Patch to fix usbmon crash on Opteron

From: Pete Zaitcev
Date: Tue Jun 02 2009 - 23:12:43 EST

Here's my proposal: forget the clever-by-half tricks and simply use
transfer_buffer. This should not only fix Opteron, but also future IOMMUs
that Intel and AMD promise. It may also make usbmon useable on PPC at last.

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.
- Out of tree drivers may crash usbmon if they store garbage in
transfer_buffer. I went over the tree with a comb and fixed obvious
bugs, and clarified the documentation in comments.
- Drivers that use get_user_pages will not be possible to monitor
- Similar deal is with usb_storage transferring from highmem, but
it works fine on 64-bit systems, so I think it's not a concern.

I'm adding a sign-off line in case, but in general this is a patch
for testing. In particular, sisusb is a concern.

David & John, I am quite certain that your Opterons will not crash now,
but please give it a try, and also you can use this code to produce usbmon
traces you needed for debugging of other things.

Signed-off-by: Pete Zaitcev <zaitcev@xxxxxxxxxx>

diff --git a/drivers/staging/rspiusb/rspiusb.c b/drivers/staging/rspiusb/rspiusb.c
index ecaffb5..fe97451 100644
--- a/drivers/staging/rspiusb/rspiusb.c
+++ b/drivers/staging/rspiusb/rspiusb.c
@@ -432,8 +432,7 @@ static void piusb_write_bulk_callback(struct urb *urb)
__func__, status);

pdx->pendingWrite = 0;
- usb_buffer_free(urb->dev, urb->transfer_buffer_length,
- urb->transfer_buffer, urb->transfer_dma);
+ kfree(urb->transfer_buffer);
}

int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len,
@@ -445,9 +444,7 @@ int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len,

urb = usb_alloc_urb(0, GFP_KERNEL);
if (urb != NULL) {
- kbuf =
- usb_buffer_alloc(pdx->udev, len, GFP_KERNEL,
- &urb->transfer_dma);
+ kbuf = kmalloc(len, GFP_KERNEL);
if (!kbuf) {
info("buffer_alloc failed\n");
return -ENOMEM;
@@ -455,7 +452,6 @@ int piusb_output(struct ioctl_struct * io, unsigned char *uBuf, int len,
memcpy(kbuf, uBuf, len);
usb_fill_bulk_urb(urb, pdx->udev, pdx->hEP[io->endpoint], kbuf,
len, piusb_write_bulk_callback, pdx);
- urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
err = usb_submit_urb(urb, GFP_KERNEL);
if (err) {
dev_err(&pdx->udev->dev,
@@ -617,7 +613,7 @@ static int MapUserBuffer(struct ioctl_struct *io, struct device_extension *pdx)
numPagesRequired =
((uaddr & ~PAGE_MASK) + count + ~PAGE_MASK) >> PAGE_SHIFT;
dbg("Number of pages needed = %d", numPagesRequired);
- maplist_p = vmalloc(numPagesRequired * sizeof(struct page)); //, GFP_ATOMIC);
+ maplist_p = vmalloc(numPagesRequired * sizeof(struct page *)); //, GFP_ATOMIC);
if (!maplist_p) {
dbg("Can't Allocate Memory for maplist_p");
return -ENOMEM;
@@ -681,9 +677,7 @@ static int MapUserBuffer(struct ioctl_struct *io, struct device_extension *pdx)
usb_fill_bulk_urb(pdx->PixelUrb[frameInfo][i],
pdx->udev,
epAddr,
- (dma_addr_t *) sg_dma_address(&pdx->
- sgl[frameInfo]
- [i]),
+ NULL, // non-DMA HC? buy a better hardware
sg_dma_len(&pdx->sgl[frameInfo][i]),
piusb_readPIXEL_callback, (void *)pdx);
pdx->PixelUrb[frameInfo][i]->transfer_dma =
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index be86ae3..8fb176f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1070,7 +1070,7 @@ static int hub_configure(struct usb_hub *hub,
goto fail;
}

- usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
+ usb_fill_int_urb(hub->urb, hdev, pipe, hub->buffer, maxp, hub_irq,
hub, endpoint->bInterval);
hub->urb->transfer_dma = hub->buffer_dma;
hub->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index b626283..f06d095 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -421,30 +421,18 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
/*
* Some systems need to revert to PIO when DMA is temporarily
* unavailable. For their sakes, both transfer_buffer and
- * transfer_dma are set when possible. However this can only
- * work on systems without:
- *
- * - HIGHMEM, since DMA buffers located in high memory are
- * not directly addressable by the CPU for PIO;
- *
- * - IOMMU, since dma_map_sg() is allowed to use an IOMMU to
- * make virtually discontiguous buffers be "dma-contiguous"
- * so that PIO and DMA need diferent numbers of URBs.
- *
- * So when HIGHMEM or IOMMU are in use, transfer_buffer is NULL
- * to prevent stale pointers and to help spot bugs.
+ * transfer_dma are set when possible.
*/
+ if (PageHighMem(sg_page(sg))) {
+ io->urbs[i]->transfer_buffer = NULL;
+ } else {
+ io->urbs[i]->transfer_buffer = sg_virt(sg);
+ }
if (dma) {
io->urbs[i]->transfer_dma = sg_dma_address(sg);
len = sg_dma_len(sg);
-#if defined(CONFIG_HIGHMEM) || defined(CONFIG_GART_IOMMU)
- io->urbs[i]->transfer_buffer = NULL;
-#else
- io->urbs[i]->transfer_buffer = sg_virt(sg);
-#endif
} else {
/* hc may use _only_ transfer_buffer */
- io->urbs[i]->transfer_buffer = sg_virt(sg);
len = sg->length;
}

diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c
index b4ec716..0025847 100644
--- a/drivers/usb/misc/sisusbvga/sisusb.c
+++ b/drivers/usb/misc/sisusbvga/sisusb.c
@@ -79,14 +79,12 @@ sisusb_free_buffers(struct sisusb_usb_data *sisusb)

for (i = 0; i < NUMOBUFS; i++) {
if (sisusb->obuf[i]) {
- usb_buffer_free(sisusb->sisusb_dev, sisusb->obufsize,
- sisusb->obuf[i], sisusb->transfer_dma_out[i]);
+ kfree(sisusb->obuf[i]);
sisusb->obuf[i] = NULL;
}
}
if (sisusb->ibuf) {
- usb_buffer_free(sisusb->sisusb_dev, sisusb->ibufsize,
- sisusb->ibuf, sisusb->transfer_dma_in);
+ kfree(sisusb->ibuf);
sisusb->ibuf = NULL;
}
}
@@ -230,8 +228,7 @@ sisusb_bulk_completeout(struct urb *urb)

static int
sisusb_bulkout_msg(struct sisusb_usb_data *sisusb, int index, unsigned int pipe, void *data,
- int len, int *actual_length, int timeout, unsigned int tflags,
- dma_addr_t transfer_dma)
+ int len, int *actual_length, int timeout, unsigned int tflags)
{
struct urb *urb = sisusb->sisurbout[index];
int retval, byteswritten = 0;
@@ -245,9 +242,6 @@ sisusb_bulkout_msg(struct sisusb_usb_data *sisusb, int index, unsigned int pipe,
urb->transfer_flags |= tflags;
urb->actual_length = 0;

- if ((urb->transfer_dma = transfer_dma))
- urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
-
/* Set up context */
sisusb->urbout_context[index].actual_length = (timeout) ?
NULL : actual_length;
@@ -297,8 +291,8 @@ sisusb_bulk_completein(struct urb *urb)
}

static int
-sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data, int len,
- int *actual_length, int timeout, unsigned int tflags, dma_addr_t transfer_dma)
+sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data,
+ int len, int *actual_length, int timeout, unsigned int tflags)
{
struct urb *urb = sisusb->sisurbin;
int retval, readbytes = 0;
@@ -311,9 +305,6 @@ sisusb_bulkin_msg(struct sisusb_usb_data *sisusb, unsigned int pipe, void *data,
urb->transfer_flags |= tflags;
urb->actual_length = 0;

