diff options
Diffstat (limited to 'kernel/arch/x86/kernel/tracepoint.c')
-rw-r--r-- | kernel/arch/x86/kernel/tracepoint.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/kernel/arch/x86/kernel/tracepoint.c b/kernel/arch/x86/kernel/tracepoint.c new file mode 100644 index 000000000..1c113db9e --- /dev/null +++ b/kernel/arch/x86/kernel/tracepoint.c @@ -0,0 +1,59 @@ +/* + * Code for supporting irq vector tracepoints. + * + * Copyright (C) 2013 Seiji Aguchi <seiji.aguchi@hds.com> + * + */ +#include <asm/hw_irq.h> +#include <asm/desc.h> +#include <linux/atomic.h> + +atomic_t trace_idt_ctr = ATOMIC_INIT(0); +struct desc_ptr trace_idt_descr = { NR_VECTORS * 16 - 1, + (unsigned long) trace_idt_table }; + +/* No need to be aligned, but done to keep all IDTs defined the same way. */ +gate_desc trace_idt_table[NR_VECTORS] __page_aligned_bss; + +static int trace_irq_vector_refcount; +static DEFINE_MUTEX(irq_vector_mutex); + +static void set_trace_idt_ctr(int val) +{ + atomic_set(&trace_idt_ctr, val); + /* Ensure the trace_idt_ctr is set before sending IPI */ + wmb(); +} + +static void switch_idt(void *arg) +{ + unsigned long flags; + + local_irq_save(flags); + load_current_idt(); + local_irq_restore(flags); +} + +void trace_irq_vector_regfunc(void) +{ + mutex_lock(&irq_vector_mutex); + if (!trace_irq_vector_refcount) { + set_trace_idt_ctr(1); + smp_call_function(switch_idt, NULL, 0); + switch_idt(NULL); + } + trace_irq_vector_refcount++; + mutex_unlock(&irq_vector_mutex); +} + +void trace_irq_vector_unregfunc(void) +{ + mutex_lock(&irq_vector_mutex); + trace_irq_vector_refcount--; + if (!trace_irq_vector_refcount) { + set_trace_idt_ctr(0); + smp_call_function(switch_idt, NULL, 0); + switch_idt(NULL); + } + mutex_unlock(&irq_vector_mutex); +} |