From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8C2F2C17B2 for ; Wed, 3 Sep 2025 03:02:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756868551; cv=none; b=Kh67sKilX615SXSMZ9PL7ocVQGXDzjM/80YDHQHpr7LQm46TOmJk3+8e2bBIpNSx1DFdcY41CZyGxdPFyjFUSIjNZ3as4Q+nTGCtX9I5nRDBxvti/GDyAJmkS3g/5KVNWJyCvn9lw/anv+btK7KlgbnyRbepk3lD+s6OFaHgWRk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756868551; c=relaxed/simple; bh=w9hUK+dRlUOgZ73nZQFMw0tDODSshINp6P9j9jqXgPI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=PSG2l58U7FOlZq+X9LHC6QRFspBU8iVyKASxQBy8gqUt7NujGhzWNZt3bXUvhRE2C0nXxaYcR2yfLCkBToepfKJoE3RlB/Q0iR/Fkl1GY3EANoKXFu2woVJ1UfPjMg9Zj1jkeSuB2rYhKX/XKmQy32M7XNjGEj2xw3fm1Vu90Xk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Rg9FFLbI; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Rg9FFLbI" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756868547; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=T4b0Kpf/tl9a1URo/4A0Vd1S2ONlllDvpb/j2reoa1Y=; b=Rg9FFLbISnAC0DPDnwOyxhM3/tWaI9dO48YHk+2Zx+Px4b26FA/g59xDqdb8kU0ifLAzbZ QUuy+e7ju/GJb7rMqHwaRLzi4t9JApYlARrogxSm0/0ctvnD8mcKnDlAZyRzhuJU3Kl6kx 902Zc7obQiMhI82H91bln5hrImWAc0E= From: Youling Tang To: Huacai Chen Cc: WANG Xuerui , Baoquan He , Yao Zi , kexec@lists.infradead.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, youling.tang@linux.dev, Youling Tang Subject: [PATCH v4 5/7] LoongArch/kexec_file: Add crash dump support Date: Wed, 3 Sep 2025 11:00:58 +0800 Message-Id: <20250903030100.196744-6-youling.tang@linux.dev> In-Reply-To: <20250903030100.196744-1-youling.tang@linux.dev> References: <20250903030100.196744-1-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-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Youling Tang Enabling crash dump (kdump) includes: - Prepare contents of ELF header of a core dump file, /proc/vmcore, using crash_prepare_elf64_headers(). - Add "elfcorehdr=size@start" to cmdline. - Add the "mem=size@start" parameter to the command line and pass it to the capture kernel. Limit the runtime memory area of the captured kernel to avoid disrupting the production kernel's runtime state. The basic usage for kdump(add the cmdline parameter crashkernel=512M to grub.cfg): 1) Load capture kernel image(vmlinux.efi or vmlinux can also be used): # kexec -s -p vmlinuz.efi --initrd=initrd.img --reuse-cmdline 2) Do something to crash, like: # echo c > /proc/sysrq-trigger Signed-off-by: Youling Tang --- arch/loongarch/kernel/machine_kexec_file.c | 116 +++++++++++++++++++++ 1 file changed, 116 insertions(+) diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c index 81913359b7a1..907a3286fa0d 100644 --- a/arch/loongarch/kernel/machine_kexec_file.c +++ b/arch/loongarch/kernel/machine_kexec_file.c @@ -35,6 +35,82 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image) return kexec_image_post_load_cleanup_default(image); } +#ifdef CONFIG_CRASH_DUMP + +static int prepare_elf_headers(void **addr, unsigned long *sz) +{ + struct crash_mem *cmem; + unsigned int nr_ranges; + int ret; + u64 i; + phys_addr_t start, end; + + nr_ranges = 2; /* for exclusion of crashkernel region */ + for_each_mem_range(i, &start, &end) + nr_ranges++; + + cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL); + if (!cmem) + return -ENOMEM; + + cmem->max_nr_ranges = nr_ranges; + cmem->nr_ranges = 0; + for_each_mem_range(i, &start, &end) { + cmem->ranges[cmem->nr_ranges].start = start; + cmem->ranges[cmem->nr_ranges].end = end - 1; + cmem->nr_ranges++; + } + + /* Exclude crashkernel region */ + ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); + if (ret) + goto out; + + if (crashk_low_res.end) { + ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end); + if (ret) + goto out; + } + + ret = crash_prepare_elf64_headers(cmem, true, addr, sz); + +out: + kfree(cmem); + return ret; +} + +/* Adds the "elfcorehdr=size@start" command line parameter to command line. */ +static void cmdline_add_elfcorehdr(struct kimage *image, unsigned long *cmdline_tmplen, + char *modified_cmdline, unsigned long elfcorehdr_sz) +{ + int elfcorehdr_strlen = 0; + + elfcorehdr_strlen = sprintf(modified_cmdline + (*cmdline_tmplen), "elfcorehdr=0x%lx@0x%lx ", + elfcorehdr_sz, image->elf_load_addr); + *cmdline_tmplen += elfcorehdr_strlen; +} + +/* + * Adds the "mem=size@start" command line parameter to command line, indicating the + * memory region the new kernel can use to boot into. + */ +static void cmdline_add_mem(unsigned long *cmdline_tmplen, char *modified_cmdline) +{ + int mem_strlen = 0; + + mem_strlen = sprintf(modified_cmdline + (*cmdline_tmplen), "mem=0x%llx@0x%llx ", + crashk_res.end - crashk_res.start + 1, crashk_res.start); + *cmdline_tmplen += mem_strlen; + + if (crashk_low_res.end) { + mem_strlen = sprintf(modified_cmdline + (*cmdline_tmplen), "mem=0x%llx@0x%llx ", + crashk_low_res.end - crashk_low_res.start + 1, crashk_low_res.start); + *cmdline_tmplen += mem_strlen; + } +} + +#endif + /* Adds the "initrd=start,size" command line parameter to command line. */ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmplen, char *modified_cmdline, unsigned long initrd) @@ -86,6 +162,46 @@ int load_other_segments(struct kimage *image, /* Ensure it's null terminated */ modified_cmdline[COMMAND_LINE_SIZE - 1] = '\0'; +#ifdef CONFIG_CRASH_DUMP + /* load elf core header */ + void *headers; + unsigned long headers_sz; + + if (image->type == KEXEC_TYPE_CRASH) { + ret = prepare_elf_headers(&headers, &headers_sz); + if (ret) { + pr_err("Preparing elf core header failed\n"); + goto out_err; + } + + kbuf.buffer = headers; + kbuf.bufsz = headers_sz; + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; + kbuf.memsz = headers_sz; + kbuf.buf_align = SZ_64K; /* largest supported page size */ + kbuf.buf_max = ULONG_MAX; + kbuf.top_down = true; + + ret = kexec_add_buffer(&kbuf); + if (ret) { + vfree(headers); + goto out_err; + } + image->elf_headers = headers; + image->elf_load_addr = kbuf.mem; + image->elf_headers_sz = headers_sz; + + kexec_dprintk("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n", + image->elf_load_addr, kbuf.bufsz, kbuf.memsz); + + /* Add the elfcorehdr=size@start parameter to the command line */ + cmdline_add_elfcorehdr(image, &cmdline_tmplen, modified_cmdline, headers_sz); + + /* Add the mem=size@start parameter to the command line */ + cmdline_add_mem(&cmdline_tmplen, modified_cmdline); + } +#endif + /* load initrd */ if (initrd) { kbuf.buffer = initrd; -- 2.43.0