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[209.132.180.67]) by mx.google.com with ESMTP id f23si1040534oti.283.2020.02.26.23.45.19; Wed, 26 Feb 2020 23:45:34 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=PWjCPWiS; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728420AbgB0HpE (ORCPT + 99 others); Thu, 27 Feb 2020 02:45:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:40122 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728389AbgB0HpD (ORCPT ); Thu, 27 Feb 2020 02:45:03 -0500 Received: from mail-wr1-f52.google.com (mail-wr1-f52.google.com [209.85.221.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6C05824687 for ; Thu, 27 Feb 2020 07:45:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582789502; bh=1DKVZpJ1NMtFpDCRoT/3aJcM0IW1AcSqjMAJKvtYKlg=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=PWjCPWiSzkS936HvR7EliMT4UotLlAUAyE6IsUwh67LXlMZlO+934ykpYZRPKQwm7 51/VPBx1n6Yx3D78qnKZGhOQyVw3UIUy1gG50RIBSSDHPVHXI4mLN75S/VBXwNLjJy PdAdFOmoq348lU9BkwQnlE0aJFJiiJgvXszG5zbs= Received: by mail-wr1-f52.google.com with SMTP id w12so2055420wrt.2 for ; Wed, 26 Feb 2020 23:45:02 -0800 (PST) X-Gm-Message-State: APjAAAWhm1Gc0KdNLGxrQdnl0rOm+EA2eJLJwO6rSPH5eh8j4CekDWxR lJAzrhLumMqaIYMEWjKdHbKIg6NJnBDbx506gaE7Dw== X-Received: by 2002:a5d:5188:: with SMTP id k8mr3225259wrv.151.1582789500393; Wed, 26 Feb 2020 23:45:00 -0800 (PST) MIME-Version: 1.0 References: <20200226011037.7179-1-atish.patra@wdc.com> <20200226011037.7179-5-atish.patra@wdc.com> <4c55e171ecc7a728c331ccb6d9057f7b9d79af8d.camel@wdc.com> In-Reply-To: <4c55e171ecc7a728c331ccb6d9057f7b9d79af8d.camel@wdc.com> From: Ard Biesheuvel Date: Thu, 27 Feb 2020 08:44:50 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH 4/5] RISC-V: Add PE/COFF header for EFI stub To: Atish Patra Cc: "alexios.zavras@intel.com" , "tglx@linutronix.de" , "mchehab+samsung@kernel.org" , "pbonzini@redhat.com" , "michal.simek@xilinx.com" , "linux@armlinux.org.uk" , "abner.chang@hpe.com" , "linux-riscv@lists.infradead.org" , "catalin.marinas@arm.com" , "linux-kernel@vger.kernel.org" , "daniel.schaefer@hpe.com" , Anup Patel , "kstewart@linuxfoundation.org" , "palmer@dabbelt.com" , "aou@eecs.berkeley.edu" , "arnd@arndb.de" , "rppt@linux.ibm.com" , "linux-efi@vger.kernel.org" , "bp@suse.de" , "greentime.hu@sifive.com" , "keescook@chromium.org" , "agraf@csgraf.de" , "will@kernel.org" , "gregkh@linuxfoundation.org" , "mingo@kernel.org" , "allison@lohutok.net" , "han_mao@c-sky.com" , "paul.walmsley@sifive.com" , "linus.walleij@linaro.org" , "leif@nuviainc.com" , "akpm@linux-foundation.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 27 Feb 2020 at 02:29, Atish Patra wrote: > > On Wed, 2020-02-26 at 08:14 +0100, Ard Biesheuvel wrote: > > On Wed, 26 Feb 2020 at 02:10, Atish Patra > > wrote: > > > Linux kernel Image can appear as an EFI application With > > > appropriate > > > PE/COFF header fields in the beginning of the Image header. An EFI > > > application loader can directly load a Linux kernel Image and an > > > EFI > > > stub residing in kernel can boot Linux kernel directly. > > > > > > Add the necessary PE/COFF header. > > > > > > Signed-off-by: Atish Patra > > > --- > > > arch/riscv/include/asm/Kbuild | 1 - > > > arch/riscv/include/asm/sections.h | 13 ++++ > > > arch/riscv/kernel/Makefile | 4 ++ > > > arch/riscv/kernel/efi-header.S | 107 > > > ++++++++++++++++++++++++++++++ > > > arch/riscv/kernel/head.S | 15 +++++ > > > arch/riscv/kernel/image-vars.h | 52 +++++++++++++++ > > > arch/riscv/kernel/vmlinux.lds.S | 27 ++++++-- > > > 7 files changed, 212 insertions(+), 7 deletions(-) > > > create mode 100644 arch/riscv/include/asm/sections.h > > > create mode 100644 arch/riscv/kernel/efi-header.S > > > create mode 100644 arch/riscv/kernel/image-vars.h > > > > > > diff --git a/arch/riscv/include/asm/Kbuild > > > b/arch/riscv/include/asm/Kbuild > > > index 517394390106..ef797fe44934 100644 > > > --- a/arch/riscv/include/asm/Kbuild > > > +++ b/arch/riscv/include/asm/Kbuild > > > @@ -24,7 +24,6 @@ generic-y += local64.h > > > generic-y += mm-arch-hooks.h > > > generic-y += percpu.h > > > generic-y += preempt.h > > > -generic-y += sections.h > > > generic-y += serial.h > > > generic-y += shmparam.h > > > generic-y += topology.h > > > diff --git a/arch/riscv/include/asm/sections.h > > > b/arch/riscv/include/asm/sections.h > > > new file mode 100644 > > > index 000000000000..3a9971b1210f > > > --- /dev/null > > > +++ b/arch/riscv/include/asm/sections.h > > > @@ -0,0 +1,13 @@ > > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > > +/* > > > + * Copyright (C) 2020 Western Digital Corporation or its > > > affiliates. > > > + */ > > > +#ifndef __ASM_SECTIONS_H > > > +#define __ASM_SECTIONS_H > > > + > > > +#include > > > + > > > +extern char _start[]; > > > +extern char _start_kernel[]; > > > + > > > +#endif /* __ASM_SECTIONS_H */ > > > diff --git a/arch/riscv/kernel/Makefile > > > b/arch/riscv/kernel/Makefile > > > index 9601ac907f70..471b1c73f77d 100644 > > > --- a/arch/riscv/kernel/Makefile > > > +++ b/arch/riscv/kernel/Makefile > > > @@ -29,6 +29,10 @@ obj-y += cacheinfo.o > > > obj-$(CONFIG_MMU) += vdso.o vdso/ > > > > > > obj-$(CONFIG_RISCV_M_MODE) += clint.o > > > +OBJCOPYFLAGS := --prefix-symbols=__efistub_ > > > +$(obj)/%.stub.o: $(obj)/%.o FORCE > > > + $(call if_changed,objcopy) > > > + > > > obj-$(CONFIG_FPU) += fpu.o > > > obj-$(CONFIG_SMP) += smpboot.o > > > obj-$(CONFIG_SMP) += smp.o > > > diff --git a/arch/riscv/kernel/efi-header.S > > > b/arch/riscv/kernel/efi-header.S > > > new file mode 100644 > > > index 000000000000..af959e748d93 > > > --- /dev/null > > > +++ b/arch/riscv/kernel/efi-header.S > > > @@ -0,0 +1,107 @@ > > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > > +/* > > > + * Copyright (C) 2019 Western Digital Corporation or its > > > affiliates. > > > + * Adapted from arch/arm64/kernel/efi-header.S > > > + */ > > > + > > > +#include > > > +#include > > > + > > > + .macro __EFI_PE_HEADER > > > + .long PE_MAGIC > > > +coff_header: > > > + .short IMAGE_FILE_MACHINE_RISCV64 // Machine > > > + .short section_count // > > > NumberOfSections > > > + .long 0 // > > > TimeDateStamp > > > + .long 0 // > > > PointerToSymbolTable > > > + .long 0 // > > > NumberOfSymbols > > > + .short section_table - optional_header // > > > SizeOfOptionalHeader > > > + .short IMAGE_FILE_DEBUG_STRIPPED | \ > > > + IMAGE_FILE_EXECUTABLE_IMAGE | \ > > > + IMAGE_FILE_LINE_NUMS_STRIPPED // > > > Characteristics > > > + > > > +optional_header: > > > + .short PE_OPT_MAGIC_PE32PLUS // PE32+ > > > format > > > + .byte 0x02 // > > > MajorLinkerVersion > > > + .byte 0x14 // > > > MinorLinkerVersion > > > + .long __text_end - efi_header_end // > > > SizeOfCode > > > + .long _end - __text_end // > > > SizeOfInitializedData > > > + .long 0 // > > > SizeOfUninitializedData > > > + .long __efistub_efi_entry - _start // > > > AddressOfEntryPoint > > > + .long efi_header_end - _start // > > > BaseOfCode > > > + > > > +extra_header_fields: > > > + .quad 0 // > > > ImageBase > > > + .long SZ_4K // > > > SectionAlignment > > > + .long PECOFF_FILE_ALIGNMENT // > > > FileAlignment > > > + .short 0 // > > > MajorOperatingSystemVersion > > > + .short 0 // > > > MinorOperatingSystemVersion > > > + .short 0 // > > > MajorImageVersion > > > + .short 0 // > > > MinorImageVersion > > > > Put LINUX_EFISTUB_MAJOR_VERSION and LINUX_EFISTUB_MINOR_VERSION here > > > > Sure. > > > > + .short 0 // > > > MajorSubsystemVersion > > > + .short 0 // > > > MinorSubsystemVersion > > > + .long 0 // > > > Win32VersionValue > > > + > > > + .long _end - _start // > > > SizeOfImage > > > + > > > + // Everything before the kernel image is considered part of > > > the header > > > + .long efi_header_end - _start // > > > SizeOfHeaders > > > + .long 0 // CheckSum > > > + .short IMAGE_SUBSYSTEM_EFI_APPLICATION // > > > Subsystem > > > + .short 0 // > > > DllCharacteristics > > > + .quad 0 // > > > SizeOfStackReserve > > > + .quad 0 // > > > SizeOfStackCommit > > > + .quad 0 // > > > SizeOfHeapReserve > > > + .quad 0 // > > > SizeOfHeapCommit > > > + .long 0 // > > > LoaderFlags > > > + .long (section_table - .) / 8 // > > > NumberOfRvaAndSizes > > > + > > > + .quad 0 // > > > ExportTable > > > + .quad 0 // > > > ImportTable > > > + .quad 0 // > > > ResourceTable > > > + .quad 0 // > > > ExceptionTable > > > + .quad 0 // > > > CertificationTable > > > + .quad 0 // > > > BaseRelocationTable > > > + > > > + // Section table > > > +section_table: > > > + .ascii ".text\0\0\0" > > > + .long __text_end - efi_header_end // > > > VirtualSize > > > + .long efi_header_end - _start // > > > VirtualAddress > > > + .long __text_end - efi_header_end // > > > SizeOfRawData > > > + .long efi_header_end - _start // > > > PointerToRawData > > > + > > > + .long 0 // > > > PointerToRelocations > > > + .long 0 // > > > PointerToLineNumbers > > > + .short 0 // > > > NumberOfRelocations > > > + .short 0 // > > > NumberOfLineNumbers > > > + .long IMAGE_SCN_CNT_CODE | \ > > > + IMAGE_SCN_MEM_READ | \ > > > + IMAGE_SCN_MEM_EXECUTE // > > > Characteristics > > > + > > > + .ascii ".data\0\0\0" > > > + .long __data_virt_size // > > > VirtualSize > > > + .long __text_end - _start // > > > VirtualAddress > > > + .long __data_raw_size // > > > SizeOfRawData > > > + .long __text_end - _start // > > > PointerToRawData > > > + > > > + .long 0 // > > > PointerToRelocations > > > + .long 0 // > > > PointerToLineNumbers > > > + .short 0 // > > > NumberOfRelocations > > > + .short 0 // > > > NumberOfLineNumbers > > > + .long IMAGE_SCN_CNT_INITIALIZED_DATA | \ > > > + IMAGE_SCN_MEM_READ | \ > > > + IMAGE_SCN_MEM_WRITE // > > > Characteristics > > > + > > > + .set section_count, (. - section_table) / 40 > > > + > > > > You dropped the debug header here, which is actually *very* useful if > > you want to single step through the stub from DEBUG edk2 firmware. > > > > Ahh I see. I was not sure how to use the debug feature :). Can we do > the same in U-boot ? > You could, but I doubt it has been implemented yet. Adding the debug header will cause the firmware to record the image path and its load address in a special debug table, which the firmware can use to expose the load address and path of the image as it is loaded (i.e. before moving itself into place) When I run this under a DEBUG build of EDK2, it prints a line like add-symbol-file /home/ardbie01/linux-build-arm64/vmlinux 0x74E0B000 which I can paste into the GDB command window, set a breakpoint on efi_entry(), and single step through the stub. > How about adding it back later once I can verify it with EDK2 ? > Sure, that is fine > > > + /* > > > + * EFI will load .text onwards at the 4k section alignment > > > + * described in the PE/COFF header. To ensure that > > > instruction > > > + * sequences using an adrp and a :lo12: immediate will > > > function > > > > Surely, this is inaccurate for RISC-V? > > Sorry. I should have removed the comment. We keep the the _start and > .head.text section aligned to a PAGE_SIZE anyways using the linker > script. ok > > > > > + * correctly at this alignment, we must ensure that .text > > > is > > > + * placed at a 4k boundary in the Image to begin with. > > > + */ > > > + .align 12 > > > +efi_header_end: > > > + .endm > > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > > > index ac5b0e0a02f6..835dc76de285 100644 > > > --- a/arch/riscv/kernel/head.S > > > +++ b/arch/riscv/kernel/head.S > > > @@ -13,6 +13,7 @@ > > > #include > > > #include > > > #include > > > +#include "efi-header.S" > > > > > > __HEAD > > > ENTRY(_start) > > > @@ -22,10 +23,17 @@ ENTRY(_start) > > > * Do not modify it without modifying the structure and all > > > bootloaders > > > * that expects this header format!! > > > */ > > > +#ifdef CONFIG_EFI > > > + /* > > > + * This instruction decodes to "MZ" ASCII required by UEFI. > > > + */ > > > + li s4,-13 > > > > What happens if you try to do plain boot on an EFI kernel? On ARM and > > x86, we took care to use a 'MZ' opcode that behaves as a pseudo-NOP, > > and jump to start_kernel right after, so if you boot the EFI kernel > > as > > a normal kernel, it still works. > > > > There should have been a "j _start_kernel" after the "MZ" ascii. I just > tested EFI kernel can now boot as a normal kernel as well with that > change. Thanks for pointing that out. > Sure > > > +#else > > > /* jump to start kernel */ > > > j _start_kernel > > > /* reserved */ > > > .word 0 > > > +#endif > > > .balign 8 > > > #if __riscv_xlen == 64 > > > /* Image load offset(2MB) from start of RAM */ > > > @@ -43,7 +51,14 @@ ENTRY(_start) > > > .ascii RISCV_IMAGE_MAGIC > > > .balign 4 > > > .ascii RISCV_IMAGE_MAGIC2 > > > +#ifdef CONFIG_EFI > > > + .word pe_head_start - _start > > > +pe_head_start: > > > + > > > + __EFI_PE_HEADER > > > +#else > > > .word 0 > > > +#endif > > > > > > .align 2 > > > #ifdef CONFIG_MMU > > > diff --git a/arch/riscv/kernel/image-vars.h > > > b/arch/riscv/kernel/image-vars.h > > > new file mode 100644 > > > index 000000000000..57abb85065e9 > > > --- /dev/null > > > +++ b/arch/riscv/kernel/image-vars.h > > > @@ -0,0 +1,52 @@ > > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > > +/* > > > + * Linker script variables to be set after section resolution, as > > > + * ld.lld does not like variables assigned before SECTIONS is > > > processed. > > > + * Based on arch/arm64/kerne/image-vars.h > > > + */ > > > +#ifndef __RISCV_KERNEL_IMAGE_VARS_H > > > +#define __RISCV_KERNEL_IMAGE_VARS_H > > > + > > > +#ifndef LINKER_SCRIPT > > > +#error This file should only be included in vmlinux.lds.S > > > +#endif > > > + > > > +#ifdef CONFIG_EFI > > > + > > > +__efistub_stext_offset = _start_kernel - _start; > > > + > > > +/* > > > + * The EFI stub has its own symbol namespace prefixed by > > > __efistub_, to > > > + * isolate it from the kernel proper. The following symbols are > > > legally > > > + * accessed by the stub, so provide some aliases to make them > > > accessible. > > > + * Only include data symbols here, or text symbols of functions > > > that are > > > + * guaranteed to be safe when executed at another offset than they > > > were > > > + * linked at. The routines below are all implemented in assembler > > > in a > > > + * position independent manner > > > + */ > > > +__efistub_memcmp = memcmp; > > > +__efistub_memchr = memchr; > > > +__efistub_memcpy = memcpy; > > > +__efistub_memmove = memmove; > > > +__efistub_memset = memset; > > > +__efistub_strlen = strlen; > > > +__efistub_strnlen = strnlen; > > > +__efistub_strcmp = strcmp; > > > +__efistub_strncmp = strncmp; > > > +__efistub_strrchr = strrchr; > > > + > > > +#ifdef CONFIG_KASAN > > > +__efistub___memcpy = memcpy; > > > +__efistub___memmove = memmove; > > > +__efistub___memset = memset; > > > +#endif > > > + > > > +__efistub__start = _start; > > > +__efistub__start_kernel = _start_kernel; > > > +__efistub__end = _end; > > > +__efistub__edata = _edata; > > > +__efistub_screen_info = screen_info; > > > + > > > +#endif > > > + > > > +#endif /* __RISCV_KERNEL_IMAGE_VARS_H */ > > > diff --git a/arch/riscv/kernel/vmlinux.lds.S > > > b/arch/riscv/kernel/vmlinux.lds.S > > > index b32640300d07..933b9e9a4b39 100644 > > > --- a/arch/riscv/kernel/vmlinux.lds.S > > > +++ b/arch/riscv/kernel/vmlinux.lds.S > > > @@ -9,6 +9,7 @@ > > > #include > > > #include > > > #include > > > +#include "image-vars.h" > > > > > > #include > > > OUTPUT_ARCH(riscv) > > > @@ -16,6 +17,14 @@ ENTRY(_start) > > > > > > jiffies = jiffies_64; > > > > > > +PECOFF_FILE_ALIGNMENT = 0x200; > > > +#ifdef CONFIG_EFI > > > +#define PECOFF_EDATA_PADDING \ > > > + .pecoff_edata_padding : { BYTE(0); . = > > > ALIGN(PECOFF_FILE_ALIGNMENT); } > > > +#else > > > +#define PECOFF_EDATA_PADDING > > > +#endif > > > + > > > SECTIONS > > > { > > > /* Beginning of code and text segment */ > > > @@ -26,12 +35,15 @@ SECTIONS > > > > > > __init_begin = .; > > > INIT_TEXT_SECTION(PAGE_SIZE) > > > + > > > + /* Start of data section */ > > > INIT_DATA_SECTION(16) > > > /* we have to discard exit text and such at runtime, not > > > link time */ > > > .exit.text : > > > { > > > EXIT_TEXT > > > } > > > + > > > .exit.data : > > > { > > > EXIT_DATA > > > @@ -54,7 +66,8 @@ SECTIONS > > > _etext = .; > > > } > > > > > > - /* Start of data section */ > > > + __text_end = .; > > > + > > > _sdata = .; > > > RO_DATA(L1_CACHE_BYTES) > > > .srodata : { > > > @@ -65,19 +78,21 @@ SECTIONS > > > .sdata : { > > > __global_pointer$ = . + 0x800; > > > *(.sdata*) > > > - /* End of data section */ > > > - _edata = .; > > > *(.sbss*) > > > } > > > - > > > - BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0) > > > - > > > + PECOFF_EDATA_PADDING > > > + __data_raw_size = ABSOLUTE(. - __text_end); > > > + /* End of data section */ > > > + _edata = .; > > > EXCEPTION_TABLE(0x10) > > > > > > .rel.dyn : { > > > *(.rel.dyn*) > > > } > > > > > > + BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0) > > > + __data_virt_size = ABSOLUTE(. - __text_end); > > > + > > > _end = .; > > > > > > STABS_DEBUG > > > -- > > > 2.24.0 > > > > > -- > Regards, > Atish