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[Purpose of this patch] As Vaibhav explained in the thread below, tracepoints for irq vectors are useful. http://www.spinics.net/lists/mm-commits/msg85707.html <snip> The current interrupt traces from irq_handler_entry and irq_handler_exit provide when an interrupt is handled. They provide good data about when the system has switched to kernel space and how it affects the currently running processes. There are some IRQ vectors which trigger the system into kernel space, which are not handled in generic IRQ handlers. Tracing such events gives us the information about IRQ interaction with other system events. The trace also tells where the system is spending its time. We want to know which cores are handling interrupts and how they are affecting other processes in the system. Also, the trace provides information about when the cores are idle and which interrupts are changing that state. <snip> On the other hand, my usecase is tracing just local timer event and getting a value of instruction pointer. I suggested to add an argument local timer event to get instruction pointer before. But there is another way to get it with external module like systemtap. So, I don't need to add any argument to irq vector tracepoints now. [Patch Description] Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events. But there is an above use case to trace specific irq_vector rather than tracing all events. In this case, we are concerned about overhead due to unwanted events. So, add following tracepoints instead of introducing irq_vector_entry/exit. so that we can enable them independently. - local_timer_vector - reschedule_vector - call_function_vector - call_function_single_vector - irq_work_entry_vector - error_apic_vector - thermal_apic_vector - threshold_apic_vector - spurious_apic_vector - x86_platform_ipi_vector Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty makes a zero when tracepoints are disabled. Detailed explanations are as follows. - Create trace irq handlers with entering_irq()/exiting_irq(). - Create a new IDT, trace_idt_table, at boot time by adding a logic to _set_gate(). It is just a copy of original idt table. - Register the new handlers for tracpoints to the new IDT by introducing macros to alloc_intr_gate() called at registering time of irq_vector handlers. - Add checking, whether irq vector tracing is on/off, into load_current_idt(). This has to be done below debug checking for these reasons. - Switching to debug IDT may be kicked while tracing is enabled. - On the other hands, switching to trace IDT is kicked only when debugging is disabled. In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being used for other purposes. Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com> Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Steven Rostedt <rostedt@goodmis.org>
117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
#ifndef _XEN_EVENTS_H
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#define _XEN_EVENTS_H
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#include <linux/interrupt.h>
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#include <xen/interface/event_channel.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/events.h>
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int bind_evtchn_to_irq(unsigned int evtchn);
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int bind_evtchn_to_irqhandler(unsigned int evtchn,
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irq_handler_t handler,
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unsigned long irqflags, const char *devname,
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void *dev_id);
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int bind_virq_to_irq(unsigned int virq, unsigned int cpu);
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int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
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irq_handler_t handler,
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unsigned long irqflags, const char *devname,
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void *dev_id);
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int bind_ipi_to_irqhandler(enum ipi_vector ipi,
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unsigned int cpu,
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irq_handler_t handler,
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unsigned long irqflags,
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const char *devname,
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void *dev_id);
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int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
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unsigned int remote_port,
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irq_handler_t handler,
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unsigned long irqflags,
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const char *devname,
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void *dev_id);
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/*
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* Common unbind function for all event sources. Takes IRQ to unbind from.
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* Automatically closes the underlying event channel (even for bindings
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* made with bind_evtchn_to_irqhandler()).
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*/
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void unbind_from_irqhandler(unsigned int irq, void *dev_id);
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/*
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* Allow extra references to event channels exposed to userspace by evtchn
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*/
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int evtchn_make_refcounted(unsigned int evtchn);
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int evtchn_get(unsigned int evtchn);
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void evtchn_put(unsigned int evtchn);
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void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector);
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int resend_irq_on_evtchn(unsigned int irq);
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void rebind_evtchn_irq(int evtchn, int irq);
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static inline void notify_remote_via_evtchn(int port)
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{
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struct evtchn_send send = { .port = port };
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(void)HYPERVISOR_event_channel_op(EVTCHNOP_send, &send);
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}
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void notify_remote_via_irq(int irq);
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void xen_irq_resume(void);
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/* Clear an irq's pending state, in preparation for polling on it */
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void xen_clear_irq_pending(int irq);
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void xen_set_irq_pending(int irq);
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bool xen_test_irq_pending(int irq);
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/* Poll waiting for an irq to become pending. In the usual case, the
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irq will be disabled so it won't deliver an interrupt. */
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void xen_poll_irq(int irq);
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/* Poll waiting for an irq to become pending with a timeout. In the usual case,
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* the irq will be disabled so it won't deliver an interrupt. */
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void xen_poll_irq_timeout(int irq, u64 timeout);
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/* Determine the IRQ which is bound to an event channel */
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unsigned irq_from_evtchn(unsigned int evtchn);
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/* Xen HVM evtchn vector callback */
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void xen_hvm_callback_vector(void);
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#ifdef CONFIG_TRACING
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#define trace_xen_hvm_callback_vector xen_hvm_callback_vector
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#endif
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extern int xen_have_vector_callback;
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int xen_set_callback_via(uint64_t via);
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void xen_evtchn_do_upcall(struct pt_regs *regs);
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void xen_hvm_evtchn_do_upcall(void);
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/* Bind a pirq for a physical interrupt to an irq. */
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int xen_bind_pirq_gsi_to_irq(unsigned gsi,
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unsigned pirq, int shareable, char *name);
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#ifdef CONFIG_PCI_MSI
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/* Allocate a pirq for a MSI style physical interrupt. */
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int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc);
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/* Bind an PSI pirq to an irq. */
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int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
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int pirq, const char *name, domid_t domid);
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#endif
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/* De-allocates the above mentioned physical interrupt. */
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int xen_destroy_irq(int irq);
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/* Return irq from pirq */
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int xen_irq_from_pirq(unsigned pirq);
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/* Return the pirq allocated to the irq. */
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int xen_pirq_from_irq(unsigned irq);
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/* Return the irq allocated to the gsi */
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int xen_irq_from_gsi(unsigned gsi);
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/* Determine whether to ignore this IRQ if it is passed to a guest. */
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int xen_test_irq_shared(int irq);
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/* initialize Xen IRQ subsystem */
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void xen_init_IRQ(void);
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#endif /* _XEN_EVENTS_H */
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