From 18736eef12137c59f60cc9f56dc5bea05c92e0eb Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Fri, 15 Feb 2019 13:56:54 +0200 Subject: [PATCH] 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 Signed-off-by: Alexander Shishkin Tested-by: Mathieu Poirier Acked-by: Peter Zijlstra Cc: Jiri Olsa Fixes: 375637bc5249 ("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 --- kernel/events/core.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 5aeb4c74fb99..2d89efc0a3e0 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -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; } -- 2.30.2