[PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

Subsystems: linux for powerpc (32-bit and 64-bit), the rest

STALE3812d

10 messages, 4 authors, 2016-02-23 · open the first message on its own page

[PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Christophe Leroy <hidden>
Date: 2016-02-11 16:16:55

This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)

Changes in v4: ACCOUNT_CPU_USER_ENTRY/EXIT() needed updates in other
places than entry_32.S and entry_64.S (reported by kbuild-robot)
Related defines in asm-offset.c need to be conditional to
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE (reported by kbuild-robot)

Changes in v5: Using PPC_LL et PPC_STL instead of defining new macros
AC_LD and AC_STD

 arch/powerpc/Kconfig                     |  1 +
 arch/powerpc/include/asm/cputime.h       |  4 ++++
 arch/powerpc/include/asm/exception-64s.h |  2 +-
 arch/powerpc/include/asm/ppc_asm.h       | 24 ++++++++++----------
 arch/powerpc/include/asm/reg.h           |  1 +
 arch/powerpc/include/asm/thread_info.h   | 11 +++++++++
 arch/powerpc/kernel/asm-offsets.c        |  7 ++++++
 arch/powerpc/kernel/entry_32.S           | 17 ++++++++++++++
 arch/powerpc/kernel/entry_64.S           |  6 ++---
 arch/powerpc/kernel/exceptions-64e.S     |  4 ++--
 arch/powerpc/kernel/time.c               | 38 ++++++++++++++++++++++++++------
 arch/powerpc/platforms/Kconfig.cputype   |  1 -
 12 files changed, 90 insertions(+), 26 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3a557be..57ce4ff 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -159,6 +159,7 @@ config PPC
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select HAVE_ARCH_SECCOMP_FILTER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select HAVE_VIRT_CPU_ACCOUNTING
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index e245255..c4c33be 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -230,7 +230,11 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
 
+#ifdef CONFIG_PPC64
 static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+#else
+void arch_vtime_task_switch(struct task_struct *tsk);
+#endif
 
 #endif /* __KERNEL__ */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 93ae809..8bc38d1 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -287,7 +287,7 @@ do_kvm_##n:								\
 	std	r0,GPR0(r1);		/* save r0 in stackframe	*/ \
 	std	r10,GPR1(r1);		/* save r1 in stackframe	*/ \
 	beq	4f;			/* if from kernel mode		*/ \
-	ACCOUNT_CPU_USER_ENTRY(r9, r10);				   \
+	ACCOUNT_CPU_USER_ENTRY(r13, r9, r10);				   \
 	SAVE_PPR(area, r9, r10);					   \
 4:	EXCEPTION_PROLOG_COMMON_2(area)					   \
 	EXCEPTION_PROLOG_COMMON_3(n)					   \
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 499d9f8..07d1bfc 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -24,27 +24,27 @@
  */
 
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)
-#define ACCOUNT_CPU_USER_EXIT(ra, rb)
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)
 #define ACCOUNT_STOLEN_TIME
 #else
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)					\
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME_USER(r13);				\
-	std	ra,PACA_STARTTIME(r13);					\
+	PPC_LL	rb, PACA_STARTTIME_USER(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_USER_TIME(r13);					\
+	PPC_LL	ra, PACA_USER_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to user time */	\
-	std	ra,PACA_USER_TIME(r13);					\
+	PPC_STL	ra, PACA_USER_TIME(ptr);				\
 
-#define ACCOUNT_CPU_USER_EXIT(ra, rb)					\
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME(r13);					\
-	std	ra,PACA_STARTTIME_USER(r13);				\
+	PPC_LL	rb, PACA_STARTTIME(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME_USER(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_SYSTEM_TIME(r13);				\
+	PPC_LL	ra, PACA_SYSTEM_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to system time */	\
-	std	ra,PACA_SYSTEM_TIME(r13)
+	PPC_STL	ra, PACA_SYSTEM_TIME(ptr)
 
 #ifdef CONFIG_PPC_SPLPAR
 #define ACCOUNT_STOLEN_TIME						\
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index c4cb2ff..ff6b591 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1275,6 +1275,7 @@ static inline unsigned long mfvtb (void)
 			asm volatile("mfspr %0, %1" : "=r" (rval) : \
 				"i" (SPRN_TBRU)); rval;})
 #endif
+#define mftb()		mftbl()
 #endif /* !__powerpc64__ */
 
 #define mttbl(v)	asm volatile("mttbl %0":: "r"(v))
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 7efee4a..4f19e96 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -44,6 +44,17 @@ struct thread_info {
 						   <0 => BUG */
 	unsigned long	local_flags;		/* private flags for thread */
 
+#if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC32)
+	/* Stuff for accurate time accounting */
+	unsigned long user_time;	/* accumulated usermode TB ticks */
+	unsigned long system_time;	/* accumulated system TB ticks */
+	unsigned long user_time_scaled;	/* accumulated usermode SPURR ticks */
+	unsigned long starttime;	/* TB value snapshot */
+	unsigned long starttime_user;	/* TB value on exit to usermode */
+	unsigned long startspurr;	/* SPURR value snapshot */
+	unsigned long utime_sspurr;	/* ->user_time when ->startspurr set */
+#endif
+
 	/* low level flags - has atomic operations done on it */
 	unsigned long	flags ____cacheline_aligned_in_smp;
 };
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 07cebc3..b04b957 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -256,6 +256,13 @@ int main(void)
 	DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
 	DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost));
 	DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso));
+#else /* CONFIG_PPC64 */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	DEFINE(PACA_STARTTIME, offsetof(struct thread_info, starttime));
+	DEFINE(PACA_STARTTIME_USER, offsetof(struct thread_info, starttime_user));
+	DEFINE(PACA_USER_TIME, offsetof(struct thread_info, user_time));
+	DEFINE(PACA_SYSTEM_TIME, offsetof(struct thread_info, system_time));
+#endif
 #endif /* CONFIG_PPC64 */
 
 	/* RTAS */
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 2405631..9899032 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -175,6 +175,12 @@ transfer_to_handler:
 	addi	r12,r12,-1
 	stw	r12,4(r11)
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	tophys(r9, r9)
+	ACCOUNT_CPU_USER_ENTRY(r9, r11, r12)
+#endif
+
 	b	3f
 
