From 8e23dacd12a48e58125b84c817da50850b73280a Mon Sep 17 00:00:00 2001 From: James Morse Date: Fri, 4 Dec 2015 11:02:27 +0000 Subject: arm64: Add do_softirq_own_stack() and enable irq_stacks entry.S is modified to switch to the per_cpu irq_stack during el{0,1}_irq. irq_count is used to detect recursive interrupts on the irq_stack, it is updated late by do_softirq_own_stack(), when called on the irq_stack, before __do_softirq() re-enables interrupts to process softirqs. do_softirq_own_stack() is added by this patch, but does not yet switch stack. This patch adds the dummy stack frame and data needed by the previous stack tracing patches. Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Will Deacon --- arch/arm64/kernel/irq.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) (limited to 'arch/arm64/kernel/irq.c') diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index 1e3cef578e21..ff7ebb710e51 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -25,14 +25,24 @@ #include #include #include +#include #include #include unsigned long irq_err_count; -/* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned */ +/* + * irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. + * irq_stack[0] is used as irq_count, a non-zero value indicates the stack + * is in use, and el?_irq() shouldn't switch to it. This is used to detect + * recursive use of the irq_stack, it is lazily updated by + * do_softirq_own_stack(), which is called on the irq_stack, before + * re-enabling interrupts to process softirqs. + */ DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16); +#define IRQ_COUNT() (*per_cpu(irq_stack, smp_processor_id())) + int arch_show_interrupts(struct seq_file *p, int prec) { show_ipi_list(p, prec); @@ -56,3 +66,29 @@ void __init init_IRQ(void) if (!handle_arch_irq) panic("No interrupt controller found."); } + +/* + * do_softirq_own_stack() is called from irq_exit() before __do_softirq() + * re-enables interrupts, at which point we may re-enter el?_irq(). We + * increase irq_count here so that el1_irq() knows that it is already on the + * irq stack. + * + * Called with interrupts disabled, so we don't worry about moving cpu, or + * being interrupted while modifying irq_count. + * + * This function doesn't actually switch stack. + */ +void do_softirq_own_stack(void) +{ + int cpu = smp_processor_id(); + + WARN_ON_ONCE(!irqs_disabled()); + + if (on_irq_stack(current_stack_pointer, cpu)) { + IRQ_COUNT()++; + __do_softirq(); + IRQ_COUNT()--; + } else { + __do_softirq(); + } +} -- cgit