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Subject[PATCH 1/6] perf_counter: powerpc: Enable use of software counters on 32-bit powerpc
This enables the perf_counter subsystem on 32-bit powerpc.  Since we
don't have any support for hardware counters on 32-bit powerpc yet,
only software counters can be used.

Besides selecting HAVE_PERF_COUNTERS for 32-bit powerpc as well as
64-bit, the main thing this does is add an implementation of
set_perf_counter_pending(). This needs to arrange for
perf_counter_do_pending() to be called when interrupts are enabled.
Rather than add code to local_irq_restore as 64-bit does, the 32-bit
set_perf_counter_pending() generates an interrupt by setting the
decrementer to 1 so that a decrementer interrupt will become pending
in 1 or 2 timebase ticks (if a decrementer interrupt isn't already
pending). When interrupts are enabled, timer_interrupt() will be
called, and some new code in there calls perf_counter_do_pending().
We use a per-cpu array of flags to indicate whether we need to call
perf_counter_do_pending() or not.

This introduces a couple of new Kconfig symbols: PPC_HAVE_PMU_SUPPORT,
which is selected by processor families for which we have hardware PMU
support (currently only PPC64), and PPC_PERF_CTRS, which enables the
powerpc-specific perf_counter back-end.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
This depends on the generic atomic64_t patches, which are now in
Linus' tree. Ingo, if you're putting these in, please pull Linus'
tree in first.
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/hw_irq.h | 5 ++++-
arch/powerpc/include/asm/perf_counter.h | 10 ++++++++--
arch/powerpc/kernel/Makefile | 6 +++---
arch/powerpc/kernel/time.c | 25 +++++++++++++++++++++++++
arch/powerpc/platforms/Kconfig.cputype | 11 ++++++++++-
6 files changed, 51 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9fb344d..bf6cedf 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -126,6 +126,7 @@ config PPC
select HAVE_OPROFILE
select HAVE_SYSCALL_WRAPPERS if PPC64
select GENERIC_ATOMIC64 if PPC32
+ select HAVE_PERF_COUNTERS

config EARLY_PRINTK
bool
diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index 10a642d..867ab8e 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -131,6 +131,8 @@ static inline int irqs_disabled_flags(unsigned long flags)
struct irq_chip;

#ifdef CONFIG_PERF_COUNTERS
+
+#ifdef CONFIG_PPC64
static inline unsigned long test_perf_counter_pending(void)
{
unsigned long x;
@@ -154,8 +156,9 @@ static inline void clear_perf_counter_pending(void)
"r" (0),
"i" (offsetof(struct paca_struct, perf_counter_pending)));
}
+#endif /* CONFIG_PPC64 */

-#else
+#else /* CONFIG_PERF_COUNTERS */

static inline unsigned long test_perf_counter_pending(void)
{
diff --git a/arch/powerpc/include/asm/perf_counter.h b/arch/powerpc/include/asm/perf_counter.h
index b398a84..2c2d9f6 100644
--- a/arch/powerpc/include/asm/perf_counter.h
+++ b/arch/powerpc/include/asm/perf_counter.h
@@ -57,11 +57,17 @@ extern struct power_pmu *ppmu;

struct pt_regs;
extern unsigned long perf_misc_flags(struct pt_regs *regs);
-#define perf_misc_flags(regs) perf_misc_flags(regs)
-
extern unsigned long perf_instruction_pointer(struct pt_regs *regs);

/*
+ * Only override the default definitions in include/linux/perf_counter.h
+ * if we have hardware PMU support.
+ */
+#ifdef CONFIG_PPC_PERF_CTRS
+#define perf_misc_flags(regs) perf_misc_flags(regs)
+#endif
+
+/*
* The power_pmu.get_constraint function returns a 64-bit value and
* a 64-bit mask that express the constraints between this event and
* other events.
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 612b0c4..c5f93f0 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -95,9 +95,9 @@ obj64-$(CONFIG_AUDIT) += compat_audit.o

obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
-obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o power4-pmu.o ppc970-pmu.o \
- power5-pmu.o power5+-pmu.o power6-pmu.o \
- power7-pmu.o
+obj-$(CONFIG_PPC_PERF_CTRS) += perf_counter.o
+obj64-$(CONFIG_PPC_PERF_CTRS) += power4-pmu.o ppc970-pmu.o power5-pmu.o \
+ power5+-pmu.o power6-pmu.o power7-pmu.o

obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 15391c2..eae4511 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -53,6 +53,7 @@
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/delay.h>
+#include <linux/perf_counter.h>

#include <asm/io.h>
#include <asm/processor.h>
@@ -525,6 +526,26 @@ void __init iSeries_time_init_early(void)
}
#endif /* CONFIG_PPC_ISERIES */

+#if defined(CONFIG_PERF_COUNTERS) && defined(CONFIG_PPC32)
+DEFINE_PER_CPU(u8, perf_counter_pending);
+
+void set_perf_counter_pending(void)
+{
+ get_cpu_var(perf_counter_pending) = 1;
+ set_dec(1);
+ put_cpu_var(perf_counter_pending);
+}
+
+#define test_perf_counter_pending() __get_cpu_var(perf_counter_pending)
+#define clear_perf_counter_pending() __get_cpu_var(perf_counter_pending) = 0
+
+#else /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
+
+#define test_perf_counter_pending() 0
+#define clear_perf_counter_pending()
+
+#endif /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
+
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
@@ -551,6 +572,10 @@ void timer_interrupt(struct pt_regs * regs)
set_dec(DECREMENTER_MAX);

#ifdef CONFIG_PPC32
+ if (test_perf_counter_pending()) {
+ clear_perf_counter_pending();
+ perf_counter_do_pending();
+ }
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index cca6b4f..dd9f3ec 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,7 +1,7 @@
config PPC64
bool "64-bit kernel"
default n
- select HAVE_PERF_COUNTERS
+ select PPC_HAVE_PMU_SUPPORT
help
This option selects whether a 32-bit or a 64-bit kernel
will be built.
@@ -243,6 +243,15 @@ config VIRT_CPU_ACCOUNTING

If in doubt, say Y here.

+config PPC_HAVE_PMU_SUPPORT
+ bool
+
+config PPC_PERF_CTRS
+ def_bool y
+ depends on PERF_COUNTERS && PPC_HAVE_PMU_SUPPORT
+ help
+ This enables the powerpc-specific perf_counter back-end.
+
config SMP
depends on PPC_STD_MMU || FSL_BOOKE
bool "Symmetric multi-processing support"
--
1.6.0.4


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