linux/tools/perf
Andi Kleen 61f611593f perf script: Fix LBR skid dump problems in brstackinsn
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 <ak@linux.intel.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Link: http://lkml.kernel.org/r/20181120050617.4119-1-andi@firstfloor.org
[ Resolved conflict with dd2e18e9ac ("perf tools: Support 'srccode' output") ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-12-28 16:33:02 -03:00
..
arch perf annotate: Introduce basic support for ARC 2018-12-17 14:59:42 -03:00
bench perf bench: Add epoll_ctl(2) benchmark 2018-11-21 22:39:55 -03:00
Documentation perf trace: Allow asking for not suppressing common string prefixes 2018-12-18 16:07:42 -03:00
examples/bpf perf augmented_raw_syscalls: Copy 'access' arg as well 2018-12-18 16:15:18 -03:00
include/bpf perf bpf: Move perf_event_output() from stdio.h to bpf.h 2018-12-18 12:23:58 -03:00
jvmti perf jvmti: Separate jvmti cmlr check 2018-11-21 22:39:58 -03:00
pmu-events perf vendor events intel: Fix Load_Miss_Real_Latency on SKL/SKX 2018-12-17 14:59:32 -03:00
python perf python: Make twatch.py work with both python2 and python3 2018-02-19 12:28:08 -03:00
scripts perf scripts python: exported-sql-viewer.py: Fix table find when table re-ordered 2018-11-05 14:53:00 -03:00
tests perf tests: Use shebangs in the shell scripts 2018-12-18 12:21:44 -03:00
trace perf trace: Use correct SECCOMP prefix spelling, "SECOMP_*" -> "SECCOMP_*" 2018-12-28 16:32:54 -03:00
ui perf ui helpline: Use strlcpy() as a shorter form of strncpy() + explicit set nul 2018-12-17 14:59:23 -03:00
util perf script: Fix LBR skid dump problems in brstackinsn 2018-12-28 16:33:02 -03:00
.gitignore perf tools: Add trace/beauty/generated/ into .gitignore 2018-02-05 13:58:02 -03:00
Build perf trace: Remove audit-libs dependency if syscall tables are present 2018-01-23 09:51:38 -03:00
builtin-annotate.c perf tools: Remove perf_tool from event_op2 2018-09-19 10:25:10 -03:00
builtin-bench.c perf bench: Add epoll_ctl(2) benchmark 2018-11-21 22:39:55 -03:00
builtin-buildid-cache.c perf buildid-cache: Warn --purge-all failures 2018-05-15 10:32:16 -03:00
builtin-buildid-list.c Merge branch 'linus' into perf/core, to fix conflicts 2017-11-07 10:30:18 +01:00
builtin-c2c.c perf c2c report: Fix crash for empty browser 2018-07-31 10:53:20 -03:00
builtin-config.c perf config: Show the configuration when no arguments are provided 2018-12-18 12:24:00 -03:00
builtin-data.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
builtin-diff.c perf hists: Clarify callchain disabling when available 2018-07-24 14:37:33 -03:00
builtin-evlist.c Merge branch 'linus' into perf/core, to fix conflicts 2017-11-07 10:30:18 +01:00
builtin-ftrace.c perf ftrace: Append an EOL when write tracing files 2018-02-19 09:49:12 -03:00
builtin-help.c perf help: Remove needless use of strncpy() 2018-12-17 14:59:18 -03:00
builtin-inject.c perf tools: Report itrace options in help 2018-09-19 15:06:59 -03:00
builtin-kallsyms.c perf machine: Ditch find_kernel_function variants 2018-04-30 12:20:54 -03:00
builtin-kmem.c tools lib traceevent, perf tools: Rename 'enum pevent_flag' to 'enum tep_flag' 2018-08-13 15:22:18 -03:00
builtin-kvm.c perf tools: Allow specifying proc-map-timeout in config file 2018-12-17 14:56:57 -03:00
builtin-list.c Merge branch 'linus' into perf/core, to fix conflicts 2017-11-07 10:30:18 +01:00
builtin-lock.c Merge branch 'linus' into perf/core, to fix conflicts 2017-11-07 10:30:18 +01:00
builtin-mem.c perf mem: Allow all record/report options 2018-04-18 15:35:48 -03:00
builtin-probe.c perf tools: No need to check if the argument to __get() function is NULL 2018-06-04 10:28:50 -03:00
builtin-record.c perf tools: Allow specifying proc-map-timeout in config file 2018-12-17 14:56:57 -03:00
builtin-report.c perf report: Display average IPC and IPC coverage per symbol 2018-12-17 14:55:44 -03:00
builtin-sched.c perf sched: Use sched->show_callchain where appropriate 2018-06-05 10:09:54 -03:00
builtin-script.c perf script: Fix LBR skid dump problems in brstackinsn 2018-12-28 16:33:02 -03:00
builtin-stat.c perf stat: Avoid segfaults caused by negated options 2018-12-18 12:21:44 -03:00
builtin-timechart.c perf tools: Add missing open_memstream() prototype for systems lacking it 2018-12-18 12:23:57 -03:00
builtin-top.c perf top: Move perf_top__reset_sample_counters() to after counts display 2018-12-17 14:58:47 -03:00
builtin-trace.c perf trace: Do not hardcode the size of the tracepoint common_ fields 2018-12-21 09:42:46 -03:00
builtin-version.c perf version: Print status for syscall_table 2018-04-12 10:33:34 -03:00
builtin.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
check-headers.sh tools headers uapi: Grab a copy of fadvise.h 2018-12-18 16:17:40 -03:00
command-list.txt perf help: Add missing subcommand version 2018-09-19 14:53:36 -03:00
CREDITS
design.txt
Makefile perf tools: Disable parallelism for 'make clean' 2018-08-20 08:54:58 -03:00
Makefile.config perf build: Don't unconditionally link the libbfd feature test to -liberty and -lz 2018-12-21 09:42:46 -03:00
Makefile.perf perf trace: Wire up the fadvise 'advice' table generator 2018-12-18 16:17:41 -03:00
MANIFEST perf tools: Get all of tools/{arch,include}/ in the MANIFEST 2017-09-25 10:39:43 -03:00
perf-archive.sh License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf-completion.sh perf tools: Auto-complete for events with ':' 2017-12-27 12:16:00 -03:00
perf-read-vdso.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf-sys.h Drop a bunch of metag references 2018-02-23 14:29:59 +00:00
perf-with-kcore.sh
perf.c perf tools: Remove dead quote.[ch] code 2018-06-04 10:28:50 -03:00
perf.h perf tools: Allow specifying proc-map-timeout in config file 2018-12-17 14:56:57 -03:00