*** Background *** As more PE format kernel images are introduced, it post challenge to kexec to cope with the new format. In my attempt to add support for arm64 zboot image in the kernel [1], Ard suggested using an emulator to tackle this issue. Last year, when Jan tried to introduce UKI support in the kernel [2], Ard mentioned the emulator approach again [3] After discussion, Ard's approach seems to be a more promising solution to handle PE format kernels once and for all. This series follows that approach and implements an emulator to emulate EFI boot time services, allowing the efistub kernel to self-extract and boot. Another year has passed, and UKI kernel is more and more frequently used in product. I think it is time to pay effort to resolve this issue. *** Overview of implement *** The whole model consits of three parts: -1. The emulator It is a self-relocatable PIC code, which is finally linked into kernel, but not export any internal symbol to kernel. It mainly contains: a PE file parser, which loads PE format kernel, a group of functions to emulate efi boot service. -2. inside kernel, PE-format loader Its main task is to set up two extra kexec_segment, one for emulator, the other for passing information from the first kernel to emulator. -3. set up identity mapping only for the memory used by the emulator. Here it relies on kimage_alloc_control_pages() to get pages, which will not stamped during the process of kexec relocate (cp from src to dst). And since the mapping only covers a small range of memory, it cost small amount memory. *** To do *** Currently, it only works on arm64 virt machine. For x86, it needs some slightly changes. (I plan to do it in the next version) Also, this series does not implement a memory allocator, which I plan to implement with the help of bitmap. About console, currently it hard code for arm64 virt machine, later it should extract the information through ACPI table. For kdump code, it is not implmented yet. But it should share the majority of this series. *** Test of this series *** I have tested this series on arm64 virt machine. There I booted the vmlinuz.efi and kexec_file_load a UKI image, then switch to the second kernel. I used a modified kexec-tools [4], which just skips the check of the file format and passes the file directly to kernel. [1]: https://lore.kernel.org/linux-arm-kernel/ZBvKSis+dfnqa+Vz@xxxxxxxxxxxxxxxxxxxxxxxxxx/T/#m42abb0ad3c10126b8b3bfae8a596deb707d6f76e [2]: https://lore.kernel.org/lkml/20230918173607.421d2616@rotkaeppchen/T/ [3]: https://lore.kernel.org/lkml/20230918173607.421d2616@rotkaeppchen/T/#mc60aa591cb7616ceb39e1c98f352383f9ba6e985 [4]: https://github.com/pfliu/kexec-tools.git branch: kexec_uefi_emulator RFCv1 -> RFCv2: -1.Support to run UKI kernel by: add LoadImage() and StartImage(), add PE file relocation support, add InstallMultiProtocol() -2.Also set up idmap for EFI runtime memory descriptor since UKI's systemd-stub calls runtime service -3.Move kexec_pe_image.c from arch/arm64/kernel to kernel/, since it aims to provide a more general architecture support. RFCv1: https://lore.kernel.org/linux-efi/20240718085759.13247-1-piliu@xxxxxxxxxx/ RFCv2: https://github.com/pfliu/linux.git branch kexec_uefi_emulator_RFCv2 Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: Jan Hendrik Farr <kernel@xxxxxxxx> Cc: Philipp Rudo <prudo@xxxxxxxxxx> Cc: Lennart Poettering <mzxreary@xxxxxxxxxxx> Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: kexec@xxxxxxxxxxxxxxxxxxx Cc: linux-efi@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Pingfan Liu (9): efi/libstub: Ask efi_random_alloc() to skip unusable memory efi/libstub: Complete efi_simple_text_output_protocol efi/emulator: Initial rountines to emulate EFI boot time service efi/emulator: Turn on mmu for arm64 kexec: Introduce kexec_pe_image to parse and load PE file arm64: kexec: Introduce a new member param_mem to kimage_arch arm64: mm: Change to prototype of arm64: kexec: Prepare page table for emulator arm64: kexec: Enable kexec_pe_image arch/arm64/Kconfig | 4 + arch/arm64/include/asm/kexec.h | 1 + arch/arm64/include/asm/mmu.h | 6 + arch/arm64/kernel/asm-offsets.c | 2 +- arch/arm64/kernel/machine_kexec.c | 103 +++- arch/arm64/kernel/machine_kexec_file.c | 4 + arch/arm64/kernel/relocate_kernel.S | 2 +- arch/arm64/mm/mmu.c | 67 ++- drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/efi_emulator/Makefile | 99 ++++ .../firmware/efi/efi_emulator/amba-pl011.c | 81 +++ .../efi_emulator/arm64_emulator_service.lds | 45 ++ .../firmware/efi/efi_emulator/arm64_proc.S | 175 ++++++ .../firmware/efi/efi_emulator/config_table.c | 25 + drivers/firmware/efi/efi_emulator/core.c | 376 +++++++++++++ .../firmware/efi/efi_emulator/device_handle.c | 138 +++++ drivers/firmware/efi/efi_emulator/earlycon.h | 19 + .../firmware/efi/efi_emulator/efi_emulator.S | 12 + drivers/firmware/efi/efi_emulator/emulator.h | 106 ++++ drivers/firmware/efi/efi_emulator/entry.c | 68 +++ drivers/firmware/efi/efi_emulator/head.S | 10 + drivers/firmware/efi/efi_emulator/lib.c | 73 +++ drivers/firmware/efi/efi_emulator/memory.c | 27 + .../firmware/efi/efi_emulator/memory_api.c | 74 +++ drivers/firmware/efi/efi_emulator/misc.c | 43 ++ drivers/firmware/efi/efi_emulator/pe_loader.c | 173 ++++++ drivers/firmware/efi/efi_emulator/printf.c | 373 +++++++++++++ .../efi/efi_emulator/protocol_device_path.c | 75 +++ .../protocol_simple_text_output.c | 50 ++ drivers/firmware/efi/libstub/efistub.h | 7 + drivers/firmware/efi/libstub/randomalloc.c | 5 + include/linux/efi_emulator.h | 46 ++ include/linux/kexec.h | 6 + kernel/Makefile | 1 + kernel/kexec_pe_image.c | 503 ++++++++++++++++++ 35 files changed, 2764 insertions(+), 36 deletions(-) create mode 100644 drivers/firmware/efi/efi_emulator/Makefile create mode 100644 drivers/firmware/efi/efi_emulator/amba-pl011.c create mode 100644 drivers/firmware/efi/efi_emulator/arm64_emulator_service.lds create mode 100644 drivers/firmware/efi/efi_emulator/arm64_proc.S create mode 100644 drivers/firmware/efi/efi_emulator/config_table.c create mode 100644 drivers/firmware/efi/efi_emulator/core.c create mode 100644 drivers/firmware/efi/efi_emulator/device_handle.c create mode 100644 drivers/firmware/efi/efi_emulator/earlycon.h create mode 100644 drivers/firmware/efi/efi_emulator/efi_emulator.S create mode 100644 drivers/firmware/efi/efi_emulator/emulator.h create mode 100644 drivers/firmware/efi/efi_emulator/entry.c create mode 100644 drivers/firmware/efi/efi_emulator/head.S create mode 100644 drivers/firmware/efi/efi_emulator/lib.c create mode 100644 drivers/firmware/efi/efi_emulator/memory.c create mode 100644 drivers/firmware/efi/efi_emulator/memory_api.c create mode 100644 drivers/firmware/efi/efi_emulator/misc.c create mode 100644 drivers/firmware/efi/efi_emulator/pe_loader.c create mode 100644 drivers/firmware/efi/efi_emulator/printf.c create mode 100644 drivers/firmware/efi/efi_emulator/protocol_device_path.c create mode 100644 drivers/firmware/efi/efi_emulator/protocol_simple_text_output.c create mode 100644 include/linux/efi_emulator.h create mode 100644 kernel/kexec_pe_image.c -- 2.41.0
