Add the perf_evlist__mmap_cb_get() function to return 'struct perf_mmap'
object during perf_evlist__mmap_ops() call.

The array of 'struct mmap' is allocated via evlist__alloc_mmap(), in
this callback we simply returns pointer to the base object.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-20-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add perf_evlist__mmap_cb_idx function to call auxtrace_mmap_params__set_idx()
on each new index during perf_evlist__mmap_ops call.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-19-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add the perf_evlist_mmap_ops::mmap callback to be called in
mmap_per_evsel() to actually mmap the map.

Add libperf's perf_evlist__mmap_cb_mmap() function as libperf's mmap
callback.

New mmaped map gets refcount set to 2 in mmap__mmap(), we follow that in
mmap callback. We will move this to common place after we switch to
perf_evlist__mmap().
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-18-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add the perf_evlist_mmap_ops::get callback to be called in
mmap_per_evsel() to get/allocate the 'struct perf_mmap' object.

Add the libperf's perf_evlist__mmap_cb_get() function as libperf's get
callback.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-17-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add the perf_evlist_mmap_ops::idx callback to be called in
mmap_per_cpu() and mmap_per_thread() with current cpu and thread
indexes.

It's used by current aux code, so perf will use this callback to set the
aux index.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-16-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To be able to pass specific callbacks to evlist's mmap.

There will be a specific call to this function from perf's
evlist__mmap() and libperf's perf_evlist__mmap() functions in following
changes.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-15-jolsa@kernel.orgSigned-off-by: NJiri Olsa <jolsa@kernel.org>

Add libperf's version of perf_evlist__mmap()/munmap() functions and
exporting them in the perf/evlist.h header.

It's the backbone of what we have in perf code. The following changes
will add needed callbacks and then we'll finally switch the perf code to
use libperf's version.

Add mmap/mmap_ovw 'struct perf_mmap' object arrays to hold maps for
libperf's evlist.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-14-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__read_event() from tools/perf to libperf and export it in
the perf/mmap.h header.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-13-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__read_init() from tools/perf to libperf and export it in
the perf/mmap.h header.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-12-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__read_init() from tools/perf to libperf and export it in
perf/mmap.h header.

And add pr_debug2()/pr_debug3() macros support, because the code is
using them.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-11-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__consume() vrom tools/perf to libperf and export it in
the perf/mmap.h header.

Move also the needed helpers perf_mmap__write_tail(),
perf_mmap__read_head() and perf_mmap__empty().
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-10-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We will move this code to libperf shortly, so we need to free it of
'struct auxtrace_mmap' usage, because it won't be available in libperf
(for now).

The perf_event_mmap_page::aux_size is set when the aux mmap is mapped,
so the check is equivalent.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-9-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__put() from tools/perf to libperf.

Once perf_mmap__put() is moved, we need a way to call application
related unmap code (AIO and aux related code for eprf), when the map
goes away.

Add the perf_mmap::unmap callback to do that.

The unmap path from perf is:

  perf_mmap__put                           (libperf)
    perf_mmap__munmap                      (libperf)
      map->unmap_cb -> perf_mmap__unmap_cb (perf)
        mmap__munmap                       (perf)

Committer notes:

Add missing linux/kernel.h to tools/perf/lib/mmap.c to get the BUG_ON
definition.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-8-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__unmap() from tools/perf to libperf, to internal header
internal/mmap.h. It will be used in the following patches. And rename
the existing perf's function to mmap__munmap().
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-7-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__get() from tools/perf to libperf in the internal header
internal/mmap.h.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-6-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__mmap() from tools/perf to libperf, it will be used in
the following patches. And rename the existing perf's function to
mmap__mmap().
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-5-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Move perf_mmap__mmap_len() from tools/perf wto libperf, it will be used
in the following patches. And rename the existing perf's function to
mmap__mmap_len().
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-4-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add libperf's version of mmap params 'struct perf_mmap_param' object
with the basics: 'prot' and 'mask'.  Encapsulate it in the current
'struct mmap_params' object.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-3-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Add perf_mmap__init() function to initialize 'struct perf_mmap' objects.

