RE: [PATCH v12 3/3] trace,x86: code-sharing between non-trace andtrace irq handlers

From: Seiji Aguchi
Date: Fri Apr 05 2013 - 15:26:15 EST

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Previous message: Seiji Aguchi: "[PATCH v12 3/3] trace,x86: code-sharing between non-trace and traceirq handlers"
In reply to: Seiji Aguchi: "[PATCH v12 3/3] trace,x86: code-sharing between non-trace and traceirq handlers"
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Steven,

I confirmed that smp_apic_timer_interrupt is traced in a function graph tracing below.
If additional testing is needed, please let me know.

trace-cmd start -p function_graph -g "smp_trace_apic_timer_interrupt" -g "smp_apic_timer_interrupt" -e irq_vectors
plugin function_graph

Seiji

> -----Original Message-----
> From: Seiji Aguchi
> Sent: Friday, April 05, 2013 3:22 PM
> To: linux-kernel@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx; rostedt@xxxxxxxxxxx; hpa@xxxxxxxxx
> Cc: Thomas Gleixner (tglx@xxxxxxxxxxxxx); 'mingo@xxxxxxx' (mingo@xxxxxxx); Borislav Petkov (bp@xxxxxxxxx); linux-
> edac@xxxxxxxxxxxxxxx; Luck, Tony (tony.luck@xxxxxxxxx); dle-develop@xxxxxxxxxxxxxxxxxxxxx; Tomoki Sekiyama
> Subject: [PATCH v12 3/3] trace,x86: code-sharing between non-trace and trace irq handlers
>
> [Issue]
>
> Currently, irq vector handlers for tracing are just copied non-trace handlers by simply inserting tracepoints.
>
> It is difficult to manage the codes.
>
> [Solution]
>
> This patch shares common codes between non-trace and trace handlers as follows to make them manageable and readable.
>
> Non-trace irq handler:
> smp_irq_handler()
> {
> entering_irq(); /* pre-processing of this handler */
> __smp_irq_handler(); /*
> * common logic between non-trace and trace handlers
> * in a vector.
> */
> exiting_irq(); /* post-processing of this handler */
>
> }
>
> Trace irq_handler:
> smp_trace_irq_handler()
> {
> entering_irq(); /* pre-processing of this handler */
> trace_irq_entry(); /* tracepoint for irq entry */
> __smp_irq_handler(); /*
> * common logic between non-trace and trace handlers
> * in a vector.
> */
> trace_irq_exit(); /* tracepoint for irq exit */
> exiting_irq(); /* post-processing of this handler */
>
> }
>
> If tracepoints can place outside entering_irq()/exiting_irq() as follows, it looks \ cleaner.
>
> smp_trace_irq_handler()
> {
> trace_irq_entry();
> smp_irq_handler();
> trace_irq_exit();
> }
>
> But it doesn't work.
> The problem is with irq_enter/exit() being called. They must be called before \ trace_irq_enter/exit(), because of the rcu_irq_enter()
> must be called before any \ tracepoints are used, as tracepoints use rcu to synchronize.
>
> As a possible alternative, we may be able to call irq_enter() first as follows if \
> irq_enter() can nest.
>
> smp_trace_irq_hander()
> {
> irq_entry();
> trace_irq_entry();
> smp_irq_handler();
> trace_irq_exit();
> irq_exit();
> }
>
> But it doesn't work, either.
> If irq_enter() is nested, it may have a time penalty because it has to check if it \ was already called or not. The time penalty is not
> desired in performance sensitive \ paths even if it is tiny.
