From cf910e83ae23692fdeefc7e506e504c4c468d38a Mon Sep 17 00:00:00 2001 From: Seiji Aguchi Date: Thu, 20 Jun 2013 11:46:53 -0400 Subject: x86, trace: Add irq vector tracepoints [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 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. 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 Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com Signed-off-by: H. Peter Anvin Cc: Steven Rostedt --- arch/x86/kernel/entry_64.S | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) (limited to 'arch/x86/kernel/entry_64.S') diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 727208941030..11eef43f971f 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1138,7 +1138,7 @@ END(common_interrupt) /* * APIC interrupts. */ -.macro apicinterrupt num sym do_sym +.macro apicinterrupt3 num sym do_sym ENTRY(\sym) INTR_FRAME ASM_CLAC @@ -1150,15 +1150,32 @@ ENTRY(\sym) END(\sym) .endm +#ifdef CONFIG_TRACING +#define trace(sym) trace_##sym +#define smp_trace(sym) smp_trace_##sym + +.macro trace_apicinterrupt num sym +apicinterrupt3 \num trace(\sym) smp_trace(\sym) +.endm +#else +.macro trace_apicinterrupt num sym do_sym +.endm +#endif + +.macro apicinterrupt num sym do_sym +apicinterrupt3 \num \sym \do_sym +trace_apicinterrupt \num \sym +.endm + #ifdef CONFIG_SMP -apicinterrupt IRQ_MOVE_CLEANUP_VECTOR \ +apicinterrupt3 IRQ_MOVE_CLEANUP_VECTOR \ irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt -apicinterrupt REBOOT_VECTOR \ +apicinterrupt3 REBOOT_VECTOR \ reboot_interrupt smp_reboot_interrupt #endif #ifdef CONFIG_X86_UV -apicinterrupt UV_BAU_MESSAGE \ +apicinterrupt3 UV_BAU_MESSAGE \ uv_bau_message_intr1 uv_bau_message_interrupt #endif apicinterrupt LOCAL_TIMER_VECTOR \ @@ -1167,7 +1184,7 @@ apicinterrupt X86_PLATFORM_IPI_VECTOR \ x86_platform_ipi smp_x86_platform_ipi #ifdef CONFIG_HAVE_KVM -apicinterrupt POSTED_INTR_VECTOR \ +apicinterrupt3 POSTED_INTR_VECTOR \ kvm_posted_intr_ipi smp_kvm_posted_intr_ipi #endif @@ -1451,13 +1468,13 @@ ENTRY(xen_failsafe_callback) CFI_ENDPROC END(xen_failsafe_callback) -apicinterrupt HYPERVISOR_CALLBACK_VECTOR \ +apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ xen_hvm_callback_vector xen_evtchn_do_upcall #endif /* CONFIG_XEN */ #if IS_ENABLED(CONFIG_HYPERV) -apicinterrupt HYPERVISOR_CALLBACK_VECTOR \ +apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ hyperv_callback_vector hyperv_vector_handler #endif /* CONFIG_HYPERV */ -- cgit v1.2.3 From 33e5ff634f07dec26b7ed1fd7f9e32978fe1f2b2 Mon Sep 17 00:00:00 2001 From: Seiji Aguchi Date: Sat, 22 Jun 2013 07:33:30 -0400 Subject: x86/tracing: Add config option checking to the definitions of mce handlers In case CONFIG_X86_MCE_THRESHOLD and CONFIG_X86_THERMAL_VECTOR are disabled, kernel build fails as follows. arch/x86/built-in.o: In function `trace_threshold_interrupt': (.entry.text+0x122b): undefined reference to `smp_trace_threshold_interrupt' arch/x86/built-in.o: In function `trace_thermal_interrupt': (.entry.text+0x132b): undefined reference to `smp_trace_thermal_interrupt' In this case, trace_threshold_interrupt/trace_thermal_interrupt are not needed to define. So, add config option checking to their definitions in entry_64.S. Signed-off-by: Seiji Aguchi Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/51C58B8A.2080808@hds.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/entry_64.S | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/x86/kernel/entry_64.S') diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 11eef43f971f..53d639831a6c 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1188,10 +1188,15 @@ apicinterrupt3 POSTED_INTR_VECTOR \ kvm_posted_intr_ipi smp_kvm_posted_intr_ipi #endif +#ifdef CONFIG_X86_MCE_THRESHOLD apicinterrupt THRESHOLD_APIC_VECTOR \ threshold_interrupt smp_threshold_interrupt +#endif + +#ifdef CONFIG_X86_THERMAL_VECTOR apicinterrupt THERMAL_APIC_VECTOR \ thermal_interrupt smp_thermal_interrupt +#endif #ifdef CONFIG_SMP apicinterrupt CALL_FUNCTION_SINGLE_VECTOR \ -- cgit v1.2.3