TSC packets contain only 7 bytes of TSC. The 8th byte is assumed to
change so infrequently that its value can be inferred. However the
logic must cater for a 7 byte wraparound, which it does by adding 1 to
the top byte.
The existing code was doing that with a while loop even though the
addition should only need to be done once. That logic won't work (will
loop forever) if TSC wraps around at the 8th byte. Theoretically that
would take at least 10 years, unless something else went wrong.
And what else could go wrong. Well, if the chunks of trace data are
processed out of order, it will make it look like the 7-byte TSC has
gone backwards (i.e. wrapped). If that happens 256 times then stuck in
the while loop it will be.
Fix that by getting rid of the unnecessary while loop.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1443186956-18718-4-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
A TRACESTOP packet is produced when an Intel PT trace enters a defined
region of the address space at which point the tracing stops.
This patch just adds decoder support.
Support for specifying TRACESTOP regions is left until later.
For details refer to the June 2015 or later Intel 64 and IA-32
Architectures SDM Chapter 36 Intel Processor Trace.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-25-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
CYC packets provide even finer grain timestamp information than MTC and
TSC packets. A CYC packet contains the number of CPU cycles since the
last CYC packet.
This patch just adds decoder support. The CPU frequency can be related
to TSC using the Maximum Non-Turbo Ratio in combination with the CBR
(core-to-bus ratio) packet. However more accuracy is achieved by simply
interpolating the number of cycles between other timing packets like MTC
or TSC. This patch takes the latter approach.
Support for a default value and validation of values is provided by a
later patch. Also documentation is updated in a separate patch.
For details refer to the June 2015 or later Intel 64 and IA-32
Architectures SDM Chapter 36 Intel Processor Trace.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-23-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
MTC packets provide finer grain timestamp information than TSC packets.
MTC packets record time using the hardware crystal clock (CTC) which is
related to TSC packets using a TMA packet.
This patch just adds decoder support.
Support for a default value and validation of values is provided by a
later patch. Also documentation is updated in a separate patch.
For details refer to the June 2015 or later Intel 64 and IA-32
Architectures SDM Chapter 36 Intel Processor Trace.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-21-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
New features have been added to Intel PT which include a number of new
packet definitions.
This patch adds packet definitions for new packets: TMA, MTC, CYC, VMCS,
TRACESTOP and MNT. Also another bit in PIP is defined.
This patch only adds support for the definitions. Later patches add
support for decoding TMA, MTC, CYC and TRACESTOP which is where those
packets are explained.
VMCS and the newly defined bit in PIP are used with virtualization which
is not supported yet. MNT is a maintenance packet which the decoder
should ignore.
For details, refer to the June 2015 or later Intel 64 and IA-32
Architectures SDM Chapter 36 Intel Processor Trace.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-19-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The period on synthesized 'instructions' samples was being set to a
fixed value, whereas the correct value is the number of instructions
since the last sample, which is a value that the decoder can provide.
So do it that way.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-14-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add support for decoding an Intel Processor Trace.
Intel PT trace data must be 'decoded' which involves walking the object
code and matching the trace data packets.
The decoder requests a buffer of binary data via a get_trace()
call-back, which it decodes using instruction information which it gets
via another call-back walk_insn().
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1437150840-31811-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Adrian Hunter