v4.19.13 snapshot.
diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c
new file mode 100644
index 0000000..21d86c3
--- /dev/null
+++ b/arch/arc/kernel/smp.c
@@ -0,0 +1,427 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * RajeshwarR: Dec 11, 2007
+ * -- Added support for Inter Processor Interrupts
+ *
+ * Vineetg: Nov 1st, 2007
+ * -- Initial Write (Borrowed heavily from ARM)
+ */
+
+#include <linux/spinlock.h>
+#include <linux/sched/mm.h>
+#include <linux/interrupt.h>
+#include <linux/profile.h>
+#include <linux/mm.h>
+#include <linux/cpu.h>
+#include <linux/irq.h>
+#include <linux/atomic.h>
+#include <linux/cpumask.h>
+#include <linux/reboot.h>
+#include <linux/irqdomain.h>
+#include <linux/export.h>
+#include <linux/of_fdt.h>
+
+#include <asm/processor.h>
+#include <asm/setup.h>
+#include <asm/mach_desc.h>
+
+#ifndef CONFIG_ARC_HAS_LLSC
+arch_spinlock_t smp_atomic_ops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+arch_spinlock_t smp_bitops_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+
+EXPORT_SYMBOL_GPL(smp_atomic_ops_lock);
+EXPORT_SYMBOL_GPL(smp_bitops_lock);
+#endif
+
+struct plat_smp_ops __weak plat_smp_ops;
+
+/* XXX: per cpu ? Only needed once in early seconday boot */
+struct task_struct *secondary_idle_tsk;
+
+/* Called from start_kernel */
+void __init smp_prepare_boot_cpu(void)
+{
+}
+
+static int __init arc_get_cpu_map(const char *name, struct cpumask *cpumask)
+{
+ unsigned long dt_root = of_get_flat_dt_root();
+ const char *buf;
+
+ buf = of_get_flat_dt_prop(dt_root, name, NULL);
+ if (!buf)
+ return -EINVAL;
+
+ if (cpulist_parse(buf, cpumask))
+ return -EINVAL;
+
+ return 0;
+}
+
+/*
+ * Read from DeviceTree and setup cpu possible mask. If there is no
+ * "possible-cpus" property in DeviceTree pretend all [0..NR_CPUS-1] exist.
+ */
+static void __init arc_init_cpu_possible(void)
+{
+ struct cpumask cpumask;
+
+ if (arc_get_cpu_map("possible-cpus", &cpumask)) {
+ pr_warn("Failed to get possible-cpus from dtb, pretending all %u cpus exist\n",
+ NR_CPUS);
+
+ cpumask_setall(&cpumask);
+ }
+
+ if (!cpumask_test_cpu(0, &cpumask))
+ panic("Master cpu (cpu[0]) is missed in cpu possible mask!");
+
+ init_cpu_possible(&cpumask);
+}
+
+/*
+ * Called from setup_arch() before calling setup_processor()
+ *
+ * - Initialise the CPU possible map early - this describes the CPUs
+ * which may be present or become present in the system.
+ * - Call early smp init hook. This can initialize a specific multi-core
+ * IP which is say common to several platforms (hence not part of
+ * platform specific int_early() hook)
+ */
+void __init smp_init_cpus(void)
+{
+ arc_init_cpu_possible();
+
+ if (plat_smp_ops.init_early_smp)
+ plat_smp_ops.init_early_smp();
+}
+
+/* called from init ( ) => process 1 */
+void __init smp_prepare_cpus(unsigned int max_cpus)
+{
+ /*
+ * if platform didn't set the present map already, do it now
+ * boot cpu is set to present already by init/main.c
+ */
+ if (num_present_cpus() <= 1)
+ init_cpu_present(cpu_possible_mask);
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
+
+}
+
+/*
+ * Default smp boot helper for Run-on-reset case where all cores start off
+ * together. Non-masters need to wait for Master to start running.
+ * This is implemented using a flag in memory, which Non-masters spin-wait on.
+ * Master sets it to cpu-id of core to "ungate" it.
