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authorMarc Zyngier <marc.zyngier@arm.com>2014-08-26 11:03:16 +0100
committerJason Cooper <jason@lakedaemon.net>2014-09-03 12:57:27 +0000
commit76ba59f8366f2d9282cb5bda9de75b4b68cbe55f (patch)
tree567c5a7b10fb8f7a1e597a8cc83c0afe92dbce50
parent7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff)
downloadlinux-76ba59f8366f2d9282cb5bda9de75b4b68cbe55f.tar.bz2
genirq: Add irq_domain-aware core IRQ handler
Calling irq_find_mapping from outside a irq_{enter,exit} section is unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled: If coming from the idle state, the rcu_read_lock call in irq_find_mapping will generate an unpleasant warning: <quote> =============================== [ INFO: suspicious RCU usage. ] 3.16.0-rc1+ #135 Not tainted ------------------------------- include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: (rcu_read_lock){......}, at: [<ffffffc00010206c>] irq_find_mapping+0x4c/0x198 </quote> As this issue is fairly widespread and involves at least three different architectures, a possible solution is to add a new handle_domain_irq entry point into the generic IRQ code that the interrupt controller code can call. This new function takes an irq_domain, and calls into irq_find_domain inside the irq_{enter,exit} block. An additional "lookup" parameter is used to allow non-domain architecture code to be replaced by this as well. Interrupt controllers can then be updated to use the new mechanism. This code is sitting behind a new CONFIG_HANDLE_DOMAIN_IRQ, as not all architectures implement set_irq_regs (yes, mn10300, I'm looking at you...). Reported-by: Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Link: https://lkml.kernel.org/r/1409047421-27649-2-git-send-email-marc.zyngier@arm.com Signed-off-by: Jason Cooper <jason@lakedaemon.net>
-rw-r--r--include/linux/irqdesc.h19
-rw-r--r--kernel/irq/Kconfig3
-rw-r--r--kernel/irq/irqdesc.c42
3 files changed, 64 insertions, 0 deletions
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 472c021a2d4f..ff24667cd86c 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -12,6 +12,8 @@ struct irq_affinity_notify;
struct proc_dir_entry;
struct module;
struct irq_desc;
+struct irq_domain;
+struct pt_regs;
/**
* struct irq_desc - interrupt descriptor
@@ -118,6 +120,23 @@ static inline void generic_handle_irq_desc(unsigned int irq, struct irq_desc *de
int generic_handle_irq(unsigned int irq);
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+/*
+ * Convert a HW interrupt number to a logical one using a IRQ domain,
+ * and handle the result interrupt number. Return -EINVAL if
+ * conversion failed. Providing a NULL domain indicates that the
+ * conversion has already been done.
+ */
+int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
+ bool lookup, struct pt_regs *regs);
+
+static inline int handle_domain_irq(struct irq_domain *domain,
+ unsigned int hwirq, struct pt_regs *regs)
+{
+ return __handle_domain_irq(domain, hwirq, true, regs);
+}
+#endif
+
/* Test to see if a driver has successfully requested an irq */
static inline int irq_has_action(unsigned int irq)
{
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index d269cecdfbf0..225086b2652e 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -55,6 +55,9 @@ config GENERIC_IRQ_CHIP
config IRQ_DOMAIN
bool
+config HANDLE_DOMAIN_IRQ
+ bool
+
config IRQ_DOMAIN_DEBUG
bool "Expose hardware/virtual IRQ mapping via debugfs"
depends on IRQ_DOMAIN && DEBUG_FS
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 1487a123db5c..a1782f88f0af 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -14,6 +14,7 @@
#include <linux/kernel_stat.h>
#include <linux/radix-tree.h>
#include <linux/bitmap.h>
+#include <linux/irqdomain.h>
#include "internals.h"
@@ -336,6 +337,47 @@ int generic_handle_irq(unsigned int irq)
}
EXPORT_SYMBOL_GPL(generic_handle_irq);
+#ifdef CONFIG_HANDLE_DOMAIN_IRQ
+/**
+ * __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain
+ * @domain: The domain where to perform the lookup
+ * @hwirq: The HW irq number to convert to a logical one
+ * @lookup: Whether to perform the domain lookup or not
+ * @regs: Register file coming from the low-level handling code
+ *
+ * Returns: 0 on success, or -EINVAL if conversion has failed
+ */
+int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
+ bool lookup, struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+ unsigned int irq = hwirq;
+ int ret = 0;
+
+ irq_enter();
+
+#ifdef CONFIG_IRQ_DOMAIN
+ if (lookup)
+ irq = irq_find_mapping(domain, hwirq);
+#endif
+
+ /*
+ * Some hardware gives randomly wrong interrupts. Rather
+ * than crashing, do something sensible.
+ */
+ if (unlikely(!irq || irq >= nr_irqs)) {
+ ack_bad_irq(irq);
+ ret = -EINVAL;
+ } else {
+ generic_handle_irq(irq);
+ }
+
+ irq_exit();
+ set_irq_regs(old_regs);
+ return ret;
+}
+#endif
+
/* Dynamic interrupt handling */
/**