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Athira Rajeev 875b2bf469 powerpc/perf: Optimize clearing the pending PMI and remove WARN_ON for PMI check in power_pmu_disable 
[ Upstream commit 890005a7d9 ]

commit 2c9ac51b85 ("powerpc/perf: Fix PMU callbacks to clear
pending PMI before resetting an overflown PMC") added a new
function "pmi_irq_pending" in hw_irq.h. This function is to check
if there is a PMI marked as pending in Paca (PACA_IRQ_PMI).This is
used in power_pmu_disable in a WARN_ON. The intention here is to
provide a warning if there is PMI pending, but no counter is found
overflown.

During some of the perf runs, below warning is hit:

WARNING: CPU: 36 PID: 0 at arch/powerpc/perf/core-book3s.c:1332 power_pmu_disable+0x25c/0x2c0
 Modules linked in:
 -----

 NIP [c000000000141c3c] power_pmu_disable+0x25c/0x2c0
 LR [c000000000141c8c] power_pmu_disable+0x2ac/0x2c0
 Call Trace:
 [c000000baffcfb90] [c000000000141c8c] power_pmu_disable+0x2ac/0x2c0 (unreliable)
 [c000000baffcfc10] [c0000000003e2f8c] perf_pmu_disable+0x4c/0x60
 [c000000baffcfc30] [c0000000003e3344] group_sched_out.part.124+0x44/0x100
 [c000000baffcfc80] [c0000000003e353c] __perf_event_disable+0x13c/0x240
 [c000000baffcfcd0] [c0000000003dd334] event_function+0xc4/0x140
 [c000000baffcfd20] [c0000000003d855c] remote_function+0x7c/0xa0
 [c000000baffcfd50] [c00000000026c394] flush_smp_call_function_queue+0xd4/0x300
 [c000000baffcfde0] [c000000000065b24] smp_ipi_demux_relaxed+0xa4/0x100
 [c000000baffcfe20] [c0000000000cb2b0] xive_muxed_ipi_action+0x20/0x40
 [c000000baffcfe40] [c000000000207c3c] __handle_irq_event_percpu+0x8c/0x250
 [c000000baffcfee0] [c000000000207e2c] handle_irq_event_percpu+0x2c/0xa0
 [c000000baffcff10] [c000000000210a04] handle_percpu_irq+0x84/0xc0
 [c000000baffcff40] [c000000000205f14] generic_handle_irq+0x54/0x80
 [c000000baffcff60] [c000000000015740] __do_irq+0x90/0x1d0
 [c000000baffcff90] [c000000000016990] __do_IRQ+0xc0/0x140
 [c0000009732f3940] [c000000bafceaca8] 0xc000000bafceaca8
 [c0000009732f39d0] [c000000000016b78] do_IRQ+0x168/0x1c0
 [c0000009732f3a00] [c0000000000090c8] hardware_interrupt_common_virt+0x218/0x220

This means that there is no PMC overflown among the active events
in the PMU, but there is a PMU pending in Paca. The function
"any_pmc_overflown" checks the PMCs on active events in
cpuhw->n_events. Code snippet:

<<>>
if (any_pmc_overflown(cpuhw))
 	clear_pmi_irq_pending();
 else
 	WARN_ON(pmi_irq_pending());
<<>>

Here the PMC overflown is not from active event. Example: When we do
perf record, default cycles and instructions will be running on PMC6
and PMC5 respectively. It could happen that overflowed event is currently
not active and pending PMI is for the inactive event. Debug logs from
trace_printk:

<<>>
any_pmc_overflown: idx is 5: pmc value is 0xd9a
power_pmu_disable: PMC1: 0x0, PMC2: 0x0, PMC3: 0x0, PMC4: 0x0, PMC5: 0xd9a, PMC6: 0x80002011
<<>>

Here active PMC (from idx) is PMC5 , but overflown PMC is PMC6(0x80002011).
When we handle PMI interrupt for such cases, if the PMC overflown is
from inactive event, it will be ignored. Reference commit:
commit bc09c219b2 ("powerpc/perf: Fix finding overflowed PMC in interrupt")

Patch addresses two changes:
1) Fix 1 : Removal of warning ( WARN_ON(pmi_irq_pending()); )
   We were printing warning if no PMC is found overflown among active PMU
   events, but PMI pending in PACA. But this could happen in cases where
   PMC overflown is not in active PMC. An inactive event could have caused
   the overflow. Hence the warning is not needed. To know pending PMI is
   from an inactive event, we need to loop through all PMC's which will
   cause more SPR reads via mfspr and increase in context switch. Also in
   existing function: perf_event_interrupt, already we ignore PMI's
   overflown when it is from an inactive PMC.

2) Fix 2: optimization in clearing pending PMI.
   Currently we check for any active PMC overflown before clearing PMI
   pending in Paca. This is causing additional SPR read also. From point 1,
   we know that if PMI pending in Paca from inactive cases, that is going
   to be ignored during replay. Hence if there is pending PMI in Paca, just
   clear it irrespective of PMC overflown or not.

In summary, remove the any_pmc_overflown check entirely in
power_pmu_disable. ie If there is a pending PMI in Paca, clear it, since
we are in pmu_disable. There could be cases where PMI is pending because
of inactive PMC ( which later when replayed also will get ignored ), so
WARN_ON could give false warning. Hence removing it.

Fixes: 2c9ac51b85 ("powerpc/perf: Fix PMU callbacks to clear pending PMI before resetting an overflown PMC")
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220522142256.24699-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-21 15:16:06 +02:00
arch powerpc/perf: Optimize clearing the pending PMI and remove WARN_ON for PMI check in power_pmu_disable 2022-08-21 15:16:06 +02:00
block block: remove the request_queue to argument request based tracepoints 2022-08-21 15:15:36 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:13:18 +02:00
Documentation x86: Handle idle=nomwait cmdline properly for x86_idle 2022-08-21 15:15:28 +02:00
drivers remoteproc: k3-r5: Fix refcount leak in k3_r5_cluster_of_init 2022-08-21 15:16:05 +02:00
fs jbd2: fix assertion 'jh->b_frozen_data == NULL' failure when journal aborted 2022-08-21 15:16:04 +02:00
include netfilter: xtables: Bring SPDX identifier back 2022-08-21 15:15:54 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:21:25 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:21:17 +02:00
kernel profiling: fix shift too large makes kernel panic 2022-08-21 15:16:05 +02:00
lib selftests/livepatch: better synchronize test_klp_callbacks_busy 2022-08-21 15:16:05 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region 2022-08-21 15:16:02 +02:00
net dccp: put dccp_qpolicy_full() and dccp_qpolicy_push() in the same lock 2022-08-21 15:15:52 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts x86/retbleed: Add fine grained Kconfig knobs 2022-07-25 11:26:50 +02:00
security selinux: Add boundary check in put_entry() 2022-08-21 15:15:31 +02:00
sound ASoC: samsung: h1940_uda1380: include proepr GPIO consumer header 2022-08-21 15:16:06 +02:00
tools selftests: kvm: set rax before vmcall 2022-08-21 15:16:03 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Don't set Accessed/Dirty bits for ZERO_PAGE 2022-08-21 15:15:54 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
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.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Amir as xfs maintainer for 5.10.y 2022-07-02 16:39:22 +02:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-21 15:15:18 +02:00
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