Add it to a new mmap.c source file, that will carry all the mmap related
functions.
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-2-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Will and I have an interest in reviewing the pmu-events changes related
to arm64, so add a specific entry for this.
Signed-off-by: NJohn Garry <john.garry@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: linuxarm@huawei.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will@kernel.org>
Link: http://lore.kernel.org/lkml/1570611273-108281-1-git-send-email-john.garry@huawei.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Being const + weak breaks with some compilers that constant-propagate
from the weak symbol. This behavior is outside of the specification, but
in LLVM is chosen to match GCC's behavior.

LLVM's implementation was set in this patch:

  https://github.com/llvm/llvm-project/commit/f49573d1eedcf1e44893d5a062ac1b72c8419646

A const + weak symbol is set to be weak_odr:

  https://llvm.org/docs/LangRef.html

ODR is one definition rule, and given there is one constant definition
constant-propagation is possible. It is possible to get this code to
miscompile with LLVM when applying link time optimization. As compilers
become more aggressive, this is likely to break in more instances.

Move the definition of sample_reg_masks to the conditional part of
perf_regs.h and guard usage with HAVE_PERF_REGS_SUPPORT. This avoids the
weak symbol.

Fix an issue when HAVE_PERF_REGS_SUPPORT isn't defined from patch v1.
In v3, add perf_regs.c for architectures that HAVE_PERF_REGS_SUPPORT but
don't declare sample_regs_masks.

Further notes:

Jiri asked:

  "Is this just a precaution or you actualy saw some breakage?"

Ian answered:

  "We saw a breakage with clang with thinlto enabled for linking. Our
   compiler team had recently seen, and were surprised by, a similar issue
   and were able to dig out the weak ODR issue."
Signed-off-by: NIan Rogers <irogers@google.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Acked-by: NJiri Olsa <jolsa@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: clang-built-linux@googlegroups.com
Cc: Guo Ren <guoren@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: linux-riscv@lists.infradead.org
Cc: Mao Han <han_mao@c-sky.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20191001003623.255186-1-irogers@google.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Continuing from the previous cset comment, now that filter expression
works:

  # perf trace -e msr:* --filter="msr!=FS_BASE && msr != IA32_TSC_DEADLINE && msr != 0x830 && msr != 0x83f && msr !=IA32_SPEC_CTRL" --filter-pids 3750
     0.000 Timer/5033 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
     0.009 Timer/5033 msr:write_msr(msr: LSTAR, val: -1398800368)
     0.010 Timer/5033 msr:write_msr(msr: TSC_AUX, val: 4)
     0.050 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
    45.661 gnome-terminal/12595 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
    45.672 gnome-terminal/12595 msr:write_msr(msr: LSTAR, val: -1398800368)
    45.675 gnome-terminal/12595 msr:write_msr(msr: TSC_AUX, val: 3)
    54.852 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   130.508 Timer/4050 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
   130.527 Timer/4050 msr:write_msr(msr: LSTAR, val: -1398800368)
   130.531 Timer/4050 msr:write_msr(msr: TSC_AUX, val: 3)
   140.924 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   164.738 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   603.578 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   620.809 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   690.115 JS Watchdog/4259 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
   690.136 JS Watchdog/4259 msr:write_msr(msr: LSTAR, val: -1398800368)
   690.141 JS Watchdog/4259 msr:write_msr(msr: TSC_AUX, val: 3)
   690.186 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
   759.016 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
^C[root@quaco ~]#

Or look at the first 3 write_msr events for that IA32_TSC_DEADLINE to learn why
it happens so often:

  # perf trace --max-events=3 --max-stack=8 -e msr:* --filter="msr==IA32_TSC_DEADLINE" --filter-pids 3750
     0.000 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 19296732550862)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       lapic_next_deadline ([kernel.kallsyms])
                                       clockevents_program_event ([kernel.kallsyms])
                                       hrtimer_interrupt ([kernel.kallsyms])
                                       smp_apic_timer_interrupt ([kernel.kallsyms])
                                       apic_timer_interrupt ([kernel.kallsyms])
                                       cpuidle_enter_state ([kernel.kallsyms])
    32.646 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 19296800134158)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       lapic_next_deadline ([kernel.kallsyms])
                                       clockevents_program_event ([kernel.kallsyms])
                                       hrtimer_start_range_ns ([kernel.kallsyms])
                                       tick_nohz_restart_sched_tick ([kernel.kallsyms])
                                       tick_nohz_idle_exit ([kernel.kallsyms])
                                       do_idle ([kernel.kallsyms])
    32.802 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 19297507436922)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       lapic_next_deadline ([kernel.kallsyms])
                                       clockevents_program_event ([kernel.kallsyms])
                                       hrtimer_try_to_cancel ([kernel.kallsyms])
                                       hrtimer_cancel ([kernel.kallsyms])
                                       tick_nohz_restart_sched_tick ([kernel.kallsyms])
                                       tick_nohz_idle_exit ([kernel.kallsyms])
  #

And if some of the strings can't be found:

  # trace -e msr:* --filter="msr!=SPECULATIVE_EXECUTION_PROBLEMS_SOLUTION && msr != IA32_TSC_DEADLINE && msr != 0x830 && msr != 0x83f && msr !=IA32_SPEC_CTRL" --filter-pids 3750
  "SPECULATIVE_EXECUTION_PROBLEMS_SOLUTION" not found for "msr" in "msr:read_msr", can't set filter "(msr!=SPECULATIVE_EXECUTION_PROBLEMS_SOLUTION && msr != IA32_TSC_DEADLINE && msr != 0x830 && msr != 0x83f && msr !=IA32_SPEC_CTRL) && (common_pid != 28131 && common_pid != 3750)"
  #

Next step is to automatically wire up the pre-existing strarrays, which there
are quite a few.

The strtoul() methods will be further enhanced to allow for looking at other
arguments in a syscall/tracepoint, just like going from integer to string
(scnprintf methods), so that those "val" lines for the msr tracepoints can be
properly formatted or even resolved into some string.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-4qaai5iqjgefd11k4ddm7qg8@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

So that one can try things like:

  # perf trace -e msr:* --filter="msr!=FS_BASE && msr != IA32_TSC_DEADLINE && msr != 0x830 && msr != 0x83f && msr !=IA32_SPEC_CTRL" --filter-pids 3750

That, at this point in the patchset, without any strtoul in place for
tracepoint arguments, will result in:

  No resolver (strtoul) for "msr" in "msr:read_msr", can't set filter "(msr!=FS_BASE && msr != IA32_TSC_DEADLINE && msr != 0x830 && msr != 0x83f && msr !=IA32_SPEC_CTRL) && (common_pid != 25407 && common_pid != 3750)"
  #

See you in the next cset!

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-dx5j70fv2rgkeezd1cb3hv2p@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

And also for 'struct strarray', since its needed to implement
strarrays__strtoul(). This just traverses the entries and when finding a
match, returns (offset + index), i.e. the value associated with the
searched string.

E.g. "EFER" (MSR_EFER) returns:

  # grep -w EFER -B2 /tmp/build/perf/trace/beauty/generated/x86_arch_MSRs_array.c
  #define x86_64_specific_MSRs_offset 0xc0000080
  static const char *x86_64_specific_MSRs[] = {
	[0xc0000080 - x86_64_specific_MSRs_offset] = "EFER",
  #

  0xc0000080

This will be auto-attached to 'struct syscall_arg_fmt' entries
associated with strarrays as soon as we add a ->strarray and ->strarrays
to 'struct syscall_arg_fmt'.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-r2hpaahf8lishyb1owko9vs1@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This will go from a string to a number, so that filter expressions can
be constructed with strings and then, before applying the tracepoint
filters (or eBPF, in the future) we can map those strings to numbers.

The first one will be for 'msr' tracepoint arguments, but real quickly
we will be able to reuse all strarrays for that.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-wgqq48agcgr95b8dmn6fygtr@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Similar to what is in 'perf record', works just like there:

  # perf trace -e msr:*
   328.297 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.302 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.306 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.317 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.322 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.327 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.331 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.336 :0/0 msr:write_msr(msr: FS_BASE, val: 140240388381888)
   328.340 :0/0 ^Cmsr:write_msr(msr: FS_BASE, val: 140240388381888)
  #

So, for a system wide trace session looking at the write_msr tracepoint
we see a flood of MSR_FS_BASE, we need to get the number for that:

  # grep FS_BASE /tmp/build/perf/trace/beauty/generated/x86_arch_MSRs_array.c
	[0xc0000100 - x86_64_specific_MSRs_offset] = "FS_BASE",
  #

And then use it in a filter:

  # perf trace -e msr:* --filter="msr!=0xc0000100"
  <SNIP>
   942.177 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 3056931068232)
   942.199 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 3057135655252)
   942.203 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 3056931068222)
   942.231 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 3056998373022)
   942.241 :0/0 msr:write_msr(msr: IA32_TSC_DEADLINE, val: 3056931068236)
  <SNIP>
  #

Ok, lets filter that too, too noisy:

  # grep TSC_DEADLINE /tmp/build/perf/trace/beauty/generated/x86_arch_MSRs_array.c
	[0x000006E0] = "IA32_TSC_DEADLINE",
  #

  # perf trace -e msr:* --filter="msr!=0xc0000100 && msr!=0x6e0" -a sleep 0.1
     0.000 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
     0.066 CPU 0/KVM/4895 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
     0.070 CPU 0/KVM/4895 msr:write_msr(msr: 0x830, val: 34359740667)
     0.099 CPU 0/KVM/4895 msr:read_msr(msr: IA32_SYSENTER_ESP, val: -2199021993472)
     0.100 CPU 0/KVM/4895 msr:read_msr(msr: IA32_APICBASE, val: 4276096000)
     0.101 CPU 0/KVM/4895 msr:read_msr(msr: IA32_DEBUGCTLMSR)
     0.109 :0/0 msr:write_msr(msr: IA32_SPEC_CTRL)
     1.000 :0/0 msr:write_msr(msr: 0x830, val: 17179871485)
    18.893 :0/0 msr:write_msr(msr: 0x83f, val: 246)
    28.810 :0/0 msr:write_msr(msr: 0x830, val: 68719479037)
    40.117 CPU 0/KVM/4895 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
    40.127 CPU 0/KVM/4895 msr:read_msr(msr: IA32_DEBUGCTLMSR)
    40.139 CPU 0/KVM/4895 msr:write_msr(msr: LSTAR, val: -2130661312)
    40.141 CPU 0/KVM/4895 msr:write_msr(msr: SYSCALL_MASK, val: 14080)
    40.142 CPU 0/KVM/4895 msr:write_msr(msr: TSC_AUX)
    40.144 CPU 0/KVM/4895 msr:write_msr(msr: KERNEL_GS_BASE)
    40.147 CPU 0/KVM/4895 msr:write_msr(msr: IA32_SPEC_CTRL)
    40.148 CPU 0/KVM/4895 msr:write_msr(msr: IA32_FLUSH_CMD, val: 1)
    40.151 CPU 0/KVM/4895 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
  ^C
  #

One can combine that with filtering pids as well:

  # perf trace -e msr:* --filter="msr!=0xc0000100 && msr!=0x6e0" --filter-pids 4895 -a sleep 0.09
     0.000 :0/0 msr:write_msr(msr: 0x830, val: 4294969597)
     0.291 gnome-terminal/2790 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
     0.294 gnome-terminal/2790 msr:write_msr(msr: LSTAR, val: -1935671280)
     0.295 gnome-terminal/2790 msr:write_msr(msr: TSC_AUX, val: 6)
    10.940 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    15.943 gnome-shell/2096 msr:write_msr(msr: 0x830, val: 4294969597)
    16.975 :0/0 msr:write_msr(msr: 0x830, val: 4294969597)
    19.560 :0/0 msr:write_msr(msr: 0x83f, val: 246)
    25.162 :0/0 msr:read_msr(msr: IA32_TSC_ADJUST)
    25.807 JS Watchdog/3635 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
    25.820 :0/0 msr:write_msr(msr: IA32_SPEC_CTRL)
    25.941 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    26.941 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    29.942 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    45.313 :0/0 msr:write_msr(msr: 0x83f, val: 246)
    56.945 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    60.946 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 4294969597)
    74.096 JS Watchdog/8971 msr:write_msr(msr: IA32_SPEC_CTRL, val: 6)
    74.130 :0/0 msr:write_msr(msr: IA32_SPEC_CTRL)
    79.673 :0/0 msr:write_msr(msr: 0x83f, val: 246)
    79.947 gnome-terminal/2790 msr:write_msr(msr: 0x830, val: 17179871485)
  #

