linux-kernel - [PATCH v4 20/22] perf: Allocate ring buffers for inherited per-task kernel events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1408538179-792-21-git-send-email-alexander.shishkin@linux.intel.com>
Date:	Wed, 20 Aug 2014 15:36:17 +0300
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	Robert Richter <rric@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <ak@...ux.intel.com>, kan.liang@...el.com,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Subject: [PATCH v4 20/22] perf: Allocate ring buffers for inherited per-task kernel events

When a new event is inherited from a per-task kernel event that has a
ring buffer, allocate a new buffer for this event so that data from the
child task is collected and can later be retrieved for sample annotation
or whatnot.

Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
 kernel/events/core.c     |  9 +++++++++
 kernel/events/internal.h | 11 +++++++++++
 2 files changed, 20 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3b1550fd0e..9d7f6086d5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8230,6 +8230,15 @@ inherit_event(struct perf_event *parent_event,
 		(void)perf_event_set_output(child_event, parent_event);
 
 	/*
+	 * For per-task kernel events with ring buffers, set_output doesn't
+	 * make sense, but we can allocate a new buffer here.
+	 */
+	if (parent_event->cpu == -1 && kernel_rb_event(parent_event)) {
+		(void)rb_alloc_kernel(child_event, parent_event->rb->nr_pages,
+				      parent_event->rb->aux_nr_pages);
+	}
+
+	/*
 	 * Precalculate sample_data sizes
 	 */
 	perf_event__header_size(child_event);
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index bb035dd645..b306bc9307 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -120,6 +120,17 @@ static inline unsigned long perf_aux_size(struct ring_buffer *rb)
 	return rb->aux_nr_pages << PAGE_SHIFT;
 }
 
+static inline bool kernel_rb_event(struct perf_event *event)
+{
+	/*
+	 * Having a ring buffer and not being on any ring buffers' wakeup
+	 * list means it was attached by rb_alloc_kernel() and not
+	 * ring_buffer_attach(). It's the only case when these two
+	 * conditions take place at the same time.
+	 */
+	return event->rb && list_empty(&event->rb_entry);
+}
+
 #define DEFINE_OUTPUT_COPY(func_name, memcpy_func)			\
 static inline unsigned long						\
 func_name(struct perf_output_handle *handle,				\
-- 
2.1.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/