Perf has supported the CPU_PMU_CAPS feature to display a list of CPU PMU
capabilities. But on a hybrid platform, it may have several CPU PMUs (such
as "cpu_core" and "cpu_atom"). The CPU_PMU_CAPS feature is hard to extend
to support multiple CPU PMUs well if it needs to be compatible for the case
of old perf data file + new perf tool.
So for better compatibility we now create a new feature HYBRID_CPU_PMU_CAPS
in the header.
For the perf.data generated on hybrid platform,
root@otcpl-adl-s-2:~# perf report --header-only -I
# cpu_core pmu capabilities: branches=32, max_precise=3, pmu_name=alderlake_hybrid
# cpu_atom pmu capabilities: branches=32, max_precise=3, pmu_name=alderlake_hybrid
# missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CPU_PMU_CAPS CLOCK_DATA
For the perf.data generated on non-hybrid platform
root@kbl-ppc:~# perf report --header-only -I
# cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake
# missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CLOCK_DATA HYBRID_TOPOLOGY HYBRID_CPU_PMU_CAPS
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210514122948.9472-3-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
It is useful to let the user know about the hybrid topology.
Add the HYBRID_TOPOLOGY feature in header to indicate the core CPUs
and the atom CPUs.
With this patch a perf.data generated on a hybrid platform reports
the hybrid CPU list:
root@otcpl-adl-s-2:~# perf report --header-only -I
...
# hybrid cpu system:
# cpu_core cpu list : 0-15
# cpu_atom cpu list : 16-23
For a perf.data generated on a non-hybrid platform, reports a message
that HYBRID_TOPOLOGY is missing:
root@kbl-ppc:~# perf report --header-only -I
...
# missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CLOCK_DATA HYBRID_TOPOLOGY
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210514122948.9472-2-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The following attribute is set when synthesising samples in
timed decoding mode:
attr.sample_type |= PERF_SAMPLE_TIME;
This results in new samples that appear to have timestamps but
because we don't assign any timestamps to the samples, when the
resulting inject file is opened again, the synthesised samples
will be on the wrong side of the MMAP or COMM events.
For example, this results in the samples being associated with
the perf binary, rather than the target of the record:
perf record -e cs_etm/@tmc_etr0/u top
perf inject -i perf.data -o perf.inject --itrace=i100il
perf report -i perf.inject
Where 'Command' == perf should show as 'top':
# Overhead Command Source Shared Object Source Symbol Target Symbol Basic Block Cycles
# ........ ....... .................... ...................... ...................... ..................
#
31.08% perf [unknown] [.] 0x000000000040c3f8 [.] 0x000000000040c3e8 -
If the perf.data file is opened directly with perf, without the
inject step, then this already works correctly because the
events are synthesised after the COMM and MMAP events and
no second sorting happens. Re-sorting only happens when opening
the perf.inject file for the second time so timestamps are
needed.
Using the timestamp from the AUX record mirrors the current
behaviour when opening directly with perf, because the events
are generated on the call to cs_etm__process_queues().
The ETM trace could optionally contain time stamps, but there is
no way to correlate this with the kernel time. So, the best available
time value is that of the AUX_RECORD header. This patch uses
the timestamp from the header for all the samples. The ordering of the
samples are implicit in the trace and thus is fine with respect to
relative ordering.
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Co-developed-by: Al Grant <al.grant@arm.com>
Signed-off-by: Al Grant <al.grant@arm.com>
Signed-off-by: James Clark <james.clark@arm.com>
Acked-by: Suzuki K Poulos <suzuki.poulose@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Branislav Rankov <branislav.rankov@arm.com>
Cc: Denis Nikitin <denik@chromium.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: coresight@lists.linaro.org
Link: https://lore.kernel.org/r/20210510143248.27423-3-james.clark@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
VM Time Correlation means determining if each TSC packet belongs to a VM
Guest or the Host. When the trace is "in context" that is indicated by
the NR flag in the PIP packet. However, when tracing kernel-only,
userspace only, or using address filters, the trace can be "out of context"
in which case timing packets are produced but not PIP packets.
Nevertheless, it is very unlikely the VM Guest timestamps will be in
the same range as the Host timestamps. Host time ranges are established
by a starting side-band event timestamp, and subsequently by the buffer
timestamp, written when the buffer is copied to the perf.data file.
This patch supports updating the VM Guest timestamp packets, assuming an
unchanging (during perf record) VMX TSC Offset and no VMX TSC scaling.
Furthermore, it is possible to determine what the VMX TSC Offset is,
although not necessarily at the start. The dry-run option lets that
information be determined so that the user can pass it to a subsequent
run. For more detail, refer to the example in the Intel PT documentation
in a subsequent patch.
VM Time Correlation is also performed on the TSC value in PEBs-via-PT
records.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210430070309.17624-12-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Even when VMX TSC Offset is not changing (during perf record), different
virtual machines can have different TSC Offsets. There is a Virtual Machine
Control Structure (VMCS) for each virtual CPU, the address of which is
reported to Intel PT in the VMCS packet. We do not know which VMCS belongs
to which virtual machine, so use a tree to keep track of VMCS information.
Then the decoder will be able to use the current VMCS value to look up the
current TSC Offset.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210430070309.17624-9-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Intel PT timestamps are affected by virtualization. Add a new option
that will allow the Intel PT decoder to correlate the timestamps and
translate the virtual machine timestamps to host timestamps.
The advantages of making this a separate step, rather than a part of
normal decoding are that it is simpler to implement, and it needs to
be done only once.
This patch adds only the option. Later patches add Intel PT support.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20210430070309.17624-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
It's confusing which one is effective when the both options are given.
The current code happens to use -c in this case but users might not be
aware of it. We can change it to complain about that instead of relying
on the implicit priority.
Before:
$ perf record -c 111111 -F 99 true
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.031 MB perf.data (8 samples) ]
$ perf evlist -F
cycles: sample_period=111111
$
After:
$ perf record -c 111111 -F 99 true
cannot set frequency and period at the same time
$
So this change can break existing usages, but I think it's rare to have
both options and it'd be better changing them.
Suggested-by: Alexey Alexandrov <aalexand@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210402094020.28164-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull perf tool updates from Arnaldo Carvalho de Melo:
"perf stat:
- Add support for hybrid PMUs to support systems such as Intel
Alderlake and its BIG/little core/atom cpus.
- Introduce 'bperf' to share hardware PMCs with BPF.
- New --iostat option to collect and present IO stats on Intel
hardware.
This functionality is based on recently introduced sysfs attributes
for Intel® Xeon® Scalable processor family (code name Skylake-SP)
in commit bb42b3d397 ("perf/x86/intel/uncore: Expose an Uncore
unit to IIO PMON mapping")
It is intended to provide four I/O performance metrics in MB per
each PCIe root port:
- Inbound Read: I/O devices below root port read from the host memory
- Inbound Write: I/O devices below root port write to the host memory
- Outbound Read: CPU reads from I/O devices below root port
- Outbound Write: CPU writes to I/O devices below root port
- Align CSV output for summary.
- Clarify --null use cases: Assess raw overhead of 'perf stat' or
measure just wall clock time.
- Improve readability of shadow stats.
perf record:
- Change the COMM when starting tha workload so that --exclude-perf
doesn't seem to be not honoured.
- Improve 'Workload failed' message printing events + what was
exec'ed.
- Fix cross-arch support for TIME_CONV.
perf report:
- Add option to disable raw event ordering.
- Dump the contents of PERF_RECORD_TIME_CONV in 'perf report -D'.
- Improvements to --stat output, that shows information about
PERF_RECORD_ events.
- Preserve identifier id in OCaml demangler.
perf annotate:
- Show full source location with 'l' hotkey in the 'perf annotate'
TUI.
- Add line number like in TUI and source location at EOL to the 'perf
annotate' --stdio mode.
- Add --demangle and --demangle-kernel to 'perf annotate'.
- Allow configuring annotate.demangle{,_kernel} in 'perf config'.
- Fix sample events lost in stdio mode.
perf data:
- Allow converting a perf.data file to JSON.
libperf:
- Add support for user space counter access.
- Update topdown documentation to permit rdpmc calls.
perf test:
- Add 'perf test' for 'perf stat' CSV output.
- Add 'perf test' entries to test the hybrid PMU support.
- Cleanup 'perf test daemon' if its 'perf test' is interrupted.
- Handle metric reuse in pmu-events parsing 'perf test' entry.
- Add test for PE executable support.
- Add timeout for wait for daemon start in its 'perf test' entries.
Build:
- Enable libtraceevent dynamic linking.
- Improve feature detection output.
- Fix caching of feature checks caching.
- First round of updates for tools copies of kernel headers.
- Enable warnings when compiling BPF programs.
Vendor specific events:
- Intel:
- Add missing skylake & icelake model numbers.
- arm64:
- Add Hisi hip08 L1, L2 and L3 metrics.
- Add Fujitsu A64FX PMU events.
- PowerPC:
- Initial JSON/events list for power10 platform.
- Remove unsupported power9 metrics.
- AMD:
- Add Zen3 events.
- Fix broken L2 Cache Hits from L2 HWPF metric.
- Use lowercases for all the eventcodes and umasks.
Hardware tracing:
- arm64:
- Update CoreSight ETM metadata format.
- Fix bitmap for CS-ETM option.
- Support PID tracing in config.
- Detect pid in VMID for kernel running at EL2.
Arch specific updates:
- MIPS:
- Support MIPS unwinding and dwarf-regs.
- Generate mips syscalls_n64.c syscall table.
- PowerPC:
- Add support for PERF_SAMPLE_WEIGH_STRUCT on PowerPC.
- Support pipeline stage cycles for powerpc.
libbeauty:
- Fix fsconfig generator"
* tag 'perf-tools-for-v5.13-2021-04-29' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (132 commits)
perf build: Defer printing detected features to the end of all feature checks
tools build: Allow deferring printing the results of feature detection
perf build: Regenerate the FEATURE_DUMP file after extra feature checks
perf session: Dump PERF_RECORD_TIME_CONV event
perf session: Add swap operation for event TIME_CONV
perf jit: Let convert_timestamp() to be backwards-compatible
perf tools: Change fields type in perf_record_time_conv
perf tools: Enable libtraceevent dynamic linking
perf Documentation: Document intel-hybrid support
perf tests: Skip 'perf stat metrics (shadow stat) test' for hybrid
perf tests: Support 'Convert perf time to TSC' test for hybrid
perf tests: Support 'Session topology' test for hybrid
perf tests: Support 'Parse and process metrics' test for hybrid
perf tests: Support 'Track with sched_switch' test for hybrid
perf tests: Skip 'Setup struct perf_event_attr' test for hybrid
perf tests: Add hybrid cases for 'Roundtrip evsel->name' test
perf tests: Add hybrid cases for 'Parse event definition strings' test
perf record: Uniquify hybrid event name
perf stat: Warn group events from different hybrid PMU
perf stat: Filter out unmatched aggregation for hybrid event
...
If a group has events which are from different hybrid PMUs,
shows a warning:
"WARNING: events in group from different hybrid PMUs!"
This is to remind the user not to put the core event and atom
event into one group.
Next, just disable grouping.
# perf stat -e "{cpu_core/cycles/,cpu_atom/cycles/}" -a -- sleep 1
WARNING: events in group from different hybrid PMUs!
WARNING: grouped events cpus do not match, disabling group:
anon group { cpu_core/cycles/, cpu_atom/cycles/ }
Performance counter stats for 'system wide':
5,438,125 cpu_core/cycles/
3,914,586 cpu_atom/cycles/
1.004250966 seconds time elapsed
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427070139.25256-17-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
On hybrid platform, user may want to enable events on one pmu.
Following syntax are supported:
cpu_core/<event>/
cpu_atom/<event>/
But the syntax doesn't work for cache event.
Before:
# perf stat -e cpu_core/LLC-loads/ -a -- sleep 1
event syntax error: 'cpu_core/LLC-loads/'
\___ unknown term 'LLC-loads' for pmu 'cpu_core'
Cache events are a bit complex. We can't create aliases for them.
We use another solution. For example, if we use "cpu_core/LLC-loads/",
in parse_events_add_pmu(), term->config is "LLC-loads".
Then we create a new parser to scan "LLC-loads". The
parse_events_add_cache() would be called during parsing.
The parse_state->hybrid_pmu_name is used to identify the pmu
where the event should be enabled on.
