*
* X86-64 port
* Andi Kleen.
- *
+ *
+ * CPU hotplug support - ashok.raj@intel.com
* $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
*/
#include <stdarg.h>
+#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
}
EXPORT_SYMBOL_GPL(cpu_idle_wait);
+#ifdef CONFIG_HOTPLUG_CPU
+DECLARE_PER_CPU(int, cpu_state);
+
+#include <asm/nmi.h>
+/* We don't actually take CPU down, just spin without interrupts. */
+static inline void play_dead(void)
+{
+ idle_task_exit();
+ wbinvd();
+ mb();
+ /* Ack it */
+ __get_cpu_var(cpu_state) = CPU_DEAD;
+
+ while (1)
+ safe_halt();
+}
+#else
+static inline void play_dead(void)
+{
+ BUG();
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
idle = pm_idle;
if (!idle)
idle = default_idle;
+ if (cpu_is_offline(smp_processor_id()))
+ play_dead();
idle();
}
}
}
-void __init select_idle_routine(const struct cpuinfo_x86 *c)
+void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
{
static int printed;
if (cpu_has(c, X86_FEATURE_MWAIT)) {
return err;
}
+/*
+ * This function selects if the context switch from prev to next
+ * has to tweak the TSC disable bit in the cr4.
+ */
+static inline void disable_tsc(struct task_struct *prev_p,
+ struct task_struct *next_p)
+{
+ struct thread_info *prev, *next;
+
+ /*
+ * gcc should eliminate the ->thread_info dereference if
+ * has_secure_computing returns 0 at compile time (SECCOMP=n).
+ */
+ prev = prev_p->thread_info;
+ next = next_p->thread_info;
+
+ if (has_secure_computing(prev) || has_secure_computing(next)) {
+ /* slow path here */
+ if (has_secure_computing(prev) &&
+ !has_secure_computing(next)) {
+ write_cr4(read_cr4() & ~X86_CR4_TSD);
+ } else if (!has_secure_computing(prev) &&
+ has_secure_computing(next))
+ write_cr4(read_cr4() | X86_CR4_TSD);
+ }
+}
+
/*
* This special macro can be used to load a debugging register
*/
}
}
+ disable_tsc(prev_p, next_p);
+
return prev_p;
}