- if ((urb->transfer_dma = transfer_dma))
- urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
-
sisusb->completein = 0;
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval == 0) {
@@ -422,8 +413,7 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len,
thispass,
&transferred_len,
async ? 0 : 5 * HZ,
- tflags,
- sisusb->transfer_dma_out[index]);
+ tflags);

if (result == -ETIMEDOUT) {

@@ -432,29 +422,16 @@ static int sisusb_send_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len,
return -ETIME;

continue;
+ }

- } else if ((result == 0) && !async && transferred_len) {
+ if ((result == 0) && !async && transferred_len) {

thispass -= transferred_len;
- if (thispass) {
- if (sisusb->transfer_dma_out) {
- /* If DMA, copy remaining
- * to beginning of buffer
- */
- memcpy(buffer,
- buffer + transferred_len,
- thispass);
- } else {
- /* If not DMA, simply increase
- * the pointer
- */
- buffer += transferred_len;
- }
- }
+ buffer += transferred_len;

} else
break;
- };
+ }

if (result)
return result;
@@ -530,8 +507,7 @@ static int sisusb_recv_bulk_msg(struct sisusb_usb_data *sisusb, int ep, int len,
thispass,
&transferred_len,
5 * HZ,
- tflags,
- sisusb->transfer_dma_in);
+ tflags);

if (transferred_len)
thispass = transferred_len;
@@ -3132,8 +3108,7 @@ static int sisusb_probe(struct usb_interface *intf,

/* Allocate buffers */
sisusb->ibufsize = SISUSB_IBUF_SIZE;
- if (!(sisusb->ibuf = usb_buffer_alloc(dev, SISUSB_IBUF_SIZE,
- GFP_KERNEL, &sisusb->transfer_dma_in))) {
+ if (!(sisusb->ibuf = kmalloc(SISUSB_IBUF_SIZE, GFP_KERNEL))) {
dev_err(&sisusb->sisusb_dev->dev, "Failed to allocate memory for input buffer");
retval = -ENOMEM;
goto error_2;
@@ -3142,9 +3117,7 @@ static int sisusb_probe(struct usb_interface *intf,
sisusb->numobufs = 0;
sisusb->obufsize = SISUSB_OBUF_SIZE;
for (i = 0; i < NUMOBUFS; i++) {
- if (!(sisusb->obuf[i] = usb_buffer_alloc(dev, SISUSB_OBUF_SIZE,
- GFP_KERNEL,
- &sisusb->transfer_dma_out[i]))) {
+ if (!(sisusb->obuf[i] = kmalloc(SISUSB_OBUF_SIZE, GFP_KERNEL))) {
if (i == 0) {
dev_err(&sisusb->sisusb_dev->dev, "Failed to allocate memory for output buffer\n");
retval = -ENOMEM;
diff --git a/drivers/usb/misc/sisusbvga/sisusb.h b/drivers/usb/misc/sisusbvga/sisusb.h
index cf0b4a5..55492a5 100644
--- a/drivers/usb/misc/sisusbvga/sisusb.h
+++ b/drivers/usb/misc/sisusbvga/sisusb.h
@@ -123,8 +123,6 @@ struct sisusb_usb_data {
int numobufs; /* number of obufs = number of out urbs */
char *obuf[NUMOBUFS], *ibuf; /* transfer buffers */
int obufsize, ibufsize;
- dma_addr_t transfer_dma_out[NUMOBUFS];
- dma_addr_t transfer_dma_in;
struct urb *sisurbout[NUMOBUFS];
struct urb *sisurbin;
unsigned char urbstatus[NUMOBUFS];
diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile
index c6516b5..384b198 100644
--- a/drivers/usb/mon/Makefile
+++ b/drivers/usb/mon/Makefile
@@ -2,6 +2,6 @@
# Makefile for USB monitor
#

