From: Jonathan Schleifer <js@nil.im>
Subject: Re: devel/objfw: add BTCFI landing pads for amd64 and arm64
To: Mark Kettenis <mark.kettenis@xs4all.nl>
Cc: tb@theobuehler.org, ports@openbsd.org, kettenis@openbsd.org
Date: Sat, 24 Feb 2024 23:32:45 +0100

Am 24.02.24 um 23:22 schrieb Mark Kettenis:

> This is how the hardware behaves; see the documentation for
> PSTATE.BTYPE in Part D of the ARM Architecture Reference Manual
> (document DDI0487).
> 
> The difference is that this will allow an attacker to exploit a "BR"
> type branch (jump) to jump to the start of a function.  Not a big risk
> perhaps but still an uneccesary risk.

Thanks for the pointers! I guess it's also part of the ABI then to only 
do tail call eliminations when using x16/x17 then?

Anyway, changed to just c upstream - though I don't think that alone 
warrants a new release ;). (But it will be included in the next release.)

-- 
Jonathan