lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 22 Oct 2007 11:53:06 +0200
From:	Andi Kleen <>
To:	Mathieu Desnoyers <>
Cc:	Jeremy Fitzhardinge <>,
	"H. Peter Anvin" <>,,, Chuck Ebbert <>,
	Christoph Hellwig <>
Subject: Re: [patch 4/7] Immediate Values - i386 Optimization

> - Either I use a "r" constraint and let gcc produce the instructions,
>   that I need to assume to have correct size so I can align their
>   immediate values (therefore, taking the offset from the end of the
>   instruction will not help). Here, if gas changes its behavior
>   dramatically for a given immediate value size, it will break.

I wouldn't expect it to do that, but you could perhaps add a self
test somewhere to check for it.

> - Second choice is to stick to a particular register, choosing the one
>   with the less side-effect, and encoding the instruction ourselves. I
>   start to think that this second solution might be safer, even though
>   we wouldn't let the compiler select the register which has the less
>   impact by itself.

Such effects caused occassional bugs in the alternative() implementation
which requires a maximum size for the replacement.

But in this case it should be safe enough to trust gas stability.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists