[PATCH] arm64: bti: Set PROT_BTI on all BTI executables mapped by the kernel

[Szabolcs Nagy]

The 02/08/2021 15:06, Mark Brown via Libc-alpha wrote:
> On Mon, Feb 08, 2021 at 02:53:16PM +0000, Dave Martin wrote:
> 
> > Question: will this change prevent BTI executables from working under a
> > non-BTI-aware ld.so?  And do we care?  (I think "probably not" for both,
> > but I'd be interested in others' views.)
> 
> Yes, I'd expect that we'd end up allowing a BTIed main executable
> without a BTI ld.so.  We already have the case where we will enable BTI
> for the vDSO even if nothing outside the kernel supports BTI and BTI is
> intended to interwork happily so I'd be surprised if there were
> problems.

note that this is unlikely to happen (as opposed
to the other way: bti marked ld.so & non-bti exe)
because if the libc is not built with bti then
the start code (crt1.o) has no bti marking either
so the exe will not get bti marked.