+ */
+static volatile int wake_flag;
+
+#ifdef CONFIG_ISA_ARCOMPACT
+
+#define __boot_read(f) f
+#define __boot_write(f, v) f = v
+
+#else
+
+#define __boot_read(f) arc_read_uncached_32(&f)
+#define __boot_write(f, v) arc_write_uncached_32(&f, v)
+
+#endif
+
+static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
+{
+ BUG_ON(cpu == 0);
+
+ __boot_write(wake_flag, cpu);
+}
+
+void arc_platform_smp_wait_to_boot(int cpu)
+{
+ /* for halt-on-reset, we've waited already */
+ if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
+ return;
+
+ while (__boot_read(wake_flag) != cpu)
+ ;
+
+ __boot_write(wake_flag, 0);
+}
+
+const char *arc_platform_smp_cpuinfo(void)
+{
+ return plat_smp_ops.info ? : "";
+}
+
+/*
+ * The very first "C" code executed by secondary
+ * Called from asm stub in head.S
+ * "current"/R25 already setup by low level boot code
+ */
+void start_kernel_secondary(void)
+{
+ struct mm_struct *mm = &init_mm;
+ unsigned int cpu = smp_processor_id();
+
+ /* MMU, Caches, Vector Table, Interrupts etc */
+ setup_processor();
+
+ mmget(mm);
+ mmgrab(mm);
+ current->active_mm = mm;
+ cpumask_set_cpu(cpu, mm_cpumask(mm));
+
+ /* Some SMP H/w setup - for each cpu */
+ if (plat_smp_ops.init_per_cpu)
+ plat_smp_ops.init_per_cpu(cpu);
+
+ if (machine_desc->init_per_cpu)
+ machine_desc->init_per_cpu(cpu);
+
+ notify_cpu_starting(cpu);
+ set_cpu_online(cpu, true);
+
+ pr_info("## CPU%u LIVE ##: Executing Code...\n", cpu);
+
+ local_irq_enable();
+ preempt_disable();
+ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+}
+
+/*
+ * Called from kernel_init( ) -> smp_init( ) - for each CPU
+ *
+ * At this point, Secondary Processor is "HALT"ed:
+ * -It booted, but was halted in head.S
+ * -It was configured to halt-on-reset
+ * So need to wake it up.
+ *
+ * Essential requirements being where to run from (PC) and stack (SP)
+*/
+int __cpu_up(unsigned int cpu, struct task_struct *idle)
+{
+ unsigned long wait_till;
+
+ secondary_idle_tsk = idle;
+
+ pr_info("Idle Task [%d] %p", cpu, idle);
+ pr_info("Trying to bring up CPU%u ...\n", cpu);
+
+ if (plat_smp_ops.cpu_kick)
+ plat_smp_ops.cpu_kick(cpu,
+ (unsigned long)first_lines_of_secondary);
+ else
+ arc_default_smp_cpu_kick(cpu, (unsigned long)NULL);
+
+ /* wait for 1 sec after kicking the secondary */
+ wait_till = jiffies + HZ;
+ while (time_before(jiffies, wait_till)) {
+ if (cpu_online(cpu))
+ break;
+ }
+
+ if (!cpu_online(cpu)) {
+ pr_info("Timeout: CPU%u FAILED to comeup !!!\n", cpu);
+ return -1;
+ }
+
+ secondary_idle_tsk = NULL;
+
+ return 0;
+}
+
+/*
+ * not supported here
+ */
+int setup_profiling_timer(unsigned int multiplier)
+{
+ return -EINVAL;
+}
+
+/*****************************************************************************/
+/* Inter Processor Interrupt Handling */
+/*****************************************************************************/
+
+enum ipi_msg_type {
+ IPI_EMPTY = 0,
+ IPI_RESCHEDULE = 1,
+ IPI_CALL_FUNC,
+ IPI_CPU_STOP,
+};
+
+/*
+ * In arches with IRQ for each msg type (above), receiver can use IRQ-id to
+ * figure out what msg was sent. For those which don't (ARC has dedicated IPI
+ * IRQ), the msg-type needs to be conveyed via per-cpu data
+ */
+
+static DEFINE_PER_CPU(unsigned long, ipi_data);
+
+static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
+{
+ unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
+ unsigned long old, new;
+ unsigned long flags;
+
+ pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
+
+ local_irq_save(flags);
+
+ /*
+ * Atomically write new msg bit (in case others are writing too),
+ * and read back old value
+ */
+ do {
+ new = old = READ_ONCE(*ipi_data_ptr);
+ new |= 1U << msg;
+ } while (cmpxchg(ipi_data_ptr, old, new) != old);
+
+ /*
+ * Call the platform specific IPI kick function, but avoid if possible:
+ * Only do so if there's no pending msg from other concurrent sender(s).
