diff options
| -rw-r--r-- | arch/arm/Kconfig | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/machine_kexec.c | 4 | ||||
| -rw-r--r-- | arch/arm/kernel/process.c | 43 | ||||
| -rw-r--r-- | arch/arm/kernel/smp.c | 13 |
4 files changed, 42 insertions, 20 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 239fa96c12bb..2651b1da1c56 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -2016,7 +2016,7 @@ config XIP_PHYS_ADDR config KEXEC bool "Kexec system call (EXPERIMENTAL)" - depends on (!SMP || HOTPLUG_CPU) + depends on (!SMP || PM_SLEEP_SMP) help kexec is a system call that implements the ability to shutdown your current kernel, and to start another kernel. It is like a reboot diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8ef8c9337809..4fb074c446bf 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -134,6 +134,10 @@ void machine_kexec(struct kimage *image) unsigned long reboot_code_buffer_phys; void *reboot_code_buffer; + if (num_online_cpus() > 1) { + pr_err("kexec: error: multiple CPUs still online\n"); + return; + } page_list = image->head & PAGE_MASK; diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index 282de4826abb..6e8931ccf13e 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -184,30 +184,61 @@ int __init reboot_setup(char *str) __setup("reboot=", reboot_setup); +/* + * 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(); + smp_send_stop(); + local_irq_disable(); 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(); + 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(); + smp_send_stop(); arm_pm_restart(reboot_mode, cmd); diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 550d63cef68e..5919eb451bb9 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -651,17 +651,6 @@ void smp_send_reschedule(int cpu) smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); } -#ifdef CONFIG_HOTPLUG_CPU -static void smp_kill_cpus(cpumask_t *mask) -{ - unsigned int cpu; - for_each_cpu(cpu, mask) - platform_cpu_kill(cpu); -} -#else -static void smp_kill_cpus(cpumask_t *mask) { } -#endif - void smp_send_stop(void) { unsigned long timeout; @@ -679,8 +668,6 @@ void smp_send_stop(void) if (num_online_cpus() > 1) pr_warning("SMP: failed to stop secondary CPUs\n"); - - smp_kill_cpus(&mask); } /* |