4e9e920035
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 <zaitcev@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
8 lines
125 B
Makefile
8 lines
125 B
Makefile
#
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# Makefile for USB monitor
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#
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usbmon-objs := mon_main.o mon_stat.o mon_text.o mon_bin.o
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obj-$(CONFIG_USB_MON) += usbmon.o
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