-usbmon-objs := mon_main.o mon_stat.o mon_text.o mon_bin.o mon_dma.o
+usbmon-objs := mon_main.o mon_stat.o mon_text.o mon_bin.o

obj-$(CONFIG_USB_MON) += usbmon.o
diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
index 2efdf44..ef4b322 100644
--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -220,9 +220,8 @@ static void mon_free_buff(struct mon_pgmap *map, int npages);

/*
* This is a "chunked memcpy". It does not manipulate any counters.
- * But it returns the new offset for repeated application.
*/
-unsigned int mon_copy_to_buff(const struct mon_reader_bin *this,
+static void mon_copy_to_buff(const struct mon_reader_bin *this,
unsigned int off, const unsigned char *from, unsigned int length)
{
unsigned int step_len;
@@ -247,7 +246,6 @@ unsigned int mon_copy_to_buff(const struct mon_reader_bin *this,
from += step_len;
length -= step_len;
}
- return off;
}

/*
@@ -400,15 +398,8 @@ static char mon_bin_get_data(const struct mon_reader_bin *rp,
unsigned int offset, struct urb *urb, unsigned int length)
{

- if (urb->dev->bus->uses_dma &&
- (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
- mon_dmapeek_vec(rp, offset, urb->transfer_dma, length);
- return 0;
- }
-
if (urb->transfer_buffer == NULL)
return 'Z';
-
mon_copy_to_buff(rp, offset, urb->transfer_buffer, length);
return 0;
}
diff --git a/drivers/usb/mon/mon_dma.c b/drivers/usb/mon/mon_dma.c
deleted file mode 100644
index 140cc80..0000000
--- a/drivers/usb/mon/mon_dma.c
+++ /dev/null
@@ -1,95 +0,0 @@
-/*
- * The USB Monitor, inspired by Dave Harding's USBMon.
- *
- * mon_dma.c: Library which snoops on DMA areas.
- *
- * Copyright (C) 2005 Pete Zaitcev (zaitcev@xxxxxxxxxx)
- */
-#include <linux/kernel.h>
-#include <linux/list.h>
-#include <linux/highmem.h>
-#include <asm/page.h>
-
-#include <linux/usb.h> /* Only needed for declarations in usb_mon.h */
-#include "usb_mon.h"
-
-/*
- * PC-compatibles, are, fortunately, sufficiently cache-coherent for this.
- */
-#if defined(__i386__) || defined(__x86_64__) /* CONFIG_ARCH_I386 doesn't exit */
-#define MON_HAS_UNMAP 1
-
-#define phys_to_page(phys) pfn_to_page((phys) >> PAGE_SHIFT)
-
-char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
-{
- struct page *pg;
- unsigned long flags;
- unsigned char *map;
- unsigned char *ptr;
-
- /*
- * On i386, a DMA handle is the "physical" address of a page.
- * In other words, the bus address is equal to physical address.
- * There is no IOMMU.
- */
- pg = phys_to_page(dma_addr);
-
- /*
- * We are called from hardware IRQs in case of callbacks.
- * But we can be called from softirq or process context in case
- * of submissions. In such case, we need to protect KM_IRQ0.
- */
- local_irq_save(flags);
- map = kmap_atomic(pg, KM_IRQ0);
- ptr = map + (dma_addr & (PAGE_SIZE-1));
- memcpy(dst, ptr, len);
- kunmap_atomic(map, KM_IRQ0);
- local_irq_restore(flags);
- return 0;
-}
-
-void mon_dmapeek_vec(const struct mon_reader_bin *rp,
- unsigned int offset, dma_addr_t dma_addr, unsigned int length)
-{
- unsigned long flags;
- unsigned int step_len;
- struct page *pg;
- unsigned char *map;
- unsigned long page_off, page_len;
-
- local_irq_save(flags);
- while (length) {
- /* compute number of bytes we are going to copy in this page */
- step_len = length;
- page_off = dma_addr & (PAGE_SIZE-1);
- page_len = PAGE_SIZE - page_off;
- if (page_len < step_len)
- step_len = page_len;
-
- /* copy data and advance pointers */
- pg = phys_to_page(dma_addr);
- map = kmap_atomic(pg, KM_IRQ0);
- offset = mon_copy_to_buff(rp, offset, map + page_off, step_len);
- kunmap_atomic(map, KM_IRQ0);
- dma_addr += step_len;
- length -= step_len;
- }
- local_irq_restore(flags);
-}
-
-#endif /* __i386__ */
-
-#ifndef MON_HAS_UNMAP
-char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
-{
- return 'D';
-}
-
-void mon_dmapeek_vec(const struct mon_reader_bin *rp,
- unsigned int offset, dma_addr_t dma_addr, unsigned int length)
-{
- ;
-}
-
-#endif /* MON_HAS_UNMAP */
diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
index 1f71543..56bb62f 100644
--- a/drivers/usb/mon/mon_text.c
+++ b/drivers/usb/mon/mon_text.c
@@ -150,20 +150,6 @@ static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
return '>';
}

