Re: [PATCH v4 2/3] powerpc/fadump: Use the correct VMCOREINFO_NOTE_SIZE for phdr

[Mahesh Jagannath Salgaonkar]

On 04/26/2017 12:41 PM, Dave Young wrote:
> Ccing ppc list
> On 04/20/17 at 07:39pm, Xunlei Pang wrote:
>> vmcoreinfo_max_size stands for the vmcoreinfo_data, the
>> correct one we should use is vmcoreinfo_note whose total
>> size is VMCOREINFO_NOTE_SIZE.
>>
>> Like explained in commit 77019967f06b ("kdump: fix exported
>> size of vmcoreinfo note"), it should not affect the actual
>> function, but we better fix it, also this change should be
>> safe and backward compatible.
>>
>> After this, we can get rid of variable vmcoreinfo_max_size,
>> let's use the corresponding macros directly, fewer variables
>> means more safety for vmcoreinfo operation.
>>
>> Cc: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>
>> Cc: Hari Bathini <hbathini@xxxxxxxxxxxxxxxxxx>
>> Signed-off-by: Xunlei Pang <xlpang@xxxxxxxxxx>

Reviewed-by: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx>

Thanks,
-Mahesh.

>> ---
>> v3->v4:
>> -Rebased on the latest linux-next
>>
>>  arch/powerpc/kernel/fadump.c | 3 +--
>>  include/linux/crash_core.h   | 1 -
>>  kernel/crash_core.c          | 3 +--
>>  3 files changed, 2 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index 466569e..7bd6cd0 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -893,8 +893,7 @@ static int fadump_create_elfcore_headers(char *bufp)
>>  
>>  	phdr->p_paddr	= fadump_relocate(paddr_vmcoreinfo_note());
>>  	phdr->p_offset	= phdr->p_paddr;
>> -	phdr->p_memsz	= vmcoreinfo_max_size;
>> -	phdr->p_filesz	= vmcoreinfo_max_size;
>> +	phdr->p_memsz	= phdr->p_filesz = VMCOREINFO_NOTE_SIZE;
>>  
>>  	/* Increment number of program headers. */
>>  	(elf->e_phnum)++;
>> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
>> index ba283a2..7d6bc7b 100644
>> --- a/include/linux/crash_core.h
>> +++ b/include/linux/crash_core.h
>> @@ -55,7 +55,6 @@
>>  
>>  extern u32 *vmcoreinfo_note;
>>  extern size_t vmcoreinfo_size;
>> -extern size_t vmcoreinfo_max_size;
>>  
>>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>>  			  void *data, size_t data_len);
>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
>> index 0321f04..43cdb00 100644
>> --- a/kernel/crash_core.c
>> +++ b/kernel/crash_core.c
>> @@ -16,7 +16,6 @@
>>  /* vmcoreinfo stuff */
>>  static unsigned char *vmcoreinfo_data;
>>  size_t vmcoreinfo_size;
>> -size_t vmcoreinfo_max_size = VMCOREINFO_BYTES;
>>  u32 *vmcoreinfo_note;
>>  
>>  /*
>> @@ -343,7 +342,7 @@ void vmcoreinfo_append_str(const char *fmt, ...)
>>  	r = vscnprintf(buf, sizeof(buf), fmt, args);
>>  	va_end(args);
>>  
>> -	r = min(r, vmcoreinfo_max_size - vmcoreinfo_size);
>> +	r = min(r, VMCOREINFO_BYTES - vmcoreinfo_size);
>>  
>>  	memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
>>  
>> -- 
>> 1.8.3.1
>>
>>
>> _______________________________________________
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> 
> Reviewed-by: Dave Young <dyoung@xxxxxxxxxx>
> 
> Thanks
> Dave
>