On Sun, 24 Jun 2018, Ard Biesheuvel wrote: > On 24 June 2018 at 15:16, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > Ard, thank you for Cc-ing me on this. > > > > I've tested a 64 bit kernel build on a 32 bit UEFI firmware (so mixed mode) > > and this patch causes a reboot loop there. I do get grub (no surprise there > > as grub is unchanged), but as soon as the kernel loads the device resets. > > > > So I think we need some special casing there to deal with a 64 bit kernel > > calling into 32 bit UEFI. > > > > OK, so mixed mode rears its ugly hand again :-( > > Considering we had other weird issues involving uint64_t types with > the TPM code just this week, I wonder if this isn't a fundamental > problem with the mixed mode thunking, and so I need some help from the > x86 gurus (Ingo?) > > If the thunking code simply maps each 64-bit argument onto a 32-bit > stack slot, it is obvious that passing uint64_t type arguments is > impossible. > > So would it be possible to have a efi_config::call() variant that is > annotated as expecting the i386 calling convention, and let the > compiler handle this? All we'd need to do in the mixed mode thunking > code is pushing an additional word [as we do know] for the function > pointer. Grumbl. This thing just went into rc2 a few minutes ago. -- 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
