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

[Randy Dunlap]

On 2/3/21 7:57 PM, Jinyang He wrote:
> On 02/04/2021 11:28 AM, Randy Dunlap wrote:
> 
>> 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@xxxxxxxxxxx>
>> Hm, looks like that would require CONFIG_CRASH_DUMP?
> Hi,
> 
> I don't think so. We expect to generate a /proc/vmcore when we reserved
> memory for elfcorehdr. So put it under CONFIG_PROC_VMCORE. If only rely
> on CONFIG_CRASH_DUMP and CONFIG_PROC_VMCORE is not enabled, we will
> reserve these memory while cannot use these later. And the reason why
> kernel/crash_dump.c being under CONFIG_CRASH_DUMP is that it provide
> is_kdump_kernel() for others.
> 
> Thanks,
> Jinyang

Hi,

I'm referring to kernel/Makefile:

obj-$(CONFIG_CRASH_DUMP) += crash_dump.o

so that's not an issue here?  Please explain.

>>> ---
>>>   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