* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-11 14:58 [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use Aneesh Kumar K.V
@ 2019-07-12 0:43 ` Nicholas Piggin
2019-07-12 5:31 ` Christophe Leroy
` (2 subsequent siblings)
3 siblings, 0 replies; 8+ messages in thread
From: Nicholas Piggin @ 2019-07-12 0:43 UTC (permalink / raw)
To: Aneesh Kumar K.V, mpe, paulus; +Cc: linuxppc-dev
Aneesh Kumar K.V's on July 12, 2019 12:58 am:
> 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@linux.ibm.com>
> ---
>
> Changes from V1:
> * Don't clear the HPTE feature flag.
Thanks,
Acked-by: Nicholas Piggin <npiggin@gmail.com>
>
> 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)) : "",
> --
> 2.21.0
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-11 14:58 [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use Aneesh Kumar K.V
2019-07-12 0:43 ` Nicholas Piggin
@ 2019-07-12 5:31 ` Christophe Leroy
2019-07-12 6:25 ` Michael Ellerman
2019-11-14 9:07 ` Michael Ellerman
3 siblings, 0 replies; 8+ messages in thread
From: Christophe Leroy @ 2019-07-12 5:31 UTC (permalink / raw)
To: Aneesh Kumar K.V, npiggin, paulus, mpe; +Cc: linuxppc-dev
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@linux.ibm.com>
Looks good.
Reviewed-by: Christophe Leroy <christophe.leroy@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)) : "",
>
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-11 14:58 [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use Aneesh Kumar K.V
2019-07-12 0:43 ` Nicholas Piggin
2019-07-12 5:31 ` Christophe Leroy
@ 2019-07-12 6:25 ` Michael Ellerman
2019-07-12 6:48 ` Christophe Leroy
2019-11-14 9:07 ` Michael Ellerman
3 siblings, 1 reply; 8+ messages in thread
From: Michael Ellerman @ 2019-07-12 6:25 UTC (permalink / raw)
To: Aneesh Kumar K.V, npiggin, paulus; +Cc: Aneesh Kumar K.V, linuxppc-dev
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> 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@linux.ibm.com>
> ---
>
> 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 "";
> +}
We don't change MMU once we're up, so just do this logic once and stash
it into a static string, rather than rechecking on every oops.
cheers
> 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)) : "",
> --
> 2.21.0
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-12 6:25 ` Michael Ellerman
@ 2019-07-12 6:48 ` Christophe Leroy
2019-07-12 12:22 ` Michael Ellerman
0 siblings, 1 reply; 8+ messages in thread
From: Christophe Leroy @ 2019-07-12 6:48 UTC (permalink / raw)
To: Michael Ellerman, Aneesh Kumar K.V, npiggin, paulus; +Cc: linuxppc-dev
Le 12/07/2019 à 08:25, Michael Ellerman a écrit :
> "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
>
>> 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@linux.ibm.com>
>> ---
>>
>> 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 "";
>> +}
>
> We don't change MMU once we're up, so just do this logic once and stash
> it into a static string, rather than rechecking on every oops.
Do we really have oops so often that we have to worry about that ?
Christophe
>
> cheers
>
>> 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)) : "",
>> --
>> 2.21.0
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-12 6:48 ` Christophe Leroy
@ 2019-07-12 12:22 ` Michael Ellerman
2019-07-12 12:25 ` Christophe Leroy
0 siblings, 1 reply; 8+ messages in thread
From: Michael Ellerman @ 2019-07-12 12:22 UTC (permalink / raw)
To: Christophe Leroy, Aneesh Kumar K.V, npiggin, paulus; +Cc: linuxppc-dev
Christophe Leroy <christophe.leroy@c-s.fr> writes:
> Le 12/07/2019 à 08:25, Michael Ellerman a écrit :
>> "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
...
>>> 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 "";
>>> +}
>>
>> We don't change MMU once we're up, so just do this logic once and stash
>> it into a static string, rather than rechecking on every oops.
>
> Do we really have oops so often that we have to worry about that ?
Sometimes :)
But no I don't mean it's a performance issue, it just seems simpler to
compute the value once and store it. In fact for most platforms it can
just be a static string at compile time, it's only 64-bit Book3S that
needs to do anything at runtime.
cheers
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-12 12:22 ` Michael Ellerman
@ 2019-07-12 12:25 ` Christophe Leroy
0 siblings, 0 replies; 8+ messages in thread
From: Christophe Leroy @ 2019-07-12 12:25 UTC (permalink / raw)
To: Michael Ellerman, Aneesh Kumar K.V, npiggin, paulus; +Cc: linuxppc-dev
Le 12/07/2019 à 14:22, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>> Le 12/07/2019 à 08:25, Michael Ellerman a écrit :
>>> "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> ...
>>>> 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 "";
>>>> +}
>>>
>>> We don't change MMU once we're up, so just do this logic once and stash
>>> it into a static string, rather than rechecking on every oops.
>>
>> Do we really have oops so often that we have to worry about that ?
>
> Sometimes :)
>
> But no I don't mean it's a performance issue, it just seems simpler to
> compute the value once and store it. In fact for most platforms it can
> just be a static string at compile time, it's only 64-bit Book3S that
> needs to do anything at runtime.
Right, but I'm sure GCC will take care of that since the function is
static and called only once.
Christophe
>
> cheers
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
2019-07-11 14:58 [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use Aneesh Kumar K.V
` (2 preceding siblings ...)
2019-07-12 6:25 ` Michael Ellerman
@ 2019-11-14 9:07 ` Michael Ellerman
3 siblings, 0 replies; 8+ messages in thread
From: Michael Ellerman @ 2019-11-14 9:07 UTC (permalink / raw)
To: Aneesh Kumar K.V, npiggin, paulus; +Cc: Aneesh Kumar K.V, linuxppc-dev
On Thu, 2019-07-11 at 14:58:14 UTC, "Aneesh Kumar K.V" wrote:
> 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@linux.ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/d7e02f7b7991dbe14a2acfb0e53d675cd149001c
cheers
^ permalink raw reply [flat|nested] 8+ messages in thread