From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from layka.disroot.org (layka.disroot.org [178.21.23.139]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5807521B9FD for ; Wed, 20 Aug 2025 06:50:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=178.21.23.139 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755672626; cv=none; b=D+27hWAcgBAYd2N380TeIW3uHP7mkS1P4nISN7cAhdtbjVevVt6Iifb73M/AIblCUVpWO4xIWxykrI4sl4ATQiutTa9HeXRy0NERIQ5iBgKTrWu5N3OfJTiSlI151h19epOIAnVUbhYobaXstFhMv+lnWtX6/uug8p6ZkLEMXOU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755672626; c=relaxed/simple; bh=wQ8qM95j2gviU1QGJ8rgqDjbocACb6XZzCLsLaODwvY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kjbTPtek0Jyd8P6KwH0Uj3YiPwVBm6wJS/4eILSbswvy2OQhHbXcj35AIxMXTF65W4fCdSRGK8dArPYP4uJNxDGY/js+zrkQQodxHiLdMj+bIT1Kbw5mt0na3E3kVYK3wlmo1BrVv81UycsgSmhCtDP6G0Br53ET2TRoOG7LaZg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=disroot.org; spf=pass smtp.mailfrom=disroot.org; dkim=pass (2048-bit key) header.d=disroot.org header.i=@disroot.org header.b=UtEHQMRl; arc=none smtp.client-ip=178.21.23.139 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=disroot.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=disroot.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=disroot.org header.i=@disroot.org header.b="UtEHQMRl" Received: from mail01.disroot.lan (localhost [127.0.0.1]) by disroot.org (Postfix) with ESMTP id 941A125EFA; Wed, 20 Aug 2025 08:50:20 +0200 (CEST) X-Virus-Scanned: SPAM Filter at disroot.org Received: from layka.disroot.org ([127.0.0.1]) by localhost (disroot.org [127.0.0.1]) (amavis, port 10024) with ESMTP id 9fau3ZIC3Npm; Wed, 20 Aug 2025 08:50:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=disroot.org; s=mail; t=1755672619; bh=wQ8qM95j2gviU1QGJ8rgqDjbocACb6XZzCLsLaODwvY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=UtEHQMRlQ8rFrMqm+LHFQT49TgwWd3va36RPDXBR7xncfCUX10XX4FyWdzKwgt6Lb 18LHJZDgky6OaiFfnAxm1KsLWsuTLYCJMqN1Ka2i+xv/shW19/KB2f390u4GIJGm08 S77rKKia+72cEmXCIQZkGcrFoWlHBTUuOsqEnUuzaoSCIxwMZJe4e714jmv/SOZ6Ft CRrDb7oKPNGVKhCnefHSoPsp2KvbmCz034WIhxcsZRQBKwu138knkFNElpCtGtkJA0 y5o7Ly4URMwyHxBOe9gDM4SraJtw3I2FDSFgZMEOfpCiYDQ5FnuiKYyLRC223Miyak 7qjAWxmVGmABw== Date: Wed, 20 Aug 2025 06:50:04 +0000 From: Yao Zi To: Youling Tang , Huacai Chen Cc: WANG Xuerui , Baoquan He , kexec@lists.infradead.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, Youling Tang Subject: Re: [PATCH v2 2/5] LoongArch: Add kexec_file support Message-ID: References: <20250820055700.24344-1-youling.tang@linux.dev> <20250820055700.24344-3-youling.tang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250820055700.24344-3-youling.tang@linux.dev> On Wed, Aug 20, 2025 at 01:56:57PM +0800, Youling Tang wrote: > From: Youling Tang > > This patch adds support for kexec_file on LoongArch. > > The efi_kexec_load() as two parts: > - the first part loads the kernel image (vmlinuz.efi or vmlinux.efi) > - the second part loads other segments (eg: initrd, cmdline) > > This initrd will be passed to the second kernel via the command line > 'initrd=start,size'. > > Currently, pez(vmlinuz.efi) and pei(vmlinux.efi) format images are supported, > but ELF format is not supported. > > Signed-off-by: Youling Tang > --- > arch/loongarch/Kconfig | 9 ++ > arch/loongarch/include/asm/image.h | 17 +++ > arch/loongarch/include/asm/kexec.h | 12 +++ > arch/loongarch/kernel/Makefile | 1 + > arch/loongarch/kernel/kexec_efi.c | 111 +++++++++++++++++++ > arch/loongarch/kernel/machine_kexec.c | 33 ++++-- > arch/loongarch/kernel/machine_kexec_file.c | 117 +++++++++++++++++++++ > 7 files changed, 289 insertions(+), 11 deletions(-) > create mode 100644 arch/loongarch/kernel/kexec_efi.c > create mode 100644 arch/loongarch/kernel/machine_kexec_file.c ... > diff --git a/arch/loongarch/include/asm/image.h b/arch/loongarch/include/asm/image.h > index 