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perf/core: Fix reentry problem in perf_output_read_group()
commit 6b959ba22d
upstream.
perf_output_read_group may respond to IPI request of other cores and invoke
__perf_install_in_context function. As a result, hwc configuration is modified.
causing inconsistency and unexpected consequences.
Interrupts are not disabled when perf_output_read_group reads PMU counter.
In this case, IPI request may be received from other cores.
As a result, PMU configuration is modified and an error occurs when
reading PMU counter:
CPU0 CPU1
__se_sys_perf_event_open
perf_install_in_context
perf_output_read_group smp_call_function_single
for_each_sibling_event(sub, leader) { generic_exec_single
if ((sub != event) && remote_function
(sub->state == PERF_EVENT_STATE_ACTIVE)) |
<enter IPI handler: __perf_install_in_context> <----RAISE IPI-----+
__perf_install_in_context
ctx_resched
event_sched_out
armpmu_del
...
hwc->idx = -1; // event->hwc.idx is set to -1
...
<exit IPI>
sub->pmu->read(sub);
armpmu_read
armv8pmu_read_counter
armv8pmu_read_hw_counter
int idx = event->hw.idx; // idx = -1
u64 val = armv8pmu_read_evcntr(idx);
u32 counter = ARMV8_IDX_TO_COUNTER(idx); // invalid counter = 30
read_pmevcntrn(counter) // undefined instruction
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220902082918.179248-1-yangjihong1@huawei.com
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
ccd9fe71b9
commit
36b5c35d43
1 changed files with 9 additions and 0 deletions
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@ -7119,9 +7119,16 @@ static void perf_output_read_group(struct perf_output_handle *handle,
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{
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struct perf_event *leader = event->group_leader, *sub;
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u64 read_format = event->attr.read_format;
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unsigned long flags;
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u64 values[6];
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int n = 0;
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/*
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* Disabling interrupts avoids all counter scheduling
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* (context switches, timer based rotation and IPIs).
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*/
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local_irq_save(flags);
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values[n++] = 1 + leader->nr_siblings;
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if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
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@ -7157,6 +7164,8 @@ static void perf_output_read_group(struct perf_output_handle *handle,
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__output_copy(handle, values, n * sizeof(u64));
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}
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local_irq_restore(flags);
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}
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#define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
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