Date: Wed, 1 Mar 2006 10:54:49 -0500 From: John Baldwin <jhb@freebsd.org> To: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> Cc: freebsd-hackers@freebsd.org Subject: Re: Accessing address space of a process through kld!! Message-ID: <200603011054.50628.jhb@freebsd.org> In-Reply-To: <20060301140635.GA669@pm513-1.comsys.ntu-kpi.kiev.ua> References: <cdc1d1310602270026o6b17101et14ddf301269edc37@mail.gmail.com> <200602281333.49277.jhb@freebsd.org> <20060301140635.GA669@pm513-1.comsys.ntu-kpi.kiev.ua>
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On Wednesday 01 March 2006 09:06, Andrey Simonenko wrote: > 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. Those are outside of my realm of knowledge unfortunately, but there are some other folks you can ask including probably truckman@ and alc@. > -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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