 2:	/* if from kernel, check interrupted DOZE/NAP mode and
@@ -398,6 +404,13 @@ BEGIN_FTR_SECTION
 	lwarx	r7,0,r1
 END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 	stwcx.	r0,0,r1			/* to clear the reservation */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	andi.	r4,r8,MSR_PR
+	beq	3f
+	CURRENT_THREAD_INFO(r4, r1)
+	ACCOUNT_CPU_USER_EXIT(r4, r5, r7)
+3:
+#endif
 	lwz	r4,_LINK(r1)
 	lwz	r5,_CCR(r1)
 	mtlr	r4
@@ -769,6 +782,10 @@ restore_user:
 	andis.	r10,r0,DBCR0_IDM@h
 	bnel-	load_dbcr0
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	ACCOUNT_CPU_USER_EXIT(r9, r10, r11)
+#endif
 
 	b	restore
 
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 0d525ce..d9bf82b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -70,7 +70,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
 	std	r0,GPR0(r1)
 	std	r10,GPR1(r1)
 	beq	2f			/* if from kernel mode */
-	ACCOUNT_CPU_USER_ENTRY(r10, r11)
+	ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
 2:	std	r2,GPR2(r1)
 	std	r3,GPR3(r1)
 	mfcr	r2
@@ -222,7 +222,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	ld	r4,_LINK(r1)
 
 	beq-	1f
-	ACCOUNT_CPU_USER_EXIT(r11, r12)
+	ACCOUNT_CPU_USER_EXIT(r13, r11, r12)
 
 BEGIN_FTR_SECTION
 	HMT_MEDIUM_LOW
@@ -822,7 +822,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 BEGIN_FTR_SECTION
 	mtspr	SPRN_PPR,r2	/* Restore PPR */
 END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-	ACCOUNT_CPU_USER_EXIT(r2, r4)
+	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
 	REST_GPR(13, r1)
 1:
 	mtspr	SPRN_SRR1,r3
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 488e631..a9bc548 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -386,7 +386,7 @@ exc_##n##_common:							    \
 	std	r10,_NIP(r1);		/* save SRR0 to stackframe */	    \
 	std	r11,_MSR(r1);		/* save SRR1 to stackframe */	    \
 	beq	2f;			/* if from kernel mode */	    \
-	ACCOUNT_CPU_USER_ENTRY(r10,r11);/* accounting (uses cr0+eq) */	    \
+	ACCOUNT_CPU_USER_ENTRY(r13,r10,r11);/* accounting (uses cr0+eq) */ \
 2:	ld	r3,excf+EX_R10(r13);	/* get back r10 */		    \
 	ld	r4,excf+EX_R11(r13);	/* get back r11 */		    \
 	mfspr	r5,scratch;		/* get back r13 */		    \
@@ -1059,7 +1059,7 @@ fast_exception_return:
 	andi.	r6,r10,MSR_PR
 	REST_2GPRS(6, r1)
 	beq	1f
-	ACCOUNT_CPU_USER_EXIT(r10, r11)
+	ACCOUNT_CPU_USER_EXIT(r13, r10, r11)
 	ld	r0,GPR13(r1)
 
 1:	stdcx.	r0,0,r1		/* to clear the reservation */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 81b0900..6307b09 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -165,7 +165,13 @@ DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
 
 cputime_t cputime_one_jiffy;
 
+#ifdef CONFIG_PPC_SPLPAR
 void (*dtl_consumer)(struct dtl_entry *, u64);
+#endif
+
+#ifdef CONFIG_PPC32
+#define get_paca()	task_thread_info(tsk)
+#endif
 
 static void calc_cputime_factors(void)
 {
@@ -185,7 +191,7 @@ static void calc_cputime_factors(void)
  * Read the SPURR on systems that have it, otherwise the PURR,
  * or if that doesn't exist return the timebase value passed in.
  */
-static u64 read_spurr(u64 tb)
+static unsigned long read_spurr(unsigned long tb)
 {
 	if (cpu_has_feature(CPU_FTR_SPURR))
 		return mfspr(SPRN_SPURR);
@@ -294,11 +300,12 @@ static inline u64 calculate_stolen_time(u64 stop_tb)
  * Account time for a transition between system, hard irq
  * or soft irq state.
  */
-static u64 vtime_delta(struct task_struct *tsk,
-			u64 *sys_scaled, u64 *stolen)
+static unsigned long vtime_delta(struct task_struct *tsk,
+				 unsigned long *sys_scaled,
+				 unsigned long *stolen)
 {
-	u64 now, nowscaled, deltascaled;
-	u64 udelta, delta, user_scaled;
+	unsigned long now, nowscaled, deltascaled;
+	unsigned long udelta, delta, user_scaled;
 
 	WARN_ON_ONCE(!irqs_disabled());
 
@@ -343,7 +350,7 @@ static u64 vtime_delta(struct task_struct *tsk,
 
 void vtime_account_system(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;
 
 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_system_time(tsk, 0, delta, sys_scaled);
@@ -354,7 +361,7 @@ EXPORT_SYMBOL_GPL(vtime_account_system);
 
 void vtime_account_idle(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;
 
 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_idle_time(delta + stolen);
@@ -381,6 +388,23 @@ void vtime_account_user(struct task_struct *tsk)
 	account_user_time(tsk, utime, utimescaled);
 }
 
+#ifdef CONFIG_PPC32
+/*
+ * Called from the context switch with interrupts disabled, to charge all
+ * accumulated times to the current process, and to prepare accounting on
+ * the next process.
+ */
+void arch_vtime_task_switch(struct task_struct *prev)
+{
+	struct thread_info *pi = task_thread_info(prev);
+	struct thread_info *ni = task_thread_info(current);
+
+	ni->starttime = pi->starttime;
+	ni->system_time = 0;
+	ni->user_time = 0;
+}
+#endif /* CONFIG_PPC32 */
+
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 #define calc_cputime_factors()
 #endif
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 142dff5..54b8043 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,7 +1,6 @@
 config PPC64
 	bool "64-bit kernel"
 	default n
-	select HAVE_VIRT_CPU_ACCOUNTING
 	select ZLIB_DEFLATE
 	help
 	  This option selects whether a 32-bit or a 64-bit kernel
-- 
2.1.0

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Denis Kirjanov <hidden>
Date: 2016-02-12 08:25:35

On 2/11/16, Christophe Leroy [off-list ref] wrote:
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
I'll try it out on my ppc32 machines.

Thanks!
quoted hunk
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)

Changes in v4: ACCOUNT_CPU_USER_ENTRY/EXIT() needed updates in other
places than entry_32.S and entry_64.S (reported by kbuild-robot)
Related defines in asm-offset.c need to be conditional to
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE (reported by kbuild-robot)

Changes in v5: Using PPC_LL et PPC_STL instead of defining new macros
AC_LD and AC_STD

 arch/powerpc/Kconfig                     |  1 +
 arch/powerpc/include/asm/cputime.h       |  4 ++++
 arch/powerpc/include/asm/exception-64s.h |  2 +-
 arch/powerpc/include/asm/ppc_asm.h       | 24 ++++++++++----------
 arch/powerpc/include/asm/reg.h           |  1 +
 arch/powerpc/include/asm/thread_info.h   | 11 +++++++++
 arch/powerpc/kernel/asm-offsets.c        |  7 ++++++
 arch/powerpc/kernel/entry_32.S           | 17 ++++++++++++++
 arch/powerpc/kernel/entry_64.S           |  6 ++---
 arch/powerpc/kernel/exceptions-64e.S     |  4 ++--
 arch/powerpc/kernel/time.c               | 38
++++++++++++++++++++++++++------
 arch/powerpc/platforms/Kconfig.cputype   |  1 -
 12 files changed, 90 insertions(+), 26 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3a557be..57ce4ff 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -159,6 +159,7 @@ config PPC
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select HAVE_ARCH_SECCOMP_FILTER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select HAVE_VIRT_CPU_ACCOUNTING

 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/cputime.h
b/arch/powerpc/include/asm/cputime.h
index e245255..c4c33be 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -230,7 +230,11 @@ static inline cputime_t clock_t_to_cputime(const
unsigned long clk)

 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))

+#ifdef CONFIG_PPC64
 static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+#else
+void arch_vtime_task_switch(struct task_struct *tsk);
+#endif

 #endif /* __KERNEL__ */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
diff --git a/arch/powerpc/include/asm/exception-64s.h
b/arch/powerpc/include/asm/exception-64s.h
index 93ae809..8bc38d1 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -287,7 +287,7 @@ do_kvm_##n:								\
 	std	r0,GPR0(r1);		/* save r0 in stackframe	*/ \
 	std	r10,GPR1(r1);		/* save r1 in stackframe	*/ \
 	beq	4f;			/* if from kernel mode		*/ \
-	ACCOUNT_CPU_USER_ENTRY(r9, r10);				   \
+	ACCOUNT_CPU_USER_ENTRY(r13, r9, r10);				   \
 	SAVE_PPR(area, r9, r10);					   \
 4:	EXCEPTION_PROLOG_COMMON_2(area)					   \
 	EXCEPTION_PROLOG_COMMON_3(n)					   \
diff --git a/arch/powerpc/include/asm/ppc_asm.h
b/arch/powerpc/include/asm/ppc_asm.h
index 499d9f8..07d1bfc 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -24,27 +24,27 @@
  */

 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)
-#define ACCOUNT_CPU_USER_EXIT(ra, rb)
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)
 #define ACCOUNT_STOLEN_TIME
 #else
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)					\
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME_USER(r13);				\
-	std	ra,PACA_STARTTIME(r13);					\
+	PPC_LL	rb, PACA_STARTTIME_USER(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_USER_TIME(r13);					\
+	PPC_LL	ra, PACA_USER_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to user time */	\
-	std	ra,PACA_USER_TIME(r13);					\
+	PPC_STL	ra, PACA_USER_TIME(ptr);				\

-#define ACCOUNT_CPU_USER_EXIT(ra, rb)					\
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME(r13);					\
-	std	ra,PACA_STARTTIME_USER(r13);				\
+	PPC_LL	rb, PACA_STARTTIME(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME_USER(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_SYSTEM_TIME(r13);				\
+	PPC_LL	ra, PACA_SYSTEM_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to system time */	\
-	std	ra,PACA_SYSTEM_TIME(r13)
+	PPC_STL	ra, PACA_SYSTEM_TIME(ptr)

 #ifdef CONFIG_PPC_SPLPAR
 #define ACCOUNT_STOLEN_TIME						\
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index c4cb2ff..ff6b591 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1275,6 +1275,7 @@ static inline unsigned long mfvtb (void)
 			asm volatile("mfspr %0, %1" : "=r" (rval) : \
 				"i" (SPRN_TBRU)); rval;})
 #endif
+#define mftb()		mftbl()
 #endif /* !__powerpc64__ */

 #define mttbl(v)	asm volatile("mttbl %0":: "r"(v))
diff --git a/arch/powerpc/include/asm/thread_info.h
b/arch/powerpc/include/asm/thread_info.h
index 7efee4a..4f19e96 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -44,6 +44,17 @@ struct thread_info {
 						   <0 => BUG */
 	unsigned long	local_flags;		/* private flags for thread */

+#if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC32)
+	/* Stuff for accurate time accounting */
+	unsigned long user_time;	/* accumulated usermode TB ticks */
+	unsigned long system_time;	/* accumulated system TB ticks */
+	unsigned long user_time_scaled;	/* accumulated usermode SPURR ticks */
+	unsigned long starttime;	/* TB value snapshot */
+	unsigned long starttime_user;	/* TB value on exit to usermode */
+	unsigned long startspurr;	/* SPURR value snapshot */
+	unsigned long utime_sspurr;	/* ->user_time when ->startspurr set */
+#endif
+
 	/* low level flags - has atomic operations done on it */
 	unsigned long	flags ____cacheline_aligned_in_smp;
 };
diff --git a/arch/powerpc/kernel/asm-offsets.c
b/arch/powerpc/kernel/asm-offsets.c
index 07cebc3..b04b957 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -256,6 +256,13 @@ int main(void)
 	DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
 	DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost));
 	DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso));
+#else /* CONFIG_PPC64 */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	DEFINE(PACA_STARTTIME, offsetof(struct thread_info, starttime));
+	DEFINE(PACA_STARTTIME_USER, offsetof(struct thread_info, starttime_user));
+	DEFINE(PACA_USER_TIME, offsetof(struct thread_info, user_time));
+	DEFINE(PACA_SYSTEM_TIME, offsetof(struct thread_info, system_time));
+#endif
 #endif /* CONFIG_PPC64 */

 	/* RTAS */
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 2405631..9899032 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -175,6 +175,12 @@ transfer_to_handler:
 	addi	r12,r12,-1
 	stw	r12,4(r11)
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	tophys(r9, r9)
+	ACCOUNT_CPU_USER_ENTRY(r9, r11, r12)
+#endif
+
 	b	3f

 2:	/* if from kernel, check interrupted DOZE/NAP mode and
@@ -398,6 +404,13 @@ BEGIN_FTR_SECTION
 	lwarx	r7,0,r1
 END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 	stwcx.	r0,0,r1			/* to clear the reservation */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	andi.	r4,r8,MSR_PR
+	beq	3f
+	CURRENT_THREAD_INFO(r4, r1)
+	ACCOUNT_CPU_USER_EXIT(r4, r5, r7)
+3:
+#endif
 	lwz	r4,_LINK(r1)
 	lwz	r5,_CCR(r1)
 	mtlr	r4
@@ -769,6 +782,10 @@ restore_user:
 	andis.	r10,r0,DBCR0_IDM@h
 	bnel-	load_dbcr0
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	ACCOUNT_CPU_USER_EXIT(r9, r10, r11)
+#endif

 	b	restore
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 0d525ce..d9bf82b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -70,7 +70,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
 	std	r0,GPR0(r1)
 	std	r10,GPR1(r1)
 	beq	2f			/* if from kernel mode */
-	ACCOUNT_CPU_USER_ENTRY(r10, r11)
+	ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
 2:	std	r2,GPR2(r1)
 	std	r3,GPR3(r1)
 	mfcr	r2
@@ -222,7 +222,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	ld	r4,_LINK(r1)

 	beq-	1f
-	ACCOUNT_CPU_USER_EXIT(r11, r12)
+	ACCOUNT_CPU_USER_EXIT(r13, r11, r12)

 BEGIN_FTR_SECTION
 	HMT_MEDIUM_LOW
@@ -822,7 +822,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 BEGIN_FTR_SECTION
 	mtspr	SPRN_PPR,r2	/* Restore PPR */
 END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-	ACCOUNT_CPU_USER_EXIT(r2, r4)
+	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
 	REST_GPR(13, r1)
 1:
 	mtspr	SPRN_SRR1,r3
diff --git a/arch/powerpc/kernel/exceptions-64e.S
b/arch/powerpc/kernel/exceptions-64e.S
index 488e631..a9bc548 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -386,7 +386,7 @@ exc_##n##_common:							    \
 	std	r10,_NIP(r1);		/* save SRR0 to stackframe */	    \
 	std	r11,_MSR(r1);		/* save SRR1 to stackframe */	    \
 	beq	2f;			/* if from kernel mode */	    \
-	ACCOUNT_CPU_USER_ENTRY(r10,r11);/* accounting (uses cr0+eq) */	    \
+	ACCOUNT_CPU_USER_ENTRY(r13,r10,r11);/* accounting (uses cr0+eq) */ \
 2:	ld	r3,excf+EX_R10(r13);	/* get back r10 */		    \
 	ld	r4,excf+EX_R11(r13);	/* get back r11 */		    \
 	mfspr	r5,scratch;		/* get back r13 */		    \
@@ -1059,7 +1059,7 @@ fast_exception_return:
 	andi.	r6,r10,MSR_PR
 	REST_2GPRS(6, r1)
 	beq	1f
-	ACCOUNT_CPU_USER_EXIT(r10, r11)
+	ACCOUNT_CPU_USER_EXIT(r13, r10, r11)
 	ld	r0,GPR13(r1)

 1:	stdcx.	r0,0,r1		/* to clear the reservation */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 81b0900..6307b09 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -165,7 +165,13 @@ DEFINE_PER_CPU(unsigned long,
cputime_scaled_last_delta);

 cputime_t cputime_one_jiffy;

+#ifdef CONFIG_PPC_SPLPAR
 void (*dtl_consumer)(struct dtl_entry *, u64);
+#endif
+
+#ifdef CONFIG_PPC32
+#define get_paca()	task_thread_info(tsk)
+#endif

 static void calc_cputime_factors(void)
 {
@@ -185,7 +191,7 @@ static void calc_cputime_factors(void)
  * Read the SPURR on systems that have it, otherwise the PURR,
  * or if that doesn't exist return the timebase value passed in.
  */
-static u64 read_spurr(u64 tb)
+static unsigned long read_spurr(unsigned long tb)
 {
 	if (cpu_has_feature(CPU_FTR_SPURR))
 		return mfspr(SPRN_SPURR);
@@ -294,11 +300,12 @@ static inline u64 calculate_stolen_time(u64 stop_tb)
  * Account time for a transition between system, hard irq
  * or soft irq state.
  */
-static u64 vtime_delta(struct task_struct *tsk,
-			u64 *sys_scaled, u64 *stolen)
+static unsigned long vtime_delta(struct task_struct *tsk,
+				 unsigned long *sys_scaled,
+				 unsigned long *stolen)
 {
-	u64 now, nowscaled, deltascaled;
-	u64 udelta, delta, user_scaled;
+	unsigned long now, nowscaled, deltascaled;
+	unsigned long udelta, delta, user_scaled;

 	WARN_ON_ONCE(!irqs_disabled());
@@ -343,7 +350,7 @@ static u64 vtime_delta(struct task_struct *tsk,

 void vtime_account_system(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;

 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_system_time(tsk, 0, delta, sys_scaled);
@@ -354,7 +361,7 @@ EXPORT_SYMBOL_GPL(vtime_account_system);

 void vtime_account_idle(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;

 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_idle_time(delta + stolen);
@@ -381,6 +388,23 @@ void vtime_account_user(struct task_struct *tsk)
 	account_user_time(tsk, utime, utimescaled);
 }

+#ifdef CONFIG_PPC32
+/*
+ * Called from the context switch with interrupts disabled, to charge all
+ * accumulated times to the current process, and to prepare accounting on
+ * the next process.
+ */
+void arch_vtime_task_switch(struct task_struct *prev)
+{
+	struct thread_info *pi = task_thread_info(prev);
+	struct thread_info *ni = task_thread_info(current);
+
+	ni->starttime = pi->starttime;
+	ni->system_time = 0;
+	ni->user_time = 0;
+}
+#endif /* CONFIG_PPC32 */
+
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 #define calc_cputime_factors()
 #endif
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index 142dff5..54b8043 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,7 +1,6 @@
 config PPC64
 	bool "64-bit kernel"
 	default n
-	select HAVE_VIRT_CPU_ACCOUNTING
 	select ZLIB_DEFLATE
 	help
 	  This option selects whether a 32-bit or a 64-bit kernel
--
2.1.0

_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Denis Kirjanov <hidden>
Date: 2016-02-14 20:40:06

On 2/11/16, Christophe Leroy [off-list ref] wrote:
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
Doesn't build for me with the patch applied

To see full details build your kernel with:
'make CONFIG_DEBUG_SECTION_MISMATCH=y'
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  LD      init/built-in.o
drivers/built-in.o: In function `get_cpu_idle_time':
(.text+0x1261c4): undefined reference to `__umoddi3'
drivers/built-in.o: In function `get_cpu_idle_time':
(.text+0x1261e0): undefined reference to `__udivdi3'
Makefile:936: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1

quoted hunk
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)

Changes in v4: ACCOUNT_CPU_USER_ENTRY/EXIT() needed updates in other
places than entry_32.S and entry_64.S (reported by kbuild-robot)
Related defines in asm-offset.c need to be conditional to
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE (reported by kbuild-robot)

Changes in v5: Using PPC_LL et PPC_STL instead of defining new macros
AC_LD and AC_STD

 arch/powerpc/Kconfig                     |  1 +
 arch/powerpc/include/asm/cputime.h       |  4 ++++
 arch/powerpc/include/asm/exception-64s.h |  2 +-
 arch/powerpc/include/asm/ppc_asm.h       | 24 ++++++++++----------
 arch/powerpc/include/asm/reg.h           |  1 +
 arch/powerpc/include/asm/thread_info.h   | 11 +++++++++
 arch/powerpc/kernel/asm-offsets.c        |  7 ++++++
 arch/powerpc/kernel/entry_32.S           | 17 ++++++++++++++
 arch/powerpc/kernel/entry_64.S           |  6 ++---
 arch/powerpc/kernel/exceptions-64e.S     |  4 ++--
 arch/powerpc/kernel/time.c               | 38
++++++++++++++++++++++++++------
 arch/powerpc/platforms/Kconfig.cputype   |  1 -
 12 files changed, 90 insertions(+), 26 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3a557be..57ce4ff 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -159,6 +159,7 @@ config PPC
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select HAVE_ARCH_SECCOMP_FILTER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select HAVE_VIRT_CPU_ACCOUNTING

 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
diff --git a/arch/powerpc/include/asm/cputime.h
b/arch/powerpc/include/asm/cputime.h
index e245255..c4c33be 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -230,7 +230,11 @@ static inline cputime_t clock_t_to_cputime(const
unsigned long clk)

 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))

+#ifdef CONFIG_PPC64
 static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+#else
+void arch_vtime_task_switch(struct task_struct *tsk);
+#endif

 #endif /* __KERNEL__ */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
diff --git a/arch/powerpc/include/asm/exception-64s.h
b/arch/powerpc/include/asm/exception-64s.h
index 93ae809..8bc38d1 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -287,7 +287,7 @@ do_kvm_##n:								\
 	std	r0,GPR0(r1);		/* save r0 in stackframe	*/ \
 	std	r10,GPR1(r1);		/* save r1 in stackframe	*/ \
 	beq	4f;			/* if from kernel mode		*/ \
-	ACCOUNT_CPU_USER_ENTRY(r9, r10);				   \
+	ACCOUNT_CPU_USER_ENTRY(r13, r9, r10);				   \
 	SAVE_PPR(area, r9, r10);					   \
 4:	EXCEPTION_PROLOG_COMMON_2(area)					   \
 	EXCEPTION_PROLOG_COMMON_3(n)					   \
diff --git a/arch/powerpc/include/asm/ppc_asm.h
b/arch/powerpc/include/asm/ppc_asm.h
index 499d9f8..07d1bfc 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -24,27 +24,27 @@
  */

 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)
-#define ACCOUNT_CPU_USER_EXIT(ra, rb)
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)
 #define ACCOUNT_STOLEN_TIME
 #else
-#define ACCOUNT_CPU_USER_ENTRY(ra, rb)					\
+#define ACCOUNT_CPU_USER_ENTRY(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME_USER(r13);				\
-	std	ra,PACA_STARTTIME(r13);					\
+	PPC_LL	rb, PACA_STARTTIME_USER(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_USER_TIME(r13);					\
+	PPC_LL	ra, PACA_USER_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to user time */	\
-	std	ra,PACA_USER_TIME(r13);					\
+	PPC_STL	ra, PACA_USER_TIME(ptr);				\

-#define ACCOUNT_CPU_USER_EXIT(ra, rb)					\
+#define ACCOUNT_CPU_USER_EXIT(ptr, ra, rb)				\
 	MFTB(ra);			/* get timebase */		\
-	ld	rb,PACA_STARTTIME(r13);					\
-	std	ra,PACA_STARTTIME_USER(r13);				\
+	PPC_LL	rb, PACA_STARTTIME(ptr);				\
+	PPC_STL	ra, PACA_STARTTIME_USER(ptr);				\
 	subf	rb,rb,ra;		/* subtract start value */	\
-	ld	ra,PACA_SYSTEM_TIME(r13);				\
+	PPC_LL	ra, PACA_SYSTEM_TIME(ptr);				\
 	add	ra,ra,rb;		/* add on to system time */	\
-	std	ra,PACA_SYSTEM_TIME(r13)
+	PPC_STL	ra, PACA_SYSTEM_TIME(ptr)

 #ifdef CONFIG_PPC_SPLPAR
 #define ACCOUNT_STOLEN_TIME						\
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index c4cb2ff..ff6b591 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1275,6 +1275,7 @@ static inline unsigned long mfvtb (void)
 			asm volatile("mfspr %0, %1" : "=r" (rval) : \
 				"i" (SPRN_TBRU)); rval;})
 #endif
+#define mftb()		mftbl()
 #endif /* !__powerpc64__ */

 #define mttbl(v)	asm volatile("mttbl %0":: "r"(v))
diff --git a/arch/powerpc/include/asm/thread_info.h
b/arch/powerpc/include/asm/thread_info.h
index 7efee4a..4f19e96 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -44,6 +44,17 @@ struct thread_info {
 						   <0 => BUG */
 	unsigned long	local_flags;		/* private flags for thread */

+#if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC32)
+	/* Stuff for accurate time accounting */
+	unsigned long user_time;	/* accumulated usermode TB ticks */
+	unsigned long system_time;	/* accumulated system TB ticks */
+	unsigned long user_time_scaled;	/* accumulated usermode SPURR ticks */
+	unsigned long starttime;	/* TB value snapshot */
+	unsigned long starttime_user;	/* TB value on exit to usermode */
+	unsigned long startspurr;	/* SPURR value snapshot */
+	unsigned long utime_sspurr;	/* ->user_time when ->startspurr set */
+#endif
+
 	/* low level flags - has atomic operations done on it */
 	unsigned long	flags ____cacheline_aligned_in_smp;
 };
diff --git a/arch/powerpc/kernel/asm-offsets.c
b/arch/powerpc/kernel/asm-offsets.c
index 07cebc3..b04b957 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -256,6 +256,13 @@ int main(void)
 	DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
 	DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct, nap_state_lost));
 	DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso));
+#else /* CONFIG_PPC64 */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	DEFINE(PACA_STARTTIME, offsetof(struct thread_info, starttime));
+	DEFINE(PACA_STARTTIME_USER, offsetof(struct thread_info, starttime_user));
+	DEFINE(PACA_USER_TIME, offsetof(struct thread_info, user_time));
+	DEFINE(PACA_SYSTEM_TIME, offsetof(struct thread_info, system_time));
+#endif
 #endif /* CONFIG_PPC64 */

 	/* RTAS */
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 2405631..9899032 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -175,6 +175,12 @@ transfer_to_handler:
 	addi	r12,r12,-1
 	stw	r12,4(r11)
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	tophys(r9, r9)
+	ACCOUNT_CPU_USER_ENTRY(r9, r11, r12)
+#endif
+
 	b	3f

 2:	/* if from kernel, check interrupted DOZE/NAP mode and
@@ -398,6 +404,13 @@ BEGIN_FTR_SECTION
 	lwarx	r7,0,r1
 END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
 	stwcx.	r0,0,r1			/* to clear the reservation */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	andi.	r4,r8,MSR_PR
+	beq	3f
+	CURRENT_THREAD_INFO(r4, r1)
+	ACCOUNT_CPU_USER_EXIT(r4, r5, r7)
+3:
+#endif
 	lwz	r4,_LINK(r1)
 	lwz	r5,_CCR(r1)
 	mtlr	r4
@@ -769,6 +782,10 @@ restore_user:
 	andis.	r10,r0,DBCR0_IDM@h
 	bnel-	load_dbcr0
 #endif
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	CURRENT_THREAD_INFO(r9, r1)
+	ACCOUNT_CPU_USER_EXIT(r9, r10, r11)
+#endif

 	b	restore
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 0d525ce..d9bf82b 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -70,7 +70,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
 	std	r0,GPR0(r1)
 	std	r10,GPR1(r1)
 	beq	2f			/* if from kernel mode */
-	ACCOUNT_CPU_USER_ENTRY(r10, r11)
+	ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
 2:	std	r2,GPR2(r1)
 	std	r3,GPR3(r1)
 	mfcr	r2
@@ -222,7 +222,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
 	ld	r4,_LINK(r1)

 	beq-	1f
-	ACCOUNT_CPU_USER_EXIT(r11, r12)
+	ACCOUNT_CPU_USER_EXIT(r13, r11, r12)

 BEGIN_FTR_SECTION
 	HMT_MEDIUM_LOW
@@ -822,7 +822,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 BEGIN_FTR_SECTION
 	mtspr	SPRN_PPR,r2	/* Restore PPR */
 END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
-	ACCOUNT_CPU_USER_EXIT(r2, r4)
+	ACCOUNT_CPU_USER_EXIT(r13, r2, r4)
 	REST_GPR(13, r1)
 1:
 	mtspr	SPRN_SRR1,r3
diff --git a/arch/powerpc/kernel/exceptions-64e.S
b/arch/powerpc/kernel/exceptions-64e.S
index 488e631..a9bc548 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -386,7 +386,7 @@ exc_##n##_common:							    \
 	std	r10,_NIP(r1);		/* save SRR0 to stackframe */	    \
 	std	r11,_MSR(r1);		/* save SRR1 to stackframe */	    \
 	beq	2f;			/* if from kernel mode */	    \
-	ACCOUNT_CPU_USER_ENTRY(r10,r11);/* accounting (uses cr0+eq) */	    \
+	ACCOUNT_CPU_USER_ENTRY(r13,r10,r11);/* accounting (uses cr0+eq) */ \
 2:	ld	r3,excf+EX_R10(r13);	/* get back r10 */		    \
 	ld	r4,excf+EX_R11(r13);	/* get back r11 */		    \
 	mfspr	r5,scratch;		/* get back r13 */		    \
@@ -1059,7 +1059,7 @@ fast_exception_return:
 	andi.	r6,r10,MSR_PR
 	REST_2GPRS(6, r1)
 	beq	1f
-	ACCOUNT_CPU_USER_EXIT(r10, r11)
+	ACCOUNT_CPU_USER_EXIT(r13, r10, r11)
 	ld	r0,GPR13(r1)

 1:	stdcx.	r0,0,r1		/* to clear the reservation */
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 81b0900..6307b09 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -165,7 +165,13 @@ DEFINE_PER_CPU(unsigned long,
cputime_scaled_last_delta);

 cputime_t cputime_one_jiffy;

