linux-stable.git/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c, branch v5.16.2

perf intel-pt: Fix missing 'instruction' events with 'q' option

2021-12-11T11:19:47+00:00

FUP packets contain IP information, which makes them also an 'instruction'
event in 'hop' mode i.e. the itrace 'q' option.  That wasn't happening, so
restructure the logic so that FUP events are added along with appropriate
'instruction' and 'branch' events.

Fixes: 7c1b16ba0e26e6 ("perf intel-pt: Add support for decoding FUP/TIP only")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-7-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix next 'err' value, walking trace

2021-12-11T11:19:47+00:00

Code after label 'next:' in intel_pt_walk_trace() assumes 'err' is zero,
but it may not be, if arrived at via a 'goto'. Ensure it is zero.

Fixes: 7c1b16ba0e26e6 ("perf intel-pt: Add support for decoding FUP/TIP only")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix state setting when receiving overflow (OVF) packet

2021-12-11T11:19:47+00:00

An overflow (OVF packet) is treated as an error because it represents a
loss of trace data, but there is no loss of synchronization, so the packet
state should be INTEL_PT_STATE_IN_SYNC not INTEL_PT_STATE_ERR_RESYNC.

To support that, some additional variables must be reset, and the FUP
packet that may follow OVF is treated as an FUP event.

Fixes: f4aa081949e7b6 ("perf tools: Add Intel PT decoder")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix intel_pt_fup_event() assumptions about setting state type

2021-12-11T11:19:47+00:00

intel_pt_fup_event() assumes it can overwrite the state type if there has
been an FUP event, but this is an unnecessary and unexpected constraint on
callers.

Fix by touching only the state type flags that are affected by an FUP
event.

Fixes: a472e65fc490a ("perf intel-pt: Add decoder support for ptwrite and power event packets")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix sync state when a PSB (synchronization) packet is found

2021-12-11T11:19:47+00:00

When syncing, it may be that branch packet generation is not enabled at
that point, in which case there will not immediately be a control-flow
packet, so some packets before a control flow packet turns up, get
ignored.  However, the decoder is in sync as soon as a PSB is found, so
the state should be set accordingly.

Fixes: f4aa081949e7b6 ("perf tools: Add Intel PT decoder")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix some PGE (packet generation enable/control flow packets) usage

2021-12-11T11:19:47+00:00

Packet generation enable (PGE) refers to whether control flow (COFI)
packets are being produced.

PGE may be false even when branch-tracing is enabled, due to being
out-of-context, or outside a filter address range.  Fix some missing PGE
usage.

Fixes: 7c1b16ba0e26e6 ("perf intel-pt: Add support for decoding FUP/TIP only")
Fixes: 839598176b0554 ("perf intel-pt: Allow decoding with branch tracing disabled")
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org # v5.15+
Link: https://lore.kernel.org/r/20211210162303.2288710-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Support itrace A option to approximate IPC

2021-10-27T19:20:18+00:00

Normally, for cycle-acccurate mode, IPC values are an exact number of
instructions and cycles. Due to the granularity of timestamps, that happens
only when a CYC packet correlates to the event.

Support the itrace 'A' option, to use instead, the number of cycles
associated with the current timestamp. This provides IPC information for
every change of timestamp, but at the expense of accuracy. Due to the
granularity of timestamps, the actual number of cycles increases even
though the cycles reported does not. The number of instructions is known,
but if IPC is reported, cycles can be too low and so IPC is too high. Note
that inaccuracy decreases as the period of sampling increases i.e. if the
number of cycles is too low by a small amount, that becomes less
significant if the number of cycles is large.

Furthermore, it can be used in conjunction with dlfilter-show-cycles.so
to provide higher granularity cycle information.

Reviewed-by: Andi Kleen 
Signed-off-by: Adrian Hunter 
Cc: Jiri Olsa 
Link: https://lore.kernel.org/r/20211027080334.365596-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Add a config for max loops without consuming a packet

2021-07-07T14:40:56+00:00

The Intel PT decoder limits the number of unconditional branches (e.g.
jmps) decoded without consuming any trace packets. Generally, a loop
needs a conditional branch which generates a TNT packet, whereas a "ret"
instruction will generate a TIP or TNT packet. So exceeding the limit is
assumed to be a never-ending loop, which can happen if there has been a
decoding error putting the decoder at the wrong place in the code.

