// SPDX-License-Identifier: GPL-2.0-only /* * SMP Support * * Copyright (C) 1999 Walt Drummond * Copyright (C) 1999, 2001, 2003 David Mosberger-Tang * * Lots of stuff stolen from arch/alpha/kernel/smp.c * * 01/05/16 Rohit Seth IA64-SMP functions. Reorganized * the existing code (on the lines of x86 port). * 00/09/11 David Mosberger Do loops_per_jiffy * calibration on each CPU. * 00/08/23 Asit Mallick fixed logical processor id * 00/03/31 Rohit Seth Fixes for Bootstrap Processor * & cpu_online_map now gets done here (instead of setup.c) * 99/10/05 davidm Update to bring it in sync with new command-line processing * scheme. * 10/13/00 Goutham Rao Updated smp_call_function and * smp_call_function_single to resend IPI on timeouts */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Note: alignment of 4 entries/cacheline was empirically determined * to be a good tradeoff between hot cachelines & spreading the array * across too many cacheline. */ static struct local_tlb_flush_counts { unsigned int count; } __attribute__((__aligned__(32))) local_tlb_flush_counts[NR_CPUS]; static DEFINE_PER_CPU_SHARED_ALIGNED(unsigned short [NR_CPUS], shadow_flush_counts); #define IPI_CALL_FUNC 0 #define IPI_CPU_STOP 1 #define IPI_CALL_FUNC_SINGLE 2 #define IPI_KDUMP_CPU_STOP 3 /* This needs to be cacheline aligned because it is written to by *other* CPUs. */ static DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, ipi_operation); extern void cpu_halt (void); static void stop_this_cpu(void) { /* * Remove this CPU: */ set_cpu_online(smp_processor_id(), false); max_xtp(); local_irq_disable(); cpu_halt(); } void cpu_die(void) { max_xtp(); local_irq_disable(); cpu_halt(); /* Should never be here */ BUG(); for (;;); } irqreturn_t handle_IPI (int irq, void *dev_id) { int this_cpu = get_cpu(); unsigned long *pending_ipis = &__ia64_per_cpu_var(ipi_operation); unsigned long ops; mb(); /* Order interrupt and bit testing. */ while ((ops = xchg(pending_ipis, 0)) != 0) { mb(); /* Order bit clearing and data access. */ do { unsigned long which; which = ffz(~ops); ops &= ~(1 << which); switch (which) { case IPI_CPU_STOP: stop_this_cpu(); break; case IPI_CALL_FUNC: generic_smp_call_function_interrupt(); break; case IPI_CALL_FUNC_SINGLE: generic_smp_call_function_single_interrupt(); break; #ifdef CONFIG_KEXEC case IPI_KDUMP_CPU_STOP: unw_init_running(kdump_cpu_freeze, NULL); break; #endif default: printk(KERN_CRIT "Unknown IPI on CPU %d: %lu\n", this_cpu, which); break; } } while (ops); mb(); /* Order data access and bit testing. */ } put_cpu(); return IRQ_HANDLED; } /* * Called with preemption disabled. */ static inline void send_IPI_single (int dest_cpu, int op) { set_bit(op, &per_cpu(ipi_operation, dest_cpu)); ia64_send_ipi(dest_cpu, IA64_IPI_VECTOR, IA64_IPI_DM_INT, 0); } /* * Called with preemption disabled. */ static inline void send_IPI_allbutself (int op) { unsigned int i; for_each_online_cpu(i) { if (i != smp_processor_id()) send_IPI_single(i, op); } } /* * Called with preemption disabled. */ static inline void send_IPI_mask(const struct cpumask *mask, int op) { unsigned int cpu; for_each_cpu(cpu, mask) { send_IPI_single(cpu, op); } } /* * Called with preemption disabled. */ static inline void send_IPI_all (int op) { int i; for_each_online_cpu(i) { send_IPI_single(i, op); } } /* * Called with preemption disabled. */ static inline void send_IPI_self (int op) { send_IPI_single(smp_processor_id(), op); } #ifdef CONFIG_KEXEC void kdump_smp_send_stop(void) { send_IPI_allbutself(IPI_KDUMP_CPU_STOP); } void kdump_smp_send_init(void) { unsigned int cpu, self_cpu; self_cpu = smp_processor_id(); for_each_online_cpu(cpu) { if (cpu != self_cpu) { if(kdump_status[cpu] == 0) ia64_send_ipi(cpu, 0, IA64_IPI_DM_INIT, 0); } } } #endif /* * Called with preemption disabled. */ void smp_send_reschedule (int cpu) { ia64_send_ipi(cpu, IA64_IPI_RESCHEDULE, IA64_IPI_DM_INT, 0); } EXPORT_SYMBOL_GPL(smp_send_reschedule); /* * Called with preemption disabled. */ static void smp_send_local_flush_tlb (int cpu) { ia64_send_ipi(cpu, IA64_IPI_LOCAL_TLB_FLUSH, IA64_IPI_DM_INT, 0); } void smp_local_flush_tlb(void) { /* * Use atomic ops. Otherwise, the load/increment/store sequence from * a "++" operation can have the line stolen between the load & store. * The overhead of the atomic op in negligible in this case & offers * significant benefit for the brief periods where lots of cpus * are simultaneously flushing TLBs. */ ia64_fetchadd(1, &local_tlb_flush_counts[smp_processor_id()].count, acq); local_flush_tlb_all(); } #define FLUSH_DELAY 5 /* Usec backoff to eliminate excessive cacheline bouncing */ void smp_flush_tlb_cpumask(cpumask_t xcpumask) { unsigned short *counts = __ia64_per_cpu_var(shadow_flush_counts); cpumask_t cpumask = xcpumask; int mycpu, cpu, flush_mycpu = 0; preempt_disable(); mycpu = smp_processor_id(); for_each_cpu(cpu, &cpumask) counts[cpu] = local_tlb_flush_counts[cpu].count & 0xffff; mb(); for_each_cpu(cpu, &cpumask) { if (cpu == mycpu) flush_mycpu = 1; else smp_send_local_flush_tlb(cpu); } if (flush_mycpu) smp_local_flush_tlb(); for_each_cpu(cpu, &cpumask) while(counts[cpu] == (local_tlb_flush_counts[cpu].count & 0xffff)) udelay(FLUSH_DELAY); preempt_enable(); } void smp_flush_tlb_all (void) { on_each_cpu((void (*)(void *))local_flush_tlb_all, NULL, 1); } void smp_flush_tlb_mm (struct mm_struct *mm) { cpumask_var_t cpus; preempt_disable(); /* this happens for the common case of a single-threaded fork(): */ if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1)) { local_finish_flush_tlb_mm(mm); preempt_enable(); return; } if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) { smp_call_function((void (*)(void *))local_finish_flush_tlb_mm, mm, 1); } else { cpumask_copy(cpus, mm_cpumask(mm)); smp_call_function_many(cpus, (void (*)(void *))local_finish_flush_tlb_mm, mm, 1); free_cpumask_var(cpus); } local_irq_disable(); local_finish_flush_tlb_mm(mm); local_irq_enable(); preempt_enable(); } void arch_send_call_function_single_ipi(int cpu) { send_IPI_single(cpu, IPI_CALL_FUNC_SINGLE); } void arch_send_call_function_ipi_mask(const struct cpumask *mask) { send_IPI_mask(mask, IPI_CALL_FUNC); } /* * this function calls the 'stop' function on all other CPUs in the system. */ void smp_send_stop (void) { send_IPI_allbutself(IPI_CPU_STOP); }