* [PATCH 0/3] powerpc: fix regression of per-CPU DSCR setting
@ 2014-05-21 6:32 Sam Bobroff
2014-05-21 6:32 ` [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro Sam Bobroff
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Sam Bobroff @ 2014-05-21 6:32 UTC (permalink / raw)
To: benh; +Cc: aik, mikey, linuxppc-dev
Hello,
This patch corrects a regression on PowerPC CPUs that causes their
per-CPU DSCR SPR value (exposed via /sys/devices/system/cpuN/dscr) to
be quickly lost during context switching, effectively meaning that the
DSCR can no longer be set on a per-CPU basis.
My intent is to restore the functionality of the per-CPU value in a
way that is compatible with the newer global default and task-specific
DSCR setting system. Users of either the old or new systems should
now get pretty much what they expect.
A couple of notes:
I've split an existing "ifdef CONFIG_PPC_STD_MMU_64" block in
paca_struct into two parts because it allows dscr_default to be placed
into a cache line hole. (This seems be the case even without
CONFIG_PPC_STD_MMU_64 being defined.) Comments or ideas on alternative
placements are welcome.
PowerPC context switching is touched but there should not be any
performance cost; if anything it should get slightly faster due to the
per-CPU value being easier to access than the old global default.
Sam Bobroff (3):
powerpc: Split __SYSFS_SPRSETUP macro
powerpc: fix regression of per-CPU DSCR setting
powerpc: Document sysfs DSCR interface
Documentation/ABI/stable/sysfs-devices-system-cpu | 25 ++++++++++
arch/powerpc/include/asm/paca.h | 3 ++
arch/powerpc/kernel/asm-offsets.c | 1 +
arch/powerpc/kernel/entry_64.S | 9 +---
arch/powerpc/kernel/sysfs.c | 51 +++++++++++++--------
arch/powerpc/kernel/tm.S | 16 ++-----
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 +-
7 files changed, 67 insertions(+), 41 deletions(-)
create mode 100644 Documentation/ABI/stable/sysfs-devices-system-cpu
--
1.7.10.4
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro 2014-05-21 6:32 [PATCH 0/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff @ 2014-05-21 6:32 ` Sam Bobroff 2014-06-02 9:09 ` Madhavan Srinivasan 2014-05-21 6:32 ` [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff 2014-05-21 6:32 ` [PATCH 3/3] powerpc: Document sysfs DSCR interface Sam Bobroff 2 siblings, 1 reply; 6+ messages in thread From: Sam Bobroff @ 2014-05-21 6:32 UTC (permalink / raw) To: benh; +Cc: aik, mikey, linuxppc-dev Split the __SYSFS_SPRSETUP macro into two parts so that registers requiring custom read and write functions can use common code for their show and store functions. Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> --- arch/powerpc/kernel/sysfs.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index d90d4b7..e2a1d6f 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -404,7 +404,7 @@ void ppc_enable_pmcs(void) } EXPORT_SYMBOL(ppc_enable_pmcs); -#define __SYSFS_SPRSETUP(NAME, ADDRESS, EXTRA) \ +#define __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, EXTRA) \ static void read_##NAME(void *val) \ { \ *(unsigned long *)val = mfspr(ADDRESS); \ @@ -413,7 +413,9 @@ static void write_##NAME(void *val) \ { \ EXTRA; \ mtspr(ADDRESS, *(unsigned long *)val); \ -} \ +} + +#define __SYSFS_SPRSETUP_SHOW_STORE(NAME) \ static ssize_t show_##NAME(struct device *dev, \ struct device_attribute *attr, \ char *buf) \ @@ -436,10 +438,15 @@ static ssize_t __used \ return count; \ } -#define SYSFS_PMCSETUP(NAME, ADDRESS) \ - __SYSFS_SPRSETUP(NAME, ADDRESS, ppc_enable_pmcs()) -#define SYSFS_SPRSETUP(NAME, ADDRESS) \ - __SYSFS_SPRSETUP(NAME, ADDRESS, ) +#define SYSFS_PMCSETUP(NAME, ADDRESS) \ + __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, ppc_enable_pmcs()) \ + __SYSFS_SPRSETUP_SHOW_STORE(NAME) +#define SYSFS_SPRSETUP(NAME, ADDRESS) \ + __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, ) \ + __SYSFS_SPRSETUP_SHOW_STORE(NAME) + +#define SYSFS_SPRSETUP_SHOW_STORE(NAME) \ + __SYSFS_SPRSETUP_SHOW_STORE(NAME) /* Let's define all possible registers, we'll only hook up the ones * that are implemented on the current processor -- 1.7.10.4 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro 2014-05-21 6:32 ` [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro Sam Bobroff @ 2014-06-02 9:09 ` Madhavan Srinivasan 0 siblings, 0 replies; 6+ messages in thread From: Madhavan Srinivasan @ 2014-06-02 9:09 UTC (permalink / raw) To: linuxppc-dev On Wednesday 21 May 2014 12:02 PM, Sam Bobroff wrote: > Split the __SYSFS_SPRSETUP macro into two parts so that registers requiring > custom read and write functions can use common code for their show and store > functions. > > Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> > --- > arch/powerpc/kernel/sysfs.c | 19 +++++++++++++------ > 1 file changed, 13 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c > index d90d4b7..e2a1d6f 100644 > --- a/arch/powerpc/kernel/sysfs.c > +++ b/arch/powerpc/kernel/sysfs.c > @@ -404,7 +404,7 @@ void ppc_enable_pmcs(void) > } > EXPORT_SYMBOL(ppc_enable_pmcs); > > -#define __SYSFS_SPRSETUP(NAME, ADDRESS, EXTRA) \ > +#define __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, EXTRA) \ > static void read_##NAME(void *val) \ > { \ > *(unsigned long *)val = mfspr(ADDRESS); \ > @@ -413,7 +413,9 @@ static void write_##NAME(void *val) \ > { \ > EXTRA; \ > mtspr(ADDRESS, *(unsigned long *)val); \ > -} \ > +} > + > +#define __SYSFS_SPRSETUP_SHOW_STORE(NAME) \ > static ssize_t show_##NAME(struct device *dev, \ > struct device_attribute *attr, \ > char *buf) \ > @@ -436,10 +438,15 @@ static ssize_t __used \ > return count; \ > } > > -#define SYSFS_PMCSETUP(NAME, ADDRESS) \ > - __SYSFS_SPRSETUP(NAME, ADDRESS, ppc_enable_pmcs()) > -#define SYSFS_SPRSETUP(NAME, ADDRESS) \ > - __SYSFS_SPRSETUP(NAME, ADDRESS, ) > +#define SYSFS_PMCSETUP(NAME, ADDRESS) \ > + __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, ppc_enable_pmcs()) \ > + __SYSFS_SPRSETUP_SHOW_STORE(NAME) > +#define SYSFS_SPRSETUP(NAME, ADDRESS) \ > + __SYSFS_SPRSETUP_READ_WRITE(NAME, ADDRESS, ) \ > + __SYSFS_SPRSETUP_SHOW_STORE(NAME) > + > +#define SYSFS_SPRSETUP_SHOW_STORE(NAME) \ > + __SYSFS_SPRSETUP_SHOW_STORE(NAME) > > /* Let's define all possible registers, we'll only hook up the ones > * that are implemented on the current processor > Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com> ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting 2014-05-21 6:32 [PATCH 0/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff 2014-05-21 6:32 ` [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro Sam Bobroff @ 2014-05-21 6:32 ` Sam Bobroff 2014-06-02 9:27 ` Madhavan Srinivasan 2014-05-21 6:32 ` [PATCH 3/3] powerpc: Document sysfs DSCR interface Sam Bobroff 2 siblings, 1 reply; 6+ messages in thread From: Sam Bobroff @ 2014-05-21 6:32 UTC (permalink / raw) To: benh; +Cc: aik, mikey, linuxppc-dev Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)" it is no longer possible to set the DSCR on a per-CPU basis. The old behaviour was to minipulate the DSCR SPR directly but this is no longer sufficient: the value is quickly overwritten by context switching. This patch stores the per-CPU DSCR value in a kernel variable rather than directly in the SPR and it is used whenever a process has not set the DSCR itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged. Writes to the old global default (/sys/devices/system/cpu/dscr_default) now set all of the per-CPU values and reads return the last written value. The new per-CPU default is added to the paca_struct and is used everywhere outside of sysfs.c instead of the old global default. Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> --- arch/powerpc/include/asm/paca.h | 3 +++ arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kernel/entry_64.S | 9 +-------- arch/powerpc/kernel/sysfs.c | 32 ++++++++++++++++++------------- arch/powerpc/kernel/tm.S | 16 ++++------------ arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 +-- 6 files changed, 29 insertions(+), 35 deletions(-) diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h index 8e956a0..bb0bd25 100644 --- a/arch/powerpc/include/asm/paca.h +++ b/arch/powerpc/include/asm/paca.h @@ -92,7 +92,10 @@ struct paca_struct { struct slb_shadow *slb_shadow_ptr; struct dtl_entry *dispatch_log; struct dtl_entry *dispatch_log_end; +#endif /* CONFIG_PPC_STD_MMU_64 */ + u64 dscr_default; /* per-CPU default DSCR */ +#ifdef CONFIG_PPC_STD_MMU_64 /* * Now, starting in cacheline 2, the exception save areas */ diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index dba8140..cba2697 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -247,6 +247,7 @@ int main(void) #endif DEFINE(PACAHWCPUID, offsetof(struct paca_struct, hw_cpu_id)); DEFINE(PACAKEXECSTATE, offsetof(struct paca_struct, kexec_state)); + DEFINE(PACA_DSCR, offsetof(struct paca_struct, dscr_default)); DEFINE(PACA_STARTTIME, offsetof(struct paca_struct, starttime)); DEFINE(PACA_STARTTIME_USER, offsetof(struct paca_struct, starttime_user)); DEFINE(PACA_USER_TIME, offsetof(struct paca_struct, user_time)); diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9fde8a1..911d453 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -387,12 +387,6 @@ _GLOBAL(ret_from_kernel_thread) li r3,0 b syscall_exit - .section ".toc","aw" -DSCR_DEFAULT: - .tc dscr_default[TC],dscr_default - - .section ".text" - /* * This routine switches between two different tasks. The process * state of one is saved on its kernel stack. Then the state @@ -577,11 +571,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) #ifdef CONFIG_PPC64 BEGIN_FTR_SECTION lwz r6,THREAD_DSCR_INHERIT(r4) - ld r7,DSCR_DEFAULT@toc(2) ld r0,THREAD_DSCR(r4) cmpwi r6,0 bne 1f - ld r0,0(r7) + ld r0,PACA_DSCR(r13) 1: BEGIN_FTR_SECTION_NESTED(70) mfspr r8, SPRN_FSCR diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index e2a1d6f..67fd2fd 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -484,7 +484,6 @@ SYSFS_PMCSETUP(pmc8, SPRN_PMC8); SYSFS_PMCSETUP(mmcra, SPRN_MMCRA); SYSFS_SPRSETUP(purr, SPRN_PURR); SYSFS_SPRSETUP(spurr, SPRN_SPURR); -SYSFS_SPRSETUP(dscr, SPRN_DSCR); SYSFS_SPRSETUP(pir, SPRN_PIR); /* @@ -494,12 +493,27 @@ SYSFS_SPRSETUP(pir, SPRN_PIR); */ static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra); static DEVICE_ATTR(spurr, 0400, show_spurr, NULL); -static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); static DEVICE_ATTR(purr, 0400, show_purr, store_purr); static DEVICE_ATTR(pir, 0400, show_pir, NULL); -unsigned long dscr_default = 0; -EXPORT_SYMBOL(dscr_default); +static unsigned long dscr_default; + +static void read_dscr(void *val) +{ + *(unsigned long *)val = get_paca()->dscr_default; +} + +static void write_dscr(void *val) +{ + get_paca()->dscr_default = *(unsigned long *)val; + if (!current->thread.dscr_inherit) { + current->thread.dscr = *(unsigned long *)val; + mtspr(SPRN_DSCR, *(unsigned long *)val); + } +} + +SYSFS_SPRSETUP_SHOW_STORE(dscr); +static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); static void add_write_permission_dev_attr(struct device_attribute *attr) { @@ -512,14 +526,6 @@ static ssize_t show_dscr_default(struct device *dev, return sprintf(buf, "%lx\n", dscr_default); } -static void