+#ifdef CONFIG_PPC_SPLPAR
 void (*dtl_consumer)(struct dtl_entry *, u64);
+#endif
+
+#ifdef CONFIG_PPC32
+#define get_paca()	task_thread_info(tsk)
+#endif

 static void calc_cputime_factors(void)
 {
@@ -185,7 +191,7 @@ static void calc_cputime_factors(void)
  * Read the SPURR on systems that have it, otherwise the PURR,
  * or if that doesn't exist return the timebase value passed in.
  */
-static u64 read_spurr(u64 tb)
+static unsigned long read_spurr(unsigned long tb)
 {
 	if (cpu_has_feature(CPU_FTR_SPURR))
 		return mfspr(SPRN_SPURR);
@@ -294,11 +300,12 @@ static inline u64 calculate_stolen_time(u64 stop_tb)
  * Account time for a transition between system, hard irq
  * or soft irq state.
  */
-static u64 vtime_delta(struct task_struct *tsk,
-			u64 *sys_scaled, u64 *stolen)
+static unsigned long vtime_delta(struct task_struct *tsk,
+				 unsigned long *sys_scaled,
+				 unsigned long *stolen)
 {
-	u64 now, nowscaled, deltascaled;
-	u64 udelta, delta, user_scaled;
+	unsigned long now, nowscaled, deltascaled;
+	unsigned long udelta, delta, user_scaled;

 	WARN_ON_ONCE(!irqs_disabled());
@@ -343,7 +350,7 @@ static u64 vtime_delta(struct task_struct *tsk,

 void vtime_account_system(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;

 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_system_time(tsk, 0, delta, sys_scaled);
@@ -354,7 +361,7 @@ EXPORT_SYMBOL_GPL(vtime_account_system);

 void vtime_account_idle(struct task_struct *tsk)
 {
-	u64 delta, sys_scaled, stolen;
+	unsigned long delta, sys_scaled, stolen;

 	delta = vtime_delta(tsk, &sys_scaled, &stolen);
 	account_idle_time(delta + stolen);
@@ -381,6 +388,23 @@ void vtime_account_user(struct task_struct *tsk)
 	account_user_time(tsk, utime, utimescaled);
 }

+#ifdef CONFIG_PPC32
+/*
+ * Called from the context switch with interrupts disabled, to charge all
+ * accumulated times to the current process, and to prepare accounting on
+ * the next process.
+ */
+void arch_vtime_task_switch(struct task_struct *prev)
+{
+	struct thread_info *pi = task_thread_info(prev);
+	struct thread_info *ni = task_thread_info(current);
+
+	ni->starttime = pi->starttime;
+	ni->system_time = 0;
+	ni->user_time = 0;
+}
+#endif /* CONFIG_PPC32 */
+
 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 #define calc_cputime_factors()
 #endif
diff --git a/arch/powerpc/platforms/Kconfig.cputype
b/arch/powerpc/platforms/Kconfig.cputype
index 142dff5..54b8043 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,7 +1,6 @@
 config PPC64
 	bool "64-bit kernel"
 	default n
-	select HAVE_VIRT_CPU_ACCOUNTING
 	select ZLIB_DEFLATE
 	help
 	  This option selects whether a 32-bit or a 64-bit kernel
--
2.1.0

_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Christophe Leroy <hidden>
Date: 2016-02-15 09:33:27

Le 14/02/2016 21:40, Denis Kirjanov a écrit :
On 2/11/16, Christophe Leroy [off-list ref] wrote:
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
Doesn't build for me with the patch applied

To see full details build your kernel with:
'make CONFIG_DEBUG_SECTION_MISMATCH=y'
   GEN     .version
   CHK     include/generated/compile.h
   UPD     include/generated/compile.h
   CC      init/version.o
   LD      init/built-in.o
drivers/built-in.o: In function `get_cpu_idle_time':
(.text+0x1261c4): undefined reference to `__umoddi3'
drivers/built-in.o: In function `get_cpu_idle_time':
(.text+0x1261e0): undefined reference to `__udivdi3'
Makefile:936: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1
Looks like you have CONFIG_CPU_FREQ, which I don't have.

The issue comes from the jiffies64_to_cputime64() defined in 
arch/powerpc/include/asm/cputime.h :

static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
{
         u64 ct;
         u64 sec;

         /* have to be a little careful about overflow */
         ct = jif % HZ;
         sec = jif / HZ;



On 32 bits, 64 bits % and / require __udivdi3() and __umoddi3(), which 
are not implemented in the kernel.

As HZ fits in 32 bits, the solution is to use do_div(). I should not 
change anything on PPC64 and would solve your issue.
I will submit an update of the patch within an hour.

Christophe

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Scott Wood <oss@buserror.net>
Date: 2016-02-16 21:21:15

On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from 32
-bit?  What is the difference between PACA and "per-cpu data", other than the
obscure name?"

I can understand wanting to avoid churn, but other than that, doing things 
differently on 64-bit versus 32-bit sucks.
quoted hunk
b/arch/powerpc/include/asm/cputime.h
index e245255..c4c33be 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -230,7 +230,11 @@ static inline cputime_t clock_t_to_cputime(const
unsigned long clk)
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
 
+#ifdef CONFIG_PPC64
 static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
+#else
+void arch_vtime_task_switch(struct task_struct *tsk);
+#endif
Add a comment explaining why this is empty on 64-bit but non-empty on 32-bit.
quoted hunk
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm
-offsets.c
index 07cebc3..b04b957 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -256,6 +256,13 @@ int main(void)
 	DEFINE(PACA_TRAP_SAVE, offsetof(struct paca_struct, trap_save));
 	DEFINE(PACA_NAPSTATELOST, offsetof(struct paca_struct,
nap_state_lost));
 	DEFINE(PACA_SPRG_VDSO, offsetof(struct paca_struct, sprg_vdso));
+#else /* CONFIG_PPC64 */
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+	DEFINE(PACA_STARTTIME, offsetof(struct thread_info, starttime));
+	DEFINE(PACA_STARTTIME_USER, offsetof(struct thread_info,
starttime_user));
+	DEFINE(PACA_USER_TIME, offsetof(struct thread_info, user_time));
+	DEFINE(PACA_SYSTEM_TIME, offsetof(struct thread_info,
system_time));
+#endif
 #endif /* CONFIG_PPC64 */
Can you change the name if it's not always going to be relative to a PACA?
+#ifdef CONFIG_PPC32
+#define get_paca()	task_thread_info(tsk)
+#endif
Likewise, this is just going to cause confusion.

