Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
Christophe Leroy writes: > Le 26/08/2019 à 13:41, Michael Ellerman a écrit : >> Christophe Leroy writes: >>> sched_clock(), used by printk(), calls __USE_RTC() to know >>> whether to use realtime clock or timebase. >>> >>> __USE_RTC() uses cpu_has_feature() which is initialised by >>> machine_init(). Before machine_init(), __USE_RTC() returns true, >>> leading to a program check exception on CPUs not having realtime >>> clock. >>> >>> In order to be able to use printk() earlier, use feature fixup. >>> Feature fixups are applies in early_init(), enabling the use of >>> printk() earlier. >>> >>> Signed-off-by: Christophe Leroy >>> --- >>> arch/powerpc/include/asm/time.h | 9 - >>> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> The other option would be just to make this a compile time decision, eg. >> add CONFIG_PPC_601 and use that to gate whether we use RTC. > > Euh ... yes OK, why not. And that would help simplify many places in the > code. I can propose something in that direction, but it will be a bigger > change. Thanks. >> Given how many 601 users there are, maybe 1?, I think that would be a >> simpler option and avoids complicating the code / binary for everyone >> else. > > However this patch doesn't complicate things more than it was with > cpu_has_feature() which does exactly the same but using static keys, > does it ? It's more complicated in that it's not using cpu_has_feature() it's doing some custom thing that is not used anywhere else. But yeah I guess it's not much extra complication. cheers
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
Benjamin Herrenschmidt writes: > On Mon, 2019-08-26 at 21:41 +1000, Michael Ellerman wrote: >> Christophe Leroy writes: >> > sched_clock(), used by printk(), calls __USE_RTC() to know >> > whether to use realtime clock or timebase. >> > >> > __USE_RTC() uses cpu_has_feature() which is initialised by >> > machine_init(). Before machine_init(), __USE_RTC() returns true, >> > leading to a program check exception on CPUs not having realtime >> > clock. >> > >> > In order to be able to use printk() earlier, use feature fixup. >> > Feature fixups are applies in early_init(), enabling the use of >> > printk() earlier. >> > >> > Signed-off-by: Christophe Leroy >> > --- >> > arch/powerpc/include/asm/time.h | 9 - >> > 1 file changed, 8 insertions(+), 1 deletion(-) >> >> The other option would be just to make this a compile time decision, eg. >> add CONFIG_PPC_601 and use that to gate whether we use RTC. >> >> Given how many 601 users there are, maybe 1?, I think that would be a >> simpler option and avoids complicating the code / binary for everyone >> else. > > Didn't we ditch 601 support years ago anyway ? We had workaround we > threw out I think... Paul said his still booted recently. cheers
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
Le 26/08/2019 à 15:25, Benjamin Herrenschmidt a écrit :
On Mon, 2019-08-26 at 21:41 +1000, Michael Ellerman wrote:
Christophe Leroy writes:
sched_clock(), used by printk(), calls __USE_RTC() to know
whether to use realtime clock or timebase.
__USE_RTC() uses cpu_has_feature() which is initialised by
machine_init(). Before machine_init(), __USE_RTC() returns true,
leading to a program check exception on CPUs not having realtime
clock.
In order to be able to use printk() earlier, use feature fixup.
Feature fixups are applies in early_init(), enabling the use of
printk() earlier.
Signed-off-by: Christophe Leroy
---
arch/powerpc/include/asm/time.h | 9 -
1 file changed, 8 insertions(+), 1 deletion(-)
The other option would be just to make this a compile time decision, eg.
add CONFIG_PPC_601 and use that to gate whether we use RTC.
Given how many 601 users there are, maybe 1?, I think that would be a
simpler option and avoids complicating the code / binary for everyone
else.
Didn't we ditch 601 support years ago anyway ? We had workaround we
threw out I think...
