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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 13, 2019 at 04:45:54PM +0100, Vincenzo Frascino wrote: > On 13/06/2019 16:35, Catalin Marinas wrote: > > On Thu, Jun 13, 2019 at 12:16:59PM +0100, Dave P Martin wrote: > >> On Wed, Jun 12, 2019 at 01:43:20PM +0200, Andrey Konovalov wrote: > >>> + > >>> +/* > >>> + * Control the relaxed ABI allowing tagged user addresses into the kernel. > >>> + */ > >>> +static unsigned int tagged_addr_prctl_allowed = 1; > >>> + > >>> +long set_tagged_addr_ctrl(unsigned long arg) > >>> +{ > >>> + if (!tagged_addr_prctl_allowed) > >>> + return -EINVAL; > >> > >> So, tagging can actually be locked on by having a process enable it and > >> then some possibly unrelated process clearing tagged_addr_prctl_allowed. > >> That feels a bit weird. > > > > The problem is that if you disable the ABI globally, lots of > > applications would crash. This sysctl is meant as a way to disable the > > opt-in to the TBI ABI. Another option would be a kernel command line > > option (I'm not keen on a Kconfig option). > > Why you are not keen on a Kconfig option? Because I don't want to rebuild the kernel/reboot just to be able to test how user space handles the ABI opt-in. I'm ok with a Kconfig option to disable this globally in addition to a run-time option (if actually needed, I'm not sure). -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel