linux-stable.git/kernel/events/core.c, branch v6.7.4

perf: Fix the nr_addr_filters fix

2024-02-05T20:17:06+00:00

[ Upstream commit 388a1fb7da6aaa1970c7e2a7d7fcd983a87a8484 ]

Thomas reported that commit 652ffc2104ec ("perf/core: Fix narrow
startup race when creating the perf nr_addr_filters sysfs file") made
the entire attribute group vanish, instead of only the nr_addr_filters
attribute.

Additionally a stray return.

Insufficient coffee was involved with both writing and merging the
patch.

Fixes: 652ffc2104ec ("perf/core: Fix narrow startup race when creating the perf nr_addr_filters sysfs file")
Reported-by: Thomas Richter 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Thomas Richter 
Link: https://lkml.kernel.org/r/20231122100756.GP8262@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin

perf/core: Fix narrow startup race when creating the perf nr_addr_filters sysfs file

2024-02-05T20:16:45+00:00

[ Upstream commit 652ffc2104ec1f69dd4a46313888c33527145ccf ]

Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/2023061204-decal-flyable-6090@gregkh
Signed-off-by: Sasha Levin

perf: Fix perf_event_validate_size() lockdep splat

2023-12-15T11:33:23+00:00

When lockdep is enabled, the for_each_sibling_event(sibling, event)
macro checks that event->ctx->mutex is held. When creating a new group
leader event, we call perf_event_validate_size() on a partially
initialized event where event->ctx is NULL, and so when
for_each_sibling_event() attempts to check event->ctx->mutex, we get a
splat, as reported by Lucas De Marchi:

  WARNING: CPU: 8 PID: 1471 at kernel/events/core.c:1950 __do_sys_perf_event_open+0xf37/0x1080

This only happens for a new event which is its own group_leader, and in
this case there cannot be any sibling events. Thus it's safe to skip the
check for siblings, which avoids having to make invasive and ugly
changes to for_each_sibling_event().

Avoid the splat by bailing out early when the new event is its own
group_leader.

Fixes: 382c27f4ed28f803 ("perf: Fix perf_event_validate_size()")
Closes: https://lore.kernel.org/lkml/20231214000620.3081018-1-lucas.demarchi@intel.com/
Closes: https://lore.kernel.org/lkml/ZXpm6gQ%2Fd59jGsuW@xpf.sh.intel.com/
Reported-by: Lucas De Marchi 
Reported-by: Pengfei Xu 
Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20231215112450.3972309-1-mark.rutland@arm.com

perf: Fix perf_event_validate_size()

2023-11-29T14:43:50+00:00

Budimir noted that perf_event_validate_size() only checks the size of
the newly added event, even though the sizes of all existing events
can also change due to not all events having the same read_format.

When we attach the new event, perf_group_attach(), we do re-compute
the size for all events.

Fixes: a723968c0ed3 ("perf: Fix u16 overflows")
Reported-by: Budimir Markovic 
Signed-off-by: Peter Zijlstra (Intel)

perf/core: Fix cpuctx refcounting

2023-11-15T03:18:31+00:00

Audit of the refcounting turned up that perf_pmu_migrate_context()
fails to migrate the ctx refcount.

Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Link: https://lkml.kernel.org/r/20230612093539.085862001@infradead.org
Cc:

Merge tag 'perf-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-10-30T23:44:35+00:00

Pull performance event updates from Ingo Molnar:
 - Add AMD Unified Memory Controller (UMC) events introduced with Zen 4
 - Simplify & clean up the uncore management code
 - Fall back from RDPMC to RDMSR on certain uncore PMUs
 - Improve per-package and cstate event reading
 - Extend the Intel ref-cycles event to GP counters
 - Fix Intel MTL event constraints
 - Improve the Intel hybrid CPU handling code
 - Micro-optimize the RAPL code
 - Optimize perf_cgroup_switch()
 - Improve large AUX area error handling
 - Misc fixes and cleanups

