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Re: [PATCH 0/2] aarch64: Enable pointer auth in PLT
On 25/06/2019 11:40, Ramana Radhakrishnan wrote:
> On Fri, Jun 21, 2019 at 12:33 PM Szabolcs Nagy <Szabolcs.Nagy@arm.com> wrote:
>> On 21/06/2019 11:46, Florian Weimer wrote:
>>> * Szabolcs Nagy:
>> the binaries work on an old system if pauth is not
>> enabled by the kernel.
>>
>> i think we don't have prctl or other control
>> in linux to enable/disable pauth per process
>> right now so it is not opt-in, the kernel just
>> informs userspace with a HWCAP that it is enabled.
>
> There was certainly talk about a prctl call for pauth with the Android
> guys as they were interested in a model with zygote.
prctl can reset the keys, it does not disable/enable
the nop space instructions.
separate disable/enable is architecturally very
difficult to do, i raised an internal issue about
this, but it's likely too late to fix the arch now.