There are still workarounds for 601 in the kernel, for exemple (in
arch/powerpc/include/asm/ppc_asm.h)
/* various errata or part fixups */
#ifdef CONFIG_PPC601_SYNC_FIX
#define SYNC\
BEGIN_FTR_SECTION \
sync; \
isync; \
END_FTR_SECTION_IFSET(CPU_FTR_601)
#define SYNC_601\
BEGIN_FTR_SECTION \
sync; \
END_FTR_SECTION_IFSET(CPU_FTR_601)
#define ISYNC_601 \
BEGIN_FTR_SECTION \
isync; \
END_FTR_SECTION_IFSET(CPU_FTR_601)
#else
#define SYNC
#define SYNC_601
#define ISYNC_601
#endif
But if you think we can get rid of 601 completely, I'm happy with that.
Christophe
Cheers,
Ben.
cheers
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 54f4ec1f9fab..3455cb54c333 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -42,7 +42,14 @@ struct div_result {
/* Accessor functions for the timebase (RTC on 601) registers. */
/* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
#ifdef CONFIG_PPC_BOOK3S_32
-#define __USE_RTC()(cpu_has_feature(CPU_FTR_USE_RTC))
+static inline bool __USE_RTC(void)
+{
+ asm_volatile_goto(ASM_FTR_IFCLR("nop;", "b %1;", %0) ::
+ "i" (CPU_FTR_USE_RTC) :: l_use_rtc);
+ return false;
+l_use_rtc:
+ return true;
+}
#else
#define __USE_RTC() 0
#endif
--
2.13.3
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
On Mon, 2019-08-26 at 21:41 +1000, Michael Ellerman wrote:
> Christophe Leroy writes:
> > sched_clock(), used by printk(), calls __USE_RTC() to know
> > whether to use realtime clock or timebase.
> >
> > __USE_RTC() uses cpu_has_feature() which is initialised by
> > machine_init(). Before machine_init(), __USE_RTC() returns true,
> > leading to a program check exception on CPUs not having realtime
> > clock.
> >
> > In order to be able to use printk() earlier, use feature fixup.
> > Feature fixups are applies in early_init(), enabling the use of
> > printk() earlier.
> >
> > Signed-off-by: Christophe Leroy
> > ---
> > arch/powerpc/include/asm/time.h | 9 -
> > 1 file changed, 8 insertions(+), 1 deletion(-)
>
> The other option would be just to make this a compile time decision, eg.
> add CONFIG_PPC_601 and use that to gate whether we use RTC.
>
> Given how many 601 users there are, maybe 1?, I think that would be a
> simpler option and avoids complicating the code / binary for everyone
> else.
Didn't we ditch 601 support years ago anyway ? We had workaround we
threw out I think...
Cheers,
Ben.
> cheers
>
> > diff --git a/arch/powerpc/include/asm/time.h
> > b/arch/powerpc/include/asm/time.h
> > index 54f4ec1f9fab..3455cb54c333 100644
> > --- a/arch/powerpc/include/asm/time.h
> > +++ b/arch/powerpc/include/asm/time.h
> > @@ -42,7 +42,14 @@ struct div_result {
> > /* Accessor functions for the timebase (RTC on 601) registers. */
> > /* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
> > #ifdef CONFIG_PPC_BOOK3S_32
> > -#define __USE_RTC()(cpu_has_feature(CPU_FTR_USE_RTC))
> > +static inline bool __USE_RTC(void)
> > +{
> > + asm_volatile_goto(ASM_FTR_IFCLR("nop;", "b %1;", %0) ::
> > + "i" (CPU_FTR_USE_RTC) :: l_use_rtc);
> > + return false;
> > +l_use_rtc:
> > + return true;
> > +}
> > #else
> > #define __USE_RTC()0
> > #endif
> > --
> > 2.13.3
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
On Mon, Aug 26, 2019 at 09:41:39PM +1000, Michael Ellerman wrote: > Given how many 601 users there are, maybe 1?, I think that would be a > simpler option and avoids complicating the code / binary for everyone > else. Or you could remove 601 support altogether? Segher
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
Le 26/08/2019 à 13:41, Michael Ellerman a écrit :
Christophe Leroy writes:
sched_clock(), used by printk(), calls __USE_RTC() to know
whether to use realtime clock or timebase.
