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author | Richard Weinberger <richard@nod.at> | 2012-03-25 21:00:04 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2012-03-26 01:16:07 (GMT) |
commit | 90e240142bd31ff10aeda5a280a53153f4eff004 (patch) | |
tree | ae612bacc2cfd2fedc4c5c22c29dd326f8b93ae7 /arch/x86/kernel/process.c | |
parent | f5243d6de7ae232e1d81e44ae9756bbd8c988fcd (diff) | |
download | linux-fsl-qoriq-90e240142bd31ff10aeda5a280a53153f4eff004.tar.xz |
x86: Merge the x86_32 and x86_64 cpu_idle() functions
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@nod.at>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: paulmck@linux.vnet.ibm.com
Cc: josh@joshtriplett.org
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1332709204-22496-1-git-send-email-richard@nod.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/process.c')
-rw-r--r-- | arch/x86/kernel/process.c | 114 |
1 files changed, 114 insertions, 0 deletions
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.. |