Messages in this thread | | | Date | Tue, 19 Nov 2013 11:38:50 -0800 | Subject | Re: [tip:x86/asm] x86-64, copy_user: Remove zero byte check before copy user buffer. | From | Linus Torvalds <> |
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On Mon, Nov 18, 2013 at 8:37 PM, H. Peter Anvin <hpa@zytor.com> wrote: > > Do you have a preference: > > 1. Considering the 32-bit truncation incidental (take it or leave it); > 2. Require the 32-bit truncation, or > 3. Get rid of it completely?
I don't have a huge preference, but I hate the current situation (with Fenghua's patch) where it's not consistent. One path uses just 32-bits of the count (thanks to the "mov %edx,%ecx") while another path uses 64 bits.
One or the other, but not a mixture of both.
And only tangentially related to this: I do think that we could be stricter about the count. Make it oops if the high bits are set, rather than overwrite a lot of memory. So I would not be adverse to limiting the count to 31 bits (or even less) explicitly, and thus making the while 32-vs-64 bit issue moot.
Linus
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