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. > I think this is harmless as we end up passing NULL to early_memunmap() which > WARN()s and returns as its outside the fixmap range. Its just more noise on > systems with a corrupt efi system table. > > Acked-by: James Morse <james.morse@xxxxxxx> > Thanks James _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