After:
# perf stat -e cpu_core/LLC-loads/ -a -- sleep 1
Performance counter stats for 'system wide':
24,593 cpu_core/LLC-loads/
1.003911601 seconds time elapsed
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427070139.25256-13-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
The functions perf_pmu__is_hybrid and perf_pmu__find_hybrid_pmu
can be used to identify the hybrid platform and return the found
hybrid cpu pmu. All the detected hybrid pmus have been saved in
'perf_pmu__hybrid_pmus' list. So we just need to search this list.
perf_pmu__hybrid_type_to_pmu converts the user specified string
to hybrid pmu name. This is used to support the '--cputype' option
in next patches.
perf_pmu__has_hybrid checks the existing of hybrid pmu. Note that,
we have to define it in pmu.c (make pmu-hybrid.c no more symbol
dependency), otherwise perf test python would be failed.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427070139.25256-7-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We identify the cpu_core pmu and cpu_atom pmu by explicitly
checking following files:
For cpu_core, checks:
"/sys/bus/event_source/devices/cpu_core/cpus"
For cpu_atom, checks:
"/sys/bus/event_source/devices/cpu_atom/cpus"
If the 'cpus' file exists and it has data, the pmu exists.
But in order not to hardcode the "cpu_core" and "cpu_atom",
and make the code in a generic way.
So if the path "/sys/bus/event_source/devices/cpu_xxx/cpus" exists, the
hybrid pmu exists. All the detected hybrid pmus are linked to a global
list 'perf_pmu__hybrid_pmus' and then next we just need to iterate the
list to get all hybrid pmu by using perf_pmu__for_each_hybrid_pmu.
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427070139.25256-6-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To make the output more readable, I think it's better to remove 0's in
the output. Also the dummy event has no event stats so it just wasts
the space. Let's use the --skip-empty option to suppress it.
$ perf report --stat --skip-empty
Aggregated stats:
TOTAL events: 16530
MMAP events: 226
COMM events: 1596
EXIT events: 2
THROTTLE events: 121
UNTHROTTLE events: 117
FORK events: 1595
SAMPLE events: 719
MMAP2 events: 12147
CGROUP events: 2
FINISHED_ROUND events: 2
THREAD_MAP events: 1
CPU_MAP events: 1
TIME_CONV events: 1
cycles stats:
SAMPLE events: 719
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210427013717.1651674-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Currently, to use BPF to aggregate perf event counters, the user uses
--bpf-counters option. Enable "use bpf by default" events with a config
option, stat.bpf-counter-events. Events with name in the option will use
BPF.
This also enables mixed BPF event and regular event in the same sesssion.
For example:
perf config stat.bpf-counter-events=instructions
perf stat -e instructions,cs
The second command will use BPF for "instructions" but not "cs".
Signed-off-by: Song Liu <song@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/r/20210425214333.1090950-4-song@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull x86 updates from Borislav Petkov:
- Turn the stack canary into a normal __percpu variable on 32-bit which
gets rid of the LAZY_GS stuff and a lot of code.
- Add an insn_decode() API which all users of the instruction decoder
should preferrably use. Its goal is to keep the details of the
instruction decoder away from its users and simplify and streamline
how one decodes insns in the kernel. Convert its users to it.
- kprobes improvements and fixes
- Set the maximum DIE per package variable on Hygon
- Rip out the dynamic NOP selection and simplify all the machinery
around selecting NOPs. Use the simplified NOPs in objtool now too.
- Add Xeon Sapphire Rapids to list of CPUs that support PPIN
- Simplify the retpolines by folding the entire thing into an
alternative now that objtool can handle alternatives with stack ops.
Then, have objtool rewrite the call to the retpoline with the
alternative which then will get patched at boot time.
- Document Intel uarch per models in intel-family.h
- Make Sub-NUMA Clustering topology the default and Cluster-on-Die the
exception on Intel.
* tag 'x86_core_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
x86, sched: Treat Intel SNC topology as default, COD as exception
x86/cpu: Comment Skylake server stepping too
x86/cpu: Resort and comment Intel models
objtool/x86: Rewrite retpoline thunk calls
objtool: Skip magical retpoline .altinstr_replacement
objtool: Cache instruction relocs
objtool: Keep track of retpoline call sites
objtool: Add elf_create_undef_symbol()
objtool: Extract elf_symbol_add()
objtool: Extract elf_strtab_concat()
objtool: Create reloc sections implicitly
objtool: Add elf_create_reloc() helper
objtool: Rework the elf_rebuild_reloc_section() logic
objtool: Fix static_call list generation
objtool: Handle per arch retpoline naming
objtool: Correctly handle retpoline thunk calls
x86/retpoline: Simplify retpolines
x86/alternatives: Optimize optimize_nops()
x86: Add insn_decode_kernel()
x86/kprobes: Move 'inline' to the beginning of the kprobe_is_ss() declaration
...
