diff options
Diffstat (limited to 'arch/powerpc/kernel/smp.c')
| -rw-r--r-- | arch/powerpc/kernel/smp.c | 109 |
1 files changed, 38 insertions, 71 deletions
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 3f15edf25a0d..e784342bdaa1 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -20,6 +20,7 @@ #include <linux/kernel.h> #include <linux/export.h> #include <linux/sched/mm.h> +#include <linux/sched/task_stack.h> #include <linux/sched/topology.h> #include <linux/smp.h> #include <linux/interrupt.h> @@ -75,7 +76,7 @@ static DEFINE_PER_CPU(int, cpu_state) = { 0 }; #endif -struct thread_info *secondary_ti; +struct task_struct *secondary_current; bool has_big_cores; DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map); @@ -358,13 +359,12 @@ void arch_send_call_function_ipi_mask(const struct cpumask *mask) * NMI IPIs may not be recoverable, so should not be used as ongoing part of * a running system. They can be used for crash, debug, halt/reboot, etc. * - * NMI IPIs are globally single threaded. No more than one in progress at - * any time. - * * The IPI call waits with interrupts disabled until all targets enter the - * NMI handler, then the call returns. + * NMI handler, then returns. Subsequent IPIs can be issued before targets + * have returned from their handlers, so there is no guarantee about + * concurrency or re-entrancy. * - * No new NMI can be initiated until targets exit the handler. + * A new NMI can be issued before all targets exit the handler. * * The IPI call may time out without all targets entering the NMI handler. * In that case, there is some logic to recover (and ignore subsequent @@ -375,7 +375,7 @@ void arch_send_call_function_ipi_mask(const struct cpumask *mask) static atomic_t __nmi_ipi_lock = ATOMIC_INIT(0); static struct cpumask nmi_ipi_pending_mask; -static int nmi_ipi_busy_count = 0; +static bool nmi_ipi_busy = false; static void (*nmi_ipi_function)(struct pt_regs *) = NULL; static void nmi_ipi_lock_start(unsigned long *flags) @@ -414,7 +414,7 @@ static void nmi_ipi_unlock_end(unsigned long *flags) */ int smp_handle_nmi_ipi(struct pt_regs *regs) { - void (*fn)(struct pt_regs *); + void (*fn)(struct pt_regs *) = NULL; unsigned long flags; int me = raw_smp_processor_id(); int ret = 0; @@ -425,29 +425,17 @@ int smp_handle_nmi_ipi(struct pt_regs *regs) * because the caller may have timed out. */ nmi_ipi_lock_start(&flags); - if (!nmi_ipi_busy_count) - goto out; - if (!cpumask_test_cpu(me, &nmi_ipi_pending_mask)) - goto out; - - fn = nmi_ipi_function; - if (!fn) - goto out; - - cpumask_clear_cpu(me, &nmi_ipi_pending_mask); - nmi_ipi_busy_count++; - nmi_ipi_unlock(); - - ret = 1; - - fn(regs); - - nmi_ipi_lock(); - if (nmi_ipi_busy_count > 1) /* Can race with caller time-out */ - nmi_ipi_busy_count--; -out: + if (cpumask_test_cpu(me, &nmi_ipi_pending_mask)) { + cpumask_clear_cpu(me, &nmi_ipi_pending_mask); + fn = READ_ONCE(nmi_ipi_function); + WARN_ON_ONCE(!fn); + ret = 1; + } nmi_ipi_unlock_end(&flags); + if (fn) + fn(regs); + return ret; } @@ -473,9 +461,10 @@ static void do_smp_send_nmi_ipi(int cpu, bool safe) * - cpu is the target CPU (must not be this CPU), or NMI_IPI_ALL_OTHERS. * - fn is the target callback function. * - delay_us > 0 is the delay before giving up waiting for targets to - * complete executing the handler, == 0 specifies indefinite delay. + * begin executing the handler, == 0 specifies indefinite delay. */ -int __smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us, bool