>
> Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
> ---
> arch/x86/include/asm/apic.h | 27 ++++++++
> arch/x86/kernel/apic/apic.c | 103 ++++++++----------------------
> arch/x86/kernel/cpu/mcheck/therm_throt.c | 24 +++----
> arch/x86/kernel/cpu/mcheck/threshold.c | 24 +++----
> arch/x86/kernel/irq.c | 34 +++-------
> arch/x86/kernel/irq_work.c | 22 ++++--
> arch/x86/kernel/smp.c | 54 ++++++++++------
> 7 files changed, 137 insertions(+), 151 deletions(-)
>
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 3388034..f8119b5 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -12,6 +12,7 @@
> #include <asm/fixmap.h>
> #include <asm/mpspec.h>
> #include <asm/msr.h>
> +#include <asm/idle.h>
>
> #define ARCH_APICTIMER_STOPS_ON_C3 1
>
> @@ -687,5 +688,31 @@ extern int default_check_phys_apicid_present(int phys_apicid); #endif
>
> #endif /* CONFIG_X86_LOCAL_APIC */
> +extern void irq_enter(void);
> +extern void irq_exit(void);
> +
> +static inline void entering_irq(void)
> +{
> + irq_enter();
> + exit_idle();
> +}
> +
> +static inline void entering_ack_irq(void) {
> + ack_APIC_irq();
> + entering_irq();
> +}
> +
> +static inline void exiting_irq(void)
> +{
> + irq_exit();
> +}
> +
> +static inline void exiting_ack_irq(void) {
> + irq_exit();
> + /* Ack only at the end to avoid potential reentry */
> + ack_APIC_irq();
> +}
>
> #endif /* _ASM_X86_APIC_H */
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 7d39c68..61ced40 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -922,17 +922,14 @@ void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
> /*
> * NOTE! We'd better ACK the irq immediately,
> * because timer handling can be slow.
> - */
> - ack_APIC_irq();
> - /*
> + *
> * update_process_times() expects us to have done irq_enter().
> * Besides, if we don't timer interrupts ignore the global
> * interrupt lock, which is the WrongThing (tm) to do.
> */
> - irq_enter();
> - exit_idle();
> + entering_ack_irq();
> local_apic_timer_interrupt();
> - irq_exit();
> + exiting_irq();
>
> set_irq_regs(old_regs);
> }
> @@ -944,19 +941,16 @@ void __irq_entry smp_trace_apic_timer_interrupt(struct pt_regs *regs)
> /*
> * NOTE! We'd better ACK the irq immediately,
> * because timer handling can be slow.
> - */
> - ack_APIC_irq();
> - /*
> + *
> * update_process_times() expects us to have done irq_enter().
> * Besides, if we don't timer interrupts ignore the global
> * interrupt lock, which is the WrongThing (tm) to do.
> */
> - irq_enter();
> - exit_idle();
> + entering_ack_irq();
> trace_local_timer_entry(LOCAL_TIMER_VECTOR);
> local_apic_timer_interrupt();
> trace_local_timer_exit(LOCAL_TIMER_VECTOR);
> - irq_exit();
> + exiting_irq();
>
> set_irq_regs(old_regs);
> }
> @@ -1934,12 +1928,10 @@ int __init APIC_init_uniprocessor(void)
> /*
> * This interrupt should _never_ happen with our APIC/SMP architecture
> */
> -void smp_spurious_interrupt(struct pt_regs *regs)
> +static inline void __smp_spurious_interrupt(void)
> {
> u32 v;
>
> - irq_enter();
> - exit_idle();
> /*
> * Check if this really is a spurious interrupt and ACK it
> * if it is a vectored one. Just in case...
> @@ -1954,38 +1946,28 @@ 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());
> - irq_exit();
> }
>
> -void smp_trace_spurious_interrupt(struct pt_regs *regs)
> +void smp_spurious_interrupt(struct pt_regs *regs)
> {
> - u32 v;
> + entering_irq();
> + __smp_spurious_interrupt();
> + exiting_irq();
> +}
>
> - irq_enter();
> - exit_idle();
> +void smp_trace_spurious_interrupt(struct pt_regs *regs) {
> + entering_irq();
> trace_spurious_apic_entry(SPURIOUS_APIC_VECTOR);
> - /*
> - * Check if this really is a spurious interrupt and ACK it
> - * if it is a vectored one. Just in case...
> - * Spurious interrupts should not be ACKed.
