From a90b858cfe27a576f7e44a456af2ee432404ee8f Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Mon, 21 Jul 2014 11:38:40 +0300 Subject: [PATCH] x86: Fix non-PC platform kernel crash on boot due to NULL dereference Upstream commit: 95d76acc7518d5 ("x86, irq: Count legacy IRQs by legacy_pic->nr_legacy_irqs instead of NR_IRQS_LEGACY") removed reserved interrupts for the platforms that do not have a legacy IOAPIC. Which breaks the boot on Intel MID platforms such as Medfield: BUG: unable to handle kernel NULL pointer dereference at 0000003a IP: [] setup_irq+0xf/0x4d [ 0.000000] *pdpt = 0000000000000000 *pde = 9bbf32453167e510 The culprit is an uncoditional setting of IRQ2 which is used as cascade IRQ on legacy platforms. It seems we have to check if we have enough legacy IRQs reserved before we can call setup_irq(). The fix adds such check in native_init_IRQ() and in setup_default_timer_irq(). Signed-off-by: Andy Shevchenko Reviewed-by: Jiang Liu Reviewed-by: Thomas Gleixner Cc: David Cohen Link: http://lkml.kernel.org/r/1405931920-12871-1-git-send-email-andriy.shevchenko@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/irqinit.c | 2 +- arch/x86/kernel/time.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c index 1e6cff5814fa..44f1ed42fdf2 100644 --- a/arch/x86/kernel/irqinit.c +++ b/arch/x86/kernel/irqinit.c @@ -203,7 +203,7 @@ void __init native_init_IRQ(void) set_intr_gate(i, interrupt[i - FIRST_EXTERNAL_VECTOR]); } - if (!acpi_ioapic && !of_ioapic) + if (!acpi_ioapic && !of_ioapic && nr_legacy_irqs()) setup_irq(2, &irq2); #ifdef CONFIG_X86_32 diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c index bf7ef5ce29df..0fa29609b2c4 100644 --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -68,6 +68,8 @@ static struct irqaction irq0 = { void __init setup_default_timer_irq(void) { + if (!nr_legacy_irqs()) + return; setup_irq(0, &irq0); } -- 2.11.0