[PATCH v2 4/5] powerpc/fadump: Make ELF eflags depend on endian

[Mahesh Jagannath Salgaonkar]

On 09/08/2016 12:30 PM, Mahesh Jagannath Salgaonkar wrote:
> On 09/06/2016 11:02 AM, Daniel Axtens wrote:
>> Firmware Assisted Dump is a facility to dump kernel core with assistance
>> from firmware.  As part of this process the kernel ELF version is
>> stored.
>>
>> Currently, fadump.h defines this to 0 if it is not already defined. This
>> clashes with a define in elf.h which sets it based on the current task -
>> not based on the kernel.
>>
>> When the kernel is compiled on LE, the kernel will always be version
>> 2. Otherwise it will be version 0. So the correct behaviour is to set
>> the ELF eflags based on the endianness of the kernel. Do that.
>>
>> Remove the definition in fadump.h, which becomes unused.
>>
>> Cc: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
>> Cc: Hari Bathini <hbathini at linux.vnet.ibm.com>
>> Signed-off-by: Daniel Axtens <dja at axtens.net>
>>
>> ---
>>
>> Mahesh or Hari: I'm not familiar with this code at all, so if either of
>> you could check that this makes sense I would really appreciate that.
>> Thanks!
>> ---
>>  arch/powerpc/include/asm/fadump.h | 4 ----
>>  arch/powerpc/kernel/fadump.c      | 6 +++++-
>>  2 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/fadump.h b/arch/powerpc/include/asm/fadump.h
>> index b4407d0add27..0031806475f0 100644
>> --- a/arch/powerpc/include/asm/fadump.h
>> +++ b/arch/powerpc/include/asm/fadump.h
>> @@ -45,10 +45,6 @@
>>
>>  #define memblock_num_regions(memblock_type)	(memblock.memblock_type.cnt)
>>
>> -#ifndef ELF_CORE_EFLAGS
>> -#define ELF_CORE_EFLAGS 0
>> -#endif
>> -
>>  /* Firmware provided dump sections */
>>  #define FADUMP_CPU_STATE_DATA	0x0001
>>  #define FADUMP_HPTE_REGION	0x0002
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index 0638b82ce294..457f08e544c6 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -779,7 +779,11 @@ static int fadump_init_elfcore_header(char *bufp)
>>  	elf->e_entry = 0;
>>  	elf->e_phoff = sizeof(struct elfhdr);
>>  	elf->e_shoff = 0;
>> -	elf->e_flags = ELF_CORE_EFLAGS;
>> +#ifdef __LITTLE_ENDIAN__
> 
> Wouldn't '#ifdef PPC64_ELF_ABI_v2' be more appropriate here ?

Hari just pointed out to me that the upstream commit
[https://git.kernel.org/cgit/linux/kernel/git/powerpc/linux.git/commit/?id=918d0355]
introduces ELF_CORE_EFLAGS with correct values.

May be we are just fine by including <asm/elf.h> in fadump.h along with
your first hunk. What do you say?

Thanks,
-Mahesh.

> 
>> +	elf->e_flags = 2;
>> +#else
>> +	elf->e_flags = 0;
>> +#endif
>>  	elf->e_ehsize = sizeof(struct elfhdr);
>>  	elf->e_phentsize = sizeof(struct elf_phdr);
>>  	elf->e_phnum = 0;
>>
> 
> Reviewed-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> 
> Thanks,
> -Mahesh.
> 
>