Or for just a pid, with callchains:

  # grep SYSCALL_MAS /tmp/build/perf/trace/beauty/generated/x86_arch_MSRs_array.c
	[0xc0000084 - x86_64_specific_MSRs_offset] = "SYSCALL_MASK",
  # perf trace -e msr:* --filter="msr==0xc0000084" --pid 2790 --call-graph=dwarf

     0.000 gnome-terminal/2790 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       kvm_on_user_return ([kvm])
                                       fire_user_return_notifiers ([kernel.kallsyms])
                                       exit_to_usermode_loop ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64 ([kernel.kallsyms])
                                       __GI___poll (inlined)
  9299.073 gnome-terminal/2790 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       kvm_on_user_return ([kvm])
                                       fire_user_return_notifiers ([kernel.kallsyms])
                                       exit_to_usermode_loop ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64 ([kernel.kallsyms])
                                       __GI___poll (inlined)
  9348.374 gnome-terminal/2790 msr:write_msr(msr: SYSCALL_MASK, val: 292608)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       kvm_on_user_return ([kvm])
                                       fire_user_return_notifiers ([kernel.kallsyms])
                                       exit_to_usermode_loop ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64 ([kernel.kallsyms])
                                       __GI___poll (inlined)
  <SNIP>
  #

Ok, just another form of KVM to emit MSRs :-)

Next step: elliminate those greps by getting the filter expression,
looking for arg names, then for the arrays associated with it to do a
reverse lookup.

Also allow those filters to be associated with strace-like syscall
names.

After that: augment the 'val' arg for 'msr:write_msr' based on the first
arg, 'msr'.

Then, do that with eBPF too, not just with tracepoint filters.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-95bfe5d4tzy5f66bx49d05rj@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We'll need this to support 'perf trace e tracepoint --filter=expr', as
the command line tracepoint filter is attache to the preceding evsel,
just like in 'perf record' and when we go to set pid filters, which we
do at the minimum to filter 'perf trace' own syscalls, we need to
append, not set the tp filter.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-daynpknni44ywuzi8iua57nn@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Will be used by 'perf trace' to support 'perf trace --filter', we need
to append to any pre-existing filter.

When parse_filter() gets invoked to process --filter, it'll set the
filter to that specified on the command line, later on, when we filter
out 'perf trace' own pid to avoid an event feedback loop, we need to
preserve the command line filter put in place by parse_filter().

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-h9rot08qmxlnfmte0holt68x@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Will be used to append such lists to existing filters.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-798vlyqfqw938ehoe8etivx1@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

So that we can go from:

  # perf trace -e msr:write_msr --max-stack=16 sleep 1
       0.000 sleep/6740 msr:write_msr(msr: 3221225728, val: 139636317451648)
                                         do_trace_write_msr ([kernel.kallsyms])
                                         do_trace_write_msr ([kernel.kallsyms])
                                         do_arch_prctl_64 ([kernel.kallsyms])
                                         __x64_sys_arch_prctl ([kernel.kallsyms])
                                         do_syscall_64 ([kernel.kallsyms])
                                         entry_SYSCALL_64 ([kernel.kallsyms])
                                         init_tls (/usr/lib64/ld-2.29.so)
                                         dl_main (/usr/lib64/ld-2.29.so)
                                         _dl_sysdep_start (/usr/lib64/ld-2.29.so)
                                         _dl_start (/usr/lib64/ld-2.29.so)
  #

To:

  # perf trace -e msr:write_msr --max-stack=16 sleep 1
     0.000 sleep/8519 msr:write_msr(msr: FS_BASE, val: 139878031705472)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_arch_prctl_64 ([kernel.kallsyms])
                                       __x64_sys_arch_prctl ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64 ([kernel.kallsyms])
                                       init_tls (/usr/lib64/ld-2.29.so)
                                       dl_main (/usr/lib64/ld-2.29.so)
                                       _dl_sysdep_start (/usr/lib64/ld-2.29.so)
                                       _dl_start (/usr/lib64/ld-2.29.so)
  #

This, in reverse, will allow for symbolic system call/tracepoint
filtering.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-q1q4unmqja5ex7dy0kb5cjaa@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We need to wrap those autogenerated string arrays with the
strarrays__scnprintf() formatter, do it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-wqjz4kwi4a0ot6lsis3kc65j@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

For instance 'msr' appears in several tracepoints, so we can associate
it with a single scnprintf() routine auto-generated from kernel headers,
as will be done in followup patches.

