genirq/debugfs: Add proper debugfs interface

Debugging (hierarchical) interupt domains is tedious as there is no
information about the hierarchy and no information about states of
interrupts in the various domain levels.

Add a debugfs directory 'irq' and subdirectories 'domains' and 'irqs'.

The domains directory contains the domain files. The content is information
about the domain. If the domain is part of a hierarchy then the parent
domains are printed as well.

# ls /sys/kernel/debug/irq/domains/
default     INTEL-IR-2	    INTEL-IR-MSI-2  IO-APIC-IR-2  PCI-MSI
DMAR-MSI    INTEL-IR-3	    INTEL-IR-MSI-3  IO-APIC-IR-3  unknown-1
INTEL-IR-0  INTEL-IR-MSI-0  IO-APIC-IR-0    IO-APIC-IR-4  VECTOR
INTEL-IR-1  INTEL-IR-MSI-1  IO-APIC-IR-1    PCI-HT

# cat /sys/kernel/debug/irq/domains/VECTOR 
name:   VECTOR
 size:   0
 mapped: 216
 flags:  0x00000041

# cat /sys/kernel/debug/irq/domains/IO-APIC-IR-0 
name:   IO-APIC-IR-0
 size:   24
 mapped: 19
 flags:  0x00000041
 parent: INTEL-IR-3
    name:   INTEL-IR-3
     size:   65536
     mapped: 167
     flags:  0x00000041
     parent: VECTOR
        name:   VECTOR
         size:   0
         mapped: 216
         flags:  0x00000041

Unfortunately there is no per cpu information about the VECTOR domain (yet).

The irqs directory contains detailed information about mapped interrupts.

# cat /sys/kernel/debug/irq/irqs/3
handler:  handle_edge_irq
status:   0x00004000
istate:   0x00000000
ddepth:   1
wdepth:   0
dstate:   0x01018000
            IRQD_IRQ_DISABLED
            IRQD_SINGLE_TARGET
            IRQD_MOVE_PCNTXT
node:     0
affinity: 0-143
effectiv: 0
pending:  
domain:  IO-APIC-IR-0
 hwirq:   0x3
 chip:    IR-IO-APIC
  flags:   0x10
             IRQCHIP_SKIP_SET_WAKE
 parent:
    domain:  INTEL-IR-3
     hwirq:   0x20000
     chip:    INTEL-IR
      flags:   0x0
     parent:
        domain:  VECTOR
         hwirq:   0x3
         chip:    APIC
          flags:   0x0

This was developed to simplify the debugging of the managed affinity
changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170619235444.537566163@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 215 insertions, 0 deletions

diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c
new file mode 100644
index 000000000000..50ee2f6593e8
--- /dev/null
+++ b/kernel/irq/debugfs.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright 2017 Thomas Gleixner <tglx@linutronix.de>
+ *
+ * This file is licensed under the GPL V2.
+ */
+#include <linux/debugfs.h>
+#include <linux/irqdomain.h>
+#include <linux/irq.h>
+
+#include "internals.h"
+
+static struct dentry *irq_dir;
+
+struct irq_bit_descr {
+	unsigned int	mask;
+	char		*name;
+};
+#define BIT_MASK_DESCR(m)	{ .mask = m, .name = #m }
+
+static void irq_debug_show_bits(struct seq_file *m, int ind, unsigned int state,
+				const struct irq_bit_descr *sd, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++, sd++) {
+		if (state & sd->mask)
+			seq_printf(m, "%*s%s\n", ind + 12, "", sd->name);
+	}
+}
+
+#ifdef CONFIG_SMP
+static void irq_debug_show_masks(struct seq_file *m, struct irq_desc *desc)
+{
+	struct irq_data *data = irq_desc_get_irq_data(desc);
+	struct cpumask *msk;
+
+	msk = irq_data_get_affinity_mask(data);
+	seq_printf(m, "affinity: %*pbl\n", cpumask_pr_args(msk));
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+	msk = desc->pending_mask;
+	seq_printf(m, "pending:  %*pbl\n", cpumask_pr_args(msk));
+#endif
+}
+#else
+static void irq_debug_show_masks(struct seq_file *m, struct irq_desc *desc) { }
+#endif
+
+static const struct irq_bit_descr irqchip_flags[] = {
+	BIT_MASK_DESCR(IRQCHIP_SET_TYPE_MASKED),
+	BIT_MASK_DESCR(IRQCHIP_EOI_IF_HANDLED),
+	BIT_MASK_DESCR(IRQCHIP_MASK_ON_SUSPEND),
+	BIT_MASK_DESCR(IRQCHIP_ONOFFLINE_ENABLED),
+	BIT_MASK_DESCR(IRQCHIP_SKIP_SET_WAKE),
+	BIT_MASK_DESCR(IRQCHIP_ONESHOT_SAFE),
+	BIT_MASK_DESCR(IRQCHIP_EOI_THREADED),
+};
+
+static void
+irq_debug_show_chip(struct seq_file *m, struct irq_data *data, int ind)
+{
+	struct irq_chip *chip = data->chip;
+
+	if (!chip) {
+		seq_printf(m, "chip: None\n");
+		return;
+	}
+	seq_printf(m, "%*schip:    %s\n", ind, "", chip->name);
+	seq_printf(m, "%*sflags:   0x%lx\n", ind + 1, "", chip->flags);
+	irq_debug_show_bits(m, ind, chip->flags, irqchip_flags,
+			    ARRAY_SIZE(irqchip_flags));
+}
+
+static void
+irq_debug_show_data(struct seq_file *m, struct irq_data *data, int ind)
+{
+	seq_printf(m, "%*sdomain:  %s\n", ind, "",
+		   data->domain ? data->domain->name : "");
+	seq_printf(m, "%*shwirq:   0x%lx\n", ind + 1, "", data->hwirq);
+	irq_debug_show_chip(m, data, ind + 1);
+#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+	if (!data->parent_data)
+		return;
+	seq_printf(m, "%*sparent:\n", ind + 1, "");
+	irq_debug_show_data(m, data->parent_data, ind + 4);
+#endif
+}
+
+static const struct irq_bit_descr irqdata_states[] = {
+	BIT_MASK_DESCR(IRQ_TYPE_EDGE_RISING),
+	BIT_MASK_DESCR(IRQ_TYPE_EDGE_FALLING),
+	BIT_MASK_DESCR(IRQ_TYPE_LEVEL_HIGH),
+	BIT_MASK_DESCR(IRQ_TYPE_LEVEL_LOW),
+	BIT_MASK_DESCR(IRQD_LEVEL),
+
+	BIT_MASK_DESCR(IRQD_ACTIVATED),
+	BIT_MASK_DESCR(IRQD_IRQ_STARTED),
+	BIT_MASK_DESCR(IRQD_IRQ_DISABLED),
+	BIT_MASK_DESCR(IRQD_IRQ_MASKED),
+	BIT_MASK_DESCR(IRQD_IRQ_INPROGRESS),
+
+	BIT_MASK_DESCR(IRQD_PER_CPU),
