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.panella@citrix.com Reviewed-by: Frediano Ziglio frediano.ziglio@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