Can you bundle up the time accounting fields into a struct, that you share
between the paca and the 32-bit thread_info, and then have a macro to grab a
pointer to that?

-Scott

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Christophe Leroy <hidden>
Date: 2016-02-17 16:29:14


Le 16/02/2016 22:21, Scott Wood a écrit :
On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from 32
-bit?  What is the difference between PACA and "per-cpu data", other than the
obscure name?"

I can understand wanting to avoid churn, but other than that, doing things
differently on 64-bit versus 32-bit sucks.
What I can see is that PACA is always available via register r13. Do we 
have anything equivalent on PPC32 ?
If we define a per-cpu data for accounting, what will be the quick way 
to get access to it in entry_32.S ?
Something like a table of accounting data for each CPU, that we index 
with thread_info->cpu ?
This would allow a quite quick access, is it the good way to proceed in 
order to have something closer to PPC64 ?

Christophe

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Scott Wood <oss@buserror.net>
Date: 2016-02-23 01:26:24

On Wed, 2016-02-17 at 17:29 +0100, Christophe Leroy wrote:
Le 16/02/2016 22:21, Scott Wood a écrit :
quoted
On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want
it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from
32
-bit?  What is the difference between PACA and "per-cpu data", other than
the
obscure name?"

I can understand wanting to avoid churn, but other than that, doing things
differently on 64-bit versus 32-bit sucks.
What I can see is that PACA is always available via register r13. Do we 
have anything equivalent on PPC32 ?
Just current in r2, which is the task_struct, not a task-independent per-cpu
area.
If we define a per-cpu data for accounting, what will be the quick way 
to get access to it in entry_32.S ?
Something like a table of accounting data for each CPU, that we index 
with thread_info->cpu ?
This would allow a quite quick access, is it the good way to proceed in 
order to have something closer to PPC64 ?
Possibly.

-Scott

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-02-23 02:04:43

On Tue, 2016-02-16 at 15:21 -0600, Scott Wood wrote:
On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from 32
-bit?
Nothing. It's just historical cruft. But we're not realistically going to get
rid of it anytime soon on 64-bit.
What is the difference between PACA and "per-cpu data", other than the
obscure name?"
Not much. The pacas are allocated differently to per-cpu data, they're
available earlier in boot etc. What we'd like is to have r13 point to the
per-cpu data area, and then the contents of the paca could just be regular
per-cpu data. But like I said above that's a big change.

cheers

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Scott Wood <oss@buserror.net>
Date: 2016-02-23 02:15:24

On Tue, 2016-02-23 at 13:04 +1100, Michael Ellerman wrote:
On Tue, 2016-02-16 at 15:21 -0600, Scott Wood wrote:
quoted
On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
quoted
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want
it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from
32
-bit?
Nothing. It's just historical cruft. But we're not realistically going to
get
rid of it anytime soon on 64-bit.
I wasn't suggesting getting rid of it on 64-bit, but rather adding it on 32
-bit, to hold things that are used by both.  I was confused by the vehemence
of Ben's objection.
quoted
What is the difference between PACA and "per-cpu data", other than the
obscure name?"
Not much. The pacas are allocated differently to per-cpu data, they're
available earlier in boot etc.
Ah, I was thinking of the general concept of per-cpu data, not the specific
mechanism that Linux implements in percpu.h etc.
 What we'd like is to have r13 point to the
per-cpu data area, and then the contents of the paca could just be regular
per-cpu data. But like I said above that's a big change.
That change seems orthogonal to the question of making the mechanism available
on 32-bit to ease unification of code which uses it.

-Scott

Re: [PATCH v5] powerpc32: provide VIRT_CPU_ACCOUNTING

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2016-02-23 03:25:48

On Mon, 2016-02-22 at 20:15 -0600, Scott Wood wrote:
On Tue, 2016-02-23 at 13:04 +1100, Michael Ellerman wrote:
quoted
On Tue, 2016-02-16 at 15:21 -0600, Scott Wood wrote:
quoted
On Thu, 2016-02-11 at 17:16 +0100, Christophe Leroy wrote:
quoted
This patch provides VIRT_CPU_ACCOUTING to PPC32 architecture.
PPC32 doesn't have the PACA structure, so we use the task_info
structure to store the accounting data.

In order to reuse on PPC32 the PPC64 functions, all u64 data has
been replaced by 'unsigned long' so that it is u32 on PPC32 and
u64 on PPC64

Signed-off-by: Christophe Leroy <redacted>
---
Changes in v3: unlike previous version of the patch that was inspired
from IA64 architecture, this new version tries to reuse as much as
possible the PPC64 implementation.

PPC32 doesn't have PACA and past discusion on v2 version has shown
that it is not worth implementing a PACA in PPC32 architecture
(see below benh opinion)

benh: PACA is actually a data structure and you really really don't want
it
on ppc32 :-) Having a register point to current works, having a register
point to per-cpu data instead works too (ie, change what we do today),
but don't introduce a PACA *please* :-)
And Ben never replied to my reply at the time:

"What is special about 64-bit that warrants doing things differently from
32
-bit?
Nothing. It's just historical cruft. But we're not realistically going to
get
rid of it anytime soon on 64-bit.
I wasn't suggesting getting rid of it on 64-bit, but rather adding it on 32
-bit, to hold things that are used by both.  I was confused by the vehemence
of Ben's objection.
OK right. I think he's just saying we'd like to (eventually) get rid of it on
64-bit, so adding it on 32-bit would be a step backward.
quoted
quoted
What is the difference between PACA and "per-cpu data", other than the
obscure name?"
Not much. The pacas are allocated differently to per-cpu data, they're
available earlier in boot etc.
Ah, I was thinking of the general concept of per-cpu data, not the specific
mechanism that Linux implements in percpu.h etc.
Oh ok, in that case no it's not special at all.
quoted
 What we'd like is to have r13 point to the
per-cpu data area, and then the contents of the paca could just be regular
per-cpu data. But like I said above that's a big change.
That change seems orthogonal to the question of making the mechanism available
on 32-bit to ease unification of code which uses it.
That's true.

Though in this case I think you actually do want to store those values in the thread_info.
If you look at eg. vtime_delta() where we use those values, it's passed a task
struct.

So your suggestion to define a common struct that is shared between the 32-bit
thread_info and the 64-bit paca would be a good solution I think.

cheers
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help