From: Thomas Gleixner Date: Tue, 3 Feb 2026 19:16:12 +0000 (+0100) Subject: irqchip/sifive-plic: Handle number of hardware interrupts correctly X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=42e025b719c128bdf8ff88584589a1e4a2448c81;p=thirdparty%2Fkernel%2Flinux.git irqchip/sifive-plic: Handle number of hardware interrupts correctly The driver is handling the number of hardware interrupts inconsistently. The reason is that the firmware enumerates the maximum number of device interrupts, but the actual number of hardware interrupts is one more because hardware interrupt 0 is reserved. There are two loop variants where this matters: 1) Iterating over the device interrupts for (irq = 1; irq < total_irqs; irq++) 2) Iterating over the number of interrupt register groups for (grp = 0; grp < irq_groups; grp++) The current code stores the number of device interrupts and that requires to write the loops as: 1) for (irq = 1; irq <= device_irqs; irq++) 2) for (grp = 0; grp < DIV_ROUND_UP(device_irqs + 1); grp++) But the code gets it wrong all over the place. Just fixing up the conditions and off by ones is not a sustainable solution as the next changes will reintroduce the same bugs over and over. Sanitize it by storing the total number of hardware interrupts during probe and precalculating the number of groups. To future proof it mark priv::total_irqs __private, provide a correct iterator macro and adjust the code to this. Marking it private allows sparse (C=1 build) to catch direct access to this member: drivers/irqchip/irq-sifive-plic.c:270:9: warning: dereference of noderef expression That should prevent at least the most obvious future damage in that area. Fixes: e80f0b6a2cf3 ("irqchip/irq-sifive-plic: Add syscore callbacks for hibernation") Reported-by: Yangyu Chen Signed-off-by: Thomas Gleixner Tested-by: Yangyu Chen Link: https://patch.msgid.link/87ikcd36i9.ffs@tglx --- diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c index 210a579596377..60fd8f91762b1 100644 --- a/drivers/irqchip/irq-sifive-plic.c +++ b/drivers/irqchip/irq-sifive-plic.c @@ -68,15 +68,17 @@ #define PLIC_QUIRK_CP100_CLAIM_REGISTER_ERRATUM 1 struct plic_priv { - struct fwnode_handle *fwnode; - struct cpumask lmask; - struct irq_domain *irqdomain; - void __iomem *regs; - unsigned long plic_quirks; - unsigned int nr_irqs; - unsigned long *prio_save; - u32 gsi_base; - int acpi_plic_id; + struct fwnode_handle *fwnode; + struct cpumask lmask; + struct irq_domain *irqdomain; + void __iomem *regs; + unsigned long plic_quirks; + /* device interrupts + 1 to compensate for the reserved hwirq 0 */ + unsigned int __private total_irqs; + unsigned int irq_groups; + unsigned long *prio_save; + u32 gsi_base; + int acpi_plic_id; }; struct plic_handler { @@ -91,6 +93,12 @@ struct plic_handler { u32 *enable_save; struct plic_priv *priv; }; + +/* + * Macro to deal with the insanity of hardware interrupt 0 being reserved */ +#define for_each_device_irq(iter, priv) \ + for (unsigned int iter = 1; iter < ACCESS_PRIVATE(priv, total_irqs); iter++) + static int plic_parent_irq __ro_after_init; static bool plic_global_setup_done __ro_after_init; static DEFINE_PER_CPU(struct plic_handler, plic_handlers); @@ -257,14 +265,11 @@ static int plic_irq_set_type(struct irq_data *d, unsigned int type) static int plic_irq_suspend(void *data) { - struct plic_priv *priv; - - priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv; + struct plic_priv *priv = this_cpu_ptr(&plic_handlers)->priv; - /* irq ID 0 is reserved */ - for (unsigned int i = 1; i < priv->nr_irqs; i++) { - __assign_bit(i, priv->prio_save, - readl(priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID)); + for_each_device_irq(irq, priv) { + __assign_bit(irq, priv->prio_save, + readl(priv->regs + PRIORITY_BASE + irq * PRIORITY_PER_ID)); } return 0; @@ -272,18 +277,15 @@ static int plic_irq_suspend(void *data) static void plic_irq_resume(void *data) { - unsigned int i, index, cpu; + struct plic_priv *priv = this_cpu_ptr(&plic_handlers)->priv; + unsigned int index, cpu; unsigned long flags; u32 __iomem *reg; - struct plic_priv *priv; - - priv = per_cpu_ptr(&plic_handlers, smp_processor_id())->priv; - /* irq ID 0 is reserved */ - for (i = 1; i < priv->nr_irqs; i++) { - index = BIT_WORD(i); - writel((priv->prio_save[index] & BIT_MASK(i)) ? 1 : 0, - priv->regs + PRIORITY_BASE + i * PRIORITY_PER_ID); + for_each_device_irq(irq, priv) { + index = BIT_WORD(irq); + writel((priv->prio_save[index] & BIT_MASK(irq)) ? 1 : 0, + priv->regs + PRIORITY_BASE + irq * PRIORITY_PER_ID); } for_each_present_cpu(cpu) { @@ -293,7 +295,7 @@ static void plic_irq_resume(void *data) continue; raw_spin_lock_irqsave(&handler->enable_lock, flags); - for (i = 0; i < DIV_ROUND_UP(priv->nr_irqs, 32); i++) { + for (unsigned int i = 0; i < priv->irq_groups; i++) { reg = handler->enable_base + i * sizeof(u32); writel(handler->enable_save[i], reg); } @@ -431,7 +433,7 @@ static u32 cp100_isolate_pending_irq(int nr_irq_groups, struct plic_handler *han static irq_hw_number_t cp100_get_hwirq(struct plic_handler *handler, void __iomem *claim) { - int nr_irq_groups = DIV_ROUND_UP(handler->priv->nr_irqs, 32); + int nr_irq_groups = handler->priv->irq_groups; u32 __iomem *enable = handler->enable_base; irq_hw_number_t hwirq = 0; u32 iso_mask; @@ -614,7 +616,6 @@ static int plic_probe(struct fwnode_handle *fwnode) struct plic_handler *handler; u32 nr_irqs, parent_hwirq; struct plic_priv *priv; - irq_hw_number_t hwirq; void __iomem *regs; int id, context_id; u32 gsi_base; @@ -647,7 +648,16 @@ static int plic_probe(struct fwnode_handle *fwnode) priv->fwnode = fwnode; priv->plic_quirks = plic_quirks; - priv->nr_irqs = nr_irqs; + /* + * The firmware provides the number of device interrupts. As + * hardware interrupt 0 is reserved, the number of total interrupts + * is nr_irqs + 1. + */ + nr_irqs++; + ACCESS_PRIVATE(priv, total_irqs) = nr_irqs; + /* Precalculate the number of register groups */ + priv->irq_groups = DIV_ROUND_UP(nr_irqs, 32); + priv->regs = regs; priv->gsi_base = gsi_base; priv->acpi_plic_id = id; @@ -686,7 +696,7 @@ static int plic_probe(struct fwnode_handle *fwnode) u32 __iomem *enable_base = priv->regs + CONTEXT_ENABLE_BASE + i * CONTEXT_ENABLE_SIZE; - for (int j = 0; j <= nr_irqs / 32; j++) + for (int j = 0; j < priv->irq_groups; j++) writel(0, enable_base + j); } continue; @@ -718,23 +728,21 @@ static int plic_probe(struct fwnode_handle *fwnode) context_id * CONTEXT_ENABLE_SIZE; handler->priv = priv; - handler->enable_save = kcalloc(DIV_ROUND_UP(nr_irqs, 32), - sizeof(*handler->enable_save), GFP_KERNEL); + handler->enable_save = kcalloc(priv->irq_groups, sizeof(*handler->enable_save), + GFP_KERNEL); if (!handler->enable_save) { error = -ENOMEM; goto fail_cleanup_contexts; } done: - for (hwirq = 1; hwirq <= nr_irqs; hwirq++) { + for_each_device_irq(hwirq, priv) { plic_toggle(handler, hwirq, 0); - writel(1, priv->regs + PRIORITY_BASE + - hwirq * PRIORITY_PER_ID); + writel(1, priv->regs + PRIORITY_BASE + hwirq * PRIORITY_PER_ID); } nr_handlers++; } - priv->irqdomain = irq_domain_create_linear(fwnode, nr_irqs + 1, - &plic_irqdomain_ops, priv); + priv->irqdomain = irq_domain_create_linear(fwnode, nr_irqs, &plic_irqdomain_ops, priv); if (WARN_ON(!priv->irqdomain)) { error = -ENOMEM; goto fail_cleanup_contexts;