Commit 1bcca862 authored by Youling Tang's avatar Youling Tang Committed by Huacai Chen
Browse files

LoongArch: Add crash dump support for kexec_file 



Enabling crash dump (kdump) includes:
- Prepare contents of ELF header of a core dump file, /proc/vmcore,
  using crash_prepare_elf64_headers().
- Add "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.
- Add "elfcorehdr=size@start" parameter to the cmdline.

The basic usage for kdump (add the cmdline parameter crashkernel=512M
to grub.cfg for production kernel):

1) Load capture kernel image (vmlinux.efi or vmlinux can both 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: default avatarYouling Tang <tangyouling@kylinos.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent fc9c112f

arch/loongarch/kernel/machine_kexec_file.c

+115 −0
Original line number Diff line number Diff line
@@ -55,6 +55,81 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl 
	*cmdline_tmplen += initrd_strlen;

}



#ifdef CONFIG_CRASH_DUMP



static int prepare_elf_headers(void **addr, unsigned long *sz)

{

	int ret, nr_ranges;

	uint64_t i;

	phys_addr_t start, end;

	struct crash_mem *cmem;



	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 < 0)

		goto out;



	if (crashk_low_res.end) {

		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);

		if (ret < 0)

			goto out;

	}



	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);



out:

	kfree(cmem);

	return ret;

}



/*

 * Add 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;

	}

}



/* Add 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;

}



#endif



/*

 * Try to add the initrd to the image. If it is not possible to find valid

 * locations, this function will undo changes to the image and return non zero.
@@ -82,6 +157,46 @@ 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 */

	if (image->type == KEXEC_TYPE_CRASH) {

		void *headers;

		unsigned long headers_sz;



		ret = prepare_elf_headers(&headers, &headers_sz);

		if (ret < 0) {

			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 < 0) {

			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 mem=size@start parameter to the command line */

		cmdline_add_mem(&cmdline_tmplen, modified_cmdline);



		/* Add the elfcorehdr=size@start parameter to the command line */

		cmdline_add_elfcorehdr(image, &cmdline_tmplen, modified_cmdline, headers_sz);

	}

#endif



	/* Load initrd */

	if (initrd) {

		kbuf.buffer = initrd;