linux-kernel - [PATCH v3 1/5] tools headers UAPI: Sync linux/perf

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Message-ID: <20251114070018.160330-2-namhyung@kernel.org>
Date: Thu, 13 Nov 2025 23:00:14 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	James Clark <james.clark@...aro.org>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Indu Bhagat <indu.bhagat@...cle.com>,
	Jens Remus <jremus@...ux.ibm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-trace-kernel@...r.kernel.org,
	bpf@...r.kernel.org
Subject: [PATCH v3 1/5] tools headers UAPI: Sync linux/perf_event.h for deferred callchains

It needs to sync with the kernel to support user space changes for the
deferred callchains.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/include/uapi/linux/perf_event.h | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
index 78a362b8002776e5..d292f96bc06f86bc 100644
--- a/tools/include/uapi/linux/perf_event.h
+++ b/tools/include/uapi/linux/perf_event.h
@@ -463,7 +463,9 @@ struct perf_event_attr {
 				inherit_thread :  1, /* children only inherit if cloned with CLONE_THREAD */
 				remove_on_exec :  1, /* event is removed from task on exec */
 				sigtrap        :  1, /* send synchronous SIGTRAP on event */
-				__reserved_1   : 26;
+				defer_callchain:  1, /* request PERF_RECORD_CALLCHAIN_DEFERRED records */
+				defer_output   :  1, /* output PERF_RECORD_CALLCHAIN_DEFERRED records */
+				__reserved_1   : 24;
 
 	union {
 		__u32		wakeup_events;	  /* wake up every n events */
@@ -1239,6 +1241,22 @@ enum perf_event_type {
 	 */
 	PERF_RECORD_AUX_OUTPUT_HW_ID		= 21,
 
+	/*
+	 * This user callchain capture was deferred until shortly before
+	 * returning to user space.  Previous samples would have kernel
+	 * callchains only and they need to be stitched with this to make full
+	 * callchains.
+	 *
+	 * struct {
+	 *	struct perf_event_header	header;
+	 *	u64				cookie;
+	 *	u64				nr;
+	 *	u64				ips[nr];
+	 *	struct sample_id		sample_id;
+	 * };
+	 */
+	PERF_RECORD_CALLCHAIN_DEFERRED		= 22,
+
 	PERF_RECORD_MAX,			/* non-ABI */
 };
 
@@ -1269,6 +1287,7 @@ enum perf_callchain_context {
 	PERF_CONTEXT_HV				= (__u64)-32,
 	PERF_CONTEXT_KERNEL			= (__u64)-128,
 	PERF_CONTEXT_USER			= (__u64)-512,
+	PERF_CONTEXT_USER_DEFERRED		= (__u64)-640,
 
 	PERF_CONTEXT_GUEST			= (__u64)-2048,
 	PERF_CONTEXT_GUEST_KERNEL		= (__u64)-2176,
-- 
2.52.0.rc1.455.g30608eb744-goog