linux-kernel - Re: [PATCH] vmcore: replace Elf64_Ehdr/Elf32

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Message-ID: <55FA88BD.3050303@windriver.com>
Date:	Thu, 17 Sep 2015 17:32:45 +0800
From:	yjin <yanjiang.jin@...driver.com>
To:	Minfei Huang <mhuang@...hat.com>
CC:	<akpm@...ux-foundation.org>, <chaowang@...hat.com>,
	<linux-kernel@...r.kernel.org>, <jinyanjiang@...il.com>,
	<kexec@...ts.infradead.org>
Subject: Re: [PATCH] vmcore: replace Elf64_Ehdr/Elf32_Ehdr with elfhdr


On 2015年09月16日 18:39, Minfei Huang wrote:
> On 09/16/15 at 10:58am, yanjiang.jin@...driver.com wrote:
>> From: Yanjiang Jin <yanjiang.jin@...driver.com>
>>
>> Function parse_crash_elf_headers() reads e_ident[EI_CLASS] then decides to
>> call parse_crash_elf64_headers() or parse_crash_elf32_headers().
>> But this happens in run time, not compile time. So compiler will report
>> the below warning:
>>
>> In file included from include/linux/elf.h:4:0,
>>                   from fs/proc/vmcore.c:13:
>> fs/proc/vmcore.c: In function 'parse_crash_elf32_headers':
>> arch/mips/include/asm/elf.h:258:23: warning: initializatio
>> n from incompatible pointer type
>>    struct elfhdr *__h = (hdr);     \
>>                         ^
> How about converting the hdr to type elfhdr in above sentence, like
> following.
>
> struct elfhdr *__h = (struct elfhdr *)(hdr);

Yes, this is a replacement, and it seems more safe because it just 
affects MIPS arch.
But I also can't see any obvious impact if modifying common vmcore.c:-)
Anyway, if you stick to your opinion, I can send a V2 patch to update 
mips' elf.h rather than vmcore.c.

Thanks!
Yanjiang
>
> Thanks
> Minfei
>
>> fs/proc/vmcore.c:1071:4: note: in expansion of macro 'elf_
>> check_arch'
>>     !elf_check_arch(&ehdr) ||
>>      ^
>>
>> Signed-off-by: Yanjiang Jin <yanjiang.jin@...driver.com>
>> ---
>>   fs/proc/vmcore.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
>> index 4e61388..576bb26 100644
>> --- a/fs/proc/vmcore.c
>> +++ b/fs/proc/vmcore.c
>> @@ -999,7 +999,7 @@ static void free_elfcorebuf(void)
>>   static int __init parse_crash_elf64_headers(void)
>>   {
>>   	int rc=0;
>> -	Elf64_Ehdr ehdr;
>> +	struct elfhdr ehdr;
>>   	u64 addr;
>>   
>>   	addr = elfcorehdr_addr;
>> @@ -1055,7 +1055,7 @@ fail:
>>   static int __init parse_crash_elf32_headers(void)
>>   {
>>   	int rc=0;
>> -	Elf32_Ehdr ehdr;
>> +	struct elfhdr ehdr;
>>   	u64 addr;
>>   
>>   	addr = elfcorehdr_addr;

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