Date: Wed, 1 Mar 2006 16:06:35 +0200 From: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Accessing address space of a process through kld!! Message-ID: <20060301140635.GA669@pm513-1.comsys.ntu-kpi.kiev.ua> In-Reply-To: <200602281333.49277.jhb@freebsd.org> References: <cdc1d1310602270026o6b17101et14ddf301269edc37@mail.gmail.com> <20060227183142.GJ840@funkthat.com> <200602281333.49277.jhb@freebsd.org>
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On Tue, Feb 28, 2006 at 01:33:47PM -0500, John Baldwin wrote: > On Monday 27 February 2006 13:31, John-Mark Gurney wrote: > > Tanmay wrote this message on Mon, Feb 27, 2006 at 13:56 +0530: > > > How do I access the address space ie text,data and stack of a (user > > > level)process whose pid I know from my kld. for eg: Suppose 'vi' is running > > > and I want to access its address space through my kld, then how do I do it? > > > > You look up the process with pfind(9), and then you can use uio(9) to > > transfer data into kernel space... Don't forget to PROC_UNLOCK the > > struct once you are done referencing it. > > You can use the proc_rwmem() function (it takes a uio and a struct proc) > to do the actual I/O portion. You can see example use in the ptrace() > syscall. I have two questions about this function: 1. vm_fault() does not guarantee, that (possibly) faulted in page will be in the object or in one of backing objects when vm_fault() returns, because a page can become not resident again. Why not to wire needed page in vm_fault() (by giving a special flag to vm_fault() function)? 2. When the object which owns the page is unlocked, which lock guarantees, then m will point to a page? I mean m, which is used in vm_page_hold(m), which is called after VM_OBJECT_UNLOCK() (I mean a gap of time between VM_OBJECT_UNLOCK() and vm_page_lock_queues() function calls). Can you answer these two question? Thanks.
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