[x86 this_cpu_has V1 0/4] Use cpu ops to implement this_cpu_has and use it in various places

[x86 this_cpu_has V1 0/4] Use cpu ops to implement this_cpu_has and use it in various places

[Christoph Lameter]

These patches were posted earlier in the context of this_cpu_ops use cases.
Tejun send them to the x86 maintainers but they seem to have gotten lost.

[x86 this_cpu_has V1 1/4] x86: A fast way to check capabilities of the current cpu

[Christoph Lameter]

[-- Attachment #1: myfeat --]
[-- Type: text/plain, Size: 6050 bytes --]

Add this_cpu_has() which determines if the current cpu has a certain
ability using a segment prefix and a bit test operation.

For that we need to add bit operations to x86s percpu.h.

Many uses of cpu_has use a pointer passed to a function to determine
the current flags. That is no longer necessary after this patch.

However, this patch only converts the straightforward cases where
cpu_has is used with this_cpu_ptr. The rest is work for later.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 arch/x86/include/asm/cpufeature.h |   13 +++++++++----
 arch/x86/include/asm/percpu.h     |   27 +++++++++++++++++++++++++++
 arch/x86/kernel/apic/apic.c       |    2 +-
 arch/x86/kernel/process.c         |    4 ++--
 arch/x86/kernel/smpboot.c         |    4 ++--
 5 files changed, 41 insertions(+), 9 deletions(-)

Index: linux-2.6/arch/x86/include/asm/cpufeature.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/cpufeature.h	2011-03-11 08:41:12.000000000 -0600
+++ linux-2.6/arch/x86/include/asm/cpufeature.h	2011-03-11 10:18:06.000000000 -0600
@@ -206,8 +206,7 @@ extern const char * const x86_power_flag
 #define test_cpu_cap(c, bit)						\
 	 test_bit(bit, (unsigned long *)((c)->x86_capability))
 
-#define cpu_has(c, bit)							\
-	(__builtin_constant_p(bit) &&					\
+#define REQUIRED_MASK_BIT_SET(bit)					\
 	 ( (((bit)>>5)==0 && (1UL<<((bit)&31) & REQUIRED_MASK0)) ||	\
 	   (((bit)>>5)==1 && (1UL<<((bit)&31) & REQUIRED_MASK1)) ||	\
 	   (((bit)>>5)==2 && (1UL<<((bit)&31) & REQUIRED_MASK2)) ||	\
@@ -217,10 +216,16 @@ extern const char * const x86_power_flag
 	   (((bit)>>5)==6 && (1UL<<((bit)&31) & REQUIRED_MASK6)) ||	\
 	   (((bit)>>5)==7 && (1UL<<((bit)&31) & REQUIRED_MASK7)) ||	\
 	   (((bit)>>5)==8 && (1UL<<((bit)&31) & REQUIRED_MASK8)) ||	\
-	   (((bit)>>5)==9 && (1UL<<((bit)&31) & REQUIRED_MASK9)) )	\
-	  ? 1 :								\
+	   (((bit)>>5)==9 && (1UL<<((bit)&31) & REQUIRED_MASK9)) )
+
+#define cpu_has(c, bit)							\
+	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :	\
 	 test_cpu_cap(c, bit))
 
+#define this_cpu_has(bit)						\
+	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : 	\
+	 x86_this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))
+
 #define boot_cpu_has(bit)	cpu_has(&boot_cpu_data, bit)
 
 #define set_cpu_cap(c, bit)	set_bit(bit, (unsigned long *)((c)->x86_capability))
Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c	2011-03-11 08:41:12.000000000 -0600
+++ linux-2.6/arch/x86/kernel/apic/apic.c	2011-03-11 09:29:46.000000000 -0600
@@ -516,7 +516,7 @@ static void __cpuinit setup_APIC_timer(v
 {
 	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
 
-	if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_ARAT)) {
+	if (this_cpu_has(X86_FEATURE_ARAT)) {
 		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_C3STOP;
 		/* Make LAPIC timer preferrable over percpu HPET */
 		lapic_clockevent.rating = 150;
Index: linux-2.6/arch/x86/include/asm/percpu.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/percpu.h	2011-03-11 08:41:12.000000000 -0600
+++ linux-2.6/arch/x86/include/asm/percpu.h	2011-03-11 10:18:06.000000000 -0600
@@ -492,6 +492,33 @@ do {									\
 	old__;								\
 })
 
