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Subject[patch 17/55] 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>
---
include/linux/irqdesc.h | 4
include/linux/irqdomain.h | 4
kernel/irq/Kconfig | 11 ++
kernel/irq/Makefile | 1
kernel/irq/debugfs.c | 215 ++++++++++++++++++++++++++++++++++++++++++++++
kernel/irq/internals.h | 22 ++++
kernel/irq/irqdesc.c | 1
kernel/irq/irqdomain.c | 87 ++++++++++++++++++
kernel/irq/manage.c | 1
9 files changed, 345 insertions(+), 1 deletion(-)

--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -46,6 +46,7 @@ struct pt_regs;
* @rcu: rcu head for delayed free
* @kobj: kobject used to represent this struct in sysfs
* @dir: /proc/irq/ procfs entry
+ * @debugfs_file: dentry for the debugfs file
* @name: flow handler name for /proc/interrupts output
*/
struct irq_desc {
@@ -88,6 +89,9 @@ struct irq_desc {
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *dir;
#endif
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+ struct dentry *debugfs_file;
+#endif
#ifdef CONFIG_SPARSE_IRQ
struct rcu_head rcu;
struct kobject kobj;
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -139,6 +139,7 @@ struct irq_domain_chip_generic;
* setting up one or more generic chips for interrupt controllers
* drivers using the generic chip library which uses this pointer.
* @parent: Pointer to parent irq_domain to support hierarchy irq_domains
+ * @debugfs_file: dentry for the domain debugfs file
*
* Revmap data, used internally by irq_domain
* @revmap_direct_max_irq: The largest hwirq that can be set for controllers that
@@ -162,6 +163,9 @@ struct irq_domain {
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
struct irq_domain *parent;
#endif
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+ struct dentry *debugfs_file;
+#endif

/* reverse map data. The linear map gets appended to the irq_domain */
irq_hw_number_t hwirq_max;
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -108,4 +108,15 @@ config SPARSE_IRQ

If you don't know what to do here, say N.

+config GENERIC_IRQ_DEBUGFS
+ bool "Expose irq internals in debugfs"
+ depends on DEBUG_FS
+ default n
+ ---help---
+
+ Exposes internal state information through debugfs. Mostly for
+ developers and debugging of hard to diagnose interrupt problems.
+
+ If you don't know what to do here, say N.
+
endmenu
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_PM_SLEEP) += pm.o
obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o
obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o
obj-$(CONFIG_SMP) += affinity.o
+obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o
--- /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, 0x444, 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);
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -169,6 +169,11 @@ irq_put_desc_unlock(struct irq_desc *des

#define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)

+static inline unsigned int irqd_get(struct irq_data *d)
+{
+ return __irqd_to_state(d);
+}
+
/*
* Manipulation functions for irq_data.state
*/
@@ -226,3 +231,20 @@ irq_pm_install_action(struct irq_desc *d
static inline void
irq_pm_remove_action(struct irq_desc *desc, struct irqaction *action) { }
#endif
+
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *desc);
+void irq_remove_debugfs_entry(struct irq_desc *desc);
+# ifdef CONFIG_IRQ_DOMAIN
+void irq_domain_debugfs_init(struct dentry *root);
+# else
+static inline void irq_domain_debugfs_init(struct dentry *root);
+# endif
+#else /* CONFIG_GENERIC_IRQ_DEBUGFS */
+static inline void irq_add_debugfs_entry(unsigned int irq, struct irq_desc *d)
+{
+}
+static inline void irq_remove_debugfs_entry(struct irq_desc *d)
+{
+}
+#endif /* CONFIG_GENERIC_IRQ_DEBUGFS */
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -394,6 +394,7 @@ static void free_desc(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);

+ irq_remove_debugfs_entry(desc);
unregister_irq_proc(irq, desc);

/*
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -29,9 +29,17 @@ struct irqchip_fwid {
struct fwnode_handle fwnode;
unsigned int type;
char *name;
- void *data;
+ void *data;
};

