From patchwork Fri May 11 17:07:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Morse X-Patchwork-Id: 10394775 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 666D460153 for ; Fri, 11 May 2018 17:12:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7FCB328F6C for ; Fri, 11 May 2018 17:12:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7400228F70; Fri, 11 May 2018 17:12:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 2C03E28F96 for ; Fri, 11 May 2018 17:12:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=SAkXdbZBQQ3nBOP2zuoKvGtwsZzpmbze9/PTJrDa/Bs=; b=q3ro+6zjmezdqx MLsKiMwIPf4RR0uIwZl+XFrLn/WKZz9+NzdieGIaYjcOR20NcO+yA7vOpe0i3axSW3Ha7Ua/thKt7 fERiv5v/4VQ0iNvJ/yP05cwr4aNNtNTPBtT0RXpe9rcbSjrB2OORiVXXdvZlNFiyq/iuHo4AOdMp/ ycYeLUKAEZI5l0LYNxrWk9Vq7wu5v25o22i+3DfKiKmx9GN+e9hB4sU6EsgMTHStLTLde9esneymA htErcrnql/fslem3cJ9beAEmB3JEIcg8+yYqKBc+xAhFx2acvM/MMpoWlJxZWwV5PdJpgKoa3C5C4 cDpGImJpxQtsLsylXYQw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fHBae-0002dG-Lh; Fri, 11 May 2018 17:12:20 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fHBYi-0000c4-H4; Fri, 11 May 2018 17:10:34 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7D1A61435; Fri, 11 May 2018 10:10:09 -0700 (PDT) Received: from [10.1.207.55] (melchizedek.cambridge.arm.com [10.1.207.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4E2943F53D; Fri, 11 May 2018 10:10:06 -0700 (PDT) Subject: Re: [PATCH v9 06/11] arm64: kexec_file: allow for loading Image-format kernel To: AKASHI Takahiro References: <20180425062629.29404-1-takahiro.akashi@linaro.org> <20180425062629.29404-7-takahiro.akashi@linaro.org> <20180507072139.GF11326@linaro.org> From: James Morse Message-ID: <6f0df3a8-a691-80f1-85de-3e0ead852f12@arm.com> Date: Fri, 11 May 2018 18:07:06 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180507072139.GF11326@linaro.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180511_101020_637664_46B150BB X-CRM114-Status: GOOD ( 34.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: herbert@gondor.apana.org.au, bhe@redhat.com, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, bhsharma@redhat.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, dhowells@redhat.com, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org, dyoung@redhat.com, davem@davemloft.net, vgoyal@redhat.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Hi Akashi, On 07/05/18 08:21, AKASHI Takahiro wrote: > On Tue, May 01, 2018 at 06:46:11PM +0100, James Morse wrote: >> On 25/04/18 07:26, AKASHI Takahiro wrote: >>> This patch provides kexec_file_ops for "Image"-format kernel. In this >>> implementation, a binary is always loaded with a fixed offset identified >>> in text_offset field of its header. >>> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h >>> index e4de1223715f..3cba4161818a 100644 >>> --- a/arch/arm64/include/asm/kexec.h >>> +++ b/arch/arm64/include/asm/kexec.h >>> @@ -102,6 +102,56 @@ struct kimage_arch { >>> void *dtb_buf; >>> }; >>> >>> +/** >>> + * struct arm64_image_header - arm64 kernel image header >>> + * >>> + * @pe_sig: Optional PE format 'MZ' signature >>> + * @branch_code: Instruction to branch to stext >>> + * @text_offset: Image load offset, little endian >>> + * @image_size: Effective image size, little endian >>> + * @flags: >>> + * Bit 0: Kernel endianness. 0=little endian, 1=big endian >> >> Page size? What about 'phys_base'?, (whatever that is...) >> Probably best to refer to Documentation/arm64/booting.txt here, its the >> authoritative source of what these fields mean. > > While we don't care other bit fields for now, I will add the reference > to the Documentation file. Thanks, I don't want to create a second, incomplete set of documentation! >>> + u64 reserved[3]; >>> + u8 magic[4]; >>> + u32 pe_header; >>> +}; >> >> I'm surprised we don't have a definition for this already, I guess its always >> done in asm. We have kernel/image.h that holds some of this stuff, if we are >> going to validate the flags, is it worth adding the code there, (and moving it >> to include/asm)? > > A comment at the beginning of this file says, > #ifndef LINKER_SCRIPT > #error This file should only be included in vmlinux.lds.S > #endif > Let me think about. Ah, I missed that. Having two definitions of something makes me nervous that they can become different... looks like that header belongs to the linker, and shouldn't be used here then. >> I guess you skip the MZ prefix as its not present for !EFI? > > CONFIG_KEXEC_IMAGE_VERIFY_SIG depends on the fact that the file > format is PE (that is, EFI is enabled). So if the signature checking is enabled, its already been checked. >> Could we check branch_code is non-zero, and text-offset points within image-size? > > We could do it, but I don't think this check is very useful. > >> >> We could check that this platform supports the page-size/endian config that this >> Image was built with... We get a message from the EFI stub if the page-size >> can't be supported, it would be nice to do the same here (as we can). > > There is no restriction on page-size