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

On Tue, Jan 10, 2017 at 11:22:15AM -0800, Andy Lutomirski wrote:

quoted

Actually, the breakage is introduced by the patch Herbert refers to

https://patchwork.kernel.org/patch/9468391/

where the state is replaced by a simple

u32 state[16] __aligned(CHACHA20_STATE_ALIGN);

which seemed harmless enough to me. So the code above works fine.

So how about just the one-line patch of adding the
force_align_arg_pointer?  Would that solve the problem?

It probably does.  However, this is too error-prone.  Surely
you can't expect random kernel developers to know to add this
force_align_arg_pointer every time they try to align a stack
variable to 16 bytes?

Cheers,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt