Re: [Qemu-devel] [PATCH v5 00/11] trace: [tcg] Allow tracing guest events in TCG-generated code

Re: [Qemu-devel] [PATCH v5 00/11] trace: [tcg] Allow tracing guest events in TCG-generated code

[Stefan Hajnoczi]

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On Fri, May 30, 2014 at 02:11:20PM +0200, Lluís Vilanova wrote:
> NOTE: TCG code for execution-time event tracing is always generated, regardless
>       of wether the event has been dynamically disabled or not (unless the event
>       has the static "disable" property).
> 
>       This approach keeps this series simple, and a future series will handle
>       the case of having per-CPU tracing states for these events, and only
>       generate the code if the event is dynamicaly enabled.
> 
> Adds the base ability to specify which events in the "trace-events" file may be
> used to trace guest activity in the TCG code (using the "tcg" event propery).
> 
> An event with that property actually generates two independent events
> "${name}_trans" and "${name}_exec", and a set of conveniency functions. Having
> two events allows us to trace both translation and execution of guest code
> (e.g., generating vs executing a basic block). See the first patch for more
> information on its usage.
> 
> Files generating guest code (TCG) must include "trace-tcg.h".
> 
> The flow of the generated routines is (convenience wrappers are inlined):
> 
> 
> [At translation time]
> 
> * trace_${name}_tcg(bool, TCGv)
>   Declared: "trace/generated-tcg-tracers.h"
>   Defined : "trace/generated-tcg-tracers.h"
> 
>   Invokes "trace_${name}_trans" (with all non-TCG arguments) and
>   "gen_helper_trace_${name}_exec" (with all arguments).
> 
> * trace_${name}_trans(bool)
>   Declared: "trace/generated-tracers.h"
>   Defined : "trace/generated-tracers.h"
> 
>   Invokes the actual tracing backends for the translation-time event.
> 
> * gen_helper_trace_${name}_exec_wrapper(bool, TCGv)
>   Declared: "trace/generated-helpers-wrappers.h"
>   Defined : "trace/generated-helpers-wrappers.h"
> 
>   Convenience wrapper that will allocate (and free) TCG temporaries for all
>   non-TCG arguments before calling "gen_helper_trace_${name}_exec_proxy".
> 
> * gen_helper_trace_${name}_exec_proxy(TCGi32, TCGv)
>   Declared: "trace/generated-helpers.h"
>   Defined : "trace/generated-helpers.h" (using helper machinery)
> 
>   The actual TCG helper function, created using QEMU's TCG helper machinery.
> 
> 
> [At execution time]
> 
> * helper_trace_${name}_exec_proxy(uint32_t, uint64_t)
>   Declared: "trace/generated-helpers.h"
>   Defined : "trace/generated-helpers.c"
> 
>   Convenience wrapper that casts arguments to the appropriate type before
>   calling "trace_${name}_exec".
> 
>   This is necessary because TCG helpers can only receive a limited number of
>   argument types (e.g., must use 'uint32_t' instead of 'bool').
> 
> * trace_${name}_exec(bool, uint64_t)
>   Declared: "trace/generated-tracers.h"
>   Defined : "trace/generated-tracers.h"
> 
>   Invokes the actual tracing backends for the execution-time event.
> 
> Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
> ---
> 
> Changes in v5:
> 
> * Rename 'gen_helper_trace_${name}_exec' as
>   'gen_helper_trace_${name}_exec_wrapper'.
> * Split generation of 'gen_helper_trace_${name}_exec_wrapper' into a separate
>   file ("trace/generated-helpers-wrappers.h"), using the new
>   'tcg-helper-wrapper-h' tracetool backend.
> 
> Changes in v4:
> 
> * Rebase on d7d3d60 (use new helper header machinery).
> 
> Changes in v3:
> 
> * None (re-send with cover).
> 
> Changes in v2:
> 
> * Split the guest memory access event out of this series.
> * Generate two independent events from each "tcg" event (one for
>   translation-time events and one for execution-time events).
> 
> 
> Lluís Vilanova (11):
>       trace: [tcg] Add documentation
>       trace: [tcg] Argument type transformation rules
>       trace: [tcg] Argument type transformation machinery
>       trace: [tcg] Add 'tcg' event property
>       trace: [tcg] Declare TCG tracing helper routines
>       trace: [tcg] Define TCG tracing helper routines
>       trace: [tcg] Define TCG tracing helper routine wrappers
>       trace: [tcg] Include TCG-tracing helpers
>       trace: [tcg] Generate TCG tracing routines
>       trace: [tcg] Include event definitions in "trace.h"
>       trace: [tcg] Include TCG-tracing header on all targets
> 
> 
>  .gitignore                                       |    4 +
>  Makefile                                         |    6 +
>  Makefile.objs                                    |    7 +
>  Makefile.target                                  |    5 +
>  docs/tracing.txt                                 |   40 +++++
>  include/exec/helper-gen.h                        |    2 
>  include/exec/helper-proto.h                      |    1 
>  include/exec/helper-tcg.h                        |    1 
>  include/trace-tcg.h                              |    7 +
>  include/trace.h                                  |    1 
>  scripts/tracetool/__init__.py                    |   95 ++++++++++++-
>  scripts/tracetool/format/events_h.py             |    5 +
>  scripts/tracetool/format/tcg_h.py                |   57 ++++++++
>  scripts/tracetool/format/tcg_helper_c.py         |   50 +++++++
>  scripts/tracetool/format/tcg_helper_h.py         |   50 +++++++
>  scripts/tracetool/format/tcg_helper_wrapper_h.py |   70 +++++++++
>  scripts/tracetool/transform.py                   |  166 ++++++++++++++++++++++
>  target-alpha/translate.c                         |    3 
>  target-arm/translate-a64.c                       |    2 
>  target-arm/translate.c                           |    3 
>  target-cris/translate.c                          |    3 
>  target-i386/translate.c                          |    3 
>  target-lm32/translate.c                          |    3 
>  target-m68k/translate.c                          |    3 
>  target-microblaze/translate.c                    |    3 
>  target-mips/translate.c                          |    3 
>  target-openrisc/translate.c                      |    3 
>  target-ppc/translate.c                           |    3 
>  target-s390x/translate.c                         |    2 
>  target-sh4/translate.c                           |    3 
>  target-sparc/translate.c                         |    3 
>  target-unicore32/translate.c                     |    3 
>  target-xtensa/translate.c                        |    3 
>  trace/Makefile.objs                              |   53 ++++++-
>  34 files changed, 654 insertions(+), 12 deletions(-)
>  create mode 100644 include/trace-tcg.h
>  create mode 100644 scripts/tracetool/format/tcg_h.py
>  create mode 100644 scripts/tracetool/format/tcg_helper_c.py
>  create mode 100644 scripts/tracetool/format/tcg_helper_h.py
>  create mode 100644 scripts/tracetool/format/tcg_helper_wrapper_h.py
>  create mode 100644 scripts/tracetool/transform.py
> 
> 
> To: qemu-devel@nongnu.org
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Richard Henderson <rth@twiddle.net>
> Cc: Peter Maydell <peter.maydell@linaro.org>
> 

Merged for QEMU 2.2.

Thanks, applied to my tracing-next tree:
https://github.com/stefanha/qemu/commits/tracing-next

Stefan

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