+ * Otherwise, recevier will see this msg as well when it takes the
+ * IPI corresponding to that msg. This is true, even if it is already in
+ * IPI handler, because !@old means it has not yet dequeued the msg(s)
+ * so @new msg can be a free-loader
+ */
+ if (plat_smp_ops.ipi_send && !old)
+ plat_smp_ops.ipi_send(cpu);
+
+ local_irq_restore(flags);
+}
+
+static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
+{
+ unsigned int cpu;
+
+ for_each_cpu(cpu, callmap)
+ ipi_send_msg_one(cpu, msg);
+}
+
+void smp_send_reschedule(int cpu)
+{
+ ipi_send_msg_one(cpu, IPI_RESCHEDULE);
+}
+
+void smp_send_stop(void)
+{
+ struct cpumask targets;
+ cpumask_copy(&targets, cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), &targets);
+ ipi_send_msg(&targets, IPI_CPU_STOP);
+}
+
+void arch_send_call_function_single_ipi(int cpu)
+{
+ ipi_send_msg_one(cpu, IPI_CALL_FUNC);
+}
+
+void arch_send_call_function_ipi_mask(const struct cpumask *mask)
+{
+ ipi_send_msg(mask, IPI_CALL_FUNC);
+}
+
+/*
+ * ipi_cpu_stop - handle IPI from smp_send_stop()
+ */
+static void ipi_cpu_stop(void)
+{
+ machine_halt();
+}
+
+static inline int __do_IPI(unsigned long msg)
+{
+ int rc = 0;
+
+ switch (msg) {
+ case IPI_RESCHEDULE:
+ scheduler_ipi();
+ break;
+
+ case IPI_CALL_FUNC:
+ generic_smp_call_function_interrupt();
+ break;
+
+ case IPI_CPU_STOP:
+ ipi_cpu_stop();
+ break;
+
+ default:
+ rc = 1;
+ }
+
+ return rc;
+}
+
+/*
+ * arch-common ISR to handle for inter-processor interrupts
+ * Has hooks for platform specific IPI
+ */
+irqreturn_t do_IPI(int irq, void *dev_id)
+{
+ unsigned long pending;
+ unsigned long __maybe_unused copy;
+
+ pr_debug("IPI [%ld] received on cpu %d\n",
+ *this_cpu_ptr(&ipi_data), smp_processor_id());
+
+ if (plat_smp_ops.ipi_clear)
+ plat_smp_ops.ipi_clear(irq);
+
+ /*
+ * "dequeue" the msg corresponding to this IPI (and possibly other
+ * piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
+ */
+ copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
+
+ do {
+ unsigned long msg = __ffs(pending);
+ int rc;
+
+ rc = __do_IPI(msg);
+ if (rc)
+ pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
+ pending &= ~(1U << msg);
+ } while (pending);
+
+ return IRQ_HANDLED;
+}
+
+/*
+ * API called by platform code to hookup arch-common ISR to their IPI IRQ
+ *
+ * Note: If IPI is provided by platform (vs. say ARC MCIP), their intc setup/map
+ * function needs to call call irq_set_percpu_devid() for IPI IRQ, otherwise
+ * request_percpu_irq() below will fail
+ */
+static DEFINE_PER_CPU(int, ipi_dev);
+
+int smp_ipi_irq_setup(int cpu, irq_hw_number_t hwirq)
+{
+ int *dev = per_cpu_ptr(&ipi_dev, cpu);
+ unsigned int virq = irq_find_mapping(NULL, hwirq);
+
+ if (!virq)
+ panic("Cannot find virq for root domain and hwirq=%lu", hwirq);
+
+ /* Boot cpu calls request, all call enable */
+ if (!cpu) {
+ int rc;
+
+ rc = request_percpu_irq(virq, do_IPI, "IPI Interrupt", dev);
+ if (rc)
+ panic("Percpu IRQ request failed for %u\n", virq);
+ }
+
+ enable_percpu_irq(virq, 0);
+
+ return 0;
+}