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Subject[PATCH 2/2] trace,x86: Add x86 irq vector entry/exit tracepoints
Date
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.

The following patch adds the event definition and trace instrumentation
for interrupt vectors. For x86, a lookup table is provided to print out
readable IRQ vector names. The template can be used to provide interrupt
vector lookup tables on other architectures.

Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
---
arch/x86/include/asm/irq_vectors.h | 50 ++++++++++++++++++++++++++
arch/x86/kernel/apic/apic.c | 7 ++++
arch/x86/kernel/cpu/mcheck/therm_throt.c | 3 ++
arch/x86/kernel/cpu/mcheck/threshold.c | 3 ++
arch/x86/kernel/irq.c | 6 +++-
arch/x86/kernel/irq_work.c | 3 ++
arch/x86/kernel/smp.c | 7 ++++
arch/x86/kernel/traps.c | 3 ++
arch/x86/mm/tlb.c | 3 ++
include/trace/events/irq_vectors.h | 56 ++++++++++++++++++++++++++++++
10 files changed, 140 insertions(+), 1 deletions(-)
create mode 100644 include/trace/events/irq_vectors.h
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index f9a3209..386b69e 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -181,4 +181,54 @@ static inline int invalid_vm86_irq(int irq)
# define NR_IRQS NR_IRQS_LEGACY
#endif

+#define irq_vector_name(sirq) { sirq, #sirq }
+#define invalidate_tlb_vector_name(i) { INVALIDATE_TLB_VECTOR_END-31+i, \
+ "INVALIDATE_TLB_VECTOR" }
+
+#define irq_vector_name_table \
+ irq_vector_name(NMI_VECTOR), \
+ irq_vector_name(LOCAL_TIMER_VECTOR), \
+ irq_vector_name(ERROR_APIC_VECTOR), \
+ irq_vector_name(RESCHEDULE_VECTOR), \
+ irq_vector_name(CALL_FUNCTION_VECTOR), \
+ irq_vector_name(CALL_FUNCTION_SINGLE_VECTOR), \
+ irq_vector_name(THERMAL_APIC_VECTOR), \
+ irq_vector_name(THRESHOLD_APIC_VECTOR), \
+ irq_vector_name(REBOOT_VECTOR), \
+ irq_vector_name(SPURIOUS_APIC_VECTOR), \
+ irq_vector_name(IRQ_WORK_VECTOR), \
+ irq_vector_name(X86_PLATFORM_IPI_VECTOR), \
+ invalidate_tlb_vector_name(0), \
+ invalidate_tlb_vector_name(1), \
+ invalidate_tlb_vector_name(2), \
+ invalidate_tlb_vector_name(3), \
+ invalidate_tlb_vector_name(4), \
+ invalidate_tlb_vector_name(5), \
+ invalidate_tlb_vector_name(6), \
+ invalidate_tlb_vector_name(7), \
+ invalidate_tlb_vector_name(8), \
+ invalidate_tlb_vector_name(9), \
+ invalidate_tlb_vector_name(10), \
+ invalidate_tlb_vector_name(11), \
+ invalidate_tlb_vector_name(12), \
+ invalidate_tlb_vector_name(13), \
+ invalidate_tlb_vector_name(14), \
+ invalidate_tlb_vector_name(15), \
+ invalidate_tlb_vector_name(16), \
+ invalidate_tlb_vector_name(17), \
+ invalidate_tlb_vector_name(18), \
+ invalidate_tlb_vector_name(19), \
+ invalidate_tlb_vector_name(20), \
+ invalidate_tlb_vector_name(21), \
+ invalidate_tlb_vector_name(22), \
+ invalidate_tlb_vector_name(23), \
+ invalidate_tlb_vector_name(24), \
+ invalidate_tlb_vector_name(25), \
+ invalidate_tlb_vector_name(26), \
+ invalidate_tlb_vector_name(27), \
+ invalidate_tlb_vector_name(28), \
+ invalidate_tlb_vector_name(29), \
+ invalidate_tlb_vector_name(30), \
+ invalidate_tlb_vector_name(31)
+
#endif /* _ASM_X86_IRQ_VECTORS_H */
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 52fa563..0fe559f 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -34,6 +34,7 @@
#include <linux/dmi.h>
#include <linux/smp.h>
#include <linux/mm.h>
+#include <trace/events/irq_vectors.h>