+	BIT_MASK_DESCR(IRQD_NO_BALANCING),
+
+	BIT_MASK_DESCR(IRQD_MOVE_PCNTXT),
+	BIT_MASK_DESCR(IRQD_AFFINITY_SET),
+	BIT_MASK_DESCR(IRQD_SETAFFINITY_PENDING),
+	BIT_MASK_DESCR(IRQD_AFFINITY_MANAGED),
+	BIT_MASK_DESCR(IRQD_MANAGED_SHUTDOWN),
+
+	BIT_MASK_DESCR(IRQD_FORWARDED_TO_VCPU),
+
+	BIT_MASK_DESCR(IRQD_WAKEUP_STATE),
+	BIT_MASK_DESCR(IRQD_WAKEUP_ARMED),
+};
+
+static const struct irq_bit_descr irqdesc_states[] = {
+	BIT_MASK_DESCR(_IRQ_NOPROBE),
+	BIT_MASK_DESCR(_IRQ_NOREQUEST),
+	BIT_MASK_DESCR(_IRQ_NOTHREAD),
+	BIT_MASK_DESCR(_IRQ_NOAUTOEN),
+	BIT_MASK_DESCR(_IRQ_NESTED_THREAD),
+	BIT_MASK_DESCR(_IRQ_PER_CPU_DEVID),
+	BIT_MASK_DESCR(_IRQ_IS_POLLED),
+	BIT_MASK_DESCR(_IRQ_DISABLE_UNLAZY),
+};
+
+static const struct irq_bit_descr irqdesc_istates[] = {
+	BIT_MASK_DESCR(IRQS_AUTODETECT),
+	BIT_MASK_DESCR(IRQS_SPURIOUS_DISABLED),
+	BIT_MASK_DESCR(IRQS_POLL_INPROGRESS),
+	BIT_MASK_DESCR(IRQS_ONESHOT),
+	BIT_MASK_DESCR(IRQS_REPLAY),
+	BIT_MASK_DESCR(IRQS_WAITING),
+	BIT_MASK_DESCR(IRQS_PENDING),
+	BIT_MASK_DESCR(IRQS_SUSPENDED),
+};
+
+
+static int irq_debug_show(struct seq_file *m, void *p)
+{
+	struct irq_desc *desc = m->private;
+	struct irq_data *data;
+
+	raw_spin_lock_irq(&desc->lock);
+	data = irq_desc_get_irq_data(desc);
+	seq_printf(m, "handler:  %pf\n", desc->handle_irq);
+	seq_printf(m, "status:   0x%08x\n", desc->status_use_accessors);
+	irq_debug_show_bits(m, 0, desc->status_use_accessors, irqdesc_states,
+			    ARRAY_SIZE(irqdesc_states));
+	seq_printf(m, "istate:   0x%08x\n", desc->istate);
+	irq_debug_show_bits(m, 0, desc->istate, irqdesc_istates,
+			    ARRAY_SIZE(irqdesc_istates));
+	seq_printf(m, "ddepth:   %u\n", desc->depth);
+	seq_printf(m, "wdepth:   %u\n", desc->wake_depth);
+	seq_printf(m, "dstate:   0x%08x\n", irqd_get(data));
+	irq_debug_show_bits(m, 0, irqd_get(data), irqdata_states,
+			    ARRAY_SIZE(irqdata_states));
+	seq_printf(m, "node:     %d\n", irq_data_get_node(data));
+	irq_debug_show_masks(m, desc);
+	irq_debug_show_data(m, data, 0);
+	raw_spin_unlock_irq(&desc->lock);
+	return 0;
+}
+
+static int irq_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, irq_debug_show, inode->i_private);
+}
+
+static const struct file_operations dfs_irq_ops = {
+	.open		= irq_debug_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc)
+{
+	char name [10];
+
+	if (!irq_dir || !desc || desc->debugfs_file)
+		return;
+
+	sprintf(name, "%d", irq);
+	desc->debugfs_file = debugfs_create_file(name, 0444, irq_dir, desc,
+						 &dfs_irq_ops);
+}
+
+void irq_remove_debugfs_entry(struct irq_desc *desc)
+{
+	if (desc->debugfs_file)
+		debugfs_remove(desc->debugfs_file);
+}
+
+static int __init irq_debugfs_init(void)
+{
+	struct dentry *root_dir;
+	int irq;
+
+	root_dir = debugfs_create_dir("irq", NULL);
+	if (!root_dir)
+		return -ENOMEM;
+
+	irq_domain_debugfs_init(root_dir);
+
+	irq_dir = debugfs_create_dir("irqs", root_dir);
+
+	irq_lock_sparse();
+	for_each_active_irq(irq)
+		irq_add_debugfs_entry(irq, irq_to_desc(irq));
+	irq_unlock_sparse();
+
+	return 0;
+}
+__initcall(irq_debugfs_init);