tree 4828f610aab906bd7f4190ac32da0f777271480c
parent 47226ad4f4cfd1e91ded7f2ec42f83ff1c624663
author Matt Fleming <matt.fleming@intel.com> 1409925146 +0100
committer Matt Fleming <matt.fleming@intel.com> 1410205922 +0100

x86/efi: Fixup GOT in all boot code paths

Maarten reported that his Macbook pro 8.2 stopped booting after commit
f23cf8bd5c1f49 ("efi/x86: efistub: Move shared dependencies to
<asm/efi.h>"), the main feature of which is changing the visibility of
symbol 'efi_early' from local to global.

By making 'efi_early' global we end up requiring an entry in the Global
Offset Table. Unfortunately, while we do include code to fixup GOT
entries in the early boot code, it's only called after we've executed
the EFI boot stub.

What this amounts to is that references to 'efi_early' in the EFI boot
stub don't point to the correct place.

Since we've got multiple boot entry points we need to be prepared to
fixup the GOT in multiple places, while ensuring that we never do it
more than once, otherwise the GOT entries will still point to the wrong
place.

Reported-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>