On Tue, Jul 10, 2018 at 08:39:16PM +0200, Ard Biesheuvel wrote: > On 10 July 2018 at 19:57, James Morse <james.morse@xxxxxxx> wrote: > > Hi Ard, > > > > On 10/07/18 00:42, AKASHI Takahiro wrote: > >> From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > >> > >> The BGRT code validates the contents of the table against the UEFI > >> memory map, and so it expects it to be mapped when the code runs. > >> > >> On ARM, this is currently not the case, since we tear down the early > >> mapping after efi_init() completes, and only create the permanent > >> mapping in arm_enable_runtime_services(), which executes as an early > >> initcall, but still leaves a window where the UEFI memory map is not > >> mapped. > >> > >> So move the call to efi_memmap_unmap() from efi_init() to > >> arm_enable_runtime_services(). > > > > I don't have a machine that generates a BGRT, but I can see that efi_mem_type() > > call in efi_bgrt_init() would cause the same problems we have with kexec and acpi. > > > > I'm not sure I follow. The BGRT table only contains natively aligned > fields, so the alignment faults should not occur when accessing this > table after kexec. The issue addressed by this patch is that > efi_mem_type() bails when called while EFI_MEMMAP is cleared. > > > > >> diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c > >> index b5214c143fee..388a929baf95 100644 > >> --- a/drivers/firmware/efi/arm-init.c > >> +++ b/drivers/firmware/efi/arm-init.c > >> @@ -259,7 +259,6 @@ void __init efi_init(void) > >> > >> reserve_regions(); > >> efi_esrt_init(); > >> - efi_memmap_unmap(); > >> > >> memblock_reserve(params.mmap & PAGE_MASK, > >> PAGE_ALIGN(params.mmap_size + > >> diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c > >> index 5889cbea60b8..59a8c0ec94d5 100644 > >> --- a/drivers/firmware/efi/arm-runtime.c > >> +++ b/drivers/firmware/efi/arm-runtime.c > >> @@ -115,6 +115,8 @@ static int __init arm_enable_runtime_services(void) > >> return 0; > >> } > >> > >> + efi_memmap_unmap(); > > > > This can get called twice if uefi_init() fails after setting the EFI_BOOT flag, > > but this can only happen if the system table signature is wrong, (or we're out > > of memory really early). > > > > I guess we should check the EFI_MEMMAP attribute here as well then. Do you plan to spin a new version of this patch? Will _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
