From bfa05f4f3398b61205567f3a5cad90804a5a1fdc Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 14 Feb 2012 11:25:58 +0000 Subject: ARM: local timers: reserve local_timer_register() to SMP When running an SMP_ON_UP enabled kernel on UP, or with nosmp passed to the kernel, we want to be able to detect that a local timer is not going to be used (local timers are only used on SMP platforms), so we could register it as a global timer instead. Return -ENXIO when the above case is detected. Signed-off-by: Marc Zyngier --- arch/arm/kernel/smp.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm/kernel/smp.c') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index addbbe8028c2..11c4148b8abb 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -454,6 +454,9 @@ static struct local_timer_ops *lt_ops; #ifdef CONFIG_LOCAL_TIMERS int local_timer_register(struct local_timer_ops *ops) { + if (!is_smp() || !setup_max_cpus) + return -ENXIO; + if (lt_ops) return -EBUSY; -- cgit v1.2.3 From 6fa99b7f80b4a7ed2cf616eae393bb6d9d51ba8f Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 27 Apr 2012 12:51:43 +0100 Subject: ARM: 7405/1: kexec: call platform_cpu_kill on the killer rather than the victim When performing a kexec on an SMP system, the secondary cores are stopped by calling machine_shutdown(), which in turn issues IPIs to offline the other CPUs. Unfortunately, this isn't enough to reboot the cores into a new kernel (since they are just executing a cpu_relax loop somewhere in memory) so we make use of platform_cpu_kill, part of the CPU hotplug implementation, to place the cores somewhere safe. This function expects to be called on the killing CPU for each core that it takes out. This patch moves the platform_cpu_kill callback out of the IPI handler and into smp_send_stop, therefore ensuring that it executes on the killing CPU rather than on the victim, matching what the hotplug code requires. Cc: stable@vger.kernel.org Reported-by: Russell King Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/smp.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) (limited to 'arch/arm/kernel/smp.c') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index addbbe8028c2..f6a4d32b0421 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -510,10 +510,6 @@ static void ipi_cpu_stop(unsigned int cpu) local_fiq_disable(); local_irq_disable(); -#ifdef CONFIG_HOTPLUG_CPU - platform_cpu_kill(cpu); -#endif - while (1) cpu_relax(); } @@ -576,17 +572,25 @@ 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; + struct cpumask mask; - if (num_online_cpus() > 1) { - struct cpumask mask; - cpumask_copy(&mask, cpu_online_mask); - cpumask_clear_cpu(smp_processor_id(), &mask); - - smp_cross_call(&mask, IPI_CPU_STOP); - } + cpumask_copy(&mask, cpu_online_mask); + cpumask_clear_cpu(smp_processor_id(), &mask); + smp_cross_call(&mask, IPI_CPU_STOP); /* Wait up to one second for other CPUs to stop */ timeout = USEC_PER_SEC; @@ -595,6 +599,8 @@ void smp_send_stop(void) if (num_online_cpus() > 1) pr_warning("SMP: failed to stop secondary CPUs\n"); + + smp_kill_cpus(&mask); } /* -- cgit v1.2.3 From fde165b2a29673aabf18ceff14dea1f1cfb0daad Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Sat, 5 May 2012 20:58:13 +0100 Subject: ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd Commit 4e8ee7de227e3ab9a72040b448ad728c5428a042 (ARM: SMP: use idmap_pgd for mapping MMU enable during secondary booting) switched secondary boot to use idmap_pgd, which is initialized during early_initcall, instead of a page table initialized during __cpu_up. This causes idmap_pgd to contain the static mappings but be missing all dynamic mappings. If a console is registered that creates a dynamic mapping, the printk in secondary_start_kernel will trigger a data abort on the missing mapping before the exception handlers have been initialized, leading to a hang. Initial boot is not affected because no consoles have been registered, and resume is usually not affected because the offending console is suspended. Onlining a cpu with hotplug triggers the problem. A workaround is to the printk in secondary_start_kernel until after the page tables have been switched back to init_mm. Cc: Signed-off-by: Colin Cross Signed-off-by: Russell King --- arch/arm/kernel/smp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/arm/kernel/smp.c') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index f6a4d32b0421..8f4644659777 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -251,8 +251,6 @@ asmlinkage void __cpuinit secondary_start_kernel(void) struct mm_struct *mm = &init_mm; unsigned int cpu = smp_processor_id(); - printk("CPU%u: Booted secondary processor\n", cpu); - /* * All kernel threads share the same mm context; grab a * reference and switch to it. @@ -264,6 +262,8 @@ asmlinkage void __cpuinit secondary_start_kernel(void) enter_lazy_tlb(mm, current); local_flush_tlb_all(); + printk("CPU%u: Booted secondary processor\n", cpu); + cpu_init(); preempt_disable(); trace_hardirqs_off(); -- cgit v1.2.3