linux-kernel - Re: [PATCH] MIPS: Use common way to parse elfcorehdr

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Message-ID: <57e74a56-abc1-dbc0-1277-5effb0e4e4c6@infradead.org>
Date:   Wed, 3 Feb 2021 19:28:42 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Jinyang He <hejinyang@...ngson.cn>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Use common way to parse elfcorehdr

On 2/3/21 7:07 PM, Jinyang He wrote:
> "elfcorehdr" can be parsed at kernel/crash_dump.c
> 
> Signed-off-by: Jinyang He <hejinyang@...ngson.cn>

Hm, looks like that would require CONFIG_CRASH_DUMP?


> ---
>  arch/mips/kernel/setup.c | 49 +++++++++++++++++++++---------------------------
>  1 file changed, 21 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 7e1f8e2..4d2f915 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -29,6 +29,7 @@
>  #include <linux/of_fdt.h>
>  #include <linux/of_reserved_mem.h>
>  #include <linux/dmi.h>
> +#include <linux/crash_dump.h>
>  
>  #include <asm/addrspace.h>
>  #include <asm/bootinfo.h>
> @@ -404,34 +405,32 @@ static int __init early_parse_memmap(char *p)
>  }
>  early_param("memmap", early_parse_memmap);
>  
> -#ifdef CONFIG_PROC_VMCORE
> -static unsigned long setup_elfcorehdr, setup_elfcorehdr_size;
> -static int __init early_parse_elfcorehdr(char *p)
> +static void __init mips_reserve_vmcore(void)
>  {
> +#ifdef CONFIG_PROC_VMCORE
>  	phys_addr_t start, end;
>  	u64 i;
>  
> -	setup_elfcorehdr = memparse(p, &p);
> -
> -	for_each_mem_range(i, &start, &end) {
> -		if (setup_elfcorehdr >= start && setup_elfcorehdr < end) {
> -			/*
> -			 * Reserve from the elf core header to the end of
> -			 * the memory segment, that should all be kdump
> -			 * reserved memory.
> -			 */
> -			setup_elfcorehdr_size = end - setup_elfcorehdr;
> -			break;
> +	if (!elfcorehdr_size) {
> +		for_each_mem_range(i, &start, &end) {
> +			if (elfcorehdr_addr >= start && elfcorehdr_addr < end) {
> +				/*
> +				 * Reserve from the elf core header to the end of
> +				 * the memory segment, that should all be kdump
> +				 * reserved memory.
> +				 */
> +				elfcorehdr_size = end - elfcorehdr_addr;
> +				break;
> +			}
>  		}
>  	}
> -	/*
> -	 * If we don't find it in the memory map, then we shouldn't
> -	 * have to worry about it, as the new kernel won't use it.
> -	 */
> -	return 0;
> -}
> -early_param("elfcorehdr", early_parse_elfcorehdr);
> +
> +	pr_info("Reserving %ldKB of memory at %ldKB for kdump\n",
> +		(unsigned long)elfcorehdr_size >> 10, (unsigned long)elfcorehdr_addr >> 10);
> +
> +	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
>  #endif
> +}
>  
>  #ifdef CONFIG_KEXEC
>  
> @@ -653,13 +652,7 @@ static void __init arch_mem_init(char **cmdline_p)
>  	 */
>  	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
>  
> -#ifdef CONFIG_PROC_VMCORE
> -	if (setup_elfcorehdr && setup_elfcorehdr_size) {
> -		printk(KERN_INFO "kdump reserved memory at %lx-%lx\n",
> -		       setup_elfcorehdr, setup_elfcorehdr_size);
> -		memblock_reserve(setup_elfcorehdr, setup_elfcorehdr_size);
> -	}
> -#endif
> +	mips_reserve_vmcore();
>  
>  	mips_parse_crashkernel();
>  #ifdef CONFIG_KEXEC
> 


-- 
~Randy