- /*
- * The check to see if it's safe to poke at data has an enormous
- * number of corner cases, but it seems that the following is
- * more or less safe.
- *
- * We do not even try to look at transfer_buffer, because it can
- * contain non-NULL garbage in case the upper level promised to
- * set DMA for the HCD.
- */
- if (urb->dev->bus->uses_dma &&
- (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
- return mon_dmapeek(ep->data, urb->transfer_dma, len);
- }
-
if (urb->transfer_buffer == NULL)
return 'Z'; /* '0' would be not as pretty. */

diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
index f5d84ff..df9a4df 100644
--- a/drivers/usb/mon/usb_mon.h
+++ b/drivers/usb/mon/usb_mon.h
@@ -65,20 +65,6 @@ 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;

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 3aa2cd1..5b58d89 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1014,9 +1014,10 @@ typedef void (*usb_complete_t)(struct urb *);
* @transfer_flags: A variety of flags may be used to affect how URB
* submission, unlinking, or operation are handled. Different
* kinds of URB can use different flags.
- * @transfer_buffer: This identifies the buffer to (or from) which
- * the I/O request will be performed (unless URB_NO_TRANSFER_DMA_MAP
- * is set). This buffer must be suitable for DMA; allocate it with
+ * @transfer_buffer: This identifies the buffer to (or from) which the I/O
+ * request will be performed unless URB_NO_TRANSFER_DMA_MAP is set
+ * (however, do not leave garbage in transfer_buffer even then).
+ * This buffer must be suitable for DMA; allocate it with
* kmalloc() or equivalent. For transfers to "in" endpoints, contents
* of this buffer will be modified. This buffer is used for the data
* stage of control transfers.
@@ -1078,9 +1079,15 @@ typedef void (*usb_complete_t)(struct urb *);
* allocate a DMA buffer with usb_buffer_alloc() or call usb_buffer_map().
* When these transfer flags are provided, host controller drivers will
* attempt to use the dma addresses found in the transfer_dma and/or
- * setup_dma fields rather than determining a dma address themselves. (Note
- * that transfer_buffer and setup_packet must still be set because not all
- * host controllers use DMA, nor do virtual root hubs).
+ * setup_dma fields rather than determining a dma address themselves.
+ *
+ * Note that transfer_buffer must still be set if the controller
+ * does not support DMA (as indicated by bus.uses_dma) and when talking
+ * to root hub. If you have to trasfer between highmem zone and the device
+ * on such controller, create a bounce buffer or bail out with an error.
+ * If transfer_buffer cannot be set (is in highmem) and the controller is DMA
+ * capable, assign NULL to it, so that usbmon knows not to use the value.
+ * The setup_packet must always be set, so it cannot be located in highmem.
*
* Initialization:
*

-- Pete
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