Start with an empty array of associations.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-89ptht6s5fez82lykuwq1eyb@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

This way we generate the source with the table for later use by plugins,
etc.

I.e. after running:

  $ make -C tools/perf O=/tmp/build/perf

We end up with:

  $ head /tmp/build/perf/trace/beauty/generated/x86_arch_MSRs_array.c
  static const char *x86_MSRs[] = {
  	[0x00000000] = "IA32_P5_MC_ADDR",
  	[0x00000001] = "IA32_P5_MC_TYPE",
  	[0x00000010] = "IA32_TSC",
  	[0x00000017] = "IA32_PLATFORM_ID",
  	[0x0000001b] = "IA32_APICBASE",
  	[0x00000020] = "KNC_PERFCTR0",
  	[0x00000021] = "KNC_PERFCTR1",
  	[0x00000028] = "KNC_EVNTSEL0",
  	[0x00000029] = "KNC_EVNTSEL1",
  $

Now its just a matter of using it, first in a libtracevent plugin.

At some point we should move tools/perf/trace/beauty to tools/beauty/,
so that it can be used more generally and even made available externally
like libbpf, libperf, libtraevent, etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-b3rmutg4igcohx6kpo67qh4j@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Without parameters it'll parse tools/arch/x86/include/asm/msr-index.h
and output a table usable by tools, that will be wired up later to a
libtraceevent plugin registered from perf's glue code:

  $ tools/perf/trace/beauty/tracepoints/x86_msr.sh
  static const char *x86_MSRs[] = {
 <SNIP>
  	[0x00000034] = "SMI_COUNT",
  	[0x0000003a] = "IA32_FEATURE_CONTROL",
  	[0x0000003b] = "IA32_TSC_ADJUST",
  	[0x00000040] = "LBR_CORE_FROM",
  	[0x00000048] = "IA32_SPEC_CTRL",
  	[0x00000049] = "IA32_PRED_CMD",
 <SNIP>
  	[0x0000010b] = "IA32_FLUSH_CMD",
  	[0x0000010F] = "TSX_FORCE_ABORT",
 <SNIP>
  	[0x00000198] = "IA32_PERF_STATUS",
  	[0x00000199] = "IA32_PERF_CTL",
  <SNIP>
  	[0x00000da0] = "IA32_XSS",
  	[0x00000dc0] = "LBR_INFO_0",
  	[0x00000ffc] = "IA32_BNDCFGS_RSVD",
  };

  #define x86_64_specific_MSRs_offset 0xc0000080
  static const char *x86_64_specific_MSRs[] = {
  	[0xc0000080 - x86_64_specific_MSRs_offset] = "EFER",
  	[0xc0000081 - x86_64_specific_MSRs_offset] = "STAR",
  	[0xc0000082 - x86_64_specific_MSRs_offset] = "LSTAR",
  	[0xc0000083 - x86_64_specific_MSRs_offset] = "CSTAR",
  	[0xc0000084 - x86_64_specific_MSRs_offset] = "SYSCALL_MASK",
  <SNIP>
  	[0xc0000103 - x86_64_specific_MSRs_offset] = "TSC_AUX",
  	[0xc0000104 - x86_64_specific_MSRs_offset] = "AMD64_TSC_RATIO",
  };

  #define x86_AMD_V_KVM_MSRs_offset 0xc0010000
  static const char *x86_AMD_V_KVM_MSRs[] = {
  	[0xc0010000 - x86_AMD_V_KVM_MSRs_offset] = "K7_EVNTSEL0",
  <SNIP>
  	[0xc0010114 - x86_AMD_V_KVM_MSRs_offset] = "VM_CR",
  	[0xc0010115 - x86_AMD_V_KVM_MSRs_offset] = "VM_IGNNE",
  	[0xc0010117 - x86_AMD_V_KVM_MSRs_offset] = "VM_HSAVE_PA",
  <SNIP>
  	[0xc0010240 - x86_AMD_V_KVM_MSRs_offset] = "F15H_NB_PERF_CTL",
  	[0xc0010241 - x86_AMD_V_KVM_MSRs_offset] = "F15H_NB_PERF_CTR",
  	[0xc0010280 - x86_AMD_V_KVM_MSRs_offset] = "F15H_PTSC",
  };

Then these will in turn be hooked up in a follow up patch to be used by
strarrays__scnprintf().