safe) +static int __smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), + u64 delay_us, bool safe) { unsigned long flags; int me = raw_smp_processor_id(); @@ -487,31 +476,33 @@ int __smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us, bool if (unlikely(!smp_ops)) return 0; - /* Take the nmi_ipi_busy count/lock with interrupts hard disabled */ nmi_ipi_lock_start(&flags); - while (nmi_ipi_busy_count) { + while (nmi_ipi_busy) { nmi_ipi_unlock_end(&flags); - spin_until_cond(nmi_ipi_busy_count == 0); + spin_until_cond(!nmi_ipi_busy); nmi_ipi_lock_start(&flags); } - + nmi_ipi_busy = true; nmi_ipi_function = fn; + WARN_ON_ONCE(!cpumask_empty(&nmi_ipi_pending_mask)); + if (cpu < 0) { /* ALL_OTHERS */ cpumask_copy(&nmi_ipi_pending_mask, cpu_online_mask); cpumask_clear_cpu(me, &nmi_ipi_pending_mask); } else { - /* cpumask starts clear */ cpumask_set_cpu(cpu, &nmi_ipi_pending_mask); } - nmi_ipi_busy_count++; + nmi_ipi_unlock(); + /* Interrupts remain hard disabled */ + do_smp_send_nmi_ipi(cpu, safe); nmi_ipi_lock(); - /* nmi_ipi_busy_count is held here, so unlock/lock is okay */ + /* nmi_ipi_busy is set here, so unlock/lock is okay */ while (!cpumask_empty(&nmi_ipi_pending_mask)) { nmi_ipi_unlock(); udelay(1); @@ -523,29 +514,15 @@ int __smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us, bool } } - while (nmi_ipi_busy_count > 1) { - nmi_ipi_unlock(); - udelay(1); - nmi_ipi_lock(); - if (delay_us) { - delay_us--; - if (!delay_us) - break; - } - } - if (!cpumask_empty(&nmi_ipi_pending_mask)) { /* Timeout waiting for CPUs to call smp_handle_nmi_ipi */ ret = 0; cpumask_clear(&nmi_ipi_pending_mask); } - if (nmi_ipi_busy_count > 1) { - /* Timeout waiting for CPUs to execute fn */ - ret = 0; - nmi_ipi_busy_count = 1; - } - nmi_ipi_busy_count--; + nmi_ipi_function = NULL; + nmi_ipi_busy = false; + nmi_ipi_unlock_end(&flags); return ret; @@ -613,17 +590,8 @@ void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *)) static void nmi_stop_this_cpu(struct pt_regs *regs) { /* - * This is a special case because it never returns, so the NMI IPI - * handling would never mark it as done, which makes any later - * smp_send_nmi_ipi() call spin forever. Mark it done now. - * * IRQs are already hard disabled by the smp_handle_nmi_ipi. */ - nmi_ipi_lock(); - if (nmi_ipi_busy_count > 1) - nmi_ipi_busy_count--; - nmi_ipi_unlock(); - spin_begin(); while (1) spin_cpu_relax(); @@ -663,7 +631,7 @@ void smp_send_stop(void) } #endif /* CONFIG_NMI_IPI */ -struct thread_info *current_set[NR_CPUS]; +struct task_struct *current_set[NR_CPUS]; static void smp_store_cpu_info(int id) { @@ -928,7 +896,7 @@ void smp_prepare_boot_cpu(void) paca_ptrs[boot_cpuid]->__current = current; #endif set_numa_node(numa_cpu_lookup_table[boot_cpuid]); - current_set[boot_cpuid] = task_thread_info(current); + current_set[boot_cpuid] = current; } #ifdef CONFIG_HOTPLUG_CPU @@ -1013,14 +981,13 @@ static bool secondaries_inhibited(void) static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle) { - struct thread_info *ti = task_thread_info(idle); - #ifdef CONFIG_PPC64 paca_ptrs[cpu]->__current = idle; - paca_ptrs[cpu]->kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD; + paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) + + THREAD_SIZE - STACK_FRAME_OVERHEAD; #endif - ti->cpu = cpu; - secondary_ti = current_set[cpu] = ti; + idle->cpu = cpu; + secondary_current = current_set[cpu] = idle; } int __cpu_up(unsigned int cpu, struct task_struct *tidle) |