| Message ID | 1347191001.3418.19.camel@hbabu-laptop (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
On Sun, 2012-09-09 at 04:43 -0700, Haren Myneni wrote: > Several macros are defined for saving and restore user defined PPR value. > > Signed-off-by: Haren Myneni <haren@us.ibm.com> > --- > arch/powerpc/include/asm/exception-64s.h | 35 ++++++++++++++++++++++++++++++ > arch/powerpc/include/asm/reg.h | 1 + > 2 files changed, 36 insertions(+) > > diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h > index bfd3f1f..618fd18 100644 > --- a/arch/powerpc/include/asm/exception-64s.h > +++ b/arch/powerpc/include/asm/exception-64s.h > @@ -62,6 +62,41 @@ > #define EXC_HV H > #define EXC_STD > > +/* > + * PPR save/restore macros - Used on P7 or later processors > + */ > +#define SAVE_PPR(area, ra, rb) \ > +BEGIN_FTR_SECTION_NESTED(940) \ > + ld ra,area+EX_PPR(r13); /* Read PPR from paca */ \ > + clrrdi rb,r1,THREAD_SHIFT; /* thread_info struct */ \ > + std ra,TI_PPR(rb); /* Save PPR in thread_info */ \ > +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940) Why the thread info and not the thread struct ? Cheers, Ben. > +#define RESTORE_PPR(ra,rb) \ > +BEGIN_FTR_SECTION_NESTED(941) \ > + clrrdi ra,r1,THREAD_SHIFT; \ > + ld rb,TI_PPR(ra); /* Read PPR from thread_info */ \ > + mtspr SPRN_PPR,rb; /* Restore PPR */ \ > +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941) > + > +#define RESTORE_PPR_PACA(area,ra) \ > +BEGIN_FTR_SECTION_NESTED(942) \ > + ld ra,area+EX_PPR(r13); \ > + mtspr SPRN_PPR,ra; \ > +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,942) > + > +#define HMT_MEDIUM_NO_PPR \ > +BEGIN_FTR_SECTION_NESTED(944) \ > + HMT_MEDIUM; \ > +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,944) /*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) /* P7 */ > + > #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/reg.h b/arch/powerpc/include/asm/reg.h > index 6386086..dff2f89 100644 > --- a/arch/powerpc/include/asm/reg.h > +++ b/arch/powerpc/include/asm/reg.h > @@ -284,6 +284,7 @@ > #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 */
On 09/09/2012 09:24 PM, Benjamin Herrenschmidt wrote: > On Sun, 2012-09-09 at 04:43 -0700, Haren Myneni wrote: >> Several macros are defined for saving and restore user defined PPR value. >> >> Signed-off-by: Haren Myneni <haren@us.ibm.com> >> --- >> arch/powerpc/include/asm/exception-64s.h | 35 ++++++++++++++++++++++++++++++ >> arch/powerpc/include/asm/reg.h | 1 + >> 2 files changed, 36 insertions(+) >> >> diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h >> index bfd3f1f..618fd18 100644 >> --- a/arch/powerpc/include/asm/exception-64s.h >> +++ b/arch/powerpc/include/asm/exception-64s.h >> @@ -62,6 +62,41 @@ >> #define EXC_HV H >> #define EXC_STD >> >> +/* >> + * PPR save/restore macros - Used on P7 or later processors >> + */ >> +#define SAVE_PPR(area, ra, rb) \ >> +BEGIN_FTR_SECTION_NESTED(940) \ >> + ld ra,area+EX_PPR(r13); /* Read PPR from paca */ \ >> + clrrdi rb,r1,THREAD_SHIFT; /* thread_info struct */ \ >> + std ra,TI_PPR(rb); /* Save PPR in thread_info */ \ >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940) > > Why the thread info and not the thread struct ? We can also use thread struct, but the saved ppr is needed as long as the process is in kernel context. Once the process exits, we do not need this value - means the kernel or any other command will not be reading this value. Even the process can change this value later. Need to add ppr in thread_struct which uses extra 8 bytes for each task. Whereas thread_info is at the top of stack. No need to allocate extra memory. Since the saved process PPR value is needed temporarily whenever the process is in kernel, thought thread_info is proper. Also easy to read - one less load instruction. Saving in thread_info: ld r4,area+EX_PPR(r13); clrrdi r5,r1,THREAD_SHIFT; std r4,TI_PPR(r5); Saving in thread_struct: ld r4,PACACURRENT(r13) addi r5,r4,THREAD ld r4,paca+EX_PPR(r13); std r4,THREAD_PPR(r5) If you prefer thread_struct, I will change the patch. Please let me know. Thanks Haren > > Cheers, > Ben. > >> +#define RESTORE_PPR(ra,rb) \ >> +BEGIN_FTR_SECTION_NESTED(941) \ >> + clrrdi ra,r1,THREAD_SHIFT; \ >> + ld rb,TI_PPR(ra); /* Read PPR from thread_info */ \ >> + mtspr SPRN_PPR,rb; /* Restore PPR */ \ >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941) >> + >> +#define RESTORE_PPR_PACA(area,ra) \ >> +BEGIN_FTR_SECTION_NESTED(942) \ >> + ld ra,area+EX_PPR(r13); \ >> + mtspr SPRN_PPR,ra; \ >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,942) >> + >> +#define HMT_MEDIUM_NO_PPR \ >> +BEGIN_FTR_SECTION_NESTED(944) \ >> + HMT_MEDIUM; \ >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,944) /*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) /* P7 */ >> + >> #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/reg.h b/arch/powerpc/include/asm/reg.h >> index 6386086..dff2f89 100644 >> --- a/arch/powerpc/include/asm/reg.h >> +++ b/arch/powerpc/include/asm/reg.h >> @@ -284,6 +284,7 @@ >> #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 */ > >