#include <asm/perf_event.h>
#include <asm/x86_init.h>
@@ -859,7 +860,9 @@ void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
*/
exit_idle();
irq_enter();
+ trace_irq_vector_entry(LOCAL_TIMER_VECTOR);
local_apic_timer_interrupt();
+ trace_irq_vector_exit(LOCAL_TIMER_VECTOR);
irq_exit();

set_irq_regs(old_regs);
@@ -1793,6 +1796,7 @@ void smp_spurious_interrupt(struct pt_regs *regs)

exit_idle();
irq_enter();
+ trace_irq_vector_entry(SPURIOUS_APIC_VECTOR);
/*
* Check if this really is a spurious interrupt and ACK it
* if it is a vectored one. Just in case...
@@ -1807,6 +1811,7 @@ void smp_spurious_interrupt(struct pt_regs *regs)
/* see sw-dev-man vol 3, chapter 7.4.13.5 */
pr_info("spurious APIC interrupt on CPU#%d, "
"should never happen.\n", smp_processor_id());
+ trace_irq_vector_exit(SPURIOUS_APIC_VECTOR);
irq_exit();
}

@@ -1830,6 +1835,7 @@ void smp_error_interrupt(struct pt_regs *regs)

exit_idle();
irq_enter();
+ trace_irq_vector_entry(ERROR_APIC_VECTOR);
/* First tickle the hardware, only then report what went on. -- REW */
v0 = apic_read(APIC_ESR);
apic_write(APIC_ESR, 0);
@@ -1850,6 +1856,7 @@ void smp_error_interrupt(struct pt_regs *regs)

apic_printk(APIC_DEBUG, KERN_CONT "\n");

+ trace_irq_vector_exit(ERROR_APIC_VECTOR);
irq_exit();
}

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index 27c6251..bd8fa96 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -23,6 +23,7 @@
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/cpu.h>
+#include <trace/events/irq_vectors.h>

#include <asm/processor.h>
#include <asm/system.h>
@@ -398,8 +399,10 @@ asmlinkage void smp_thermal_interrupt(struct pt_regs *regs)
{
exit_idle();
irq_enter();
+ trace_irq_vector_entry(THERMAL_APIC_VECTOR);
inc_irq_stat(irq_thermal_count);
smp_thermal_vector();
+ trace_irq_vector_exit(THERMAL_APIC_VECTOR);
irq_exit();
/* Ack only at the end to avoid potential reentry */
ack_APIC_irq();
diff --git a/arch/x86/kernel/cpu/mcheck/threshold.c b/arch/x86/kernel/cpu/mcheck/threshold.c
index d746df2..ffde17b 100644
--- a/arch/x86/kernel/cpu/mcheck/threshold.c
+++ b/arch/x86/kernel/cpu/mcheck/threshold.c
@@ -3,6 +3,7 @@
*/
#include <linux/interrupt.h>
#include <linux/kernel.h>
+#include <trace/events/irq_vectors.h>

#include <asm/irq_vectors.h>
#include <asm/apic.h>
@@ -21,8 +22,10 @@ asmlinkage void smp_threshold_interrupt(void)
{
exit_idle();
irq_enter();
+ trace_irq_vector_entry(THRESHOLD_APIC_VECTOR);
inc_irq_stat(irq_threshold_count);
mce_threshold_vector();
+ trace_irq_vector_exit(THRESHOLD_APIC_VECTOR);
irq_exit();
/* Ack only at the end to avoid potential reentry */
ack_APIC_irq();
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 6c0802e..3e4696b 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -17,6 +17,9 @@
#include <asm/mce.h>
#include <asm/hw_irq.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/irq_vectors.h>
+
atomic_t irq_err_count;

/* Function pointer for generic interrupt vector handling */
@@ -211,12 +214,13 @@ void smp_x86_platform_ipi(struct pt_regs *regs)
exit_idle();

irq_enter();
-
+ trace_irq_vector_entry(X86_PLATFORM_IPI_VECTOR);
inc_irq_stat(x86_platform_ipis);

if (x86_platform_ipi_callback)
x86_platform_ipi_callback();

+ trace_irq_vector_exit(X86_PLATFORM_IPI_VECTOR);
irq_exit();

set_irq_regs(old_regs);
diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c
index ca8f703..107754c 100644
--- a/arch/x86/kernel/irq_work.c
+++ b/arch/x86/kernel/irq_work.c
@@ -8,13 +8,16 @@
#include <linux/irq_work.h>
#include <linux/hardirq.h>
#include <asm/apic.h>
+#include <trace/events/irq_vectors.h>

void smp_irq_work_interrupt(struct pt_regs *regs)
{
irq_enter();
ack_APIC_irq();
+ trace_irq_vector_entry(IRQ_WORK_VECTOR);
inc_irq_stat(apic_irq_work_irqs);
irq_work_run();
+ trace_irq_vector_exit(IRQ_WORK_VECTOR);
irq_exit();
}

