Messages in this thread | | | Date | Mon, 24 Feb 2003 10:02:02 -0500 | From | Daniel Jacobowitz <> | Subject | Re: [PATCH] ptrace PTRACE_READDATA/WRITEDATA, kernel 2.5.62 |
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On Mon, Feb 24, 2003 at 03:51:22PM +0100, fcorneli@elis.rug.ac.be wrote: > Hi, > > > FYI Frank, three things. First of all, I really don't like the > > interface of adding a second address to ptrace; I believe it interferes > > with PIC on x86, since IIRC the extra argument would go in %ebx. > > The BSDs have a nice interface involving passing a request structure. > > I don't see the problem since we can pass up to 6 parameters on the i386 > architecture. The extra argument will be passed on using the stack as the > other arguments do because of the asmlinkage directive. Using a structure > slows everything down too much; if you can use the stack I think it's > better to do so. What about that PIC?
I seem to remember this (five-arg syscalls) causing problems before. Maybe it was on a different platform.
> > Secondly, the implementation should be in kernel/ptrace.c not under > > i386, we're trying to stop doing that. > > The implementation is already in kernel/ptrace.c, only the usage lives > under the arch-dependent directories since there the sys_ptrace entries > are located.
Not any more; it should be in ptrace_request for anything new. Yes, if you're adding an argument, that makes this more work.
> > Thirdly, I was going to do this, but I ended up making GDB use pread64 > > on /dev/mem instead. It works with no kernel modifications, and is > > just as fast. > > mmm... I thought it would be convenient to use ptrace for all the trace > work.
I've found it really doesn't make a difference.
-- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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