Commit 18736eef authored Feb 15, 2019 by Alexander Shishkin Committed by Arnaldo Carvalho de Melo Feb 22, 2019

perf: Copy parent's address filter offsets on clone



When a child event is allocated in the inherit_event() path, the VMA
based filter offsets are not copied from the parent, even though the
address space mapping of the new task remains the same, which leads to
no trace for the new task until exec.

Reported-by: Mansour Alharthi <malharthi9@gatech.edu>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Fixes: 375637bc ("perf/core: Introduce address range filtering")
Link: http://lkml.kernel.org/r/20190215115655.63469-2-alexander.shishkin@linux.intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent cd358012

kernel/events/core.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -1255,6 +1255,7 @@ static void put_ctx(struct perf_event_context *ctx)
		* perf_event_context::lock
		* perf_event::mmap_mutex
		* mmap_sem
		* perf_addr_filters_head::lock
		*
		* cpu_hotplug_lock
		* pmus_lock
		@@ -10312,6 +10313,20 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
		goto err_per_task;
		}

		/*
		* Clone the parent's vma offsets: they are valid until exec()
		* even if the mm is not shared with the parent.
		*/
		if (event->parent) {
		struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);

		raw_spin_lock_irq(&ifh->lock);
		memcpy(event->addr_filters_offs,
		event->parent->addr_filters_offs,
		pmu->nr_addr_filters * sizeof(unsigned long));
		raw_spin_unlock_irq(&ifh->lock);
		}

		/* force hw sync on the address filters */
		event->addr_filters_gen = 1;
		}

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