Messages in this thread | | | Subject | Re: [PATCH v2 3/5] signal: Add unsafe_copy_siginfo_to_user() | From | Christophe Leroy <> | Date | Fri, 10 Sep 2021 10:27:03 +0000 |
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On 9/8/21 6:17 PM, Eric W. Biederman wrote: > Christophe Leroy <christophe.leroy@csgroup.eu> writes: > >> Le 02/09/2021 à 20:43, Eric W. Biederman a écrit : >>> Christophe Leroy <christophe.leroy@csgroup.eu> writes: >>> >>>> In the same spirit as commit fb05121fd6a2 ("signal: Add >>>> unsafe_get_compat_sigset()"), implement an 'unsafe' version of >>>> copy_siginfo_to_user() in order to use it within user access blocks. >>>> >>>> For that, also add an 'unsafe' version of clear_user(). >>> >>> Looking at your use cases you need the 32bit compat version of this >>> as well. >>> >>> The 32bit compat version is too complicated to become a macro, so I >>> don't think you can make this work correctly for the 32bit compat case. >> >> When looking into patch 5/5 that you nacked, I think you missed the fact that we >> keep using copy_siginfo_to_user32() as it for the 32 bit compat case. > > I did. My mistake. > > However that mistake was so easy I think it mirrors the comments others > have made that this looks like a maintenance hazard. > > Is improving the performance of 32bit kernels interesting?
Yes it is, and that's what this series do.
> Is improving the performance of 32bit compat support interesting?
For me this is a corner case, so I left it aside for now.
> > If performance one or either of those cases is interesting it looks like > we already have copy_siginfo_to_external32 the factor you would need > to build unsafe_copy_siginfo_to_user32.
I'm not sure I understand your saying here. What do you expect me to do with copy_siginfo_to_external32() ?
copy_siginfo_to_user32() is for compat only.
Native 32 bits powerpc use copy_siginfo_to_user()
> > So I am not going to say impossible but please make something > maintainable. I unified all of the compat 32bit siginfo logic because > it simply did not get enough love and attention when it was implemented > per architecture.
Yes, and ? I didn't do any modification to the compat case, so what you did remains.
> > In general I think that concern applies to this case as well. We really > need an implementation that shares as much burden as possible with other > architectures.
I think yes, that's the reason why I made a generic unsafe_copy_siginfo_to_user() and didn't make a powerpc dedicated change.
Once this is merged any other architecture can use unsafe_copy_siginfo_to_user().
Did I miss something ?
Christophe
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