Re: [git pull] uaccess-related bits of vfs.git

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [git pull] uaccess-related bits of vfs.git
Date	2017-05-14 20:20 +0200
Message-ID	<tH6hz-4ZP-5@gated-at.bofh.it> (permalink)
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Fri, May 12, 2017 at 11:57 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > First, some stats: there's a thousand-odd callers of __get_user().  Out of
> > those, about 70% are in arch/, mostly in sigframe-related code.
> 
> Sure. And they can be trivially converted, and none of them should care at all.
> 
> > IOW, we have
> >         * most of users in arch/* (heavily dominated by signal-related code,
> > both loads and stores).  Those need careful massage; maybe unsafe-based
> > solution, maybe something else, but it's obviously per-architecture work
> > and these paths are sensitive.
> 
> Why are they sensitive?
> 
> Why not just do this:
> 
>   git grep -l '\<__\(\(get\)\|\(put\)\)_user(' -- arch/x86
> :^arch/x86/include/asm/uaccess.h
>         | xargs sed -i 's/__\(\(\(get\)\|\(put\)\)_user(\)/\1/g'
> 
> which converts all the x86 uses in one go.
> 
> Anybody who *relies* on not checking the address_limit is so broken as
> to be not even funny. And anything that is so performance-sensitive
> that anybody can even measure the effect of the above we can convert
> later.

I'd say that the CLAC/STAC addition pretty much killed any argument in favor of 
"optimized" __get_user() code, so I'd be very happy to see these interfaces gone 
altogether.

So as far as x86 usage goes:

  Acked-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo

Thread

Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 03:10 +0200
  Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 09:00 +0200
    Re: [git pull] uaccess-related bits of vfs.git Adam Borowski <kilobyte@angband.pl> - 2017-05-13 14:10 +0200
      Re: [git pull] uaccess-related bits of vfs.git Brian Gerst <brgerst@gmail.com> - 2017-05-13 15:50 +0200
      Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 18:50 +0200
    Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 18:20 +0200
    Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 18:20 +0200
      Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 19:10 +0200
        Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 19:20 +0200
          Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 20:10 +0200
            Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 20:30 +0200
              Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 21:20 +0200
                Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 21:40 +0200
            Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 21:10 +0200
              Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 21:20 +0200
              Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 22:00 +0200
                Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 22:10 +0200
                Re: [git pull] uaccess-related bits of vfs.git Geert Uytterhoeven <geert@linux-m68k.org> - 2017-05-13 22:40 +0200
                Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 22:50 +0200
              Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 22:40 +0200
                Re: [git pull] uaccess-related bits of vfs.git Linus Torvalds <torvalds@linux-foundation.org> - 2017-05-13 23:00 +0200
                Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 23:30 +0200
        Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-13 19:20 +0200
      Re: [git pull] uaccess-related bits of vfs.git Ingo Molnar <mingo@kernel.org> - 2017-05-14 20:20 +0200
        Re: [git pull] uaccess-related bits of vfs.git Al Viro <viro@ZenIV.linux.org.uk> - 2017-05-14 21:00 +0200

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