[PATCH] usbmon in 2.6.13: peeking into DMA areas

This code looks at urb->transfer_dma, maps the page and takes the data.
I am looking for volunteers to contribute architectures other than i386
or to develop an architecure-neutral API for it (or point me that it
was done already).

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/usb/mon/mon_dma.c b/drivers/usb/mon/mon_dma.c
new file mode 100644
index 000000000000..0a1367b760a0
--- /dev/null
+++ b/drivers/usb/mon/mon_dma.c
@@ -0,0 +1,55 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * mon_dma.c: Library which snoops on DMA areas.
+ *
+ * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
+ */
+#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"
+
+#ifdef __i386__         /* CONFIG_ARCH_I386 does not 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;
+}
+#endif /* __i386__ */
+
+#ifndef MON_HAS_UNMAP
+char mon_dmapeek(unsigned char *dst, dma_addr_t dma_addr, int len)
+{
+        return 'D';
+}
+#endif