__USE_RTC() uses cpu_has_feature() which is initialised by
machine_init(). Before machine_init(), __USE_RTC() returns true,
leading to a program check exception on CPUs not having realtime
clock.
In order to be able to use printk() earlier, use feature fixup.
Feature fixups are applies in early_init(), enabling the use of
printk() earlier.
Signed-off-by: Christophe Leroy
---
arch/powerpc/include/asm/time.h | 9 -
1 file changed, 8 insertions(+), 1 deletion(-)
The other option would be just to make this a compile time decision, eg.
add CONFIG_PPC_601 and use that to gate whether we use RTC.
Euh ... yes OK, why not. And that would help simplify many places in the
code. I can propose something in that direction, but it will be a bigger
change.
Given how many 601 users there are, maybe 1?, I think that would be a
simpler option and avoids complicating the code / binary for everyone
else.
However this patch doesn't complicate things more than it was with
cpu_has_feature() which does exactly the same but using static keys,
does it ?
Christophe
cheers
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 54f4ec1f9fab..3455cb54c333 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -42,7 +42,14 @@ struct div_result {
/* Accessor functions for the timebase (RTC on 601) registers. */
/* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
#ifdef CONFIG_PPC_BOOK3S_32
-#define __USE_RTC()(cpu_has_feature(CPU_FTR_USE_RTC))
+static inline bool __USE_RTC(void)
+{
+ asm_volatile_goto(ASM_FTR_IFCLR("nop;", "b %1;", %0) ::
+ "i" (CPU_FTR_USE_RTC) :: l_use_rtc);
+ return false;
+l_use_rtc:
+ return true;
+}
#else
#define __USE_RTC() 0
#endif
--
2.13.3
Re: [PATCH] powerpc/time: use feature fixup in __USE_RTC() instead of cpu feature.
Christophe Leroy writes:
> sched_clock(), used by printk(), calls __USE_RTC() to know
> whether to use realtime clock or timebase.
>
> __USE_RTC() uses cpu_has_feature() which is initialised by
> machine_init(). Before machine_init(), __USE_RTC() returns true,
> leading to a program check exception on CPUs not having realtime
> clock.
>
> In order to be able to use printk() earlier, use feature fixup.
> Feature fixups are applies in early_init(), enabling the use of
> printk() earlier.
>
> Signed-off-by: Christophe Leroy
> ---
> arch/powerpc/include/asm/time.h | 9 -
> 1 file changed, 8 insertions(+), 1 deletion(-)
The other option would be just to make this a compile time decision, eg.
add CONFIG_PPC_601 and use that to gate whether we use RTC.
Given how many 601 users there are, maybe 1?, I think that would be a
simpler option and avoids complicating the code / binary for everyone
else.
cheers
> diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
> index 54f4ec1f9fab..3455cb54c333 100644
> --- a/arch/powerpc/include/asm/time.h
> +++ b/arch/powerpc/include/asm/time.h
> @@ -42,7 +42,14 @@ struct div_result {
> /* Accessor functions for the timebase (RTC on 601) registers. */
> /* If one day CONFIG_POWER is added just define __USE_RTC as 1 */
> #ifdef CONFIG_PPC_BOOK3S_32
> -#define __USE_RTC() (cpu_has_feature(CPU_FTR_USE_RTC))
> +static inline bool __USE_RTC(void)
> +{
> + asm_volatile_goto(ASM_FTR_IFCLR("nop;", "b %1;", %0) ::
> + "i" (CPU_FTR_USE_RTC) :: l_use_rtc);
> + return false;
> +l_use_rtc:
> + return true;
> +}
> #else
> #define __USE_RTC() 0
> #endif
> --
> 2.13.3
