On Tue, Sep 24, 2019 at 07:10:59PM +0900, Sahibzada Irfanullah wrote: > Dear All, > > I have asked this question previously, but some people told me to explain > what I really want to do. First of all, I am completely naïve andnewbie in > the kernel development. > > I am trying to develop my own program that generate the log of guest > physical addresses by trying to save the contents of "gpa" variable (which > is present in the handle_ept_violation()functino in vmx.c ) into my file. I > have found one sample code online (which uses filp_open(), filp_close(), > kernel_read(), and kernel_write() functions), this code is working in the > kernel space as a kernel module, but not working for my task in the > handle_ept_voilation(). > > My actual goal is to generate log of physical addresses for different > applications by writing them into the file, and then perform some analysis > at runtime in this function by reading the logs from the log file. > Furthermore, I want a file which size can dynamically grow as the size of > log increases. > > I know that reading/writing in a kernel is not a good idea, but due to > nature of the task, I have to this. "have to"? What about a ring buffer that you write to in the kernel and then read out from in userspace? You can use debugfs for that. But really, a simple tracepoint is probably all you need here, and maybe not even that if you use ftrace. Have you tried that today? I doubt you need any kernel changes at all to get this information directly from the kernel to userspace. Look at all of the ebpf and tracing examples as a way to do this. good luck! greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