or endianness for kexec. No, but it won't boot if the hardware doesn't support it. The kernel will spin at a magic address that is, difficult, to debug without JTAG. The bug report will be "it didn't boot". > What will be the purpose of this check? These values are in the header so that the bootloader can check them, then print a meaningful error. Here, kexec_file_load() is playing the part of the bootloader. I'm assuming kexec_file_load() can only be used to kexec linux... unlike regular kexec. Is this where I'm going wrong? >>> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c >>> new file mode 100644 >>> index 000000000000..4dd524ad6611 >>> --- /dev/null >>> +++ b/arch/arm64/kernel/kexec_image.c >>> @@ -0,0 +1,79 @@ >> >>> +static void *image_load(struct kimage *image, >>> + char *kernel, unsigned long kernel_len, >>> + char *initrd, unsigned long initrd_len, >>> + char *cmdline, unsigned long cmdline_len) >>> +{ >>> + struct kexec_buf kbuf; >>> + struct arm64_image_header *h = (struct arm64_image_header *)kernel; >>> + unsigned long text_offset; >>> + int ret; >>> + >>> + /* Load the kernel */ >>> + kbuf.image = image; >>> + kbuf.buf_min = 0; >>> + kbuf.buf_max = ULONG_MAX; >>> + kbuf.top_down = false; >>> + >>> + kbuf.buffer = kernel; >>> + kbuf.bufsz = kernel_len; >>> + kbuf.memsz = le64_to_cpu(h->image_size); >>> + text_offset = le64_to_cpu(h->text_offset); >>> + kbuf.buf_align = SZ_2M; >> >>> + /* Adjust kernel segment with TEXT_OFFSET */ >>> + kbuf.memsz += text_offset; >>> + >>> + ret = kexec_add_buffer(&kbuf); >>> + if (ret) >>> + goto out; >>> + >>> + image->arch.kern_segment = image->nr_segments - 1; >> >> You only seem to use kern_segment here, and in load_other_segments() called >> below. Could it not be a local variable passed in? Instead of arch-specific data >> we keep forever? > > No, kern_segment is also used in load_other_segments() in machine_kexec_file.c. > To optimize memory hole allocation logic in locate_mem_hole_callback(), > we need to know the exact range of kernel image (start and end). That's the second user. My badly-made point is one calls the other, but passes the data via some until-kexec lifetime struct. (its not important, just an indicator this worked differently in the past and hasn't been cleaned up). I meant something like [0]. Thanks, James [0] a diff is worth a thousand words: --------------------%<-------------------- --------------------%<-------------------- diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_ kexec_file.c index 762f9102899c..c50ce844f09e 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -325,11 +325,10 @@ static int prepare_elf_headers(void **addr, unsigned long *sz) return ret; } -int load_other_segments(struct kimage *image, +int load_other_segments(struct kimage *image, struct kexec_segment *kern_seg, char *initrd, unsigned long initrd_len, char *cmdline, unsigned long cmdline_len) { - struct kexec_segment *kern_seg; struct kexec_buf kbuf; void *hdrs_addr; unsigned long hdrs_sz; @@ -368,7 +367,6 @@ int load_other_segments(struct kimage *image, image->arch.elf_load_addr, hdrs_sz, hdrs_sz); } - kern_seg = &image->segment[image->arch.kern_segment]; kbuf.image = image; /* not allocate anything below the kernel */ kbuf.buf_min = kern_seg->mem + kern_seg->memsz; diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h index 891f2484969d..085cb69293ca 100644 --- a/arch/arm64/include/asm/kexec.h +++ b/arch/arm64/include/asm/kexec.h @@ -173,8 +172,10 @@ static inline int arm64_header_check_pe_sig(const struct ar m64_image_header *h) extern const struct kexec_file_ops kexec_image_ops; struct kimage; +struct kexec_segment; extern int load_other_segments(struct kimage *image, + struct kexec_segment *kern_seg, char *initrd, unsigned long initrd_len, char *cmdline, unsigned long cmdline_len); #endif diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c index 7c11beefe65f..0e032d30a79c 100644 --- a/arch/arm64/kernel/kexec_image.c +++ b/arch/arm64/kernel/kexec_image.c @@ -37,6 +37,7 @@ static void *image_load(struct kimage *image, char *cmdline, unsigned long cmdline_len) { struct kexec_buf kbuf; + struct kexec_segment *kern_seg; struct arm64_image_header *h = (struct arm64_image_header *)kernel; unsigned long text_offset; int ret; @@ -65,17 +66,17 @@ static void *image_load(struct kimage *image, if (ret) goto out; - image->arch.kern_segment = image->nr_segments - 1; - image->segment[image->arch.kern_segment].mem += text_offset; - image->segment[image->arch.kern_segment].memsz -= text_offset; - image->start = image->segment[image->arch.kern_segment].mem; + kern_seg = &image->segment[image->nr_segments - 1]; + kern_seg->mem += text_offset; + kern_seg->memsz -= text_offset; + image->start = kern_seg->mem; pr_debug("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n", - image->segment[image->arch.kern_segment].mem, + kern_seg->mem, kbuf.bufsz, kbuf.memsz); /* Load additional data */ - ret = load_other_segments(image, initrd, initrd_len, + ret = load_other_segments(image, kern_seg, initrd, initrd_len, cmdline, cmdline_len); out: