm_iomap_memory() to address the issue --
if that's satisfactory to everyone involved, I can submit the following
patch.
-Steven Luo
(please cc, not subscribed)
From: Steven Luo <steven@xxxxxxxxxxxxx>
Date: Sat, 7 Dec 2013 02:11:20 -0800
Subject: [PATCH] tidspbridge: fix last patch to map same region of physical
memory as before
Commit 559c71fe5dc3 ("Staging: TIDSPBRIDGE: Use vm_iomap_memory for
mmap-ing instead of remap_pfn_range") had the effect of inadvertently
shifting the start of the physical memory area mapped by
pdata->phys_mempool_base. Correct this by subtracting that shift before
calling vm_iomap_memory() and adding it back afterwards.
Reported-by: Dheeraj CVR <cvr.dheeraj@xxxxxxxxx>
Signed-off-by: Steven Luo <steven@xxxxxxxxxxxxx>
---
drivers/staging/tidspbridge/rmgr/drv_interface.c | 29 +++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/tidspbridge/rmgr/drv_interface.c b/drivers/staging/tidspbridge/rmgr/drv_interface.c
index 83cc3a5..d7f7d04 100644
--- a/drivers/staging/tidspbridge/rmgr/drv_interface.c
+++ b/drivers/staging/tidspbridge/rmgr/drv_interface.c
@@ -258,6 +258,9 @@ err:
/* This function maps kernel space memory to user space memory. */
static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
{
+ unsigned long base_pgoff;
+ int status;
+
struct omap_dsp_platform_data *pdata =
omap_dspbridge_dev->dev.platform_data;
@@ -269,9 +272,29 @@ static int bridge_mmap(struct file *filp, struct vm_area_struct *vma)
vma->vm_start, vma->vm_end, vma->vm_page_prot,
vma->vm_flags);
- return vm_iomap_memory(vma,
- pdata->phys_mempool_base,
- pdata->phys_mempool_size);
+ /*
+ * vm_iomap_memory() expects vma->vm_pgoff to be expressed as an offset
+ * from the start of the physical memory pool, but we're called with
+ * a pfn (physical page number) stored there instead.
+ *
+ * To avoid duplicating lots of tricky overflow checking logic,
+ * temporarily convert vma->vm_pgoff to the offset vm_iomap_memory()
+ * expects, but restore the original value once the mapping has been
+ * created.
+ */
+ base_pgoff = pdata->phys_mempool_base >> PAGE_SHIFT;
+ if (vma->vm_pgoff < base_pgoff)
+ return -EINVAL;
+ vma->vm_pgoff -= base_pgoff;
+
+ status = vm_iomap_memory(vma,
+ pdata->phys_mempool_base,
+ pdata->phys_mempool_size);
+
+ /* Restore the original value of vma->vm_pgoff */
+ vma->vm_pgoff += base_pgoff;
+
+ return status;
}
static const struct file_operations bridge_fops = {
Tested on Nokia N900 with Maemo 5 and Harmattan codec nodes
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