Re: [PATCH v16 06/10] riscv: kexec_file: Use crash_prepare_headers() helper to simplify code

On 6/8/2026 3:34 PM, Jinjie Ruan wrote:
> Use the newly introduced crash_prepare_headers() function to replace
> the existing prepare_elf_headers(), allocate cmem and exclude crash kernel
> memory in the crash core, which reduce code duplication.
> 
> Only the following two architecture functions need to be implemented:
> - arch_get_system_nr_ranges(). Call get_nr_ram_ranges_callback()
>   to pre-counts the max number of memory ranges.
> 
> - arch_crash_populate_cmem(). Use prepare_elf64_ram_headers_callback()
>   to collects the memory ranges and fills them into cmem.

Hi Paul, Palmer, Albert, Alexandre and RISC-V maintainers,

Sorry for the interruption.

This patch set aims to clean up and refactor the crash memory allocation
and the exclusion logic of crashk_res, crashk_low_res, and crashk_cma.
Currently, these  routines are almost identical across different
architectures, leading to a lot of duplicated code.

This series consolidates the logic into the generic crash core, removing
redundant implementations from architecture-specific directories,
including arch/riscv.

There are no functional changes intended for RISC-V.

The patches will be queued in the liveupdate tree for wider testing.
Could you please take a look at the RISC-V side and consider providing
an Acked-by?

The patch series can be reviewed here:

https://lore.kernel.org/all/[email protected]/

Thank you very much for your time and review!

Best regards,
Jinjie

> 
> Cc: Paul Walmsley <[email protected]>
> Cc: Palmer Dabbelt <[email protected]>
> Cc: Albert Ou <[email protected]>
> Cc: Alexandre Ghiti <[email protected]>
> Cc: Guo Ren <[email protected]>
> Reviewed-by: Sourabh Jain <[email protected]>
> Acked-by: Baoquan He <[email protected]>
> Acked-by: Mike Rapoport (Microsoft) <[email protected]>
> Signed-off-by: Jinjie Ruan <[email protected]>
> ---
>  arch/riscv/kernel/machine_kexec_file.c | 47 +++++++-------------------
>  1 file changed, 12 insertions(+), 35 deletions(-)
> 
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index 3f7766057cac..439cbc50dfa6 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> +unsigned int arch_get_system_nr_ranges(void)
> +{
> +	unsigned int nr_ranges = 2; /* For exclusion of crashkernel region */
> +
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +
> +	return nr_ranges;
> +}
> +
>  static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  {
>  	struct crash_mem *cmem = arg;
> @@ -55,41 +64,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -
> -	nr_ranges = 2; /* For exclusion of crashkernel region */
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	cmem->max_nr_ranges = nr_ranges;
> -	cmem->nr_ranges = 0;
> -	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
> -	if (ret)
> -		goto out;
> -
> -	/* 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;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>  }
>  
>  static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
> @@ -281,7 +258,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
>  	if (image->type == KEXEC_TYPE_CRASH) {
>  		void *headers;
>  		unsigned long headers_sz;
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out;