On Mon, 17 Jun, at 07:50:16PM, Borislav Petkov wrote: > From: Borislav Petkov <bp@xxxxxxx> > > 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@xxxxxxx> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