update_dscr(void *dummy) -{ - if (!current->thread.dscr_inherit) { - current->thread.dscr = dscr_default; - mtspr(SPRN_DSCR, dscr_default); - } -} - static ssize_t __used store_dscr_default(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) @@ -532,7 +538,7 @@ static ssize_t __used store_dscr_default(struct device *dev, return -EINVAL; dscr_default = val; - on_each_cpu(update_dscr, NULL, 1); + on_each_cpu(write_dscr, &val, 1); return count; } diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S index ee061c3..2a324f4 100644 --- a/arch/powerpc/kernel/tm.S +++ b/arch/powerpc/kernel/tm.S @@ -78,12 +78,6 @@ _GLOBAL(tm_abort) TABORT(R3) blr - .section ".toc","aw" -DSCR_DEFAULT: - .tc dscr_default[TC],dscr_default - - .section ".text" - /* void tm_reclaim(struct thread_struct *thread, * unsigned long orig_msr, * uint8_t cause) @@ -298,9 +292,8 @@ dont_backup_fp: mtlr r0 ld r2, STK_GOT(r1) - /* Load system default DSCR */ - ld r4, DSCR_DEFAULT@toc(r2) - ld r0, 0(r4) + /* Load CPU's default DSCR */ + ld r0, PACA_DSCR(r13) mtspr SPRN_DSCR, r0 blr @@ -479,9 +472,8 @@ restore_gprs: mtlr r0 ld r2, STK_GOT(r1) - /* Load system default DSCR */ - ld r4, DSCR_DEFAULT@toc(r2) - ld r0, 0(r4) + /* Load CPU's default DSCR */ + ld r0, PACA_DSCR(r13) mtspr SPRN_DSCR, r0 blr diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 9f0ad71..12f4ce5 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -286,8 +286,7 @@ kvm_start_guest: beq kvm_no_guest /* Set HSTATE_DSCR(r13) to something sensible */ - LOAD_REG_ADDR(r6, dscr_default) - ld r6, 0(r6) + ld r6, PACA_DSCR(r13) std r6, HSTATE_DSCR(r13) bl kvmppc_hv_entry -- 1.7.10.4 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting 2014-05-21 6:32 ` [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff @ 2014-06-02 9:27 ` Madhavan Srinivasan 0 siblings, 0 replies; 6+ messages in thread From: Madhavan Srinivasan @ 2014-06-02 9:27 UTC (permalink / raw) To: linuxppc-dev On Wednesday 21 May 2014 12:02 PM, Sam Bobroff wrote: > Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)" > it is no longer possible to set the DSCR on a per-CPU basis. > > The old behaviour was to minipulate the DSCR SPR directly but this is no > longer sufficient: the value is quickly overwritten by context switching. > > This patch stores the per-CPU DSCR value in a kernel variable rather than > directly in the SPR and it is used whenever a process has not set the DSCR > itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged. > > Writes to the old global default (/sys/devices/system/cpu/dscr_default) > now set all of the per-CPU values and reads return the last written value. > > The new per-CPU default is added to the paca_struct and is used everywhere > outside of sysfs.c instead of the old global default. > > Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> > --- > arch/powerpc/include/asm/paca.h | 3 +++ > arch/powerpc/kernel/asm-offsets.c | 1 + > arch/powerpc/kernel/entry_64.S | 9 +-------- > arch/powerpc/kernel/sysfs.c | 32 ++++++++++++++++++------------- > arch/powerpc/kernel/tm.S | 16 ++++------------ > arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 +-- > 6 files changed, 29 insertions(+), 35 deletions(-) > > diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h > index 8e956a0..bb0bd25 100644 > --- a/arch/powerpc/include/asm/paca.h > +++ b/arch/powerpc/include/asm/paca.h > @@ -92,7 +92,10 @@ struct paca_struct { > struct slb_shadow *slb_shadow_ptr; > struct dtl_entry *dispatch_log; > struct dtl_entry *dispatch_log_end; > +#endif /* CONFIG_PPC_STD_MMU_64 */ > + u64 dscr_default; /* per-CPU default DSCR */ > > +#ifdef CONFIG_PPC_STD_MMU_64 > /* > * Now, starting in cacheline 2, the exception save areas > */ > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > index dba8140..cba2697 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -247,6 +247,7 @@ int main(void) > #endif > DEFINE(PACAHWCPUID, offsetof(struct paca_struct, hw_cpu_id)); > DEFINE(PACAKEXECSTATE, offsetof(struct paca_struct, kexec_state)); > + DEFINE(PACA_DSCR, offsetof(struct paca_struct, dscr_default)); > DEFINE(PACA_STARTTIME, offsetof(struct paca_struct, starttime)); > DEFINE(PACA_STARTTIME_USER, offsetof(struct paca_struct, starttime_user)); > DEFINE(PACA_USER_TIME, offsetof(struct paca_struct, user_time)); > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index 9fde8a1..911d453 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -387,12 +387,6 @@ _GLOBAL(ret_from_kernel_thread) > li r3,0 > b syscall_exit > > - .section ".toc","aw" > -DSCR_DEFAULT: > - .tc dscr_default[TC],dscr_default > - > - .section ".text" > - > /* > * This routine switches between two different tasks. The process > * state of one is saved on its kernel stack. Then the state > @@ -577,11 +571,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) > #ifdef CONFIG_PPC64 > BEGIN_FTR_SECTION > lwz r6,THREAD_DSCR_INHERIT(r4) > - ld r7,DSCR_DEFAULT@toc(2) > ld r0,THREAD_DSCR(r4) > cmpwi r6,0 > bne 1f > - ld r0,0(r7) > + ld r0,PACA_DSCR(r13) > 1: > BEGIN_FTR_SECTION_NESTED(70) > mfspr r8, SPRN_FSCR > diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c > index e2a1d6f..67fd2fd 100644 > --- a/arch/powerpc/kernel/sysfs.c > +++ b/arch/powerpc/kernel/sysfs.c > @@ -484,7 +484,6 @@ SYSFS_PMCSETUP(pmc8, SPRN_PMC8); > SYSFS_PMCSETUP(mmcra, SPRN_MMCRA); > SYSFS_SPRSETUP(purr, SPRN_PURR); > SYSFS_SPRSETUP(spurr, SPRN_SPURR); > -SYSFS_SPRSETUP(dscr, SPRN_DSCR); > SYSFS_SPRSETUP(pir, SPRN_PIR); > > /* > @@ -494,12 +493,27 @@ SYSFS_SPRSETUP(pir, SPRN_PIR); > */ > static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra); > static DEVICE_ATTR(spurr, 0400, show_spurr, NULL); > -static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); > static DEVICE_ATTR(purr, 0400, show_purr, store_purr); > static DEVICE_ATTR(pir, 0400, show_pir, NULL); > > -unsigned long dscr_default = 0; > -EXPORT_SYMBOL(dscr_default); > +static unsigned long dscr_default; > + > +static void read_dscr(void *val) > +{ > + *(unsigned long *)val = get_paca()->dscr_default; > +} > + > +static void write_dscr(void *val) > +{ > + get_paca()->dscr_default = *(unsigned long *)val; > + if (!current->thread.dscr_inherit) { > + current->thread.dscr = *(unsigned long *)val; > + mtspr(SPRN_DSCR, *(unsigned long *)val); > + } > +} > + > +SYSFS_SPRSETUP_SHOW_STORE(dscr); > +static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); > > static void add_write_permission_dev_attr(struct device_attribute *attr) > { > @@ -512,14 +526,6 @@ static ssize_t show_dscr_default(struct device *dev, > return sprintf(buf, "%lx\n", dscr_default); > } > > -static void update_dscr(void *dummy) > -{ > - if (!current->thread.dscr_inherit) { > - current->thread.dscr = dscr_default; > - mtspr(SPRN_DSCR, dscr_default); > - } > -} > - > static ssize_t __used store_dscr_default(struct device *dev, > struct device_attribute *attr, const char *buf, > size_t count) > @@ -532,7 +538,7 @@ static ssize_t __used store_dscr_default(struct device *dev, > return -EINVAL; > dscr_default = val; > > - on_each_cpu(update_dscr, NULL, 1); > + on_each_cpu(write_dscr, &val, 1); > > return count; > } Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com> > diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S > index ee061c3..2a324f4 100644 > --- a/arch/powerpc/kernel/tm.S > +++ b/arch/powerpc/kernel/tm.S > @@ -78,12 +78,6 @@ _GLOBAL(tm_abort) > TABORT(R3) > blr > > - .section ".toc","aw" > -DSCR_DEFAULT: > - .tc dscr_default[TC],dscr_default > - > - .section ".text" > - > /* void tm_reclaim(struct thread_struct *thread, > * unsigned long orig_msr, > * uint8_t cause) > @@ -298,9 +292,8 @@ dont_backup_fp: > mtlr r0 > ld r2, STK_GOT(r1) > > - /* Load system default DSCR */ > - ld r4, DSCR_DEFAULT@toc(r2) > - ld r0, 0(r4) > + /* Load CPU's default DSCR */ > + ld r0, PACA_DSCR(r13) > mtspr SPRN_DSCR, r0 > > blr > @@ -479,9 +472,8 @@ restore_gprs: > mtlr r0 > ld r2, STK_GOT(r1) > > - /* Load system default DSCR */ > - ld r4, DSCR_DEFAULT@toc(r2) > - ld r0, 0(r4) > + /* Load CPU's default DSCR */ > + ld r0, PACA_DSCR(r13) > mtspr SPRN_DSCR, r0 > > blr > diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > index 9f0ad71..12f4ce5 100644 > --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S > +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S > @@ -286,8 +286,7 @@ kvm_start_guest: > beq kvm_no_guest > > /* Set HSTATE_DSCR(r13) to something sensible */ > - LOAD_REG_ADDR(r6, dscr_default) > - ld r6, 0(r6) > + ld r6, PACA_DSCR(r13) > std r6, HSTATE_DSCR(r13) > > bl kvmppc_hv_entry > ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 3/3] powerpc: Document sysfs DSCR interface 2014-05-21 6:32 [PATCH 0/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff 2014-05-21 6:32 ` [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro Sam Bobroff 2014-05-21 6:32 ` [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff @ 2014-05-21 6:32 ` Sam Bobroff 2 siblings, 0 replies; 6+ messages in thread From: Sam Bobroff @ 2014-05-21 6:32 UTC (permalink / raw) To: benh; +Cc: aik, mikey, linuxppc-dev Add some documentation about ... /sys/devices/system/cpu/dscr_default /sys/devices/system/cpu/cpuN/dscr ... to Documentation/ABI/stable. Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> --- Documentation/ABI/stable/sysfs-devices-system-cpu | 25 +++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Documentation/ABI/stable/sysfs-devices-system-cpu diff --git a/Documentation/ABI/stable/sysfs-devices-system-cpu b/Documentation/ABI/stable/sysfs-devices-system-cpu new file mode 100644 index 0000000..33c133e --- /dev/null +++ b/Documentation/ABI/stable/sysfs-devices-system-cpu @@ -0,0 +1,25 @@ +What: /sys/devices/system/cpu/dscr_default +Date: 13-May-2014 +KernelVersion: v3.15.0 +Contact: +Description: Writes are equivalent to writing to + /sys/devices/system/cpu/cpuN/dscr on all CPUs. + Reads return the last written value or 0. + This value is not a global default: it is a way to set + all per-CPU defaults at the same time. +Values: 64 bit unsigned integer (bit field) + +What: /sys/devices/system/cpu/cpu[0-9]+/dscr +Date: 13-May-2014 +KernelVersion: v3.15.0 +Contact: +Description: Default value for the Data Stream Control Register (DSCR) on + a CPU. + This default value is used when the kernel is executing and + for any process that has not set the DSCR itself. + If a process ever sets the DSCR (via direct access to the + SPR) that value will be persisted for that process and used + on any CPU where it executes (overriding the value described + here). + If set by a process it will be inherited by child processes. +Values: 64 bit unsigned integer (bit field) -- 1.7.10.4 ^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-06-02 9:27 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-05-21 6:32 [PATCH 0/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff 2014-05-21 6:32 ` [PATCH 1/3] powerpc: Split __SYSFS_SPRSETUP macro Sam Bobroff 2014-06-02 9:09 ` Madhavan Srinivasan 2014-05-21 6:32 ` [PATCH 2/3] powerpc: fix regression of per-CPU DSCR setting Sam Bobroff 2014-06-02 9:27 ` Madhavan Srinivasan 2014-05-21 6:32 ` [PATCH 3/3] powerpc: Document sysfs DSCR interface Sam Bobroff
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