> - */
> - v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
> - if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
> - ack_APIC_irq();
> -
> - inc_irq_stat(irq_spurious_count);
> -
> - /* 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());
> + __smp_spurious_interrupt();
> trace_spurious_apic_exit(SPURIOUS_APIC_VECTOR);
> - irq_exit();
> + exiting_irq();
> }
>
> /*
> * This interrupt should never happen with our APIC/SMP architecture
> */
> -void smp_error_interrupt(struct pt_regs *regs)
> +static inline void __smp_error_interrupt(struct pt_regs *regs)
> {
> u32 v0, v1;
> u32 i = 0;
> @@ -2000,8 +1982,6 @@ void smp_error_interrupt(struct pt_regs *regs)
> "Illegal register address", /* APIC Error Bit 7 */
> };
>
> - irq_enter();
> - exit_idle();
> /* First tickle the hardware, only then report what went on. -- REW */
> v0 = apic_read(APIC_ESR);
> apic_write(APIC_ESR, 0);
> @@ -2022,49 +2002,22 @@ void smp_error_interrupt(struct pt_regs *regs)
>
> apic_printk(APIC_DEBUG, KERN_CONT "\n");
>
> - irq_exit();
> }
>
> -void smp_trace_error_interrupt(struct pt_regs *regs)
> +void smp_error_interrupt(struct pt_regs *regs)
> {
> - u32 v0, v1;
> - u32 i = 0;
> - static const char * const error_interrupt_reason[] = {
> - "Send CS error", /* APIC Error Bit 0 */
> - "Receive CS error", /* APIC Error Bit 1 */
> - "Send accept error", /* APIC Error Bit 2 */
> - "Receive accept error", /* APIC Error Bit 3 */
> - "Redirectable IPI", /* APIC Error Bit 4 */
> - "Send illegal vector", /* APIC Error Bit 5 */
> - "Received illegal vector", /* APIC Error Bit 6 */
> - "Illegal register address", /* APIC Error Bit 7 */
> - };
> + entering_irq();
> + __smp_error_interrupt(regs);
> + exiting_irq();
> +}
>
> - irq_enter();
> - exit_idle();
> +void smp_trace_error_interrupt(struct pt_regs *regs) {
> + entering_irq();
> trace_error_apic_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);
> - v1 = apic_read(APIC_ESR);
> - ack_APIC_irq();
> - atomic_inc(&irq_err_count);
> -
> - apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x(%02x)",
> - smp_processor_id(), v0 , v1);
> -
> - v1 = v1 & 0xff;
> - while (v1) {
> - if (v1 & 0x1)
> - apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
> - i++;
> - v1 >>= 1;
> - }
> -
> - apic_printk(APIC_DEBUG, KERN_CONT "\n");
> -
> + __smp_error_interrupt(regs);
> trace_error_apic_exit(ERROR_APIC_VECTOR);
> - irq_exit();
> + exiting_irq();
> }
>
> /**
> diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> index e7aa7fc..2f3a799 100644
> --- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
> +++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
> @@ -379,28 +379,26 @@ static void unexpected_thermal_interrupt(void)
>
> static void (*smp_thermal_vector)(void) = unexpected_thermal_interrupt;
>
> -asmlinkage void smp_thermal_interrupt(struct pt_regs *regs)
> +static inline void __smp_thermal_interrupt(void)
> {
> - irq_enter();
> - exit_idle();
> inc_irq_stat(irq_thermal_count);
> smp_thermal_vector();
> - irq_exit();
> - /* Ack only at the end to avoid potential reentry */
> - ack_APIC_irq();
> +}
> +
> +asmlinkage void smp_thermal_interrupt(struct pt_regs *regs) {
> + entering_irq();
> + __smp_thermal_interrupt();
> + exiting_ack_irq();
> }
>
> asmlinkage void smp_trace_thermal_interrupt(struct pt_regs *regs) {
> - irq_enter();
> - exit_idle();
> + entering_irq();
> trace_thermal_apic_entry(THERMAL_APIC_VECTOR);
> - inc_irq_stat(irq_thermal_count);
> - smp_thermal_vector();
> + __smp_thermal_interrupt();
> trace_thermal_apic_exit(THERMAL_APIC_VECTOR);
> - irq_exit();
> - /* Ack only at the end to avoid potential reentry */
> - ack_APIC_irq();
> + exiting_ack_irq();
> }
>
> /* Thermal monitoring depends on APIC, ACPI and clock modulation */ diff --git a/arch/x86/kernel/cpu/mcheck/threshold.c
