On Mon, 5 Sept 2022 at 06:34, Youling Tang <tangyouling@xxxxxxxxxxx> wrote: > > Hi, Ard & Huacai > > On 09/05/2022 11:50 AM, Huacai Chen wrote: > > Hi, Ard, > > > > On Mon, Sep 5, 2022 at 5:59 AM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > >> > >> On Sun, 4 Sept 2022 at 15:24, Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > >>> > >>> Hi, Ard, > >>> > >>> On Thu, Sep 1, 2022 at 6:40 PM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote: > >>>> > >>>> Hi, Ard, > >>>> > >>>> On Sat, Aug 27, 2022 at 3:14 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > >>>>> > >>>>> On Sat, 27 Aug 2022 at 06:41, Xi Ruoyao <xry111@xxxxxxxxxxx> wrote: > >>>>>> > >>>>>> Tested V3 with the magic number check manually removed in my GRUB build. > >>>>>> The system boots successfully. I've not tested Arnd's zBoot patch yet. > >>>>> > >>>>> I am Ard not Arnd :-) > >>>>> > >>>>> Please use this branch when testing the EFI decompressor: > >>>>> https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/?h=efi-decompressor-v4 > >>>> The root cause of LoongArch zboot boot failure has been found, it is a > >>>> binutils bug, latest toolchain with the below patch can solve the > >>>> problem. > >>>> > >>>> diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c > >>>> index 5b44901b9e0..fafdc7c7458 100644 > >>>> --- a/bfd/elfnn-loongarch.c > >>>> +++ b/bfd/elfnn-loongarch.c > >>>> @@ -2341,9 +2341,10 @@ loongarch_elf_relocate_section (bfd > >>>> *output_bfd, struct bfd_link_info *info, > >>>> case R_LARCH_SOP_PUSH_PLT_PCREL: > >>>> unresolved_reloc = false; > >>>> > >>>> - if (resolved_to_const) > >>>> + if (!is_undefweak && resolved_to_const) > >>>> { > >>>> relocation += rel->r_addend; > >>>> + relocation -= pc; > >>>> break; > >>>> } > >>>> else if (is_undefweak) > >>>> > >>>> > >>>> Huacai > >>> Now the patch is submitted here: > >>> https://sourceware.org/pipermail/binutils/2022-September/122713.html > >>> > >> > >> Great. Given the severity of this bug, I imagine that building the > >> LoongArch kernel will require a version of binutils that carries this > >> fix. > >> > >> Therefore, i will revert back to the original approach for accessing > >> uncompressed_size, using an extern declaration with an __aligned(1) > >> attribute. > >> > >>> And I have some other questions about kexec: kexec should jump to the > >>> elf entry or the pe entry? I think is the elf entry, because if we > >>> jump to the pe entry, then SVAM will be executed twice (but it should > >>> be executed only once). However, how can we jump to the elf entry if > >>> we use zboot? Maybe it is kexec-tool's responsibility to decompress > >>> the zboot kernel image? > >>> > >> > >> Yes, very good point. Kexec kernels cannot boot via the EFI entry > >> point, as the boot services will already be shutdown. So the kexec > >> kernel needs to boot via the same entrypoint in the core kernel that > >> the EFI stub calls when it hands over. > >> > >> For the EFI zboot image in particular, we will need to teach kexec how > >> to decompress them. The zboot image has a header that > >> a) describes it as a EFI linux zimg > >> b) describes the start and end offset of the compressed payload > >> c) describes which compression algorithm was used. > >> > >> This means that any non-EFI loader (including kexec) should be able to > >> extract the inner PE/COFF image and decompress it. For arm64 and > >> RISC-V, this is sufficient as the EFI and raw images are the same. For > >> LoongArch, I suppose it means we need a way to enter the core kernel > >> directly via the entrypoint that the EFI stub uses when handing over > >> (and pass the original DT argument so the kexec kernel has access to > >> the EFI and ACPI firmware tables) > > OK, then is this implementation [1] acceptable? I remember that you > > said the MS-DOS header shouldn't contain other information, so I guess > > this is unacceptable? > > > > [1] https://lore.kernel.org/loongarch/c4dbb14a-5580-1e47-3d15-5d2079e88404@xxxxxxxxxxx/T/#mb8c1dc44f7fa2d3ef638877f0cd3f958f0be96ad > > Modifications to the MS-DOS header refer to the arm64 and riscv > implementations [1], and to provide the necessary information to > kexec-tools[2] when loading uncompressed efi images. > Indeed. On top of the EFI zboot series, we need some [generic!] kexec plumbing to identify such compressed images, and decompress the payload before passing the contents to the arch specific probe/load image hooks.