+static __always_inline int x86_this_cpu_constant_test_bit(unsigned int nr,
+                        const unsigned long __percpu *addr)
+{
+	unsigned long __percpu *a = (unsigned long *)addr + nr / BITS_PER_LONG;
+
+	return ((1UL << (nr % BITS_PER_LONG)) & percpu_read(*a)) != 0;
+}
+
+static inline int x86_this_cpu_variable_test_bit(int nr,
+                        const unsigned long __percpu *addr)
+{
+	int oldbit;
+
+	asm volatile("bt "__percpu_arg(2)",%1\n\t"
+			"sbb %0,%0"
+			: "=r" (oldbit)
+			: "m" (*(unsigned long *)addr), "Ir" (nr));
+
+	return oldbit;
+}
+
+#define x86_this_cpu_test_bit(nr, addr)			\
+	(__builtin_constant_p((nr))			\
+	 ? x86_this_cpu_constant_test_bit((nr), (addr))	\
+	 : x86_this_cpu_variable_test_bit((nr), (addr)))
+
+
 #include <asm-generic/percpu.h>
 
 /* We can use this directly for local CPU (faster). */
Index: linux-2.6/arch/x86/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/process.c	2011-03-11 08:41:12.000000000 -0600
+++ linux-2.6/arch/x86/kernel/process.c	2011-03-11 09:29:46.000000000 -0600
@@ -452,7 +452,7 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
 void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
 {
 	if (!need_resched()) {
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
+		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
 			clflush((void *)&current_thread_info()->flags);
 
 		__monitor((void *)&current_thread_info()->flags, 0, 0);
@@ -468,7 +468,7 @@ static void mwait_idle(void)
 	if (!need_resched()) {
 		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
 		trace_cpu_idle(1, smp_processor_id());
-		if (cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLUSH_MONITOR))
+		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
 			clflush((void *)&current_thread_info()->flags);
 
 		__monitor((void *)&current_thread_info()->flags, 0, 0);
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c	2011-03-11 08:41:12.000000000 -0600
+++ linux-2.6/arch/x86/kernel/smpboot.c	2011-03-11 09:29:46.000000000 -0600
@@ -1404,9 +1404,9 @@ static inline void mwait_play_dead(void)
 	void *mwait_ptr;
 	struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info);
 
-	if (!(cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)))
+	if (!this_cpu_has(X86_FEATURE_MWAIT) && mwait_usable(c))
 		return;
-	if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLSH))
+	if (!this_cpu_has(X86_FEATURE_CLFLSH))
 		return;
 	if (__this_cpu_read(cpu_info.cpuid_level) < CPUID_MWAIT_LEAF)
 		return;

[x86 this_cpu_has V1 2/4] x86: Avoid passing struct cpuinfo pointer to mce_available

[Christoph Lameter]

[-- Attachment #1: myfeat2 --]
[-- Type: text/plain, Size: 6009 bytes --]

If we do not pass the pointer to cpuinfio to mce available then its possible
to use this_cpu_has.

There are two use cases of mce_available: One with the current processor
and one with the boot cpu. Define a function for both cases. However, there
is only one case in which boot_mce_available is used. If we somehow can
get rid of that then the patch could be simplified.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 arch/x86/include/asm/mce.h             |    3 +-
 arch/x86/kernel/cpu/mcheck/mce.c       |   41 +++++++++++++++++++--------------
 arch/x86/kernel/cpu/mcheck/mce_intel.c |    2 -
 3 files changed, 27 insertions(+), 19 deletions(-)

Index: linux-2.6/arch/x86/include/asm/mce.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/mce.h	2011-01-19 14:01:22.000000000 -0600
+++ linux-2.6/arch/x86/include/asm/mce.h	2011-01-19 14:02:31.000000000 -0600
@@ -177,7 +177,8 @@ void mce_amd_feature_init(struct cpuinfo
 static inline void mce_amd_feature_init(struct cpuinfo_x86 *c) { }
 #endif
 
-int mce_available(struct cpuinfo_x86 *c);
+int this_cpu_mce_available(void);
+int boot_mce_available(void);
 
 DECLARE_PER_CPU(unsigned, mce_exception_count);
 DECLARE_PER_CPU(unsigned, mce_poll_count);
Index: linux-2.6/arch/x86/kernel/cpu/mcheck/mce.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mcheck/mce.c	2011-01-19 14:01:22.000000000 -0600
+++ linux-2.6/arch/x86/kernel/cpu/mcheck/mce.c	2011-01-19 16:21:42.000000000 -0600
@@ -434,11 +434,19 @@ static int mce_ring_add(unsigned long pf
 	return 0;
 }
 
