Re: [PATCH] x86_64: fix put_user for 64-bit constant

From: Linus Torvalds
Date: Thu Jan 25 2007 - 20:50:19 EST




On Thu, 25 Jan 2007, Roland McGrath wrote:
>
> On x86-64, a put_user call using a 64-bit pointer and a constant value that
> is > 0xffffffff will produce code that doesn't assemble. This patch fixes
> the asm construct to use the Z constraint for 32-bit constants.

Ahh. Will apply.

Just out of interest: did we have such code and it just happened to use a
register, or was this found because you wrote some new code that triggered
something that had just never been triggered before? Or is there a newer
gcc that is better at optimizations and finds a constant propagation where
it used to not find it?

Inquiring minds..

Linus
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