1f090736e71d..655d5836c4e8 100644 > --- a/arch/loongarch/include/asm/image.h > +++ b/arch/loongarch/include/asm/image.h > @@ -36,5 +36,22 @@ struct loongarch_image_header { > uint32_t pe_header; > }; > > +static const uint8_t loongarch_image_pe_sig[2] = {'M', 'Z'}; > + > +/** > + * loongarch_header_check_pe_sig - Helper to check the loongarch image header. > + * > + * Returns non-zero if 'MZ' signature is found. > + */ > + > +static inline int loongarch_header_check_pe_sig(const struct loongarch_image_header *h) > +{ > + if (!h) > + return 0; > + > + return (h->pe_sig[0] == loongarch_image_pe_sig[0] > + && h->pe_sig[1] == loongarch_image_pe_sig[1]); > +} This check is still too weak and doesn't improve comparing to v1. > This could be simplified with a memcmp(). Also, this check isn't > strict enough: PE files for any architectures, and even legacy MS-DOS > COM executables all start with "MZ". I've pointed this out in my previous reply[1]. > #endif /* __ASSEMBLY__ */ > #endif /* __ASM_IMAGE_H */ ... > diff --git a/arch/loongarch/kernel/kexec_efi.c b/arch/loongarch/kernel/kexec_efi.c > new file mode 100644 > index 000000000000..7741f1139a12 > --- /dev/null > +++ b/arch/loongarch/kernel/kexec_efi.c ... > +static void *efi_kexec_load(struct kimage *image, > + char *kernel, unsigned long kernel_len, > + char *initrd, unsigned long initrd_len, > + char *cmdline, unsigned long cmdline_len) > +{ > + struct loongarch_image_header *h; > + struct kexec_buf kbuf; > + unsigned long text_offset, kernel_segment_number; > + struct kexec_segment *kernel_segment; > + int ret; > + > + h = (struct loongarch_image_header *)kernel; > + if (!h->image_size) > + return ERR_PTR(-EINVAL); > + > + /* Load the kernel */ > + kbuf.image = image; > + kbuf.buf_max = ULONG_MAX; > + kbuf.top_down = false; > + > + kbuf.buffer = kernel; > + kbuf.bufsz = kernel_len; > + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; > + kbuf.memsz = le64_to_cpu(h->image_size); > + text_offset = le64_to_cpu(h->text_offset); > + kbuf.buf_min = text_offset; > + kbuf.buf_align = SZ_2M; > + > + kernel_segment_number = image->nr_segments; > + > + /* > + * The location of the kernel segment may make it impossible to satisfy > + * the other segment requirements, so we try repeatedly to find a > + * location that will work. > + */ > + while ((ret = kexec_add_buffer(&kbuf)) == 0) { > + /* Try to load additional data */ > + kernel_segment = &image->segment[kernel_segment_number]; > + ret = load_other_segments(image, kernel_segment->mem, > + kernel_segment->memsz, initrd, > + initrd_len, cmdline, cmdline_len); > + if (!ret) > + break; > + > + /* > + * We couldn't find space for the other segments; erase the > + * kernel segment and try the next available hole. > + */ > + image->nr_segments -= 1; > + kbuf.buf_min = kernel_segment->mem + kernel_segment->memsz; > + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; > + } > + > + if (ret) { > + pr_err("Could not find any suitable kernel location!"); > + return ERR_PTR(ret); > + } > + > + kernel_segment = &image->segment[kernel_segment_number]; > + > + /* Make sure the second kernel jumps to the correct "kernel_entry". */ > + image->start = kernel_segment->mem + h->kernel_entry - text_offset; And this still assumes the loaded, secondary kernel is relocatable, with neither extra check nor comment explaining its limitation. Please see my previous reply[2] that explains why loading a non-relocatble kernel with kexec_file API is reasonable. > + kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n", > + kernel_segment->mem, kbuf.bufsz, > + kernel_segment->memsz); > + > + return NULL; > +} > + > +const struct kexec_file_ops kexec_efi_ops = { > + .probe = efi_kexec_probe, > + .load = efi_kexec_load, > +}; Thanks, Yao Zi [1]: https://lore.kernel.org/all/aJojDiHWi8cgvA2W@pie/ [2]: https://lore.kernel.org/all/aJwFa8x5BQMouB1y@pie/