summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kernel/process.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/kernel/process.c')
-rw-r--r--arch/arm64/kernel/process.c49
1 files changed, 40 insertions, 9 deletions
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6391485f342d..43b7c34f92cb 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -20,6 +20,7 @@
#include <stdarg.h>
+#include <linux/compat.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/kernel.h>
@@ -113,32 +114,62 @@ void arch_cpu_idle_dead(void)
}
#endif
+/*
+ * Called by kexec, immediately prior to machine_kexec().
+ *
+ * This must completely disable all secondary CPUs; simply causing those CPUs
+ * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
+ * kexec'd kernel to use any and all RAM as it sees fit, without having to
+ * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
+ * functionality embodied in disable_nonboot_cpus() to achieve this.
+ */
void machine_shutdown(void)
{
-#ifdef CONFIG_SMP
- smp_send_stop();
-#endif
+ disable_nonboot_cpus();
}
+/*
+ * Halting simply requires that the secondary CPUs stop performing any
+ * activity (executing tasks, handling interrupts). smp_send_stop()
+ * achieves this.
+ */
void machine_halt(void)
{
- machine_shutdown();
+ local_irq_disable();
+ smp_send_stop();
while (1);
}
+/*
+ * Power-off simply requires that the secondary CPUs stop performing any
+ * activity (executing tasks, handling interrupts). smp_send_stop()
+ * achieves this. When the system power is turned off, it will take all CPUs
+ * with it.
+ */
void machine_power_off(void)
{
- machine_shutdown();
+ local_irq_disable();
+ smp_send_stop();
if (pm_power_off)
pm_power_off();
}
+/*
+ * Restart requires that the secondary CPUs stop performing any activity
+ * while the primary CPU resets the system. Systems with a single CPU can
+ * use soft_restart() as their machine descriptor's .restart hook, since that
+ * will cause the only available CPU to reset. Systems with multiple CPUs must
+ * provide a HW restart implementation, to ensure that all CPUs reset at once.
+ * This is required so that any code running after reset on the primary CPU
+ * doesn't have to co-ordinate with other CPUs to ensure they aren't still
+ * executing pre-reset code, and using RAM that the primary CPU's code wishes
+ * to use. Implementing such co-ordination would be essentially impossible.
+ */
void machine_restart(char *cmd)
{
- machine_shutdown();
-
/* Disable interrupts first */
local_irq_disable();
+ smp_send_stop();
/* Now call the architecture specific reboot code. */
if (arm_pm_restart)
@@ -205,7 +236,7 @@ void release_thread(struct task_struct *dead_task)
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
- fpsimd_save_state(&current->thread.fpsimd_state);
+ fpsimd_preserve_current_state();
*dst = *src;
return 0;
}
@@ -300,7 +331,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
* Complete any pending TLB or cache maintenance on this CPU in case
* the thread migrates to a different CPU.
*/
- dsb();
+ dsb(ish);
/* the actual thread switch */
last = cpu_switch_to(prev, next);