* tag 'perf-core-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
  perf/x86/amd/uncore: Pass through error code for initialization failures, instead of -ENODEV
  perf/x86/amd/uncore: Fix uninitialized return value in amd_uncore_init()
  x86/cpu: Fix the AMD Fam 17h, Fam 19h, Zen2 and Zen4 MSR enumerations
  perf: Optimize perf_cgroup_switch()
  perf/x86/amd/uncore: Add memory controller support
  perf/x86/amd/uncore: Add group exclusivity
  perf/x86/amd/uncore: Use rdmsr if rdpmc is unavailable
  perf/x86/amd/uncore: Move discovery and registration
  perf/x86/amd/uncore: Refactor uncore management
  perf/core: Allow reading package events from perf_event_read_local
  perf/x86/cstate: Allow reading the package statistics from local CPU
  perf/x86/intel/pt: Fix kernel-doc comments
  perf/x86/rapl: Annotate 'struct rapl_pmus' with __counted_by
  perf/core: Rename perf_proc_update_handler() -> perf_event_max_sample_rate_handler(), for readability
  perf/x86/rapl: Fix "Using plain integer as NULL pointer" Sparse warning
  perf/x86/rapl: Use local64_try_cmpxchg in rapl_event_update()
  perf/x86/rapl: Stop doing cpu_relax() in the local64_cmpxchg() loop in rapl_event_update()
  perf/core: Bail out early if the request AUX area is out of bound
  perf/x86/intel: Extend the ref-cycles event to GP counters
  perf/x86/intel: Fix broken fixed event constraints extension
  ...

perf/core: Fix potential NULL deref

2023-10-24T10:15:12+00:00

Smatch is awesome.

Fixes: 32671e3799ca ("perf: Disallow mis-matched inherited group reads")
Reported-by: Dan Carpenter 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar

perf: Disallow mis-matched inherited group reads

2023-10-19T08:09:42+00:00

Because group consistency is non-atomic between parent (filedesc) and children
(inherited) events, it is possible for PERF_FORMAT_GROUP read() to try and sum
non-matching counter groups -- with non-sensical results.

Add group_generation to distinguish the case where a parent group removes and
adds an event and thus has the same number, but a different configuration of
events as inherited groups.

This became a problem when commit fa8c269353d5 ("perf/core: Invert
perf_read_group() loops") flipped the order of child_list and sibling_list.
Previously it would iterate the group (sibling_list) first, and for each
sibling traverse the child_list. In this order, only the group composition of
the parent is relevant. By flipping the order the group composition of the
child (inherited) events becomes an issue and the mis-match in group
composition becomes evident.

That said; even prior to this commit, while reading of a group that is not
equally inherited was not broken, it still made no sense.

(Ab)use ECHILD as error return to indicate issues with child process group
composition.

Fixes: fa8c269353d5 ("perf/core: Invert perf_read_group() loops")
Reported-by: Budimir Markovic 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20231018115654.GK33217@noisy.programming.kicks-ass.net

perf: Optimize perf_cgroup_switch()

2023-10-12T17:28:38+00:00

Namhyung reported that bd2756811766 ("perf: Rewrite core context handling")
regresses context switch overhead when perf-cgroup is in use together
with 'slow' PMUs like uncore.

Specifically, perf_cgroup_switch()'s perf_ctx_disable() /
ctx_sched_out() etc.. all iterate the full list of active PMUs for
that CPU, even if they don't have cgroup events.

Previously there was cgrp_cpuctx_list which linked the relevant PMUs
together, but that got lost in the rework. Instead of re-instruducing
a similar list, let the perf_event_pmu_context iteration skip those
that do not have cgroup events. This avoids growing multiple versions
of the perf_event_pmu_context iteration.

Measured performance (on a slightly different patch):

Before)

  $ taskset -c 0 ./perf bench sched pipe -l 10000 -G AAA,BBB
  # Running 'sched/pipe' benchmark:
  # Executed 10000 pipe operations between two processes

       Total time: 0.901 [sec]

        90.128700 usecs/op
            11095 ops/sec

After)

  $ taskset -c 0 ./perf bench sched pipe -l 10000 -G AAA,BBB
  # Running 'sched/pipe' benchmark:
  # Executed 10000 pipe operations between two processes

       Total time: 0.065 [sec]

         6.560100 usecs/op
           152436 ops/sec

Fixes: bd2756811766 ("perf: Rewrite core context handling")
Reported-by: Namhyung Kim 
Debugged-by: Namhyung Kim 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20231009210425.GC6307@noisy.programming.kicks-ass.net

perf/core: Allow reading package events from perf_event_read_local

2023-10-09T14:12:22+00:00

Per-package perf events are typically registered with a single CPU only,
however they can be read across all the CPUs within the package.
Currently perf_event_read maps the event CPU according to the topology
information to avoid an unnecessary SMP call, however
perf_event_read_local deals with hard values and rejects a read with a
failure if the CPU is not the one exactly registered. Allow similar
mapping within the perf_event_read_local if the perf event in question
can support this.

This allows users like BPF code to read the package perf events properly
across different CPUs within a package.

Signed-off-by: Tero Kristo 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20230913125956.3652667-1-tero.kristo@linux.intel.com