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-ja080xawx08kedez855usnon@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We need it for things like MSRs that are sparse and go over MAXINT.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-g8t2d0jr0mg3yimg2qrjkvlt@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

We'll use it to generate a table and then convert the
msr:{read,write}_msr 'msr' option in things like perf trace, script,
etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-y1f4s0y1s43d4drh7pd2huzn@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

So far we used the libtraceevent printing routines when showing
tracepoint arguments, but since 'perf trace' has a lot of beautifiers
for syscall arguments, and since some of those can be used to augment
tracepoint arguments, add a routine to make use of those beautifiers
and allow the user to choose which one to use.

The default now is to use the same beautifiers used for the strace-like
sys_enter+sys_exit lines, but the user can choose the libtraceevent ones
by either using the:

    perf trace --libtraceevent_print

command line option, or by setting:

  # cat ~/.perfconfig
  [trace]
	tracepoint_beautifiers = libtraceevent

For instance, here are some examples:

  # perf trace -e sched:*switch,*sleep,sched:*wakeup,exit*,sched:*exit sleep 1
       0.000 sched:sched_wakeup(comm: "perf", pid: 5273 (perf), prio: 120, success: 1, target_cpu: 6)
       0.621 nanosleep(rqtp: 0x7ffdd06d1140, rmtp: NULL) ...
       0.628 sched:sched_switch(prev_comm: "sleep", prev_pid: 5273 (sleep), prev_prio: 120, prev_state: 1, next_comm: "swapper/6", next_pid: 0, next_prio: 120)
    1000.879 sched:sched_wakeup(comm: "sleep", pid: 5273 (sleep), prio: 120, success: 1, target_cpu: 6)
       0.621  ... [continued]: nanosleep())          = 0
    1001.026 exit_group(error_code: 0)               = ?
    1001.216 sched:sched_process_exit(comm: "sleep", pid: 5273 (sleep), prio: 120)
  #

And then using libtraceevent, as before:

  # perf trace --libtraceevent_print -e sched:*switch,*sleep,sched:*wakeup,exit*,sched:*exit sleep 1
       0.000 sched:sched_wakeup(comm=perf pid=5288 prio=120 target_cpu=001)
       0.739 nanosleep(rqtp: 0x7ffeba6c2f40, rmtp: NULL) ...
       0.747 sched:sched_switch(prev_comm=sleep prev_pid=5288 prev_prio=120 prev_state=S ==> next_comm=swapper/1 next_pid=0 next_prio=120)
    1000.902 sched:sched_wakeup(comm=sleep pid=5288 prio=120 target_cpu=001)
       0.739  ... [continued]: nanosleep())          = 0
    1001.012 exit_group(error_code: 0)               = ?
  #

The new default allocates an array of 'struct syscall_arg_fmt' for the
tracepoint arguments and, just like with syscall arguments, tries to
find suitable syscall_arg__scnprintf_NAME() routines to augment those
tracepoint arguments based on their type (as in the tracefs "format"
file), or even in their name + type, for instance arguntents with names
ending in "fd" with type "int" get the fd scnprintf beautifier attached,
etc.

Soon this will take advantage of the kernel BTF information to augment
enumerations based on the tracefs "format" type info.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-o8qdluotkcb3b1x2gjqrejcl@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

So that they look a bit like normal strace-like syscall enter+exit
lines.

They will look even more when we switch from using libtraceevent's
tep_print_event() routine in favour of using all the perf beautifiers
used by the strace-like syscall enter+exit lines.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-y4fcej6v6u1m644nbxd2r4pg@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

Needed for sched's traceoints prev/next comm, where, unlike with
syscalls, we are not dealing with an integer or pointer, but an array
straight out from the ring buffer.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-rlll7tmcqe1g4odtaifil5re@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

So that the scnprintf beautifiers can access it, as will be the case
with the char array one in the following csets, that needs to know
the number of elements in an array.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-01qmjqv6cb1nj1qy4khdexce@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>