[PATCH 2/2] powerpc: Show PAGE_SIZE in __die() output

[Christophe Leroy]

Le 08/01/2019 à 13:21, Christophe Leroy a écrit :
> 
> 
> Le 08/01/2019 à 13:05, Michael Ellerman a écrit :
>> The page size the kernel is built with is useful info when debugging a
>> crash, so add it to the output in __die().
>>
>> Result looks like eg:
>>
>>    kernel BUG at drivers/misc/lkdtm/bugs.c:63!
>>    Oops: Exception in kernel mode, sig: 5 [#1]
>>    LE PAGE_SIZE=64K SMP NR_CPUS=2048 NUMA pSeries
>>    Modules linked in: vmx_crypto kvm binfmt_misc ip_tables
>>
>> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
>> ---
>>   arch/powerpc/kernel/traps.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>> index 431a86d3f772..fc972e4eee5f 100644
>> --- a/arch/powerpc/kernel/traps.c
>> +++ b/arch/powerpc/kernel/traps.c
>> @@ -268,6 +268,18 @@ static int __die(const char *str, struct pt_regs 
>> *regs, long err)
>>       else
>>           seq_buf_puts(&s, "BE ");
>> +    seq_buf_puts(&s, "PAGE_SIZE=");
>> +    if (IS_ENABLED(CONFIG_PPC_4K_PAGES))
>> +        seq_buf_puts(&s, "4K ");
>> +    else if (IS_ENABLED(CONFIG_PPC_16K_PAGES))
>> +        seq_buf_puts(&s, "16K ");
>> +    else if (IS_ENABLED(CONFIG_PPC_64K_PAGES))
>> +        seq_buf_puts(&s, "64K ");
>> +    else if (IS_ENABLED(CONFIG_PPC_256K_PAGES))
>> +        seq_buf_puts(&s, "256K ");
> 
> Can't we build all the above at once using PAGE_SHIFT ?
> 
> Something like (untested):
> 
> "%dK ", 1 << (PAGE_SHIFT - 10)

Or even simplier:

"%dK ", PAGE_SIZE / 1024

Christophe


> 
> Christophe
> 
>> +    else
>> +        BUILD_BUG_ON(1);
>> +
>>       if (IS_ENABLED(CONFIG_PREEMPT))
>>           seq_buf_puts(&s, "PREEMPT ");
>>