On Mon, 2012-09-10 at 22:18 -0700, Haren Myneni wrote: > We can also use thread struct, but the saved ppr is needed as long as > the process is in kernel context. Once the process exits, we do not need > this value - means the kernel or any other command will not be reading > this value. > > Even the process can change this value later. Need to add > ppr in thread_struct which uses extra 8 bytes for each task. Allright so the real answer is that the thread info is easier to get at than the thread struct :-) However, the most logical place to put that stuff is along the lines of the surrounding code... in the pt_regs on the stack. It should be fairly easy to carve some space here, for example softe doesn't have to be 64-bit (it's really one bit, you can make it one byte, just make sure to adapt the corresponding assembly). The main issue with that approach is that you then need to audit a bit to see how pt_regs might be constructed here or there in case you end up with a 0 (illegal PPR) value in there. > Whereas thread_info is at the top of stack. No need to allocate extra > memory. Since the saved process PPR value is needed temporarily whenever > the process is in kernel, thought thread_info is proper. Also easy to > read - one less load instruction. The advantage of pt_regs is that a signal can "peek" at the PPR value which could be useful for debugging purposes. > Saving in thread_info: > > ld r4,area+EX_PPR(r13); > clrrdi r5,r1,THREAD_SHIFT; > std r4,TI_PPR(r5); > > Saving in thread_struct: > > ld r4,PACACURRENT(r13) > addi r5,r4,THREAD > ld r4,paca+EX_PPR(r13); > std r4,THREAD_PPR(r5) > > If you prefer thread_struct, I will change the patch. Please let me know. Cheers, Ben. > Thanks > Haren > > > > > Cheers, > > Ben. > > > >> +#define RESTORE_PPR(ra,rb) \ > >> +BEGIN_FTR_SECTION_NESTED(941) \ > >> + clrrdi ra,r1,THREAD_SHIFT; \ > >> + ld rb,TI_PPR(ra); /* Read PPR from thread_info */ \ > >> + mtspr SPRN_PPR,rb; /* Restore PPR */ \ > >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941) > >> + > >> +#define RESTORE_PPR_PACA(area,ra) \ > >> +BEGIN_FTR_SECTION_NESTED(942) \ > >> + ld ra,area+EX_PPR(r13); \ > >> + mtspr SPRN_PPR,ra; \ > >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,942) > >> + > >> +#define HMT_MEDIUM_NO_PPR \ > >> +BEGIN_FTR_SECTION_NESTED(944) \ > >> + HMT_MEDIUM; \ > >> +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,944) /*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) /* P7 */ > >> + > >> #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/reg.h b/arch/powerpc/include/asm/reg.h > >> index 6386086..dff2f89 100644 > >> --- a/arch/powerpc/include/asm/reg.h > >> +++ b/arch/powerpc/include/asm/reg.h > >> @@ -284,6 +284,7 @@ > >> #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 */ > > > >
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index bfd3f1f..618fd18 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -62,6 +62,41 @@ #define EXC_HV H #define EXC_STD +/* + * PPR save/restore macros - Used on P7 or later processors + */ +#define SAVE_PPR(area, ra, rb) \ +BEGIN_FTR_SECTION_NESTED(940) \ + ld ra,area+EX_PPR(r13); /* Read PPR from paca */ \ + clrrdi rb,r1,THREAD_SHIFT; /* thread_info struct */ \ + std ra,TI_PPR(rb); /* Save PPR in thread_info */ \ +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,940) + +#define RESTORE_PPR(ra,rb) \ +BEGIN_FTR_SECTION_NESTED(941) \ + clrrdi ra,r1,THREAD_SHIFT; \ + ld rb,TI_PPR(ra); /* Read PPR from thread_info */ \ + mtspr SPRN_PPR,rb; /* Restore PPR */ \ +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,941) + +#define RESTORE_PPR_PACA(area,ra) \ +BEGIN_FTR_SECTION_NESTED(942) \ + ld ra,area+EX_PPR(r13); \ + mtspr SPRN_PPR,ra; \ +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,942) + +#define HMT_MEDIUM_NO_PPR \ +BEGIN_FTR_SECTION_NESTED(944) \ + HMT_MEDIUM; \ +END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,0,944) /*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) /* P7 */ + #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/reg.h b/arch/powerpc/include/asm/reg.h index 6386086..dff2f89 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -284,6 +284,7 @@ #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 */
Several macros are defined for saving and restore user defined PPR value. Signed-off-by: Haren Myneni <haren@us.ibm.com> --- arch/powerpc/include/asm/exception-64s.h | 35 ++++++++++++++++++++++++++++++ arch/powerpc/include/asm/reg.h | 1 + 2 files changed, 36 insertions(+)