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

Szabolcs Nagy szabolcs.nagy at arm.com
Mon Feb 8 11:47:45 EST 2021

The 02/08/2021 14:13, Szabolcs Nagy via Libc-alpha wrote:
> The 02/08/2021 12:44, Will Deacon wrote:
> > I'd like an Ack from Szabolcs before we queue this.
> i'm ok with this in principle, but i will rerun
> the glibc tests over night to be sure.

the patch applied cleanly on top of arm64 for-next/core

but it does not work as i expected:

executables that do not have the bti property note
set seems to get bti guarded by the kernel.

at least i see crash in _start when the dynamic
linker (which has bti marking) transfers control
to it and the start code has no bti c.

(according to strace the dynamic linker did not
remap/mprotect the main exe with bti so i assume
this is the kernel's doing)

can somebody verify that the notes are checked
on the executable too and not just on ld.so?

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