linux-kernel - [PATCH 06/11] rvtrace: Add function to copy into perf AUX buffer

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Message-ID: <20251002060732.100213-7-apatel@ventanamicro.com>
Date: Thu,  2 Oct 2025 11:37:27 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Ian Rogers <irogers@...gle.com>
Cc: Alexandre Ghiti <alex@...ti.fr>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Liang Kan <kan.liang@...ux.intel.com>,
	Mayuresh Chitale <mchitale@...il.com>,
	Anup Patel <anup@...infault.org>,
	Atish Patra <atish.patra@...ux.dev>,
	Andrew Jones <ajones@...tanamicro.com>,
	Sunil V L <sunilvl@...tanamicro.com>,
	linux-riscv@...ts.infradead.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Anup Patel <apatel@...tanamicro.com>,
	Mayuresh Chitale <mchitale@...tanamicro.com>
Subject: [PATCH 06/11] rvtrace: Add function to copy into perf AUX buffer

The RISC-V trace ramsink will need a mechanism to copy trace data
into the perf AUX buffer. Add rvtrace_path_copyto_auxbuf() function
and corresponding trace driver callback copyto_auxbuf() for this
purpose.

Co-developed-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 drivers/hwtracing/rvtrace/rvtrace-core.c | 22 ++++++++++++++++++++++
 include/linux/rvtrace.h                  | 21 +++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/hwtracing/rvtrace/rvtrace-core.c b/drivers/hwtracing/rvtrace/rvtrace-core.c
index 109be40d4b24..e874899c8b43 100644
--- a/drivers/hwtracing/rvtrace/rvtrace-core.c
+++ b/drivers/hwtracing/rvtrace/rvtrace-core.c
@@ -658,6 +658,28 @@ int rvtrace_path_stop(struct rvtrace_path *path)
 }
 EXPORT_SYMBOL_GPL(rvtrace_path_stop);
 
+int rvtrace_path_copyto_auxbuf(struct rvtrace_path *path,
+			       struct rvtrace_perf_auxbuf *buf,
+			       size_t *bytes_copied)
+{
+	const struct rvtrace_driver *rtdrv;
+	struct rvtrace_component *comp;
+	struct rvtrace_path_node *node;
+
+	list_for_each_entry(node, &path->comp_list, head) {
+		comp = node->comp;
+		rtdrv = to_rvtrace_driver(comp->dev.driver);
+		if (!rtdrv->copyto_auxbuf)
+			continue;
+
+		*bytes_copied = rtdrv->copyto_auxbuf(comp, buf);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_GPL(rvtrace_path_copyto_auxbuf);
+
 struct rvtrace_path *rvtrace_create_path(struct rvtrace_component *source,
 					 struct rvtrace_component *sink,
 					 enum rvtrace_component_mode mode)
diff --git a/include/linux/rvtrace.h b/include/linux/rvtrace.h
index e7bd335d388f..17d2fd9234c2 100644
--- a/include/linux/rvtrace.h
+++ b/include/linux/rvtrace.h
@@ -276,9 +276,28 @@ void rvtrace_destroy_path(struct rvtrace_path *path);
 int rvtrace_path_start(struct rvtrace_path *path);
 int rvtrace_path_stop(struct rvtrace_path *path);
 
+/**
+ * struct rvtrace_perf_auxbuf - Representation of the perf AUX buffer
+ * @length:   size of the AUX buffer
+ * @nr_pages: number of pages of the AUX buffer
+ * @base:     start address of AUX buffer
+ * @pos:      position in the AUX buffer to commit traced data
+ */
+struct rvtrace_perf_auxbuf {
+	size_t length;
+	int nr_pages;
+	void *base;
+	long pos;
+};
+
+int rvtrace_path_copyto_auxbuf(struct rvtrace_path *path,
+			       struct rvtrace_perf_auxbuf *buf,
+			       size_t *bytes_copied);
+
 /**
  * struct rvtrace_driver - Representation of a RISC-V trace driver
  * id_table: Table to match components handled by the driver
+ * copyto_auxbuf:Callback to copy data into perf AUX buffer
  * start:        Callback to start tracing
  * stop:         Callback to stop tracing
  * probe:        Driver probe() function
@@ -289,6 +308,8 @@ int rvtrace_path_stop(struct rvtrace_path *path);
  */
 struct rvtrace_driver {
 	const struct rvtrace_component_id *id_table;
+	size_t			(*copyto_auxbuf)(struct rvtrace_component *comp,
+						 struct rvtrace_perf_auxbuf *buf);
 	int			(*start)(struct rvtrace_component *comp);
 	int			(*stop)(struct rvtrace_component *comp);
 	int			(*probe)(struct rvtrace_component *comp);
-- 
2.43.0