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authorMarc Zyngier <maz@kernel.org>2021-07-06 11:38:59 +0100
committerMarc Zyngier <maz@kernel.org>2021-07-09 10:18:58 +0100
commit1fee9db9b42d821e8007289d4eea74bdf85b1543 (patch)
tree6f5b28725cd0b60ac05ccc13b073328b13eec4a2 /arch
parent0e3c1f30b03599f2ee8ff3327eca53c99564ba13 (diff)
irqchip/mips: Fix RCU violation when using irqdomain lookup on interrupt entry
Since d4a45c68dc81 ("irqdomain: Protect the linear revmap with RCU"), any irqdomain lookup requires the RCU read lock to be held. This assumes that the architecture code will be structured such as irq_enter() will be called *before* the interrupt is looked up in the irq domain. However, this isn't the case for MIPS, and a number of drivers are structured to do it the other way around when handling an interrupt in their root irqchip (secondary irqchips are OK by construction). This results in a RCU splat on a lockdep-enabled kernel when the kernel takes an interrupt from idle, as reported by Guenter Roeck. Note that this could have fired previously if any driver had used tree-based irqdomain, which always had the RCU requirement. To solve this, provide a MIPS-specific helper (do_domain_IRQ()) as the pendent of do_IRQ() that will do thing in the right order (and maybe save some cycles in the process). Ideally, MIPS would be moved over to using handle_domain_irq(), but that's much more ambitious. Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> [maz: add dependency on CONFIG_IRQ_DOMAIN after report from the kernelci bot] Signed-off-by: Marc Zyngier <maz@kernel.org> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Serge Semin <fancer.lancer@gmail.com> Link: https://lore.kernel.org/r/20210705172352.GA56304@roeck-us.net Link: https://lore.kernel.org/r/20210706110647.3979002-1-maz@kernel.org
Diffstat (limited to 'arch')
-rw-r--r--arch/mips/include/asm/irq.h3
-rw-r--r--arch/mips/kernel/irq.c16
2 files changed, 19 insertions, 0 deletions
diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
index d1477ecb1af9..57561e0e6e8d 100644
--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -57,6 +57,9 @@ asmlinkage void plat_irq_dispatch(void);
extern void do_IRQ(unsigned int irq);
+struct irq_domain;
+extern void do_domain_IRQ(struct irq_domain *domain, unsigned int irq);
+
extern void arch_init_irq(void);
extern void spurious_interrupt(void);
diff --git a/arch/mips/kernel/irq.c b/arch/mips/kernel/irq.c
index 85b6c60f285d..d20e002b3246 100644
--- a/arch/mips/kernel/irq.c
+++ b/arch/mips/kernel/irq.c
@@ -21,6 +21,7 @@
#include <linux/kallsyms.h>
#include <linux/kgdb.h>
#include <linux/ftrace.h>
+#include <linux/irqdomain.h>
#include <linux/atomic.h>
#include <linux/uaccess.h>
@@ -107,3 +108,18 @@ void __irq_entry do_IRQ(unsigned int irq)
irq_exit();
}
+#ifdef CONFIG_IRQ_DOMAIN
+void __irq_entry do_domain_IRQ(struct irq_domain *domain, unsigned int hwirq)
+{
+ struct irq_desc *desc;
+
+ irq_enter();
+ check_stack_overflow();
+
+ desc = irq_resolve_mapping(domain, hwirq);
+ if (likely(desc))
+ handle_irq_desc(desc);
+
+ irq_exit();
+}
+#endif