* [PATCH v2] powerpc/mm: Add mask of always present MMU features
@ 2020-10-12 15:39 Christophe Leroy
2020-10-21 10:32 ` Christophe Leroy
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2020-10-12 15:39 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
Cc: linux-kernel, linuxppc-dev
On the same principle as commit 773edeadf672 ("powerpc/mm: Add mask
of possible MMU features"), add mask for MMU features that are
always there in order to optimise out dead branches.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v2: Features must be anded with MMU_FTRS_POSSIBLE instead of ~0, otherwise
MMU_FTRS_ALWAYS is ~0 when no #ifdef matches.
---
arch/powerpc/include/asm/mmu.h | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 255a1837e9f7..64e7e7f7cda9 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -201,8 +201,30 @@ enum {
0,
};
+enum {
+ MMU_FTRS_ALWAYS =
+#ifdef CONFIG_PPC_8xx
+ MMU_FTR_TYPE_8xx &
+#endif
+#ifdef CONFIG_40x
+ MMU_FTR_TYPE_40x &
+#endif
+#ifdef CONFIG_PPC_47x
+ MMU_FTR_TYPE_47x &
+#elif defined(CONFIG_44x)
+ MMU_FTR_TYPE_44x &
+#endif
+#if defined(CONFIG_E200) || defined(CONFIG_E500)
+ MMU_FTR_TYPE_FSL_E &
+#endif
+ MMU_FTRS_POSSIBLE,
+};
+
static inline bool early_mmu_has_feature(unsigned long feature)
{
+ if (MMU_FTRS_ALWAYS & feature)
+ return true;
+
return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
}
@@ -231,6 +253,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
}
#endif
+ if (MMU_FTRS_ALWAYS & feature)
+ return true;
+
if (!(MMU_FTRS_POSSIBLE & feature))
return false;
--
2.25.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] powerpc/mm: Add mask of always present MMU features
2020-10-12 15:39 [PATCH v2] powerpc/mm: Add mask of always present MMU features Christophe Leroy
@ 2020-10-21 10:32 ` Christophe Leroy
2020-10-21 14:25 ` Aneesh Kumar K.V
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2020-10-21 10:32 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
Cc: linuxppc-dev, linux-kernel
Le 12/10/2020 à 17:39, Christophe Leroy a écrit :
> On the same principle as commit 773edeadf672 ("powerpc/mm: Add mask
> of possible MMU features"), add mask for MMU features that are
> always there in order to optimise out dead branches.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> v2: Features must be anded with MMU_FTRS_POSSIBLE instead of ~0, otherwise
> MMU_FTRS_ALWAYS is ~0 when no #ifdef matches.
This is still not enough. For BOOK3S/32, MMU_FTRS_POSSIBLE is still too much.
We need a #ifdef CONFIG_PPC_BOOK3S_32 with 0.
Christophe
> ---
> arch/powerpc/include/asm/mmu.h | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
> index 255a1837e9f7..64e7e7f7cda9 100644
> --- a/arch/powerpc/include/asm/mmu.h
> +++ b/arch/powerpc/include/asm/mmu.h
> @@ -201,8 +201,30 @@ enum {
> 0,
> };
>
> +enum {
> + MMU_FTRS_ALWAYS =
> +#ifdef CONFIG_PPC_8xx
> + MMU_FTR_TYPE_8xx &
> +#endif
> +#ifdef CONFIG_40x
> + MMU_FTR_TYPE_40x &
> +#endif
> +#ifdef CONFIG_PPC_47x
> + MMU_FTR_TYPE_47x &
> +#elif defined(CONFIG_44x)
> + MMU_FTR_TYPE_44x &
> +#endif
> +#if defined(CONFIG_E200) || defined(CONFIG_E500)
> + MMU_FTR_TYPE_FSL_E &
> +#endif
> + MMU_FTRS_POSSIBLE,
> +};
> +
> static inline bool early_mmu_has_feature(unsigned long feature)
> {
> + if (MMU_FTRS_ALWAYS & feature)
> + return true;
> +
> return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
> }
>
> @@ -231,6 +253,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
> }
> #endif
>
> + if (MMU_FTRS_ALWAYS & feature)
> + return true;
> +
> if (!(MMU_FTRS_POSSIBLE & feature))
> return false;
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] powerpc/mm: Add mask of always present MMU features
2020-10-21 10:32 ` Christophe Leroy
@ 2020-10-21 14:25 ` Aneesh Kumar K.V
2020-10-21 16:37 ` Christophe Leroy
0 siblings, 1 reply; 4+ messages in thread
From: Aneesh Kumar K.V @ 2020-10-21 14:25 UTC (permalink / raw)
To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman
Cc: linuxppc-dev, linux-kernel
Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 12/10/2020 à 17:39, Christophe Leroy a écrit :
>> On the same principle as commit 773edeadf672 ("powerpc/mm: Add mask
>> of possible MMU features"), add mask for MMU features that are
>> always there in order to optimise out dead branches.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>> v2: Features must be anded with MMU_FTRS_POSSIBLE instead of ~0, otherwise
>> MMU_FTRS_ALWAYS is ~0 when no #ifdef matches.
>
> This is still not enough. For BOOK3S/32, MMU_FTRS_POSSIBLE is still too much.
> We need a #ifdef CONFIG_PPC_BOOK3S_32 with 0.
