[tip: irq/drivers] irqchip/sifive-plic: Avoid signed shift in interrupt enable mask

[tip-bot2 for Pengpeng Hou]

The following commit has been merged into the irq/drivers branch of tip:

Commit-ID:     0f214e5bbee59d5952d3c061fd65ed9a1e175981
Gitweb:        https://git.kernel.org/tip/0f214e5bbee59d5952d3c061fd65ed9a1e175981
Author:        Pengpeng Hou <hppiscas@xxxxxxx>
AuthorDate:    Sun, 20 Sep 2026 21:06:53 +08:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxx>
CommitterDate: Thu, 15 Oct 2026 11:50:47 +02:00

irqchip/sifive-plic: Avoid signed shift in interrupt enable mask

__plic_toggle() builds a 32-bit interrupt enable mask using a signed
integer literal. A valid interrupt selecting bit 31 evaluates 1 << 31,
which shifts a signed int into its sign bit.

Use BIT(), matching the equivalent mask construction in plic_irq_eoi().
The resulting mask remains representable in u32 on both RV32 and RV64.

The issue was found by our static-analysis tool.

Fixes: 8237f8bc4f6e ("irqchip: add a SiFive PLIC driver")
Signed-off-by: Pengpeng Hou <hppiscas@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxx>
Assisted-by: gpt 5
Link: https://patch.msgid.link/caplitmus-rv.v2.plic.87a8fc444de44e109889ba28703c76f3@xxxxxxx
---
 drivers/irqchip/irq-sifive-plic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 70a7478..4156493 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -108,7 +108,7 @@ static int plic_irq_set_type(struct irq_data *d, unsigned int type);
 static void __plic_toggle(struct plic_handler *handler, int hwirq, int enable)
 {
 	u32 __iomem *base = handler->enable_base;
-	u32 hwirq_mask = 1 << (hwirq % 32);
+	u32 hwirq_mask = BIT(hwirq % 32);
 	int group = hwirq / 32;
 	u32 value;