+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+static void debugfs_add_domain_dir(struct irq_domain *d);
+static void debugfs_remove_domain_dir(struct irq_domain *d);
+#else
+static inline void debugfs_add_domain_dir(struct irq_domain *d) { }
+static inline void debugfs_remove_domain_dir(struct irq_domain *d) { }
+#endif
+
/**
* irq_domain_alloc_fwnode - Allocate a fwnode_handle suitable for
* identifying an irq domain
@@ -172,6 +180,7 @@ struct irq_domain *__irq_domain_add(stru
irq_domain_check_hierarchy(domain);

mutex_lock(&irq_domain_mutex);
+ debugfs_add_domain_dir(domain);
list_add(&domain->link, &irq_domain_list);
mutex_unlock(&irq_domain_mutex);

@@ -191,6 +200,7 @@ EXPORT_SYMBOL_GPL(__irq_domain_add);
void irq_domain_remove(struct irq_domain *domain)
{
mutex_lock(&irq_domain_mutex);
+ debugfs_remove_domain_dir(domain);

WARN_ON(!radix_tree_empty(&domain->revmap_tree));

@@ -1577,3 +1587,78 @@ static void irq_domain_check_hierarchy(s
{
}
#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */
+
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+static struct dentry *domain_dir;
+
+static void
+irq_domain_debug_show_one(struct seq_file *m, struct irq_domain *d, int ind)
+{
+ seq_printf(m, "%*sname: %s\n", ind, "", d->name);
+ seq_printf(m, "%*ssize: %u\n", ind + 1, "",
+ d->revmap_size + d->revmap_direct_max_irq);
+ seq_printf(m, "%*smapped: %u\n", ind + 1, "", d->mapcount);
+ seq_printf(m, "%*sflags: 0x%08x\n", ind +1 , "", d->flags);
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+ if (!d->parent)
+ return;
+ seq_printf(m, "%*sparent: %s\n", ind + 1, "", d->parent->name);
+ irq_domain_debug_show_one(m, d->parent, ind + 4);
+#endif
+}
+
+static int irq_domain_debug_show(struct seq_file *m, void *p)
+{
+ struct irq_domain *d = m->private;
+
+ /* Default domain? Might be NULL */
+ if (!d) {
+ if (!irq_default_domain)
+ return 0;
+ d = irq_default_domain;
+ }
+ irq_domain_debug_show_one(m, d, 0);
+ return 0;
+}
+
+static int irq_domain_debug_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, irq_domain_debug_show, inode->i_private);
+}
+
+static const struct file_operations dfs_domain_ops = {
+ .open = irq_domain_debug_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static void debugfs_add_domain_dir(struct irq_domain *d)
+{
+ if (!d->name || !domain_dir || d->debugfs_file)
+ return;
+ d->debugfs_file = debugfs_create_file(d->name, 0x444, domain_dir, d,
+ &dfs_domain_ops);
+}
+
+static void debugfs_remove_domain_dir(struct irq_domain *d)
+{
+ if (d->debugfs_file)
+ debugfs_remove(d->debugfs_file);
+}
+
+void __init irq_domain_debugfs_init(struct dentry *root)
+{
+ struct irq_domain *d;
+
+ domain_dir = debugfs_create_dir("domains", root);
+ if (!domain_dir)
+ return;
+
+ debugfs_create_file("default", 0444, domain_dir, NULL, &dfs_domain_ops);
+ mutex_lock(&irq_domain_mutex);
+ list_for_each_entry(d, &irq_domain_list, link)
+ debugfs_add_domain_dir(d);
+ mutex_unlock(&irq_domain_mutex);
+}
+#endif
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1396,6 +1396,7 @@ static int
wake_up_process(new->secondary->thread);

register_irq_proc(irq, desc);
+ irq_add_debugfs_entry(irq, desc);
new->dir = NULL;
register_handler_proc(irq, new);
free_cpumask_var(mask);

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