>
> Christophe
>
>> ---
>> arch/powerpc/include/asm/mmu.h | 25 +++++++++++++++++++++++++
>> 1 file changed, 25 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
>> index 255a1837e9f7..64e7e7f7cda9 100644
>> --- a/arch/powerpc/include/asm/mmu.h
>> +++ b/arch/powerpc/include/asm/mmu.h
>> @@ -201,8 +201,30 @@ enum {
>> 0,
>> };
>>
>> +enum {
>> + MMU_FTRS_ALWAYS =
>> +#ifdef CONFIG_PPC_8xx
>> + MMU_FTR_TYPE_8xx &
>> +#endif
>> +#ifdef CONFIG_40x
>> + MMU_FTR_TYPE_40x &
>> +#endif
>> +#ifdef CONFIG_PPC_47x
>> + MMU_FTR_TYPE_47x &
>> +#elif defined(CONFIG_44x)
>> + MMU_FTR_TYPE_44x &
>> +#endif
>> +#if defined(CONFIG_E200) || defined(CONFIG_E500)
>> + MMU_FTR_TYPE_FSL_E &
>> +#endif
>> + MMU_FTRS_POSSIBLE,
>> +};
Will it be simpler if we make it a #define like below?
#ifdef CONFIG_PPC_8XX
#define MMU_FTR_ALWAYS MMU_FTR_TYPE_8XX & MMU_FTR_POSSIBLE
#endif
>> +
>> static inline bool early_mmu_has_feature(unsigned long feature)
>> {
>> + if (MMU_FTRS_ALWAYS & feature)
>> + return true;
>> +
>> return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
>> }
>>
>> @@ -231,6 +253,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
>> }
>> #endif
>>
>> + if (MMU_FTRS_ALWAYS & feature)
>> + return true;
>> +
>> if (!(MMU_FTRS_POSSIBLE & feature))
>> return false;
>>
>>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] powerpc/mm: Add mask of always present MMU features
2020-10-21 14:25 ` Aneesh Kumar K.V
@ 2020-10-21 16:37 ` Christophe Leroy
0 siblings, 0 replies; 4+ messages in thread
From: Christophe Leroy @ 2020-10-21 16:37 UTC (permalink / raw)
To: Aneesh Kumar K.V, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman
Cc: linuxppc-dev, linux-kernel
Le 21/10/2020 à 16:25, Aneesh Kumar K.V a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>
>> Le 12/10/2020 à 17:39, Christophe Leroy a écrit :
>>> On the same principle as commit 773edeadf672 ("powerpc/mm: Add mask
>>> of possible MMU features"), add mask for MMU features that are
>>> always there in order to optimise out dead branches.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>>> ---
>>> v2: Features must be anded with MMU_FTRS_POSSIBLE instead of ~0, otherwise
>>> MMU_FTRS_ALWAYS is ~0 when no #ifdef matches.
>>
>> This is still not enough. For BOOK3S/32, MMU_FTRS_POSSIBLE is still too much.
>> We need a #ifdef CONFIG_PPC_BOOK3S_32 with 0.
>>
>> Christophe
>>
>>> ---
>>> arch/powerpc/include/asm/mmu.h | 25 +++++++++++++++++++++++++
>>> 1 file changed, 25 insertions(+)
>>>
>>> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
>>> index 255a1837e9f7..64e7e7f7cda9 100644
>>> --- a/arch/powerpc/include/asm/mmu.h
>>> +++ b/arch/powerpc/include/asm/mmu.h
>>> @@ -201,8 +201,30 @@ enum {
>>> 0,
>>> };
>>>
>>> +enum {
>>> + MMU_FTRS_ALWAYS =
>>> +#ifdef CONFIG_PPC_8xx
>>> + MMU_FTR_TYPE_8xx &
>>> +#endif
>>> +#ifdef CONFIG_40x
>>> + MMU_FTR_TYPE_40x &
>>> +#endif
>>> +#ifdef CONFIG_PPC_47x
>>> + MMU_FTR_TYPE_47x &
>>> +#elif defined(CONFIG_44x)
>>> + MMU_FTR_TYPE_44x &
>>> +#endif
>>> +#if defined(CONFIG_E200) || defined(CONFIG_E500)
>>> + MMU_FTR_TYPE_FSL_E &
>>> +#endif
>>> + MMU_FTRS_POSSIBLE,
>>> +};
>
> Will it be simpler if we make it a #define like below?
>
> #ifdef CONFIG_PPC_8XX
> #define MMU_FTR_ALWAYS MMU_FTR_TYPE_8XX & MMU_FTR_POSSIBLE
> #endif
Yes you are right, it will be simpler, and consistant with CPU_FTR_ALWAYS which is partly set with
defines after all.
Christophe
>
>
>
>>> +
>>> static inline bool early_mmu_has_feature(unsigned long feature)
>>> {
>>> + if (MMU_FTRS_ALWAYS & feature)
>>> + return true;
>>> +
>>> return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
>>> }
>>>
>>> @@ -231,6 +253,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
>>> }
>>> #endif
>>>
>>> + if (MMU_FTRS_ALWAYS & feature)
>>> + return true;
>>> +
>>> if (!(MMU_FTRS_POSSIBLE & feature))
>>> return false;
>>>
>>>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-10-12 15:39 [PATCH v2] powerpc/mm: Add mask of always present MMU features Christophe Leroy
2020-10-21 10:32 ` Christophe Leroy
2020-10-21 14:25 ` Aneesh Kumar K.V
2020-10-21 16:37 ` Christophe Leroy
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