> b/arch/x86/kernel/cpu/mcheck/threshold.c
> index 0cbef99..fe6b1c8 100644
> --- a/arch/x86/kernel/cpu/mcheck/threshold.c
> +++ b/arch/x86/kernel/cpu/mcheck/threshold.c
> @@ -18,26 +18,24 @@ static void default_threshold_interrupt(void)
>
> void (*mce_threshold_vector)(void) = default_threshold_interrupt;
>
> -asmlinkage void smp_threshold_interrupt(void)
> +static inline void __smp_threshold_interrupt(void)
> {
> - irq_enter();
> - exit_idle();
> inc_irq_stat(irq_threshold_count);
> mce_threshold_vector();
> - irq_exit();
> - /* Ack only at the end to avoid potential reentry */
> - ack_APIC_irq();
> +}
> +
> +asmlinkage void smp_threshold_interrupt(void) {
> + entering_irq();
> + __smp_threshold_interrupt();
> + exiting_ack_irq();
> }
>
> asmlinkage void smp_trace_threshold_interrupt(void)
> {
> - irq_enter();
> - exit_idle();
> + entering_irq();
> trace_threshold_apic_entry(THRESHOLD_APIC_VECTOR);
> - inc_irq_stat(irq_threshold_count);
> - mce_threshold_vector();
> + __smp_threshold_interrupt();
> trace_threshold_apic_exit(THRESHOLD_APIC_VECTOR);
> - irq_exit();
> - /* Ack only at the end to avoid potential reentry */
> - ack_APIC_irq();
> + exiting_ack_irq();
> }
> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 216bec1..ae836cd 100644
> --- a/arch/x86/kernel/irq.c
> +++ b/arch/x86/kernel/irq.c
> @@ -209,23 +209,21 @@ unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
> /*
> * Handler for X86_PLATFORM_IPI_VECTOR.
> */
> -void smp_x86_platform_ipi(struct pt_regs *regs)
> +void __smp_x86_platform_ipi(void)
> {
> - struct pt_regs *old_regs = set_irq_regs(regs);
> -
> - ack_APIC_irq();
> -
> - irq_enter();
> -
> - exit_idle();
> -
> inc_irq_stat(x86_platform_ipis);
>
> if (x86_platform_ipi_callback)
> x86_platform_ipi_callback();
> +}
>
> - irq_exit();
> +void smp_x86_platform_ipi(struct pt_regs *regs) {
> + struct pt_regs *old_regs = set_irq_regs(regs);
>
> + entering_ack_irq();
> + __smp_x86_platform_ipi();
> + exiting_irq();
> set_irq_regs(old_regs);
> }
>
> @@ -233,21 +231,11 @@ void smp_trace_x86_platform_ipi(struct pt_regs *regs) {
> struct pt_regs *old_regs = set_irq_regs(regs);
>
> - ack_APIC_irq();
> -
> - irq_enter();
> -
> - exit_idle();
> -
> + entering_ack_irq();
> trace_x86_platform_ipi_entry(X86_PLATFORM_IPI_VECTOR);
> - inc_irq_stat(x86_platform_ipis);
> -
> - if (x86_platform_ipi_callback)
> - x86_platform_ipi_callback();
> -
> + __smp_x86_platform_ipi();
> trace_x86_platform_ipi_exit(X86_PLATFORM_IPI_VECTOR);
> - irq_exit();
> -
> + exiting_irq();
> set_irq_regs(old_regs);
> }
>
> diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c index 09e6262..636a55e 100644
> --- a/arch/x86/kernel/irq_work.c
> +++ b/arch/x86/kernel/irq_work.c
> @@ -10,24 +10,32 @@
> #include <asm/apic.h>
> #include <asm/trace/irq_vectors.h>
>
> -void smp_irq_work_interrupt(struct pt_regs *regs)
> +static inline void irq_work_entering_irq(void)
> {
> irq_enter();
> ack_APIC_irq();
> +}
> +
> +static inline void __smp_irq_work_interrupt(void) {
> inc_irq_stat(apic_irq_work_irqs);
> irq_work_run();
> - irq_exit();
> +}
> +
> +void smp_irq_work_interrupt(struct pt_regs *regs) {
> + irq_work_entering_irq();
> + __smp_irq_work_interrupt();
> + exiting_irq();
> }
>
> void smp_trace_irq_work_interrupt(struct pt_regs *regs) {
> - irq_enter();
> - ack_APIC_irq();
> + irq_work_entering_irq();
> trace_irq_work_entry(IRQ_WORK_VECTOR);
> - inc_irq_stat(apic_irq_work_irqs);
> - irq_work_run();
> + __smp_irq_work_interrupt();
> trace_irq_work_exit(IRQ_WORK_VECTOR);
> - irq_exit();
> + exiting_irq();
> }
>
> void arch_irq_work_raise(void)
> diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index aad58af..f4fe0b8 100644
> --- a/arch/x86/kernel/smp.c
> +++ b/arch/x86/kernel/smp.c
> @@ -250,11 +250,16 @@ finish:
> /*
> * Reschedule call back.
