diff options
author | Daniel Thompson <daniel.thompson@linaro.org> | 2014-09-03 16:44:58 +0100 |
---|---|---|
committer | Daniel Thompson <daniel.thompson@linaro.org> | 2014-10-20 13:26:53 +0100 |
commit | 4a63e8f238c88e3bb0a23f658b68a2eb682237f6 (patch) | |
tree | 22062577e93df22225b6ec7fd16a00ebe09da8aa | |
parent | 305187021b7837c6a148bc1f30ddb611f9dc1099 (diff) |
irqchip: gic: Group 0 workaround.
An ARM system based on GICv1 that runs by default in secure mode and
uses both group 0 and group 1 interrupts (in order to exploit FIQ)
will suffer a problem where the IRQ handler occasionally spuriously
acknowledges a group 0 (FIQ) interrupt.
This can be prevented by ensuring the IRQ handler makes non-secure
memory access to the GIC registers but this is complex because
the non-secure bits cannot be apply to 4k pages (the bit is one level
up in the page table and applies to 1MB at a time).
This workaround uses an alternative approach that spots the spurious
acknowledgment and regenerates the FIQ. This keeps the workaround
exclusively within the GIC driver (although there is a runtime
perforamnce penalty resulting from this approach).
Reported-by: Harro Haan <hrhaan@gmail.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Harro Haan <hrhaan@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
-rw-r--r-- | drivers/irqchip/irq-gic.c | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c index 908e36dce938..0fc6f341ef89 100644 --- a/drivers/irqchip/irq-gic.c +++ b/drivers/irqchip/irq-gic.c @@ -267,14 +267,59 @@ static int gic_set_wake(struct irq_data *d, unsigned int on) #define gic_set_wake NULL #endif +#ifdef CONFIG_FIQ +/* This is a software emulation of the Aliased Interrupt Acknowledge Register + * (GIC_AIAR) found in GICv2+. + */ +static u32 gic_handle_spurious_group_0(struct gic_chip_data *gic, u32 irqstat) +{ + u32 irqnr = irqstat & GICC_IAR_INT_ID_MASK; + void __iomem *dist_base = gic_data_dist_base(gic); + u32 offset, mask; + + if (!readl_relaxed(dist_base + GIC_DIST_IGROUP + 0) || irqnr >= 1021) + return irqstat; + + offset = irqnr / 32 * 4; + mask = 1 << (irqnr % 32); + if (readl_relaxed(dist_base + GIC_DIST_IGROUP + offset) & mask) + return irqstat; + + /* this interrupt must be taken as a FIQ so put it back into the + * pending state and end our own servicing of it. + */ + writel_relaxed(mask, dist_base + GIC_DIST_PENDING_SET + offset); + readl_relaxed(dist_base + GIC_DIST_PENDING_SET + offset); + writel_relaxed(irqstat, gic_data_cpu_base(gic) + GIC_CPU_EOI); + + return 1023; +} + +static u32 gic_ack_irq(struct gic_chip_data *gic) +{ + u32 irqstat; + + local_fiq_disable(); + irqstat = readl_relaxed(gic_data_cpu_base(gic) + GIC_CPU_INTACK); + irqstat = gic_handle_spurious_group_0(gic, irqstat); + local_fiq_enable(); + + return irqstat; +} +#else +static u32 gic_ack_irq(struct gic_chip_data *gic) +{ + return readl_relaxed(gic_data_cpu_base(gic) + GIC_CPU_INTACK); +} +#endif + static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs) { u32 irqstat, irqnr; struct gic_chip_data *gic = &gic_data[0]; - void __iomem *cpu_base = gic_data_cpu_base(gic); do { - irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK); + irqstat = gic_ack_irq(gic); irqnr = irqstat & GICC_IAR_INT_ID_MASK; if (likely(irqnr > 15 && irqnr < 1021)) { @@ -282,7 +327,8 @@ static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs) continue; } if (irqnr < 16) { - writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI); + writel_relaxed(irqstat, + gic_data_cpu_base(gic) + GIC_CPU_EOI); #ifdef CONFIG_SMP handle_IPI(irqnr, regs); #endif |