怎样截获linux内核导出的函数？
怎样截获linux内核导出的函数，不是截获linux系统调用函数，如截获usb_submit_urb函数？
谢谢！！！
[解决办法]
USB驱动，有专门的分析仪，可以用软捕捉USB栈的数据包看。类似于网络包分析工具（例如wireshark)。
另外，usb也有软件监视方法：
Debugging
A USB bus analyzer magnifies the goings-on in the bus and is useful for debugging low-level problems. If you can't get hold of an analyzer, you might be able to make do with the kernel's soft USB tracer, usbmon. This tool captures traffic between USB host controllers and devices. To collect a trace, read from the debugfs[3] file /sys/kernel/debug/usbmon/Xt, where X is the bus number to which your device is connected.
[3] An in-memory filesystem to export kernel debug data to user space.
For example, consider a USB disk connected to a PC. From the associated "T:" line in /proc/bus/usb/devices, you can see that the drive is attached to bus 1:
T: Bus=01 Lev=01 Prnt=01 Port=03 Cnt=01 Dev#= 2 Spd=480 MxCh= 0
Ensure that you have enabled debugfs (CONFIG_DEBUG_FS) and usbmon (CONFIG_USB_MON) support in your kernel. This is a snapshot of usbmon output while copying a file from the disk:
Code View:
bash> mount -t debugfs none_debugs /sys/kernel/debug/
bash> cat /sys/kernel/debug/usbmon/1u
...
ee6a5c40 3718782540 S Bi:1:002:1 -115 20480 <
ee6a5cc0 3718782567 S Bi:1:002:1 -115 65536 <
ee6a5d40 3718782595 S Bi:1:002:1 -115 36864 <
ee6a5c40 3718788189 C Bi:1:002:1 0 20480 = 0f846801 118498f\ 15c60500 01680106
5e846801 608498fe 6f280087 68000000
ee6a5cc0 3718800994 C Bi:1:002:1 0 65536 = 118498fe 15c60500\ 01680106 5e846801
608498fe 6f280087 68000000 00884800
ee6a5d40 3718801001 C Bi:1:002:1 0 36864 = 13608498 fe4f4a01\ 00514a01 006f2800
87680000 00008848 00000100 b7f00100
...
Each output line starts with the URB address, followed by an event timestamp. An S in the next column indicates URB submission, and a C announces a callback. The following field has the format URBType:Bus#:DeviceAddress:Endpoint#. In the preceding output, a URBType of Bi stands for a bulk URB in the IN direction. After this, usbmon dumps the URB status, data length, a data tag (= or < in the preceding output), and the data words (if the tag is =). The last three lines in the preceding output are callbacks associated with bulk URBs submitted in earlier lines. You can match the callbacks with the related submissions using the URB addresses. Documentation/usb/usbmon.txt details usbmon syntax and contains example code to parse the output into human readable form.
If you turn on Device Drivers USB Support USB Verbose Debug Messages during kernel configuration, the kernel will emit the contents of all dev_dbg() statements present in the USB subsystem.
You can glean device and bus specific information from the USB filesystem (usbfs) node, /proc/bus/usb/devices. And as we discuss in Chapter 19, "Drivers in User Space," usbfs also lets you implement USB device drivers in user space. Even when the final destination of your USB driver is inside the kernel, starting with a user-space driver can ease debugging and testing.
The linux-usb-devel mailing list is the forum to discuss questions related to USB device drivers. Visit https://lists.sourceforge.net/lists/listinfo/linux-usb-devel for subscription and archive retrieval information. Read www.linux-usb.org/usbtest for ideas on USB testing.
The home page of the Linux-USB project is www.linux-usb.org. You may download the USB 2.0 specification, OTG supplement, and other related standards from www.usb.org/developers/docs.
