[PATCH 3/3] efi/libstub: arm64: set -fpie when building the EFI stub

[Matthias Kaehlcke]

El Thu, May 18, 2017 at 10:09:53AM +0100 Ard Biesheuvel ha dit:

> Clang may emit absolute symbol references when building in non-PIC mode,
> even when using the default 'small' code model, which is already mostly
> position independent to begin with, due to its use of adrp/add pairs
> that have a relative range of +/- 4 GB. The remedy is to pass the -fpie
> flag, which can be done safely now that the code has been updated to avoid
> GOT indirections (which may be emitted due to the compiler assuming that
> the PIC/PIE code may end up in a shared library that is subject to ELF
> symbol preemption)
> 
> Passing -fpie when building code that needs to execute at an a priori
> unknown offset is arguably an improvement in any case, and given that
> the recent visibility changes allow the PIC build to pass with GCC as
> well, let's add -fpie for all arm64 builds rather than only for Clang.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

Tested-by: Matthias Kaehlcke <mka at chromium.org>