linux-kernel - Re: [PATCH] of_reserved_mem: Save region name string into struct reserved

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Message-ID: <CAL_JsqLeVPBz4mEedXEm=rb6ghWwROB7jr-PDw3qVsNRz20Z_A@mail.gmail.com>
Date: Mon, 26 Aug 2024 09:09:31 -0500
From: Rob Herring <robh@...nel.org>
To: Jiaxun Yang <jiaxun.yang@...goat.com>
Cc: Saravana Kannan <saravanak@...gle.com>, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev, 
	chenhuacai@...nel.org, Kevin Wheatfox <enkerewpo@...mail.com>
Subject: Re: [PATCH] of_reserved_mem: Save region name string into struct reserved_mem

On Wed, Aug 21, 2024 at 8:51 AM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>
> Previously only a pointer to fdt string pool is saved to struct
> reserved_mem as region name.
>
> As on some architectures booting FDT will be wiped at later initialisation
> stages, this is breaking reserved_mem users.

What architectures? Be specific.

Why is the FDT wiped? It should be preserved and you need it later to
implement kexec.

>
> Copy and save the whole string into struct reserved_mem to avoid
> FDT lifecycle problem.
>
> Reported-by: Kevin Wheatfox <enkerewpo@...mail.com>
> Closes: https://lore.kernel.org/loongarch/ME4P282MB1397447C3C094554C7AF2E37B58E2@ME4P282MB1397.AUSP282.PROD.OUTLOOK.COM/
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> ---
>  drivers/of/of_reserved_mem.c    | 2 +-
>  include/linux/of_reserved_mem.h | 4 +++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 46e1c3fbc769..22841599cd83 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -70,7 +70,7 @@ static void __init fdt_reserved_mem_save_node(unsigned long node, const char *un
>         }
>
>         rmem->fdt_node = node;
> -       rmem->name = uname;
> +       strscpy(rmem->name, uname, RESERVED_MEM_NAME_LEN);
>         rmem->base = base;
>         rmem->size = size;
>
> diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
> index e338282da652..ed9de36c9cc9 100644
> --- a/include/linux/of_reserved_mem.h
> +++ b/include/linux/of_reserved_mem.h
> @@ -8,8 +8,10 @@
>  struct of_phandle_args;
>  struct reserved_mem_ops;
>
> +#define RESERVED_MEM_NAME_LEN  128
> +
>  struct reserved_mem {
> -       const char                      *name;
> +       char                            name[RESERVED_MEM_NAME_LEN];
>         unsigned long                   fdt_node;
>         const struct reserved_mem_ops   *ops;
>         phys_addr_t                     base;
>
> ---
> base-commit: bb1b0acdcd66e0d8eedee3570d249e076b89ab32
> change-id: 20240821-save_resv_name-4f2e2cb8883b
>
> Best regards,
> --
> Jiaxun Yang <jiaxun.yang@...goat.com>
>