Re: x86-64: Maintain 16-byte stack alignment

On Tue, Jan 10, 2017 at 08:17:17PM -0800, Linus Torvalds wrote:

That said, I do think that the "don't assume stack alignment, do it by
hand" may be the safer thing. Because who knows what the random rules
will be on other architectures.

Sure we can ban the use of attribute aligned on stacks.  But
what about indirect uses through structures?  For example, if
someone does

struct foo {
} __attribute__ ((__aligned__(16)));

int bar(...)
{
	struct foo f;

	return baz(&f);
}

then baz will end up with an unaligned argument.  The worst part
is that it is not at all obvious to the person writing the function
bar.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
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