-int mce_available(struct cpuinfo_x86 *c)
+int this_cpu_mce_available(void)
 {
 	if (mce_disabled)
 		return 0;
-	return cpu_has(c, X86_FEATURE_MCE) && cpu_has(c, X86_FEATURE_MCA);
+	return this_cpu_has(X86_FEATURE_MCE) && this_cpu_has(X86_FEATURE_MCA);
+}
+
+int boot_mce_available(void)
+{
+	if (mce_disabled)
+		return 0;
+	return cpu_has(&boot_cpu_data, X86_FEATURE_MCE) &&
+			cpu_has(&boot_cpu_data, X86_FEATURE_MCA);
 }
 
 static void mce_schedule_work(void)
@@ -1159,7 +1167,7 @@ static void mce_start_timer(unsigned lon
 
 	WARN_ON(smp_processor_id() != data);
 
-	if (mce_available(__this_cpu_ptr(&cpu_info))) {
+	if (this_cpu_mce_available()) {
 		machine_check_poll(MCP_TIMESTAMP,
 				&__get_cpu_var(mce_poll_banks));
 	}
@@ -1373,9 +1381,9 @@ static int __cpuinit __mcheck_cpu_apply_
 
 static void __cpuinit __mcheck_cpu_ancient_init(struct cpuinfo_x86 *c)
 {
-	if (c->x86 != 5)
+	if (this_cpu_read(cpu_info.x86) != 5)
 		return;
-	switch (c->x86_vendor) {
+	switch (this_cpu_read(cpu_info.x86_vendor)) {
 	case X86_VENDOR_INTEL:
 		intel_p5_mcheck_init(c);
 		break;
@@ -1402,17 +1410,16 @@ static void __mcheck_cpu_init_vendor(str
 static void __mcheck_cpu_init_timer(void)
 {
 	struct timer_list *t = &__get_cpu_var(mce_timer);
-	int *n = &__get_cpu_var(mce_next_interval);
 
 	setup_timer(t, mce_start_timer, smp_processor_id());
 
 	if (mce_ignore_ce)
 		return;
 
-	*n = check_interval * HZ;
-	if (!*n)
+	this_cpu_write(mce_next_interval, check_interval * HZ);
+	if (!this_cpu_read(mce_next_interval))
 		return;
-	t->expires = round_jiffies(jiffies + *n);
+	t->expires = round_jiffies(jiffies + this_cpu_read(mce_next_interval));
 	add_timer_on(t, smp_processor_id());
 }
 
@@ -1438,7 +1445,7 @@ void __cpuinit mcheck_cpu_init(struct cp
 
 	__mcheck_cpu_ancient_init(c);
 
-	if (!mce_available(c))
+	if (!this_cpu_mce_available())
 		return;
 
 	if (__mcheck_cpu_cap_init() < 0 || __mcheck_cpu_apply_quirks(c) < 0) {
@@ -1775,7 +1782,7 @@ static int mce_resume(struct sys_device
 static void mce_cpu_restart(void *data)
 {
 	del_timer_sync(&__get_cpu_var(mce_timer));
-	if (!mce_available(__this_cpu_ptr(&cpu_info)))
+	if (!this_cpu_mce_available())
 		return;
 	__mcheck_cpu_init_generic();
 	__mcheck_cpu_init_timer();
@@ -1790,7 +1797,7 @@ static void mce_restart(void)
 /* Toggle features for corrected errors */
 static void mce_disable_ce(void *all)
 {
-	if (!mce_available(__this_cpu_ptr(&cpu_info)))
+	if (!this_cpu_mce_available())
 		return;
 	if (all)
 		del_timer_sync(&__get_cpu_var(mce_timer));
@@ -1799,7 +1806,7 @@ static void mce_disable_ce(void *all)
 
 static void mce_enable_ce(void *all)
 {
-	if (!mce_available(__this_cpu_ptr(&cpu_info)))
+	if (!this_cpu_mce_available())
 		return;
 	cmci_reenable();
 	cmci_recheck();
@@ -1962,7 +1969,7 @@ static __cpuinit int mce_create_device(u
 	int err;
 	int i, j;
 
-	if (!mce_available(&boot_cpu_data))
+	if (!boot_mce_available())
 		return -EIO;
 
 	memset(&per_cpu(mce_dev, cpu).kobj, 0, sizeof(struct kobject));
@@ -2022,7 +2029,7 @@ static void __cpuinit mce_disable_cpu(vo
 	unsigned long action = *(unsigned long *)h;
 	int i;
 
-	if (!mce_available(__this_cpu_ptr(&cpu_info)))
+	if (!this_cpu_mce_available())
 		return;
 
 	if (!(action & CPU_TASKS_FROZEN))
@@ -2040,7 +2047,7 @@ static void __cpuinit mce_reenable_cpu(v
 	unsigned long action = *(unsigned long *)h;
 	int i;
 
-	if (!mce_available(__this_cpu_ptr(&cpu_info)))
+	if (!this_cpu_mce_available())
 		return;
 
 	if (!(action & CPU_TASKS_FROZEN))
@@ -2122,7 +2129,7 @@ static __init int mcheck_init_device(voi
 	int err;
 	int i = 0;
 
-	if (!mce_available(&boot_cpu_data))
+	if (!boot_mce_available())
 		return -EIO;
 
 	zalloc_cpumask_var(&mce_dev_initialized, GFP_KERNEL);
Index: linux-2.6/arch/x86/kernel/cpu/mcheck/mce_intel.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mcheck/mce_intel.c	2011-01-19 14:01:22.000000000 -0600
+++ linux-2.6/arch/x86/kernel/cpu/mcheck/mce_intel.c	2011-01-19 14:02:31.000000000 -0600
@@ -130,7 +130,7 @@ void cmci_recheck(void)
 	unsigned long flags;
 	int banks;
 
-	if (!mce_available(__this_cpu_ptr(&cpu_info)) || !cmci_supported(&banks))
+	if (!this_cpu_mce_available() || !cmci_supported(&banks))
 		return;
 	local_irq_save(flags);
 	machine_check_poll(MCP_TIMESTAMP, &__get_cpu_var(mce_banks_owned));

[x86 this_cpu_has V1 3/4] x86: Use this_cpu_has for thermal_interrupt

[Christoph Lameter]

[-- Attachment #1: thermal_interrupt --]
[-- Type: text/plain, Size: 1709 bytes --]

It is more effective to use a segment prefix instead of calculating the
address of the current cpu area amd then testing flags.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: linux-2.6/arch/x86/kernel/cpu/mcheck/therm_throt.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mcheck/therm_throt.c	2011-03-11 10:17:42.000000000 -0600
+++ linux-2.6/arch/x86/kernel/cpu/mcheck/therm_throt.c	2011-03-11 10:18:34.000000000 -0600
@@ -355,7 +355,6 @@ static void notify_thresholds(__u64 msr_
 static void intel_thermal_interrupt(void)
 {
 	__u64 msr_val;
-	struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
 
 	rdmsrl(MSR_IA32_THERM_STATUS, msr_val);
 
@@ -367,19 +366,19 @@ static void intel_thermal_interrupt(void
 				CORE_LEVEL) != 0)
 		mce_log_therm_throt_event(CORE_THROTTLED | msr_val);
 
-	if (cpu_has(c, X86_FEATURE_PLN))
+	if (this_cpu_has(X86_FEATURE_PLN))
 		if (therm_throt_process(msr_val & THERM_STATUS_POWER_LIMIT,
 					POWER_LIMIT_EVENT,
 					CORE_LEVEL) != 0)
 			mce_log_therm_throt_event(CORE_POWER_LIMIT | msr_val);
 
-	if (cpu_has(c, X86_FEATURE_PTS)) {
+	if (this_cpu_has(X86_FEATURE_PTS)) {
 		rdmsrl(MSR_IA32_PACKAGE_THERM_STATUS, msr_val);
 		if (therm_throt_process(msr_val & PACKAGE_THERM_STATUS_PROCHOT,
 					THERMAL_THROTTLING_EVENT,
 					PACKAGE_LEVEL) != 0)
 			mce_log_therm_throt_event(PACKAGE_THROTTLED | msr_val);
-		if (cpu_has(c, X86_FEATURE_PLN))
+		if (this_cpu_has(X86_FEATURE_PLN))
 			if (therm_throt_process(msr_val &
 					PACKAGE_THERM_STATUS_POWER_LIMIT,
 					POWER_LIMIT_EVENT,

[x86 this_cpu_has V1 4/4] acpi throttling: Use this_cpu_has and simplify code

[Christoph Lameter]

[-- Attachment #1: acpui --]
[-- Type: text/plain, Size: 2970 bytes --]

With the this_cpu information we no longer need to pass an acpi
structure to the msr management code. Simplifies code and improves
performance.

NOTE: This code is x86 specific (see #ifdef CONFIG_X86) but not under arch/x86.

Signed-off-by: Christoph Lameter <cl@linux.com>


---
 drivers/acpi/processor_throttling.c |   32 ++++++++++----------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

Index: linux-2.6/drivers/acpi/processor_throttling.c
===================================================================
--- linux-2.6.orig/drivers/acpi/processor_throttling.c	2011-01-14 08:55:53.000000000 -0600
+++ linux-2.6/drivers/acpi/processor_throttling.c	2011-01-14 09:05:26.000000000 -0600
@@ -710,20 +710,14 @@ static int acpi_processor_get_throttling
 }
 
 #ifdef CONFIG_X86
-static int acpi_throttling_rdmsr(struct acpi_processor *pr,
-					u64 *value)
+static int acpi_throttling_rdmsr(u64 *value)
 {
-	struct cpuinfo_x86 *c;
 	u64 msr_high, msr_low;
-	unsigned int cpu;
 	u64 msr = 0;
 	int ret = -1;
 
-	cpu = pr->id;
-	c = &cpu_data(cpu);
-
-	if ((c->x86_vendor != X86_VENDOR_INTEL) ||
-		!cpu_has(c, X86_FEATURE_ACPI)) {
+	if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
+		!this_cpu_has(X86_FEATURE_ACPI)) {
 		printk(KERN_ERR PREFIX
 			"HARDWARE addr space,NOT supported yet\n");
 	} else {
@@ -738,18 +732,13 @@ static int acpi_throttling_rdmsr(struct
 	return ret;
 }
 
-static int acpi_throttling_wrmsr(struct acpi_processor *pr, u64 value)
+static int acpi_throttling_wrmsr(u64 value)
 {
-	struct cpuinfo_x86 *c;
-	unsigned int cpu;
 	int ret = -1;
 	u64 msr;
 
-	cpu = pr->id;
-	c = &cpu_data(cpu);
-
-	if ((c->x86_vendor != X86_VENDOR_INTEL) ||
-		!cpu_has(c, X86_FEATURE_ACPI)) {
+	if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
+		!this_cpu_has(X86_FEATURE_ACPI)) {
 		printk(KERN_ERR PREFIX
 			"HARDWARE addr space,NOT supported yet\n");
 	} else {
@@ -761,15 +750,14 @@ static int acpi_throttling_wrmsr(struct
 	return ret;
 }
 #else
-static int acpi_throttling_rdmsr(struct acpi_processor *pr,
-				u64 *value)
+static int acpi_throttling_rdmsr(u64 *value)
 {
 	printk(KERN_ERR PREFIX
 		"HARDWARE addr space,NOT supported yet\n");
 	return -1;
 }
 
-static int acpi_throttling_wrmsr(struct acpi_processor *pr, u64 value)
+static int acpi_throttling_wrmsr(u64 value)
 {
 	printk(KERN_ERR PREFIX
 		"HARDWARE addr space,NOT supported yet\n");
@@ -801,7 +789,7 @@ static int acpi_read_throttling_status(s
 		ret = 0;
 		break;
 	case ACPI_ADR_SPACE_FIXED_HARDWARE:
-		ret = acpi_throttling_rdmsr(pr, value);
+		ret = acpi_throttling_rdmsr(value);
 		break;
 	default:
 		printk(KERN_ERR PREFIX "Unknown addr space %d\n",
@@ -834,7 +822,7 @@ static int acpi_write_throttling_state(s
 		ret = 0;
 		break;
 	case ACPI_ADR_SPACE_FIXED_HARDWARE:
-		ret = acpi_throttling_wrmsr(pr, value);
+		ret = acpi_throttling_wrmsr(value);
 		break;
 	default:
 		printk(KERN_ERR PREFIX "Unknown addr space %d\n",

Re: [x86 this_cpu_has V1 2/4] x86: Avoid passing struct cpuinfo pointer to mce_available

[Tejun Heo]

On Fri, Mar 11, 2011 at 10:23:12AM -0600, Christoph Lameter wrote:
> If we do not pass the pointer to cpuinfio to mce available then its possible
> to use this_cpu_has.
> 
> There are two use cases of mce_available: One with the current processor
> and one with the boot cpu. Define a function for both cases. However, there
> is only one case in which boot_mce_available is used. If we somehow can
> get rid of that then the patch could be simplified.
> 
> Signed-off-by: Christoph Lameter <cl@linux.com>

Christoph, I'm not sure about this one.  None of the conversions is in
hot path, which would be okay if the resulting code was simpler but,
well, it isn't necessarily worse but not distinctively better either,
so I fail to see the merits of this conversion.  I'll resend the other
three towards x86 tree.

Thank you.

-- 
tejun