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The ETM decoder incorrectly assumed that auxtrace queue indices were
equivalent to CPU number. This assumption is used for inserting records
into the queue, and for fetching queues when given a CPU number. This
assumption held when Perf always opened a dummy event on every CPU, even
if the user provided a subset of CPUs on the commandline, resulting in
the indices aligning.
For example:
# event : name = cs_etm//u, , id = { 2451, 2452 }, type = 11 (cs_etm), size = 136, config = 0x4010, { sample_period, samp>
# event : name = dummy:u, , id = { 2453, 2454, 2455, 2456 }, type = 1 (PERF_TYPE_SOFTWARE), size = 136, config = 0x9 (PER>
0 0 0x200 [0xd0]: PERF_RECORD_ID_INDEX nr: 6
... id: 2451 idx: 2 cpu: 2 tid: -1
... id: 2452 idx: 3 cpu: 3 tid: -1
... id: 2453 idx: 0 cpu: 0 tid: -1
... id: 2454 idx: 1 cpu: 1 tid: -1
... id: 2455 idx: 2 cpu: 2 tid: -1
... id: 2456 idx: 3 cpu: 3 tid: -1
Since commit 811082e ("perf parse-events: Support user CPUs mixed
with threads/processes") the dummy event no longer behaves in this way,
making the ETM event indices start from 0 on the first CPU recorded
regardless of its ID:
# event : name = cs_etm//u, , id = { 771, 772 }, type = 11 (cs_etm), size = 144, config = 0x4010, { sample_period, sample>
# event : name = dummy:u, , id = { 773, 774 }, type = 1 (PERF_TYPE_SOFTWARE), size = 144, config = 0x9 (PERF_COUNT_SW_DUM>
0 0 0x200 [0x90]: PERF_RECORD_ID_INDEX nr: 4
... id: 771 idx: 0 cpu: 2 tid: -1
... id: 772 idx: 1 cpu: 3 tid: -1
... id: 773 idx: 0 cpu: 2 tid: -1
... id: 774 idx: 1 cpu: 3 tid: -1
This causes the following segfault when decoding:
$ perf record -e cs_etm//u -C 2,3 -- true
$ perf report
perf: Segmentation fault
-------- backtrace --------
#0 0xaaaabf9fd020 in ui__signal_backtrace setup.c:110
#1 0xffffab5c7930 in __kernel_rt_sigreturn [vdso][930]
#2 0xaaaabfb68d30 in cs_etm_decoder__reset cs-etm-decoder.c:85
#3 0xaaaabfb65930 in cs_etm__get_data_block cs-etm.c:2032
#4 0xaaaabfb666fc in cs_etm__run_per_cpu_timeless_decoder cs-etm.c:2551
#5 0xaaaabfb6692c in (cs_etm__process_timeless_queues cs-etm.c:2612
#6 0xaaaabfb63390 in cs_etm__flush_events cs-etm.c:921
#7 0xaaaabfb324c0 in auxtrace__flush_events auxtrace.c:2915
#8 0xaaaabfaac378 in __perf_session__process_events session.c:2285
#9 0xaaaabfaacc9c in perf_session__process_events session.c:2442
#10 0xaaaabf8d3d90 in __cmd_report builtin-report.c:1085
#11 0xaaaabf8d6944 in cmd_report builtin-report.c:1866
#12 0xaaaabf95ebfc in run_builtin perf.c:351
#13 0xaaaabf95eeb0 in handle_internal_command perf.c:404
#14 0xaaaabf95f068 in run_argv perf.c:451
#15 0xaaaabf95f390 in main perf.c:558
#16 0xffffaab97400 in __libc_start_call_main libc_start_call_main.h:74
#17 0xffffaab974d8 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#18 0xaaaabf8aa8f0 in _start perf[7a8f0]
Fix it by inserting into the queues based on CPU number, rather than
using the index.
Fixes: 811082e ("perf parse-events: Support user CPUs mixed with threads/processes")
Signed-off-by: James Clark <james.clark@linaro.org>
Tested-by: Leo Yan <leo.yan@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: coresight@lists.linaro.org
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
mkopec
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Feb 24, 2026
When run on a kernel without BTF info, perf crashes:
libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled?
libbpf: failed to find valid kernel BTF
Program received signal SIGSEGV, Segmentation fault.
0x00005555556915b7 in btf.type_cnt ()
(gdb) bt
#0 0x00005555556915b7 in btf.type_cnt ()
#1 0x0000555555691fbc in btf_find_by_name_kind ()
#2 0x00005555556920d0 in btf.find_by_name_kind ()
#3 0x00005555558a1b7c in init_numa_data (con=0x7fffffffd0a0) at util/bpf_lock_contention.c:125
#4 0x00005555558a264b in lock_contention_prepare (con=0x7fffffffd0a0) at util/bpf_lock_contention.c:313
#5 0x0000555555620702 in __cmd_contention (argc=0, argv=0x7fffffffea10) at builtin-lock.c:2084
#6 0x0000555555622c8d in cmd_lock (argc=0, argv=0x7fffffffea10) at builtin-lock.c:2755
#7 0x0000555555651451 in run_builtin (p=0x555556104f00 <commands+576>, argc=3, argv=0x7fffffffea10)
at perf.c:349
#8 0x00005555556516ed in handle_internal_command (argc=3, argv=0x7fffffffea10) at perf.c:401
#9 0x000055555565184e in run_argv (argcp=0x7fffffffe7fc, argv=0x7fffffffe7f0) at perf.c:445
#10 0x0000555555651b9f in main (argc=3, argv=0x7fffffffea10) at perf.c:553
Check if btf loading failed, and don't do anything with it in
init_numa_data(). This leads to the following error message, instead of
just a crash:
libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled?
libbpf: failed to find valid kernel BTF
libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled?
libbpf: failed to find valid kernel BTF
libbpf: Error loading vmlinux BTF: -ESRCH
libbpf: failed to load BPF skeleton 'lock_contention_bpf': -ESRCH
Failed to load lock-contention BPF skeleton
lock contention BPF setup failed
Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Chun-Tse Shao <ctshao@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit: - Instantiates HPO HDMI encoders - Restores HPO HDMI registers to the register list - Implements set_hdmistreamclk Signed-off-by: Michał Kopeć <michal@nozomi.space>
…_hdmistreamclk Signed-off-by: Michał Kopeć <michal@nozomi.space>
…r.h: drop unused registers These don't exist on earlier DCN. Drop to make the encoder compatible with all DCN gens. Signed-off-by: Michał Kopeć <michal@nozomi.space>
…ntiate HPO HDMI Signed-off-by: Michał Kopeć <michal@nozomi.space>
…DMI stream enc register Rename HDMI_STREAM_ENC_CLOCK_RAMP_ADJUSTER_FIFO_STATUS_CONTROL0__FIFO_PIXEL_ENCODING to HDMI_STREAM_ENC_CLOCK_RAMP_ADJUSTER_FIFO_STATUS_CONTROL0__FIFO_PIXEL_ENCODING_TYPE This makes the register name the same as on DCN401, ensuring we can use a common HPO HDMI encoder implementation on all gens. Signed-off-by: Michał Kopeć <michal@nozomi.space>
…r.c: fix pixel encoding
…v mode to manual on FRL
…r.c: set audio N and CTS correctly for FRL Values dumped by running the Windows driver at different FRL rates.
…r.c: fix hdmi rate list FRL 6 appears twice, once for 3 lanes and once for 4 lanes
…h: add missing enable field
…r.c: don't double-set audio info
…div mode to manual on FRL
…r.c: set HDMI_AUDIO_INFO_CONT
…m_encoder.c: set HDMI_AUDIO_INFO_CONT" This reverts commit cb82364.
…dio clock correctly for FRL Needed when FRL is the only connected display
…mbined retry and rate fallback loop
…lay before finalizing training
… dpms off Causes issues for LG users
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