kernel/tools/perf/util/intel-pt-decoder, branch linux-5.1.y

perf intel-pt: Fix sample timestamp wrt non-taken branches

2019-05-25T16:16:39Z

commit 1b6599a9d8e6c9f7e9b0476012383b1777f7fc93 upstream. The sample timestamp is updated to ensure that the timestamp represents the time of the sample and not a branch that the decoder is still walking towards. The sample timestamp is updated when the decoder returns, but the decoder does not return for non-taken branches. Update the sample timestamp then also. Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp") was also a stable fix and appears, for example, in v4.4 stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample timestamp"). Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org # v4.4+ Fixes: 3f04d98e972b ("perf intel-pt: Improve sample timestamp") Link: http://lkml.kernel.org/r/20190510124143.27054-4-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf intel-pt: Fix improved sample timestamp

2019-05-25T16:16:39Z

commit 61b6e08dc8e3ea80b7485c9b3f875ddd45c8466b upstream. The decoder uses its current timestamp in samples. Usually that is a timestamp that has already passed, but in some cases it is a timestamp for a branch that the decoder is walking towards, and consequently hasn't reached. The intel_pt_sample_time() function decides which is which, but was not handling TNT packets exactly correctly. In the case of TNT, the timestamp applies to the first branch, so the decoder must first walk to that branch. That means intel_pt_sample_time() should return true for TNT, and this patch makes that change. However, if the first branch is a non-taken branch (i.e. a 'N'), then intel_pt_sample_time() needs to return false for subsequent taken branches in the same TNT packet. To handle that, introduce a new state INTEL_PT_STATE_TNT_CONT to distinguish the cases. Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp") was also a stable fix and appears, for example, in v4.4 stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample timestamp"). Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org # v4.4+ Fixes: 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp") Link: http://lkml.kernel.org/r/20190510124143.27054-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf intel-pt: Fix instructions sampling rate

2019-05-25T16:16:38Z

commit 7ba8fa20e26eb3c0c04d747f7fd2223694eac4d5 upstream. The timestamp used to determine if an instruction sample is made, is an estimate based on the number of instructions since the last known timestamp. A consequence is that it might go backwards, which results in extra samples. Change it so that a sample is only made when the timestamp goes forwards. Note this does not affect a sampling period of 0 or sampling periods specified as a count of instructions. Example: Before: $ perf script --itrace=i10us ls 13812 [003] 2167315.222583: 3270 instructions:u: 7fac71e2e494 __GI___tunables_init+0xf4 (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 30902 instructions:u: 7fac71e2da0f _dl_cache_libcmp+0x2f (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 10 instructions:u: 7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 8 instructions:u: 7fac71e2d9ea _dl_cache_libcmp+0xa (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 14 instructions:u: 7fac71e2d9ea _dl_cache_libcmp+0xa (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 6 instructions:u: 7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 14 instructions:u: 7fac71e2d9ff _dl_cache_libcmp+0x1f (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 4 instructions:u: 7fac71e2dab2 _dl_cache_libcmp+0xd2 (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222728: 16423 instructions:u: 7fac71e2477a _dl_map_object_deps+0x1ba (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222734: 12731 instructions:u: 7fac71e27938 _dl_name_match_p+0x68 (/lib/x86_64-linux-gnu/ld-2.28.so) ... After: $ perf script --itrace=i10us ls 13812 [003] 2167315.222583: 3270 instructions:u: 7fac71e2e494 __GI___tunables_init+0xf4 (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222667: 30902 instructions:u: 7fac71e2da0f _dl_cache_libcmp+0x2f (/lib/x86_64-linux-gnu/ld-2.28.so) ls 13812 [003] 2167315.222728: 16479 instructions:u: 7fac71e2477a _dl_map_object_deps+0x1ba (/lib/x86_64-linux-gnu/ld-2.28.so) ... Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Fixes: f4aa081949e7b ("perf tools: Add Intel PT decoder") Link: http://lkml.kernel.org/r/20190510124143.27054-2-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman

perf intel-pt: Fix TSC slip

2019-03-28T17:31:55Z

A TSC packet can slip past MTC packets so that the timestamp appears to go backwards. One estimate is that can be up to about 40 CPU cycles, which is certainly less than 0x1000 TSC ticks, but accept slippage an order of magnitude more to be on the safe side. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Fixes: 79b58424b821c ("perf tools: Add Intel PT support for decoding MTC packets") Link: http://lkml.kernel.org/r/20190325135135.18348-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Rename build libperf to perf

2019-02-14T18:18:08Z

Rename build libperf to perf, because it's used to build perf. The libperf build object name will be used for libperf library. Signed-off-by: Jiri Olsa Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20190213123246.4015-4-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Packet splitting can happen only on 32-bit

2019-02-06T13:27:54Z

Data is copied when the trace is stopped, so packets are never split between buffers except when processing if the buffer cannot fit in the address space which can only happen on 32-bit systems. Change the logic to reflect that. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Link: http://lkml.kernel.org/r/20190206103947.15750-5-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix CYC timestamp calculation after OVF

2019-02-06T13:27:27Z

CYC packet timestamp calculation depends upon CBR which was being cleared upon overflow (OVF). That can cause errors due to failing to synchronize with sideband events. Even if a CBR change has been lost, the old CBR is still a better estimate than zero. So remove the clearing of CBR. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20190206103947.15750-4-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Fix overlap calculation for padding

2019-02-06T13:27:00Z

Auxtrace records might have up to 7 bytes of padding appended. Adjust the overlap accordingly. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20190206103947.15750-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf script: Fix LBR skid dump problems in brstackinsn

2018-12-28T19:33:02Z

This is a fix for another instance of the skid problem Milian recently found [1] The LBRs don't freeze at the exact same time as the PMI is triggered. The perf script brstackinsn code that dumps LBR assembler assumes that the last branch in the LBR leads to the sample point. But with skid it's possible that the CPU executes one or more branches before the sample, but which do not appear in the LBR. What happens then is either that the sample point is before the last LBR branch. In this case the dumper sees a negative length and ignores it. Or it the sample point is long after the last branch. Then the dumper sees a very long block and dumps it upto its block limit (16k bytes), which is noise in the output. On typical sample session this can happen regularly. This patch tries to detect and handle the situation. On the last block that is dumped by the LBR dumper we always stop on the first branch. If the block length is negative just scan forward to the first branch. Otherwise scan until a branch is found. The PT decoder already has a function that uses the instruction decoder to detect branches, so we can just reuse it here. Then when a terminating branch is found print an indication and stop dumping. This might miss a few instructions, but at least shows no runaway blocks. Signed-off-by: Andi Kleen Acked-by: Adrian Hunter Cc: Jiri Olsa Cc: Milian Wolff Link: http://lkml.kernel.org/r/20181120050617.4119-1-andi@firstfloor.org [ Resolved conflict with dd2e18e9ac20 ("perf tools: Support 'srccode' output") ] Signed-off-by: Arnaldo Carvalho de Melo

perf intel-pt: Add MTC and CYC timestamps to debug log

2018-11-05T17:53:54Z

One cause of decoding errors is un-synchronized side-band data. Timestamps are needed to debug such cases. TSC packet timestamps are logged. Log also MTC and CYC timestamps. Signed-off-by: Adrian Hunter Link: http://lkml.kernel.org/r/20181105073505.8129-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo