On 04/09/19 2:32 PM, Mahesh Jagannath Salgaonkar wrote:
> On 9/3/19 9:35 PM, Hari Bathini wrote:
>>
>>
>> On 03/09/19 4:39 PM, Michael Ellerman wrote:
>>> Hari Bathini <hbath...@linux.ibm.com> writes:
>>>> Make way for refactoring platform specific FADump code by moving code
>>>> that could be referenced from multiple places to fadump-common.c file.
>>>>
>>>> Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
>>>> ---
>>>> arch/powerpc/kernel/Makefile | 2
>>>> arch/powerpc/kernel/fadump-common.c | 140
>>>> ++++++++++++++++++++++++++++++++++
>>>> arch/powerpc/kernel/fadump-common.h | 8 ++
>>>> arch/powerpc/kernel/fadump.c | 146
>>>> ++---------------------------------
>>>> 4 files changed, 158 insertions(+), 138 deletions(-)
>>>> create mode 100644 arch/powerpc/kernel/fadump-common.c
>>>
>>> I don't understand why we need fadump.c and fadump-common.c? They're
>>> both common/shared across pseries & powernv aren't they?
>>
>> The convention I tried to follow to have fadump-common.c shared between
>> fadump.c,
>> pseries & powernv code while pseries & powernv code take callback requests
>> from
>> fadump.c and use fadump-common.c (shared by both platforms), if necessary to
>> fullfil
>> those requests...
>>
>>> By the end of the series we end up with 149 lines in fadump-common.c
>>> which seems like a waste of time. Just put it all in fadump.c.
>>
>> Yeah. Probably not worth a new C file. Will just have two separate headers.
>> One for
>> internal code and one for interfacing with other modules...
>>
>> [...]
>>
>>>> + * Copyright 2019, IBM Corp.
>>>> + * Author: Hari Bathini <hbath...@linux.ibm.com>
>>>
>>> These can just be:
>>>
>>> * Copyright 2011, Mahesh Salgaonkar, IBM Corporation.
>>> * Copyright 2019, Hari Bathini, IBM Corporation.
>>>
>>
>> Sure.
>>
>>>> + */
>>>> +
>>>> +#undef DEBUG
>>>
>>> Don't undef DEBUG please.
>>>
>>
>> Sorry! Seeing such thing in most files, I thought this was the convention.
>> Will drop
>> this change in all the new files I added.
>>
>>>> +#define pr_fmt(fmt) "fadump: " fmt
>>>> +
>>>> +#include <linux/memblock.h>
>>>> +#include <linux/elf.h>
>>>> +#include <linux/mm.h>
>>>> +#include <linux/crash_core.h>
>>>> +
>>>> +#include "fadump-common.h"
>>>> +
>>>> +void *fadump_cpu_notes_buf_alloc(unsigned long size)
>>>> +{
>>>> + void *vaddr;
>>>> + struct page *page;
>>>> + unsigned long order, count, i;
>>>> +
>>>> + order = get_order(size);
>>>> + vaddr = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
>>>> + if (!vaddr)
>>>> + return NULL;
>>>> +
>>>> + count = 1 << order;
>>>> + page = virt_to_page(vaddr);
>>>> + for (i = 0; i < count; i++)
>>>> + SetPageReserved(page + i);
>>>> + return vaddr;
>>>> +}
>>>
>>> I realise you're just moving this code, but why do we need all this hand
>>> rolled allocation stuff?
>>
>> Yeah, I think alloc_pages_exact() may be better here. Mahesh, am I missing
>> something?
>
> We hook up the physical address of this buffer to ELF core header as
> PT_NOTE section. Hence we don't want these pages to be moved around or
> reclaimed.
alloc_pages_exact() + mark_page_reserved() should take care of that, I guess..
- Hari
