At Tue, 10 Dec 2013 14:20:28 +0000,
Stefano Panella wrote:
>
> When running a 32bit kernel the hda_intel driver is still reporting
> a 64bit dma_mask if the HW supports it.
>
> >From sound/pci/hda/hda_intel.c:
>
> /* allow 64bit DMA address if supported by H/W */
> if ((gcap & ICH6_GCAP_64OK) && !pci_set_dma_mask(pci,
> DMA_BIT_MASK(64)))
> pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(64));
> else {
> pci_set_dma_mask(pci, DMA_BIT_MASK(32));
> pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(32));
> }
>
> which means when there is a call to dma_alloc_coherent from
> snd_malloc_dev_pages a machine address bigger than 32bit can be returned.
> This can be true in particular if running the 32bit kernel as a pv dom0
> under the Xen Hypervisor or PAE on bare metal.
>
> The problem is that when calling setup_bdle to program the BLE the
> dma_addr_t returned from the dma_alloc_coherent is wrongly truncated
> from snd_sgbuf_get_addr if running a 32bit kernel:
>
> static inline dma_addr_t snd_sgbuf_get_addr(struct snd_dma_buffer *dmab,
> size_t offset)
> {
> struct snd_sg_buf *sgbuf = dmab->private_data;
> dma_addr_t addr = sgbuf->table[offset >> PAGE_SHIFT].addr;
> addr &= PAGE_MASK;
> return addr + offset % PAGE_SIZE;
> }
>
> where PAGE_MASK in a 32bit kernel is zeroing the upper 32bit af addr.
>
> Without this patch the HW will fetch the 32bit truncated address,
> which is not the one obtained from dma_alloc_coherent and will result
> to a non working audio but can corrupt host memory at a random location.
>
> The current patch apply to v3.13-rc3-74-g6c843f5
>
> Signed-off-by: Stefano Panella <stefano.pane...@citrix.com>
> Reviewed-by: Frediano Ziglio <frediano.zig...@citrix.com>
Thanks for spotting out. Applied now (I added Cc to stable).
It might be better to have a common PAGE_SIZE definition aligned to
dma_addr_t, but this patch should be enough for now.
Takashi
> ---
> include/sound/memalloc.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/sound/memalloc.h b/include/sound/memalloc.h
> index af99839..5f73785 100644
> --- a/include/sound/memalloc.h
> +++ b/include/sound/memalloc.h
> @@ -108,7 +108,7 @@ static inline dma_addr_t snd_sgbuf_get_addr(struct
> snd_dma_buffer *dmab,
> {
> struct snd_sg_buf *sgbuf = dmab->private_data;
> dma_addr_t addr = sgbuf->table[offset >> PAGE_SHIFT].addr;
> - addr &= PAGE_MASK;
> + addr &= ~((dma_addr_t)PAGE_SIZE - 1);
> return addr + offset % PAGE_SIZE;
> }
>
> --
> 1.7.9.5
>
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