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

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:

quoted

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.

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