Up until now, the limit of 10000 has been enough but some analytic
purposes have been reported to exceed that.

Increase the limit to 100000, and make it configurable via perf config
intel-pt.max-loops. Also amend the "Never-ending loop" message to
mention the configuration entry.

Signed-off-by: Adrian Hunter 
Reviewed-by: Andi Kleen 
Cc: Jiri Olsa 
Link: http://lore.kernel.org/lkml/20210701175132.3977-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo

Merge remote-tracking branch 'torvalds/master' into perf/core

2021-05-25T12:13:52+00:00

To pick up fixes from perf/urgent.

Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix transaction abort handling

2021-05-19T13:31:04+00:00

When adding support for power events, some handling of FUP packets was
unified. That resulted in breaking reporting of TSX aborts, by not
considering the associated TIP packet. Fix that.

Example:

A machine that supports TSX is required. It will have flag "rtm". Kernel
parameter tsx=on may be required.

 # for w in `cat /proc/cpuinfo | grep -m1 flags `;do echo $w | grep rtm ; done
 rtm

Test program:

 #include 
 #include 

 int main()
 {
        int x = 0;

        if (_xbegin() == _XBEGIN_STARTED) {
                x = 1;
                _xabort(1);
        } else {
                printf("x = %d\n", x);
        }
        return 0;
 }

Compile with -mrtm i.e.

 gcc -Wall -Wextra -mrtm xabort.c -o xabort

Record:

 perf record -e intel_pt/cyc/u --filter 'filter main @ ./xabort' ./xabort

Before:

 # perf script --itrace=be -F+flags,+addr,-period,-event --ns
          xabort  1478 [007] 92161.431348552:   tr strt                             0 [unknown] ([unknown]) =>           400b6d main+0x0 (/root/xabort)
          xabort  1478 [007] 92161.431348624:   jmp                            400b96 main+0x29 (/root/xabort) =>           400bae main+0x41 (/root/xabort)
          xabort  1478 [007] 92161.431348624:   return                         400bb4 main+0x47 (/root/xabort) =>           400b87 main+0x1a (/root/xabort)
          xabort  1478 [007] 92161.431348637:   jcc                            400b8a main+0x1d (/root/xabort) =>           400b98 main+0x2b (/root/xabort)
          xabort  1478 [007] 92161.431348644:   tr end  call                   400ba9 main+0x3c (/root/xabort) =>           40f690 printf+0x0 (/root/xabort)
          xabort  1478 [007] 92161.431360859:   tr strt                             0 [unknown] ([unknown]) =>           400bae main+0x41 (/root/xabort)
          xabort  1478 [007] 92161.431360882:   tr end  return                 400bb4 main+0x47 (/root/xabort) =>           401139 __libc_start_main+0x309 (/root/xabort)

After:

 # perf script --itrace=be -F+flags,+addr,-period,-event --ns
          xabort  1478 [007] 92161.431348552:   tr strt                             0 [unknown] ([unknown]) =>           400b6d main+0x0 (/root/xabort)
          xabort  1478 [007] 92161.431348624:   tx abrt                        400b93 main+0x26 (/root/xabort) =>           400b87 main+0x1a (/root/xabort)
          xabort  1478 [007] 92161.431348637:   jcc                            400b8a main+0x1d (/root/xabort) =>           400b98 main+0x2b (/root/xabort)
          xabort  1478 [007] 92161.431348644:   tr end  call                   400ba9 main+0x3c (/root/xabort) =>           40f690 printf+0x0 (/root/xabort)
          xabort  1478 [007] 92161.431360859:   tr strt                             0 [unknown] ([unknown]) =>           400bae main+0x41 (/root/xabort)
          xabort  1478 [007] 92161.431360882:   tr end  return                 400bb4 main+0x47 (/root/xabort) =>           401139 __libc_start_main+0x309 (/root/xabort)

Fixes: a472e65fc490a ("perf intel-pt: Add decoder support for ptwrite and power event packets")
Signed-off-by: Adrian Hunter 
Cc: Andi Kleen 
Cc: Jiri Olsa 
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210519074515.9262-2-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo