linux-kernel - Re: [PATCH 3/6] LoongArch/kexec

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Message-ID: <CAAhV-H4Sf=74-ni=qUkg3doC4iLrVt=m2bCYCgfmVC0WLNhiDQ@mail.gmail.com>
Date: Mon, 11 Aug 2025 22:12:37 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Youling Tang <youling.tang@...ux.dev>
Cc: WANG Xuerui <kernel@...0n.name>, Baoquan He <bhe@...hat.com>, kexec@...ts.infradead.org, 
	loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	Youling Tang <tangyouling@...inos.cn>
Subject: Re: [PATCH 3/6] LoongArch/kexec_file: Add initrd loading

Hi, Youling,

On Mon, Aug 11, 2025 at 5:28 PM Youling Tang <youling.tang@...ux.dev> wrote:
>
> From: Youling Tang <tangyouling@...inos.cn>
>
> Add inird loading support and pass it to the second kernel via the
> cmdline 'initrd=start,size'.
I think Patch-3 and Patch-5 should be merged into Patch-2.

Huacai

>
> Signed-off-by: Youling Tang <tangyouling@...inos.cn>
> ---
>  arch/loongarch/kernel/machine_kexec_file.c | 71 ++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
>
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index bc91ae0afa4c..e1240644f529 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -34,13 +34,84 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
>         return kexec_image_post_load_cleanup_default(image);
>  }
>
> +/* 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)
> +{
> +       int initrd_strlen;
> +
> +       initrd_strlen = sprintf(modified_cmdline + (*cmdline_tmplen), "initrd=0x%lx,0x%lx ",
> +               initrd, image->initrd_buf_len);
> +       *cmdline_tmplen += initrd_strlen;
> +}
> +
> +/*
> + * Tries 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.
> + */
>  int load_other_segments(struct kimage *image,
>                         unsigned long kernel_load_addr,
>                         unsigned long kernel_size,
>                         char *initrd, unsigned long initrd_len,
>                         char *cmdline, unsigned long cmdline_len)
>  {
> +       struct kexec_buf kbuf;
> +       unsigned long orig_segments = image->nr_segments;
> +       char *modified_cmdline = NULL;
> +       unsigned long cmdline_tmplen = 0;
> +       unsigned long initrd_load_addr = 0;
> +       int ret = 0;
> +
> +
> +       kbuf.image = image;
> +       /* not allocate anything below the kernel */
> +       kbuf.buf_min = kernel_load_addr + kernel_size;
> +
> +       modified_cmdline = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
> +       if (!modified_cmdline)
> +               return -EINVAL;
> +
> +       /* Ensure it's nul terminated */
> +       modified_cmdline[COMMAND_LINE_SIZE - 1] = '\0';
> +
> +       /* load initrd */
> +       if (initrd) {
> +               kbuf.buffer = initrd;
> +               kbuf.bufsz = initrd_len;
> +               kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
> +               kbuf.memsz = initrd_len;
> +               kbuf.buf_align = 0;
> +               /* within 1GB-aligned window of up to 32GB in size */
> +               kbuf.buf_max = round_down(kernel_load_addr, SZ_1G)
> +                                               + (unsigned long)SZ_1G * 32;
> +               kbuf.top_down = false;
> +
> +               ret = kexec_add_buffer(&kbuf);
> +               if (ret)
> +                       goto out_err;
> +               initrd_load_addr = kbuf.mem;
> +
> +               kexec_dprintk("Loaded initrd at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
> +                             initrd_load_addr, kbuf.bufsz, kbuf.memsz);
> +
> +               /* Add the initrd=start,size parameter to the command line */
> +               cmdline_add_initrd(image, &cmdline_tmplen, modified_cmdline, initrd_load_addr);
> +       }
> +
> +       if (cmdline_len + cmdline_tmplen > COMMAND_LINE_SIZE) {
> +               pr_err("Appending kdump cmdline exceeds cmdline size\n");
> +               ret = -EINVAL;
> +               goto out_err;
> +       }
> +       memcpy(modified_cmdline + cmdline_tmplen, cmdline, cmdline_len);
> +       cmdline = modified_cmdline;
>         image->arch.cmdline_ptr = (unsigned long)cmdline;
>
>         return 0;
> +
> +out_err:
> +       image->nr_segments = orig_segments;
> +       kfree(modified_cmdline);
> +       return ret;
>  }
> --
> 2.34.1
>