diff options
| author | Marc Zyngier <maz@kernel.org> | 2021-07-06 11:38:59 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2021-07-09 10:18:58 +0100 |
| commit | 1fee9db9b42d821e8007289d4eea74bdf85b1543 (patch) | |
| tree | 6f5b28725cd0b60ac05ccc13b073328b13eec4a2 /arch/mips/kernel | |
| parent | 0e3c1f30b03599f2ee8ff3327eca53c99564ba13 (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/mips/kernel')
| -rw-r--r-- | arch/mips/kernel/irq.c | 16 |
1 files changed, 16 insertions, 0 deletions
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 |