[PATCH v15 0/4] trace,x86: irq vector tracepoint support

[Seiji Aguchi]

Change log
  v14 -> v15
 - Patch 2/4
   Introduce non-trace irq handlers with entering/exiting_irq()
   by separating it from previous "patch v14 3/3".

 - Patch 3/4 (newly created)
   Separate a patch renaming variables for debugging and introducing 
   load_current_idt() from previous "patch v14 3/3".

 - Patch 4/4
   Introduce load_current_idt() to cpu_init() for i386 to handle cpu-hotplug.

 v13 -> v14
 - Rebase to 3.10-rc4
 - Patch 3/3
   - Add comments above load_current_idt() in arch/x86/include/asm/desc.h.
   - Introduce a logic selecting IDT that we currently should be using,
     based on the current state instead of current_idt_desc_ptr.
   - Rename some "nmi" variables to "debug".
   - Introduce local_irq_save/restore() in load_current_idt() to avoid races
     regardless of process/interrupt context.

 v12 -> v13
 - Rebase to 3.10-rc3
 - Patch 2/3
   - Separate a patch introducing entering/exiting_irq() from patch-v12 3/3.
 - Patch 3/3
   - Introduce write_trace_idt_entry() to remove "ifdef CONFIG_TRACING"
     from _set_gate().
   - Change DEFINE_IRQ_VECTOR_EVENT to save on repeat code.
   - Add a path of irq_vector.h to Makefile.
   - Introduce current_idt_descr_ptr and load_current_idt() to switch
     IDT in a generic way with handling Debug traps/NMI and cpu hotplug.

 v11 -> v12
 - Rebase to 3.9-rc5

 v10 -> v11
 - Rebase to 3.9-rc2
 - Add a modification for hyperv_callback vector. (patch 2/3)
 - Change a way to switch idt to check the table in use instead of saving/restoring it,
   because saving/restoring functions will break if we have to add another one. (patch 2/3)

 v9 -> v10
 - Add an explanation the reason why tracepoints has to place inside irq enter/exit handling. (patch 3/3)

 v8 -> v9
 - Rebase to 3.8-rc6
 - Add Steven's email address at the top of the message and 
   move my signed-off-by below Steven's one because it is
   originally created by Steven. (patch 1/3)
 - Introduce a irq_vector_mutex to avoid a race at registering/unregistering
   time. (patch 2/3)
 - Use a per_cpu data to orig_idt_descr because IDT descritor is needed to each cpu
   and the appropriate data type is per_cpu data. It is suggested by Steven.
   (patch 2/3)

 v7 -> v8
 - Rebase to 3.8-rc4
 - Add a patch 1 introducing DEFINE_EVENT_FN() macro.
 - Rename original patches 1 and 2 to 2 and 3.
 - Change a definition of tracepoint to use DEFINE_EVENT_FN(). (patch 2)
 - Change alloc_intr_gate() to use do{}while(0) to avoid a warning 
   of checkpatch.pl. (patch 2)
 - Move entering_irq()/exiting_irq() to arch/x86/include/asm/apic.h (patch 3)

 v6 -> v7
 - Divide into two patches to make a code review easier.
   Summery of each patch is as follows.
    - Patch 1/2
      - Add an irq_vector tracing infrastructure.
      - Create idt_table for tracing. It is refactored to avoid duplicating
        existing logic.
      - Duplicate new irq handlers inserted tracepoints.

    - Patch 2/2
      - Share a common logic among irq handlers to make them
        manageable and readable.

 v5 -> v6
 - Rebased to 3.7

 v4 -> v5
 - Rebased to 3.6.0

 - Introduce a logic switching IDT at enabling/disabling TP time 
   so that a time penalty makes a zero when tracepoints are disabled.
   This IDT is created only when CONFIG_TRACEPOINTS is enabled.

 - Remove arch_irq_vector_entry/exit and add followings again
   so that we can add each tracepoint in a generic way.
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

 - Drop nmi tracepoints to begin with apic interrupts and discuss a logic switching
   IDT first.

 - Move irq_vectors.h in the directory of arch/x86/include/asm/trace because
   I'm not sure if a logic switching IDT is sharable with other architectures.

 v3 -> v4
 - Add a latency measurement of each tracepoint
 - Rebased to 3.6-rc6

 v2 -> v3
 - Remove an invalidate_tlb_vector event because it was replaced by a call function vector
   in a following commit.
   http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=52aec3308db85f4e9f5c8b9f5dc4fbd0138c6fa4

 v1 -> v2
 - Modify variable name from irq to vector.
 - Merge arch-specific tracepoints below to an arch_irq_vector_entry/exit.
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

[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.

This patch adds 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

Seiji Aguchi (3):
  trace,x86: Introduce entering/exiting_irq()
  x86: Rename variables for debugging
  trace,x86: Add irq vector tracepoints

Steven Rostedt (1):
  tracing: Add DEFINE_EVENT_FN() macro

 arch/x86/include/asm/apic.h              |   27 +++++++
 arch/x86/include/asm/desc.h              |  119 ++++++++++++++++++++++++++++-
 arch/x86/include/asm/entry_arch.h        |    8 +-
 arch/x86/include/asm/hw_irq.h            |   17 ++++
 arch/x86/include/asm/mshyperv.h          |    1 +
 arch/x86/include/asm/trace/irq_vectors.h |  104 ++++++++++++++++++++++++++
 arch/x86/kernel/Makefile                 |    1 +
 arch/x86/kernel/apic/Makefile            |    1 +
 arch/x86/kernel/apic/apic.c              |   71 +++++++++++++++---
 arch/x86/kernel/cpu/common.c             |   20 +++---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |   24 +++++--
 arch/x86/kernel/cpu/mcheck/threshold.c   |   24 +++++--
 arch/x86/kernel/entry_32.S               |   12 +++-
 arch/x86/kernel/entry_64.S               |   31 ++++++--
 arch/x86/kernel/head_64.S                |    8 ++-
 arch/x86/kernel/irq.c                    |   31 +++++---
 arch/x86/kernel/irq_work.c               |   24 ++++++-
 arch/x86/kernel/smp.c                    |   65 ++++++++++++++--
 arch/x86/kernel/tracepoint.c             |   57 ++++++++++++++
 arch/x86/kernel/traps.c                  |    2 +-
 include/linux/tracepoint.h               |    2 +
 include/trace/define_trace.h             |    5 +
 include/trace/ftrace.h                   |    4 +
 include/xen/events.h                     |    3 +
 24 files changed, 589 insertions(+), 72 deletions(-)
 create mode 100644 arch/x86/include/asm/trace/irq_vectors.h
 create mode 100644 arch/x86/kernel/tracepoint.c
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