mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
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92 lines
3.0 KiB
Diff
92 lines
3.0 KiB
Diff
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From c3c87e770458aa004bd7ed3f29945ff436fd6511 Mon Sep 17 00:00:00 2001
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From: Peter Zijlstra <peterz@infradead.org>
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Date: Fri, 23 Jan 2015 11:19:48 +0100
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Subject: perf: Tighten (and fix) the grouping condition
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The fix from 9fc81d87420d ("perf: Fix events installation during
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moving group") was incomplete in that it failed to recognise that
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creating a group with events for different CPUs is semantically
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broken -- they cannot be co-scheduled.
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Furthermore, it leads to real breakage where, when we create an event
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for CPU Y and then migrate it to form a group on CPU X, the code gets
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confused where the counter is programmed -- triggered in practice
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as well by me via the perf fuzzer.
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Fix this by tightening the rules for creating groups. Only allow
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grouping of counters that can be co-scheduled in the same context.
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This means for the same task and/or the same cpu.
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Fixes: 9fc81d87420d ("perf: Fix events installation during moving group")
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
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Cc: Jiri Olsa <jolsa@redhat.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Link: http://lkml.kernel.org/r/20150123125834.090683288@infradead.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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---
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include/linux/perf_event.h | 6 ------
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kernel/events/core.c | 15 +++++++++++++--
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2 files changed, 13 insertions(+), 8 deletions(-)
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diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
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index 4f7a61c..664de5a 100644
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--- a/include/linux/perf_event.h
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+++ b/include/linux/perf_event.h
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@@ -450,11 +450,6 @@ struct perf_event {
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#endif /* CONFIG_PERF_EVENTS */
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};
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-enum perf_event_context_type {
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- task_context,
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- cpu_context,
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-};
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-
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/**
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* struct perf_event_context - event context structure
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*
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@@ -462,7 +457,6 @@ enum perf_event_context_type {
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*/
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struct perf_event_context {
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struct pmu *pmu;
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- enum perf_event_context_type type;
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/*
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* Protect the states of the events in the list,
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* nr_active, and the list:
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diff --git a/kernel/events/core.c b/kernel/events/core.c
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index 882f835a..19efcf1 100644
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--- a/kernel/events/core.c
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+++ b/kernel/events/core.c
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@@ -6776,7 +6776,6 @@ skip_type:
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__perf_event_init_context(&cpuctx->ctx);
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lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
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lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
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- cpuctx->ctx.type = cpu_context;
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cpuctx->ctx.pmu = pmu;
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__perf_cpu_hrtimer_init(cpuctx, cpu);
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@@ -7420,7 +7419,19 @@ SYSCALL_DEFINE5(perf_event_open,
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* task or CPU context:
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*/
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if (move_group) {
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- if (group_leader->ctx->type != ctx->type)
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+ /*
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+ * Make sure we're both on the same task, or both
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+ * per-cpu events.
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+ */
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+ if (group_leader->ctx->task != ctx->task)
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+ goto err_context;
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+
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+ /*
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+ * Make sure we're both events for the same CPU;
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+ * grouping events for different CPUs is broken; since
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+ * you can never concurrently schedule them anyhow.
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+ */
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+ if (group_leader->cpu != event->cpu)
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goto err_context;
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} else {
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if (group_leader->ctx != ctx)
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--
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cgit v1.1
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