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Message-Id: <1332709204-22496-1-git-send-email-richard@nod.at>
Date: Sun, 25 Mar 2012 23:00:04 +0200
From: Richard Weinberger <richard@....at>
To: x86@...nel.org
Cc: tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
paulmck@...ux.vnet.ibm.com, fweisbec@...il.com,
josh@...htriplett.org, tj@...nel.org, linux-kernel@...r.kernel.org,
Richard Weinberger <richard@....at>
Subject: [PATCH] x86: Merge x86_32 and x86_64 cpu_idle()
Both functions are mostly identical.
The differences are:
- x86_32's cpu_idle() makes use of check_pgt_cache(), which is a nop
on both x86_32 and x86_64.
- x86_64's cpu_idle() uses enter/__exit_idle/(), on x86_32 these
function are a nop.
- In contrast to x86_32, x86_64 calls rcu_idle_enter/exit() in the
innermost loop because idle notifications need RCU.
Calling these function on x86_32 also in the innermost loop does not
hurt.
So we can merge both functions.
Signed-off-by: Richard Weinberger <richard@....at>
Acked-by: Frederic Weisbecker <fweisbec@...il.com>
---
arch/x86/include/asm/idle.h | 1 +
arch/x86/kernel/process.c | 114 ++++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/process_32.c | 58 ---------------------
arch/x86/kernel/process_64.c | 107 ---------------------------------------
4 files changed, 115 insertions(+), 165 deletions(-)
diff --git a/arch/x86/include/asm/idle.h b/arch/x86/include/asm/idle.h
index f49253d7..c5d1785 100644
--- a/arch/x86/include/asm/idle.h
+++ b/arch/x86/include/asm/idle.h
@@ -14,6 +14,7 @@ void exit_idle(void);
#else /* !CONFIG_X86_64 */
static inline void enter_idle(void) { }
static inline void exit_idle(void) { }
+static inline void __exit_idle(void) { }
#endif /* CONFIG_X86_64 */
void amd_e400_remove_cpu(int cpu);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 14baf78..29309c4 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -12,6 +12,9 @@
#include <linux/user-return-notifier.h>
#include <linux/dmi.h>
#include <linux/utsname.h>
+#include <linux/stackprotector.h>
+#include <linux/tick.h>
+#include <linux/cpuidle.h>
#include <trace/events/power.h>
#include <linux/hw_breakpoint.h>
#include <asm/cpu.h>
@@ -23,6 +26,24 @@
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/debugreg.h>
+#include <asm/nmi.h>
+
+#ifdef CONFIG_X86_64
+static DEFINE_PER_CPU(unsigned char, is_idle);
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+ atomic_notifier_chain_register(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_register);
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+ atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+EXPORT_SYMBOL_GPL(idle_notifier_unregister);
+#endif
struct kmem_cache *task_xstate_cachep;
EXPORT_SYMBOL_GPL(task_xstate_cachep);
@@ -371,6 +392,99 @@ static inline int hlt_use_halt(void)
}
#endif
+#ifndef CONFIG_SMP
+static inline void play_dead(void)
+{
+ BUG();
+}
+#endif
+
+#ifdef CONFIG_X86_64
+void enter_idle(void)
+{
+ percpu_write(is_idle, 1);
+ atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+}
+
+static void __exit_idle(void)
+{
+ if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
+ return;
+ atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+}
+
+/* Called from interrupts to signify idle end */
+void exit_idle(void)
+{
+ /* idle loop has pid 0 */
+ if (current->pid)
+ return;
+ __exit_idle();
+}
+#endif
+
+/*
+ * The idle thread. There's no useful work to be
+ * done, so just try to conserve power and have a
+ * low exit latency (ie sit in a loop waiting for
+ * somebody to say that they'd like to reschedule)
+ */
+void cpu_idle(void)
+{
+ /*
+ * If we're the non-boot CPU, nothing set the stack canary up
+ * for us. CPU0 already has it initialized but no harm in
+ * doing it again. This is a good place for updating it, as
+ * we wont ever return from this function (so the invalid
+ * canaries already on the stack wont ever trigger).
+ */
+ boot_init_stack_canary();
+ current_thread_info()->status |= TS_POLLING;
+
+ while (1) {
+ tick_nohz_idle_enter();
+
+ while (!need_resched()) {
+ rmb();
+
+ if (cpu_is_offline(smp_processor_id()))
+ play_dead();
+
+ /*
+ * Idle routines should keep interrupts disabled
+ * from here on, until they go to idle.
+ * Otherwise, idle callbacks can misfire.
+ */
+ local_touch_nmi();
+ local_irq_disable();
+
+ enter_idle();
+
+ /* Don't trace irqs off for idle */
+ stop_critical_timings();
+
+ /* enter_idle() needs rcu for notifiers */
+ rcu_idle_enter();
+
+ if (cpuidle_idle_call())
+ pm_idle();
+
+ rcu_idle_exit();
+ start_critical_timings();
+
+ /* In many cases the interrupt that ended idle
+ has already called exit_idle. But some idle
+ loops can be woken up without interrupt. */
+ __exit_idle();
+ }
+
+ tick_nohz_idle_exit();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
+ }
+}
+
/*
* We use this if we don't have any better
* idle routine..
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 9d7d484..ea207c2 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -9,7 +9,6 @@
* This file handles the architecture-dependent parts of process handling..
*/
-#include <linux/stackprotector.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
@@ -31,14 +30,12 @@
#include <linux/kallsyms.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
-#include <linux/tick.h>
#include <linux/percpu.h>
#include <linux/prctl.h>
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/kdebug.h>
-#include <linux/cpuidle.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@@ -58,7 +55,6 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/debugreg.h>
-#include <asm/nmi.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@@ -70,60 +66,6 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
return ((unsigned long *)tsk->thread.sp)[3];
}
-#ifndef CONFIG_SMP
-static inline void play_dead(void)
-{
- BUG();
-}
-#endif
-
-/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
- */
-void cpu_idle(void)
-{
- int cpu = smp_processor_id();
-
- /*
- * If we're the non-boot CPU, nothing set the stack canary up
- * for us. CPU0 already has it initialized but no harm in
- * doing it again. This is a good place for updating it, as
- * we wont ever return from this function (so the invalid
- * canaries already on the stack wont ever trigger).
- */
- boot_init_stack_canary();
-
- current_thread_info()->status |= TS_POLLING;
-
- /* endless idle loop with no priority at all */
- while (1) {
- tick_nohz_idle_enter();
- rcu_idle_enter();
- while (!need_resched()) {
-
- check_pgt_cache();
- rmb();
-
- if (cpu_is_offline(cpu))
- play_dead();
-
- local_touch_nmi();
- local_irq_disable();
- /* Don't trace irqs off for idle */
- stop_critical_timings();
- if (cpuidle_idle_call())
- pm_idle();
- start_critical_timings();
- }
- rcu_idle_exit();
- tick_nohz_idle_exit();
- schedule_preempt_disabled();
- }
-}
-
void __show_regs(struct pt_regs *regs, int all)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 1deb467..d367757 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -14,7 +14,6 @@
* This file handles the architecture-dependent parts of process handling..
*/
-#include <linux/stackprotector.h>
#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
@@ -32,12 +31,10 @@
#include <linux/notifier.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
-#include <linux/tick.h>
#include <linux/prctl.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/ftrace.h>
-#include <linux/cpuidle.h>
#include <asm/pgtable.h>
#include <asm/system.h>
@@ -52,114 +49,10 @@
#include <asm/idle.h>
#include <asm/syscalls.h>
#include <asm/debugreg.h>
-#include <asm/nmi.h>
asmlinkage extern void ret_from_fork(void);
DEFINE_PER_CPU(unsigned long, old_rsp);
-static DEFINE_PER_CPU(unsigned char, is_idle);
-
-static ATOMIC_NOTIFIER_HEAD(idle_notifier);
-
-void idle_notifier_register(struct notifier_block *n)
-{
- atomic_notifier_chain_register(&idle_notifier, n);
-}
-EXPORT_SYMBOL_GPL(idle_notifier_register);
-
-void idle_notifier_unregister(struct notifier_block *n)
-{
- atomic_notifier_chain_unregister(&idle_notifier, n);
-}
-EXPORT_SYMBOL_GPL(idle_notifier_unregister);
-
-void enter_idle(void)
-{
- percpu_write(is_idle, 1);
- atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
-}
-
-static void __exit_idle(void)
-{
- if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
- return;
- atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
-}
-
-/* Called from interrupts to signify idle end */
-void exit_idle(void)
-{
- /* idle loop has pid 0 */
- if (current->pid)
- return;
- __exit_idle();
-}
-
-#ifndef CONFIG_SMP
-static inline void play_dead(void)
-{
- BUG();
-}
-#endif
-
-/*
- * The idle thread. There's no useful work to be
- * done, so just try to conserve power and have a
- * low exit latency (ie sit in a loop waiting for
- * somebody to say that they'd like to reschedule)
- */
-void cpu_idle(void)
-{
- current_thread_info()->status |= TS_POLLING;
-
- /*
- * If we're the non-boot CPU, nothing set the stack canary up
- * for us. CPU0 already has it initialized but no harm in
- * doing it again. This is a good place for updating it, as
- * we wont ever return from this function (so the invalid
- * canaries already on the stack wont ever trigger).
- */
- boot_init_stack_canary();
-
- /* endless idle loop with no priority at all */
- while (1) {
- tick_nohz_idle_enter();
- while (!need_resched()) {
-
- rmb();
-
- if (cpu_is_offline(smp_processor_id()))
- play_dead();
- /*
- * Idle routines should keep interrupts disabled
- * from here on, until they go to idle.
- * Otherwise, idle callbacks can misfire.
- */
- local_touch_nmi();
- local_irq_disable();
- enter_idle();
- /* Don't trace irqs off for idle */
- stop_critical_timings();
-
- /* enter_idle() needs rcu for notifiers */
- rcu_idle_enter();
-
- if (cpuidle_idle_call())
- pm_idle();
-
- rcu_idle_exit();
- start_critical_timings();
-
- /* In many cases the interrupt that ended idle
- has already called exit_idle. But some idle
- loops can be woken up without interrupt. */
- __exit_idle();
- }
-
- tick_nohz_idle_exit();
- schedule_preempt_disabled();
- }
-}
/* Prints also some state that isn't saved in the pt_regs */
void __show_regs(struct pt_regs *regs, int all)
--
1.7.7.3
--
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