Re: [PATCH 3/3] asm-generic, x86: Add bitops instrumentation for KASAN

[Peter Zijlstra]

On Wed, May 29, 2019 at 11:20:56AM +0000, David Laight wrote:
> From: Dmitry Vyukov
> > Sent: 29 May 2019 11:57

> > Interesting. Does an address passed to bitops also should be aligned,
> > or alignment is supposed to be handled by bitops themselves?
> 
> The bitops are defined on 'long []' and it is expected to be aligned.
> Any code that casts the argument is likely to be broken on big-endian.
> I did a quick grep a few weeks ago and found some very dubious code.
> Not all the casts seemed to be on code that was LE only (although
> I didn't try to find out what the casts were from).
> 
> The alignment trap on x86 could be avoided by only ever requesting 32bit
> cycles - and assuming the buffer is always 32bit aligned (eg int []).
> But on BE passing an 'int []' is just so wrong ....

Right, but as argued elsewhere, I feel we should clean up the dubious
code instead of enabling it.