[PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use

[Christophe Leroy]

Le 11/07/2019 à 16:58, Aneesh Kumar K.V a écrit :
> Avoids confusion when printing Oops message like below
> 
>   Faulting instruction address: 0xc00000000008bdb4
>   Oops: Kernel access of bad area, sig: 11 [#1]
>   LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
> 
> This was because we never clear the MMU_FTR_HPTE_TABLE feature flag
> even if we run with radix translation. It was discussed that we should
> look at this feature flag as an indication of the capability to run
> hash translation and we should not clear the flag even if we run in
> radix translation. All the code paths check for radix_enabled() check and
> if found true consider we are running with radix translation. Follow the
> same sequence for finding the MMU translation string to be used in Oops
> message.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>

Looks good.

Reviewed-by: Christophe Leroy <christophe.leroy at c-s.fr>

> ---
> 
> Changes from V1:
> * Don't clear the HPTE feature flag.
> 
>   arch/powerpc/kernel/traps.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index 11caa0291254..b181d6860f28 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -250,15 +250,22 @@ static void oops_end(unsigned long flags, struct pt_regs *regs,
>   }
>   NOKPROBE_SYMBOL(oops_end);
>   
> +static char *get_mmu_str(void)
> +{
> +	if (early_radix_enabled())
> +		return " MMU=Radix";
> +	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
> +		return " MMU=Hash";
> +	return "";
> +}
> +
>   static int __die(const char *str, struct pt_regs *regs, long err)
>   {
>   	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
>   
> -	printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s%s %s\n",
> +	printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n",
>   	       IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
> -	       PAGE_SIZE / 1024,
> -	       early_radix_enabled() ? " MMU=Radix" : "",
> -	       early_mmu_has_feature(MMU_FTR_HPTE_TABLE) ? " MMU=Hash" : "",
> +	       PAGE_SIZE / 1024, get_mmu_str(),
>   	       IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
>   	       IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
>   	       IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
>