[PATCH 05/13] task_isolation: Add task isolation hooks to arch-independent code

[Alex Belits]

From: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>

This commit adds task isolation hooks as follows:

- __handle_domain_irq() generates an isolation warning for the
  local task

- irq_work_queue_on() generates an isolation warning for the remote
  task being interrupted for irq_work

- generic_exec_single() generates a remote isolation warning for
  the remote cpu being IPI'd

- smp_call_function_many() generates a remote isolation warning for
  the set of remote cpus being IPI'd

Calls to task_isolation_remote() or task_isolation_interrupt() can
be placed in the platform-independent code like this when doing so
results in fewer lines of code changes, as for example is true of
the users of the arch_send_call_function_*() APIs. Or, they can be
placed in the per-architecture code when there are many callers,
as for example is true of the smp_send_reschedule() call.

A further cleanup might be to create an intermediate layer, so that
for example smp_send_reschedule() is a single generic function that
just calls arch_smp_send_reschedule(), allowing generic code to be
called every time smp_send_reschedule() is invoked. But for now, we
just update either callers or callees as makes most sense.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
[abelits@xxxxxxxxxxx: adapted for kernel 5.6]
Signed-off-by: Alex Belits <abelits@xxxxxxxxxxx>
---
 kernel/irq/irqdesc.c | 9 +++++++++
 kernel/irq_work.c    | 5 ++++-
 kernel/smp.c         | 6 +++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 98a5f10d1900..e2b81d035fa1 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -16,6 +16,7 @@
 #include <linux/bitmap.h>
 #include <linux/irqdomain.h>
 #include <linux/sysfs.h>
+#include <linux/isolation.h>
 
 #include "internals.h"
 
@@ -670,6 +671,10 @@ int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
 		irq = irq_find_mapping(domain, hwirq);
 #endif
 
+	task_isolation_interrupt((irq == hwirq) ?
+				 "irq %d (%s)" : "irq %d (%s hwirq %d)",
+				 irq, domain ? domain->name : "", hwirq);
+
 	/*
 	 * Some hardware gives randomly wrong interrupts.  Rather
 	 * than crashing, do something sensible.
@@ -711,6 +716,10 @@ int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
 
 	irq = irq_find_mapping(domain, hwirq);
 
+	task_isolation_interrupt((irq == hwirq) ?
+				 "NMI irq %d (%s)" : "NMI irq %d (%s hwirq %d)",
+				 irq, domain ? domain->name : "", hwirq);
+
 	/*
 	 * ack_bad_irq is not NMI-safe, just report
 	 * an invalid interrupt.
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 828cc30774bc..8fd4ece43dd8 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -18,6 +18,7 @@
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/smp.h>
+#include <linux/isolation.h>
 #include <asm/processor.h>
 
 
@@ -102,8 +103,10 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
 	if (cpu != smp_processor_id()) {
 		/* Arch remote IPI send/receive backend aren't NMI safe */
 		WARN_ON_ONCE(in_nmi());
-		if (llist_add(&work->llnode, &per_cpu(raised_list, cpu)))
+		if (llist_add(&work->llnode, &per_cpu(raised_list, cpu))) {
+			task_isolation_remote(cpu, "irq_work");
 			arch_send_call_function_single_ipi(cpu);
+		}
 	} else {
 		__irq_work_queue_local(work);
 	}
diff --git a/kernel/smp.c b/kernel/smp.c
index d0ada39eb4d4..3a8bcbdd4ce6 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -20,6 +20,7 @@
 #include <linux/sched.h>
 #include <linux/sched/idle.h>
 #include <linux/hypervisor.h>
+#include <linux/isolation.h>
 
 #include "smpboot.h"
 
@@ -176,8 +177,10 @@ static int generic_exec_single(int cpu, call_single_data_t *csd,
 	 * locking and barrier primitives. Generic code isn't really
 	 * equipped to do the right thing...
 	 */
-	if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
+	if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) {
+		task_isolation_remote(cpu, "IPI function");
 		arch_send_call_function_single_ipi(cpu);
+	}
 
 	return 0;
 }
@@ -466,6 +469,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 	}
 
 	/* Send a message to all CPUs in the map */
+	task_isolation_remote_cpumask(cfd->cpumask_ipi, "IPI function");
 	arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 
 	if (wait) {
-- 
2.20.1