From 4e9e92003529e5c7bb11281f7c2c9b3fe8858403 Mon Sep 17 00:00:00 2001 From: Pete Zaitcev Date: Thu, 11 Jun 2009 08:53:20 -0600 Subject: USB: usbmon: end ugly tricks with DMA peeking This patch fixes crashes when usbmon attempts to access GART aperture. The old code attempted to take a bus address and convert it into a virtual address, which clearly was impossible on systems with actual IOMMUs. Let us not persist in this foolishness, and use transfer_buffer in all cases instead. I think downsides are negligible. The ones I see are: - A driver may pass an address of one buffer down as transfer_buffer, and entirely different entity mapped for DMA, resulting in misleading output of usbmon. Note, however, that PIO based controllers would do transfer the same data that usbmon sees here. - Out of tree drivers may crash usbmon if they store garbage in transfer_buffer. I inspected the in-tree drivers, and clarified the documentation in comments. - Drivers that use get_user_pages will not be possible to monitor. I only found one driver with this problem (drivers/staging/rspiusb). - Same happens with with usb_storage transferring from highmem, but it works fine on 64-bit systems, so I think it's not a concern. At least we don't crash anymore. Why didn't we do this in 2.6.10? That's because back in those days it was popular not to fill in transfer_buffer, so almost all traffic would be invisible (e.g. all of HID was like that). But now, the tree is almost 100% PIO friendly, so we can do the right thing at last. Signed-off-by: Pete Zaitcev Signed-off-by: Greg Kroah-Hartman --- drivers/usb/mon/usb_mon.h | 14 -------------- 1 file changed, 14 deletions(-) (limited to 'drivers/usb/mon/usb_mon.h') diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h index f5d84ff8c101..df9a4df342c7 100644 --- a/drivers/usb/mon/usb_mon.h +++ b/drivers/usb/mon/usb_mon.h @@ -64,20 +64,6 @@ void mon_text_exit(void); int __init mon_bin_init(void); void mon_bin_exit(void); -/* - * DMA interface. - * - * XXX The vectored side needs a serious re-thinking. Abstracting vectors, - * like in Paolo's original patch, produces a double pkmap. We need an idea. -*/ -extern char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len); - -struct mon_reader_bin; -extern void mon_dmapeek_vec(const struct mon_reader_bin *rp, - unsigned int offset, dma_addr_t dma_addr, unsigned int len); -extern unsigned int mon_copy_to_buff(const struct mon_reader_bin *rp, - unsigned int offset, const unsigned char *from, unsigned int len); - /* */ extern struct mutex mon_lock; -- cgit v1.2.3