Re: [Xen-devel] [PATCH] x86: fix variable_test_bit() asm constraints

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 14/3/08 11:55, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:

>> Further, using 'void *' for the 'addr' parameter appears dangerous,
>> since bt{,c,r,s} access the full 32 bits (if 'unsigned long' was used
>> properly here, 64 bits for x86-64) pointed at, so invalid uses like
>> referencing a 'char' array cannot currently be caught.
> 
> Sure, but those invalid uses do exist, in x86-specific Xen code we inherited
> from Linux (perhaps older versions of Linux though). I don't want a huge patch
> that casts a large number of callers!

I see what you mean though: what if one of these bogus users' fields is
adjacent to a legitimate byte-sized atomic variable (e.g., a bool_t)?
Perhaps we do need to fix this, and properly without casts.

 -- Keir



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