> Instead of barrier(), this works with gcc-3.2.3 up to gcc-4.4.3
> for the purpose of making the memset() not disappear:
>
> {
> struct s { char c[n]; };
> asm("" : : "m"(*(struct s *)p));
> }
>
> Every byte in the [p,p+n[ range must be used. If you only use the
> first byte, via e.g. asm("" :: "m"(*(char*)p)), then the compiler
> _will_ skip scrubbing bytes beyond the first.
>
> An explicit loop that uses each byte individually also works, but
> results in awful code with older compilers.
I suspect it would be worth asking for a __builtin for this.
iirc Visual C already has one.
BTW I remember finding a few more such cases in random user space
code in past code review.
-Andi
--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
--
To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
