Messages in this thread | | | Date | Fri, 21 Jun 2013 12:56:28 +0100 | From | Matt Fleming <> | Subject | Re: [PATCH -v2 4/4] x86, efi: Map runtime services 1:1 |
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On Mon, 17 Jun, at 07:50:16PM, Borislav Petkov wrote: > From: Borislav Petkov <bp@suse.de> > > Due to the braindead design of EFI, we cannot map runtime services more > than once for the duration of a booted system. Thus, if we want to use > EFI runtime services in a kexec'ed kernel, maybe the only possible and > sensible approach would be to map them 1:1 so that when the kexec kernel > loads, it can simply call those addresses without the need for remapping > (which doesn't work anyway). > > Furthermore, this mapping approach could be of help with b0rked EFI > implementations for a different set of reasons. > > This implementation is 64-bit only for now. > > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > arch/x86/include/asm/efi.h | 67 +++++++++++---- > arch/x86/platform/efi/efi.c | 165 +++++++++++++++++++++++++++++------- > arch/x86/platform/efi/efi_stub_64.S | 56 ++++++++++++ > 3 files changed, 240 insertions(+), 48 deletions(-)
[...]
> + .macro SWITCH_PGT > + cmpb $0, efi_use_11_map > + je 1f;
Actually, this needs to be,
cmpb $0, efi_use_11_map(%rip)
because this code is built into the EFI boot stub which isn't loaded at a fixed address and needs to be position independent.
-- Matt Fleming, Intel Open Source Technology Center
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