From 1fee9db9b42d821e8007289d4eea74bdf85b1543 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 6 Jul 2021 11:38:59 +0100 Subject: [PATCH] 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 Tested-by: Guenter Roeck [maz: add dependency on CONFIG_IRQ_DOMAIN after report from the kernelci bot] Signed-off-by: Marc Zyngier Cc: Thomas Bogendoerfer Cc: Serge Semin Link: https://lore.kernel.org/r/20210705172352.GA56304@roeck-us.net Link: https://lore.kernel.org/r/20210706110647.3979002-1-maz@kernel.org --- arch/mips/include/asm/irq.h | 3 +++ arch/mips/kernel/irq.c | 16 ++++++++++++++++ drivers/irqchip/irq-mips-cpu.c | 10 ++++++---- drivers/irqchip/irq-mips-gic.c | 8 ++++---- drivers/irqchip/irq-pic32-evic.c | 5 ++--- 5 files changed, 31 insertions(+), 11 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 #include #include +#include #include #include @@ -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 diff --git a/drivers/irqchip/irq-mips-cpu.c b/drivers/irqchip/irq-mips-cpu.c index 0bbb0b2d0dd5..0c7ae71a0af0 100644 --- a/drivers/irqchip/irq-mips-cpu.c +++ b/drivers/irqchip/irq-mips-cpu.c @@ -127,7 +127,6 @@ static struct irq_chip mips_mt_cpu_irq_controller = { asmlinkage void __weak plat_irq_dispatch(void) { unsigned long pending = read_c0_cause() & read_c0_status() & ST0_IM; - unsigned int virq; int irq; if (!pending) { @@ -137,12 +136,15 @@ asmlinkage void __weak plat_irq_dispatch(void) pending >>= CAUSEB_IP; while (pending) { + struct irq_domain *d; + irq = fls(pending) - 1; if (IS_ENABLED(CONFIG_GENERIC_IRQ_IPI) && irq < 2) - virq = irq_linear_revmap(ipi_domain, irq); + d = ipi_domain; else - virq = irq_linear_revmap(irq_domain, irq); - do_IRQ(virq); + d = irq_domain; + + do_domain_IRQ(d, irq); pending &= ~BIT(irq); } } diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c index b146e069bf5b..54c7092cc61d 100644 --- a/drivers/irqchip/irq-mips-gic.c +++ b/drivers/irqchip/irq-mips-gic.c @@ -169,8 +169,8 @@ static void gic_handle_shared_int(bool chained) generic_handle_domain_irq(gic_irq_domain, GIC_SHARED_TO_HWIRQ(intr)); else - do_IRQ(irq_find_mapping(gic_irq_domain, - GIC_SHARED_TO_HWIRQ(intr))); + do_domain_IRQ(gic_irq_domain, + GIC_SHARED_TO_HWIRQ(intr)); } } @@ -320,8 +320,8 @@ static void gic_handle_local_int(bool chained) generic_handle_domain_irq(gic_irq_domain, GIC_LOCAL_TO_HWIRQ(intr)); else - do_IRQ(irq_find_mapping(gic_irq_domain, - GIC_LOCAL_TO_HWIRQ(intr))); + do_domain_IRQ(gic_irq_domain, + GIC_LOCAL_TO_HWIRQ(intr)); } } diff --git a/drivers/irqchip/irq-pic32-evic.c b/drivers/irqchip/irq-pic32-evic.c index 34c4b4ffacd1..1d9bb28d13e5 100644 --- a/drivers/irqchip/irq-pic32-evic.c +++ b/drivers/irqchip/irq-pic32-evic.c @@ -42,11 +42,10 @@ static void __iomem *evic_base; asmlinkage void __weak plat_irq_dispatch(void) { - unsigned int irq, hwirq; + unsigned int hwirq; hwirq = readl(evic_base + REG_INTSTAT) & 0xFF; - irq = irq_linear_revmap(evic_irq_domain, hwirq); - do_IRQ(irq); + do_domain_IRQ(evic_irq_domain, hwirq); } static struct evic_chip_data *irqd_to_priv(struct irq_data *data)