[PATCH 5/6] powerpc: Macros for saving/restore PPR
Haren Myneni
haren at linux.vnet.ibm.com
Tue Nov 27 12:49:27 EST 2012
On 11/22/2012 07:39 PM, Michael Neuling wrote:
> Haren Myneni <haren at linux.vnet.ibm.com> wrote:
>
>> [PATCH 5/6] powerpc: Macros for saving/restore PPR
>>
>> Several macros are defined for saving and restore user defined PPR value.
>>
>> Signed-off-by: Haren Myneni <haren at us.ibm.com>
>> ---
>> arch/powerpc/include/asm/exception-64s.h | 29 +++++++++++++++++++++++++++++
>> arch/powerpc/include/asm/ppc_asm.h | 25 +++++++++++++++++++++++++
>> arch/powerpc/include/asm/reg.h | 1 +
>> 3 files changed, 55 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
>> index bfd3f1f..880ef7d 100644
>> --- a/arch/powerpc/include/asm/exception-64s.h
>> +++ b/arch/powerpc/include/asm/exception-64s.h
>> @@ -62,6 +62,35 @@
>> #define EXC_HV H
>> #define EXC_STD
>>
>> +/*
>> + * PPR save/restore macros used in exceptions_64s.S
>> + * Used for P7 or later processors
>> + */
>> +#define SAVE_PPR(area, ra, rb) \
>> +BEGIN_FTR_SECTION_NESTED(940) \
>> + ld ra,PACACURRENT(r13); \
>> + ld rb,area+EX_PPR(r13); /* Read PPR from paca */ \
>> + std rb,TASKTHREADPPR(ra); \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940)
>> +
>> +#define RESTORE_PPR_PACA(area, ra) \
>> +BEGIN_FTR_SECTION_NESTED(941) \
>> + ld ra,area+EX_PPR(r13); \
>> + mtspr SPRN_PPR,ra; \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941)
>> +
>
> Can you add some documentation here on why we should use the different
> versions.
>
> I'm trying to read the next patch and it's not clear to my why some have
> HMT_MEDIUM_NO_PPR and other times HMT_MEDIUM and others
> HTM_MEDIUM_HAS_PPR.
>
> Looks like HTM_MEDIUM_NO_PPR sets the priority to medium on systems
> where we can't save/restore the PPR, hence it can be called earlier in
> the exception handler before we have free GPRs. HTM_MEDIUM_HAS_PPR
> saves the priority on systems where it can, and then sets the priority
> to medium.
>
> Maybe we should change the names
> HTM_MEDIUM_NO_PPR => HTM_MEDIUM_PPR_DISCARD and
> HTM_MEDIUM_HAS_PPR => HTM_MEDIUM_PPR_SAVE
> But now I'm heading into bike shedding territory... plus I think I
> suggested the names you have currently, so I'm feeling a bit dumb now
> :-)
No problem, We can change these macro names if HTM_MEDIUM_PPR_DISCARD/
HTM_MEDIUM_PPR_SAVE gives better description.
Right, HTM_MEDIUM_NO_PPR is used on systems where we do not save/restore
PPR. So the behaviour is same as before - just increases the priority.
HTM_MEDIUM_HAS_PPR will be executed on systems where CPU_FTR_HAS_PPR is
enabled. I will write some comments around these macros to make it clear.
We can also name them HMT_MEDIUM_CPU_NO_PPR_SAVE and
HMT_MEDIUM_CPU_HAS_PPR_SAVE since we are enabling PPR save/restore using
CPU_FTR macro.
Otherwise I will follow with your suggestions.
Thanks
Haren
> Mikey
>
>> +#define HMT_MEDIUM_NO_PPR \
>> +BEGIN_FTR_SECTION_NESTED(942) \
>> + HMT_MEDIUM; \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,942) /*non P7*/
>> +
>> +#define HMT_MEDIUM_HAS_PPR(area, ra) \
>> +BEGIN_FTR_SECTION_NESTED(943) \
>> + mfspr ra,SPRN_PPR; \
>> + std ra,area+EX_PPR(r13); \
>> + HMT_MEDIUM; \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,943)
>> +
>> #define __EXCEPTION_PROLOG_1(area, extra, vec) \
>> GET_PACA(r13); \
>> std r9,area+EX_R9(r13); /* save r9 - r12 */ \
>
>
>> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
>> index 376e36d..52649cc 100644
>> --- a/arch/powerpc/include/asm/ppc_asm.h
>> +++ b/arch/powerpc/include/asm/ppc_asm.h
>> @@ -389,6 +389,31 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601)
>> FTR_SECTION_ELSE_NESTED(848); \
>> mtocrf (FXM), RS; \
>> ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_NOEXECUTE, 848)
>> +
>> +/*
>> + * PPR restore macros used in entry_64.S
>> + * Used for P7 or later processors
>> + */
>> +#define HMT_MEDIUM_LOW_HAS_PPR \
>> +BEGIN_FTR_SECTION_NESTED(944) \
>> + HMT_MEDIUM_LOW; \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,944)
>> +
>> +#define SET_DEFAULT_THREAD_PPR(ra, rb) \
>> +BEGIN_FTR_SECTION_NESTED(945) \
>> + lis ra,0xc; /* default ppr=3 */ \
>> + ld rb,PACACURRENT(r13); \
>> + sldi ra,ra,32; /* 11- 13 bits are used for ppr */ \
>> + std ra,TASKTHREADPPR(rb); \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,945)
>> +
>> +#define RESTORE_PPR(ra, rb) \
>> +BEGIN_FTR_SECTION_NESTED(946) \
>> + ld ra,PACACURRENT(r13); \
>> + ld rb,TASKTHREADPPR(ra); \
>> + mtspr SPRN_PPR,rb; /* Restore PPR */ \
>> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,946)
>> +
>> #endif
>>
>> /*
>> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
>> index d24c141..1723be3 100644
>> --- a/arch/powerpc/include/asm/reg.h
>> +++ b/arch/powerpc/include/asm/reg.h
>> @@ -287,6 +287,7 @@
>> #define SPRN_DBAT6U 0x23C /* Data BAT 6 Upper Register */
>> #define SPRN_DBAT7L 0x23F /* Data BAT 7 Lower Register */
>> #define SPRN_DBAT7U 0x23E /* Data BAT 7 Upper Register */
>> +#define SPRN_PPR 0x380 /* SMT Thread status Register */
>>
>> #define SPRN_DEC 0x016 /* Decrement Register */
>> #define SPRN_DER 0x095 /* Debug Enable Regsiter */
>> --
>> 1.7.1
>>
>>
>>
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