Messages in this thread | | | Subject | Re: [patch] x86: ptrace and core-dump extensions for xstate | From | Suresh Siddha <> | Date | Thu, 04 Feb 2010 14:05:14 -0800 |
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On Thu, 2010-02-04 at 12:55 -0800, Roland McGrath wrote: > Just proofread it. I really did mean "obvious typos", i.e. spelling, > whitespace, punctuation, nothing more.
Roland, All I found after double checking is:
> For now, only first 8 bytes of the sw_usable_bytes[464..467]
should be
> For now, only first 8 bytes of the sw_usable_bytes[464..471]
Let me know if I am overlooking something.
> > > This issue is not new and gets handled in the same way as for existing > > fxsave/fxrstor, as they don't specify page alignment restrictions. > > I didn't suggest it was new. I was looking for some confirmation that > there is in fact no permanent (i.e. compile-time) size limit.
Yes. No size limit as of now.
> I don't think this is the right way to think about it. The regset code > does not need to do anything different at all. There will in future be > other callers of the regset hooks, that's what the whole interface is there > for. Regardless of whether modification is full or partial, you just > enforce the various bitmasks on the resultant buffer as you already do, and > that's all there is to it. If userland stores partial contents with a > bogus format, that's its problem. It's just like the program itself had > used xrstor in user mode with the same bogus buffer contents.
Ok. I think I can agree, if we are ok with giving room for the ptrace (or any other user of the API) to make a mistake and corrupt reg-state of the process under debug, if it doesn't follow rules.
> > We probably have to extend regset infrastructure to track which NT_* > > types are part of PTRACE_[GET|SET]REGSET and which are not. > > I don't understand what you mean. The point of the generic requests is > that they apply to any user_regset you want. user_regset does not need > anything new.
Thought some of them might be only relevant to core-dump or based on permissions etc. But I guess get/set routines of the regset should be able to take care of this?
> > Also, I am not sure if pushing the ptrace interpretation of the user > > pointer into the regset routines is a good idea. > > I don't understand what you mean here at all. I did not suggest anything > that affects what the regset routines themselves do in any way at all. > > It is an unacceptably bad idea to have any new ptrace interfaces for regset > access that do anything different than exactly let you get/set all or part > of a regset exactly as the arch's user_regset provides it.
So in the example you provided before:
struct iovec iov = { mybuffer, mylength }; ret = ptrace(PTRACE_GETREGSET, NT_X86_XSTATE, &iov);
You wanted to propose common data format (iov) for all of the NT_* ?
thanks, suresh
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