> */
> -void smp_reschedule_interrupt(struct pt_regs *regs)
> +static inline void __smp_reschedule_interrupt(void)
> {
> - ack_APIC_irq();
> inc_irq_stat(irq_resched_count);
> scheduler_ipi();
> +}
> +
> +void smp_reschedule_interrupt(struct pt_regs *regs) {
> + ack_APIC_irq();
> + __smp_reschedule_interrupt();
> /*
> * KVM uses this interrupt to force a cpu out of guest mode
> */
> @@ -264,52 +269,61 @@ void smp_trace_reschedule_interrupt(struct pt_regs *regs) {
> ack_APIC_irq();
> trace_reschedule_entry(RESCHEDULE_VECTOR);
> - inc_irq_stat(irq_resched_count);
> - scheduler_ipi();
> + __smp_reschedule_interrupt();
> trace_reschedule_exit(RESCHEDULE_VECTOR);
> /*
> * KVM uses this interrupt to force a cpu out of guest mode
> */
> }
>
> -void smp_call_function_interrupt(struct pt_regs *regs)
> +static inline void call_function_entering_irq(void)
> {
> ack_APIC_irq();
> irq_enter();
> +}
> +
> +static inline void __smp_call_function_interrupt(void)
> +{
> generic_smp_call_function_interrupt();
> inc_irq_stat(irq_call_count);
> - irq_exit();
> +}
> +
> +void smp_call_function_interrupt(struct pt_regs *regs) {
> + call_function_entering_irq();
> + __smp_call_function_interrupt();
> + exiting_irq();
> }
>
> void smp_trace_call_function_interrupt(struct pt_regs *regs) {
> - ack_APIC_irq();
> - irq_enter();
> + call_function_entering_irq();
> trace_call_function_entry(CALL_FUNCTION_VECTOR);
> - generic_smp_call_function_interrupt();
> - inc_irq_stat(irq_call_count);
> + __smp_call_function_interrupt();
> trace_call_function_exit(CALL_FUNCTION_VECTOR);
> - irq_exit();
> + exiting_irq();
> }
>
> -void smp_call_function_single_interrupt(struct pt_regs *regs)
> +static inline void __smp_call_function_single_interrupt(void)
> {
> - ack_APIC_irq();
> - irq_enter();
> generic_smp_call_function_single_interrupt();
> inc_irq_stat(irq_call_count);
> - irq_exit();
> +}
> +
> +void smp_call_function_single_interrupt(struct pt_regs *regs) {
> + call_function_entering_irq();
> + __smp_call_function_single_interrupt();
> + exiting_irq();
> }
>
> void smp_trace_call_function_single_interrupt(struct pt_regs *regs) {
> - ack_APIC_irq();
> - irq_enter();
> + call_function_entering_irq();
> trace_call_function_single_entry(CALL_FUNCTION_SINGLE_VECTOR);
> - generic_smp_call_function_single_interrupt();
> - inc_irq_stat(irq_call_count);
> + __smp_call_function_single_interrupt();
> trace_call_function_single_exit(CALL_FUNCTION_SINGLE_VECTOR);
> - irq_exit();
> + exiting_irq();
> }
>
> static int __init nonmi_ipi_setup(char *str)
> --
> 1.7.1

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