Messages in this thread | | | Date | Mon, 13 Nov 2017 18:26:47 -0800 | From | Ricardo Neri <> | Subject | Re: [PATCH 3/4] x86/umip: Identify the str and sldt instructions |
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On Mon, Nov 13, 2017 at 09:12:03AM +0100, Ingo Molnar wrote: > > * Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote: > > > The instructions str and sldt are not emulated in any case. Thus, it made > > sense to not implement functionality to identify them. However, a > > subsequent commit will introduce functionality to warn about the use of > > all the instructions that UMIP protect, not only those that are emulated. > > A first step for that is the ability to identify them. > > > > Plus, now that str and sldt are identified, we need to explicitly avoid > > their emulation (i.e., not rely on unsuccessful identification). Group > > togehter all the cases that we do not want to emulate: str, sldt and user > > long mode processes. > > Did you notice how in all your previous patches (both in the code and in the > changelogs) I have manually fixed up the capitalization of these instruction > mnenonics?
I am sorry, I tried to see where you made these changes but I could not find any. I did a git diff of arch/x86/kernel/umip.c between the branch rneri/umip_v11 of my repository [1] and the master branch of the tip tree and I did not find any differences.
Also, looking at the log of the master branch of the tip tree I see, for instance:
commit 1e5db223696afa55e6a038fac638f759e1fdcc01 Author: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Date: Sun Nov 5 18:27:52 2017 -0800
x86/umip: Add emulation code for UMIP instructions
The feature User-Mode Instruction Prevention present in recent Intel processor prevents a group of instructions (sgdt, sidt, sldt, smsw, and str) from being executed with CPL > 0. Otherwise, a general protection fault is issued. ...
The instruction mnemonics were not capitalized. Is the master branch the one where I can look at your fixes?
> > The capitalized form is much more readable, especially with seriously overloaded > acronyms such as 'str' ...
I see. > > You now repeat the same bad pattern, in fact you regress existing code: > > > - /* SLDT AND STR are not emulated */ > > > + /* Do not emulate sldt, str or user long mode processes. */ > > Please be more careful with such details, and please fix & resend this series.
Sure, I will submit a v2 with capitalized mnemonics in both the code and the patch descriptions. I will be more careful in the future.
Thanks and BR, Ricardo
[1]. https://github.com/ricardon/tip/commits/rneri/umip_v11
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