uprobes/perf: Avoid uprobe_apply() whenever possible
uprobe_perf_open/close call the costly uprobe_apply() every time, we can avoid it if: - "nr_systemwide != 0" is not changed. - There is another process/thread with the same ->mm. - copy_proccess() does inherit_event(). dup_mmap() preserves the inserted breakpoints. - event->attr.enable_on_exec == T, we can rely on uprobe_mmap() called by exec/mmap paths. - tp_target is exiting. Only _close() checks PF_EXITING, I don't think TRACE_REG_PERF_OPEN can hit the dying task too often. Signed-off-by: Oleg Nesterov <oleg@redhat.com>
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1 changed files with 36 additions and 6 deletions
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@ -680,30 +680,60 @@ __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
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return false;
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return false;
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}
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}
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static inline bool
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uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
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{
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return __uprobe_perf_filter(&tu->filter, event->hw.tp_target->mm);
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}
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static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
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static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
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{
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{
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bool done;
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write_lock(&tu->filter.rwlock);
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write_lock(&tu->filter.rwlock);
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if (event->hw.tp_target)
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if (event->hw.tp_target) {
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/*
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* event->parent != NULL means copy_process(), we can avoid
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* uprobe_apply(). current->mm must be probed and we can rely
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* on dup_mmap() which preserves the already installed bp's.
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*
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* attr.enable_on_exec means that exec/mmap will install the
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* breakpoints we need.
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*/
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done = tu->filter.nr_systemwide ||
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event->parent || event->attr.enable_on_exec ||
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uprobe_filter_event(tu, event);
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list_add(&event->hw.tp_list, &tu->filter.perf_events);
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list_add(&event->hw.tp_list, &tu->filter.perf_events);
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else
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} else {
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done = tu->filter.nr_systemwide;
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tu->filter.nr_systemwide++;
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tu->filter.nr_systemwide++;
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}
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write_unlock(&tu->filter.rwlock);
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write_unlock(&tu->filter.rwlock);
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uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
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if (!done)
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uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
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return 0;
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return 0;
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}
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}
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static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
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static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
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{
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{
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bool done;
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write_lock(&tu->filter.rwlock);
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write_lock(&tu->filter.rwlock);
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if (event->hw.tp_target)
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if (event->hw.tp_target) {
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list_del(&event->hw.tp_list);
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list_del(&event->hw.tp_list);
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else
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done = tu->filter.nr_systemwide ||
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(event->hw.tp_target->flags & PF_EXITING) ||
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uprobe_filter_event(tu, event);
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} else {
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tu->filter.nr_systemwide--;
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tu->filter.nr_systemwide--;
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done = tu->filter.nr_systemwide;
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}
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write_unlock(&tu->filter.rwlock);
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write_unlock(&tu->filter.rwlock);
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uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
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if (!done)
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uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
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return 0;
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return 0;
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}
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}
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