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 013e7eb..1b0ac99 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -22,6 +22,7 @@
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/gfp.h>
+#include <trace/events/irq_vectors.h>

#include <asm/mtrr.h>
#include <asm/tlbflush.h>
@@ -199,8 +200,10 @@ static void native_stop_other_cpus(int wait)
void smp_reschedule_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
+ trace_irq_vector_entry(RESCHEDULE_VECTOR);
inc_irq_stat(irq_resched_count);
scheduler_ipi();
+ trace_irq_vector_exit(RESCHEDULE_VECTOR);
/*
* KVM uses this interrupt to force a cpu out of guest mode
*/
@@ -210,8 +213,10 @@ void smp_call_function_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
irq_enter();
+ trace_irq_vector_entry(CALL_FUNCTION_VECTOR);
generic_smp_call_function_interrupt();
inc_irq_stat(irq_call_count);
+ trace_irq_vector_exit(CALL_FUNCTION_VECTOR);
irq_exit();
}

@@ -219,8 +224,10 @@ void smp_call_function_single_interrupt(struct pt_regs *regs)
{
ack_APIC_irq();
irq_enter();
+ trace_irq_vector_entry(CALL_FUNCTION_SINGLE_VECTOR);
generic_smp_call_function_single_interrupt();
inc_irq_stat(irq_call_count);
+ trace_irq_vector_exit(CALL_FUNCTION_SINGLE_VECTOR);
irq_exit();
}

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bf4aa79..d22dd48 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -31,6 +31,7 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/io.h>
+#include <trace/events/irq_vectors.h>

#define CREATE_TRACE_POINTS
#include <trace/events/trap.h>
@@ -447,12 +448,14 @@ dotraplinkage notrace __kprobes void
do_nmi(struct pt_regs *regs, long error_code)
{
nmi_enter();
+ trace_irq_vector_entry(NMI_VECTOR);

inc_irq_stat(__nmi_count);

if (!ignore_nmis)
default_do_nmi(regs);

+ trace_irq_vector_exit(NMI_VECTOR);
nmi_exit();
}

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index d6c0418..bf9475d 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -5,6 +5,7 @@
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <trace/events/irq_vectors.h>
#include <linux/cpu.h>

#include <asm/tlbflush.h>
@@ -141,6 +142,7 @@ void smp_invalidate_interrupt(struct pt_regs *regs)
sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
f = &flush_state[sender];

+ trace_irq_vector_entry(INVALIDATE_TLB_VECTOR_START + sender);
if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
goto out;
/*
@@ -167,6 +169,7 @@ out:
cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
smp_mb__after_clear_bit();
inc_irq_stat(irq_tlb_count);
+ trace_irq_vector_exit(INVALIDATE_TLB_VECTOR_START + sender);
}

static void flush_tlb_others_ipi(const struct cpumask *cpumask,
diff --git a/include/trace/events/irq_vectors.h b/include/trace/events/irq_vectors.h
new file mode 100644
index 0000000..699ddaa
--- /dev/null
+++ b/include/trace/events/irq_vectors.h
@@ -0,0 +1,56 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM irq_vectors
+
+#if !defined(_TRACE_IRQ_VECTORS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_IRQ_VECTORS_H
+
+#include <linux/tracepoint.h>
+#include <asm/irq.h>
+
+#ifndef irq_vector_name_table
+#define irq_vector_name_table { -1, NULL }
+#endif
+
+DECLARE_EVENT_CLASS(irq_vector,
+
+ TP_PROTO(int irq),
+
+ TP_ARGS(irq),
+
+ TP_STRUCT__entry(
+ __field( int, irq )
+ ),
+
+ TP_fast_assign(
+ __entry->irq = irq;
+ ),
+
+ TP_printk("irq=%d name=%s", __entry->irq,
+ __print_symbolic(__entry->irq, irq_vector_name_table))
+);
+
+/*
+ * irq_vector_entry - called before enterring a interrupt vector handler
+ */
+DEFINE_EVENT(irq_vector, irq_vector_entry,
+
+ TP_PROTO(int irq),
+
+ TP_ARGS(irq)
+);
+
+/*
+ * irq_vector_exit - called immediately after the interrupt vector
+ * handler returns
+ */
+DEFINE_EVENT(irq_vector, irq_vector_exit,
+
+ TP_PROTO(int irq),
+
+ TP_ARGS(irq)
+);
+
+#endif /* _TRACE_IRQ_VECTORS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--
1.7.3.1


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