Re: [PATCH v2 10/12] perf tools: Add RISC-V trace PMU record capabilities
From: Nutty.Liu
Date: Fri Nov 21 2025 - 03:09:26 EST
On 11/1/2025 11:42 PM, Anup Patel wrote:
From: Mayuresh Chitale <mchitale@xxxxxxxxxxxxxxxx>Seems the above comment 'page_size' is redundant.
Introduce the required auxiliary API functions allowing the perf core
to interact with RISC-V trace perf driver.
Co-developed-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx>
Signed-off-by: Mayuresh Chitale <mchitale@xxxxxxxxxxxxxxxx>
---
tools/perf/arch/riscv/util/Build | 1 +
tools/perf/arch/riscv/util/auxtrace.c | 218 ++++++++++++++++++++++++++
tools/perf/util/auxtrace.c | 1 +
tools/perf/util/auxtrace.h | 1 +
tools/perf/util/rvtrace.h | 18 +++
5 files changed, 239 insertions(+)
create mode 100644 tools/perf/arch/riscv/util/auxtrace.c
create mode 100644 tools/perf/util/rvtrace.h
diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build
index 58a672246024..2ba1fb98a0ad 100644
--- a/tools/perf/arch/riscv/util/Build
+++ b/tools/perf/arch/riscv/util/Build
@@ -3,3 +3,4 @@ perf-util-y += header.o
perf-util-$(CONFIG_LIBTRACEEVENT) += kvm-stat.o
perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
+perf-util-$(CONFIG_AUXTRACE) += auxtrace.o
diff --git a/tools/perf/arch/riscv/util/auxtrace.c b/tools/perf/arch/riscv/util/auxtrace.c
new file mode 100644
index 000000000000..adc86bd38998
--- /dev/null
+++ b/tools/perf/arch/riscv/util/auxtrace.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Risc-V E-Trace support
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/log2.h>
+#include <linux/zalloc.h>
+#include <time.h>
+
+#include <internal/lib.h> // page_size
+#include "../../../util/auxtrace.h"Nit: How about checking if 'err' is NULL since it's passed from other module ?
+#include "../../../util/cpumap.h"
+#include "../../../util/debug.h"
+#include "../../../util/event.h"
+#include "../../../util/evlist.h"
+#include "../../../util/evsel.h"
+#include "../../../util/rvtrace.h"
+#include "../../../util/pmu.h"
+#include "../../../util/record.h"
+#include "../../../util/session.h"
+#include "../../../util/tsc.h"
+
+#define RVTRACE_PMU_NAME "rvtrace"
+#define KiB(x) ((x) * 1024)
+#define MiB(x) ((x) * 1024 * 1024)
+
+struct rvtrace_recording {
+ struct auxtrace_record itr;
+ struct perf_pmu *rvtrace_pmu;
+ struct evlist *evlist;
+};
+
+static size_t rvtrace_info_priv_size(struct auxtrace_record *itr __maybe_unused,
+ struct evlist *evlist __maybe_unused)
+{
+ return RVTRACE_AUXTRACE_PRIV_SIZE;
+}
+
+static int rvtrace_info_fill(struct auxtrace_record *itr, struct perf_session *session,
+ struct perf_record_auxtrace_info *auxtrace_info, size_t priv_size)
+{
+ struct rvtrace_recording *ptr = container_of(itr, struct rvtrace_recording, itr);
+ struct perf_pmu *rvtrace_pmu = ptr->rvtrace_pmu;
+
+ if (priv_size != RVTRACE_AUXTRACE_PRIV_SIZE)
+ return -EINVAL;
+
+ if (!session->evlist->core.nr_mmaps)
+ return -EINVAL;
+
+ auxtrace_info->type = PERF_AUXTRACE_RISCV_TRACE;
+ auxtrace_info->priv[0] = rvtrace_pmu->type;
+
+ return 0;
+}
+
+static int rvtrace_set_auxtrace_mmap_page(struct record_opts *opts)
+{
+ bool privileged = perf_event_paranoid_check(-1);
+
+ if (!opts->full_auxtrace)
+ return 0;
+
+ if (opts->full_auxtrace && !opts->auxtrace_mmap_pages) {
+ if (privileged) {
+ opts->auxtrace_mmap_pages = MiB(16) / page_size;
+ } else {
+ opts->auxtrace_mmap_pages = KiB(128) / page_size;
+ if (opts->mmap_pages == UINT_MAX)
+ opts->mmap_pages = KiB(256) / page_size;
+ }
+ }
+
+ /* Validate auxtrace_mmap_pages */
+ if (opts->auxtrace_mmap_pages) {
+ size_t sz = opts->auxtrace_mmap_pages * (size_t)page_size;
+ size_t min_sz = KiB(8);
+
+ if (sz < min_sz || !is_power_of_2(sz)) {
+ pr_err("Invalid mmap size : must be at least %zuKiB and a power of 2\n",
+ min_sz / 1024);
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+static int rvtrace_recording_options(struct auxtrace_record *itr, struct evlist *evlist,
+ struct record_opts *opts)
+{
+ struct rvtrace_recording *ptr = container_of(itr, struct rvtrace_recording, itr);
+ struct perf_pmu *rvtrace_pmu = ptr->rvtrace_pmu;
+ struct evsel *evsel, *rvtrace_evsel = NULL;
+ struct evsel *tracking_evsel;
+ int err;
+
+ ptr->evlist = evlist;
+ evlist__for_each_entry(evlist, evsel) {
+ if (evsel->core.attr.type == rvtrace_pmu->type) {
+ if (rvtrace_evsel) {
+ pr_err("There may be only one " RVTRACE_PMU_NAME "x event\n");
+ return -EINVAL;
+ }
+ evsel->core.attr.freq = 0;
+ evsel->core.attr.sample_period = 1;
+ evsel->needs_auxtrace_mmap = true;
+ rvtrace_evsel = evsel;
+ opts->full_auxtrace = true;
+ }
+ }
+
+ err = rvtrace_set_auxtrace_mmap_page(opts);
+ if (err)
+ return err;
+ /*
+ * To obtain the auxtrace buffer file descriptor, the auxtrace event
+ * must come first.
+ */
+ evlist__to_front(evlist, rvtrace_evsel);
+ evsel__set_sample_bit(rvtrace_evsel, TIME);
+
+ /* Add dummy event to keep tracking */
+ err = parse_event(evlist, "dummy:u");
+ if (err)
+ return err;
+
+ tracking_evsel = evlist__last(evlist);
+ evlist__set_tracking_event(evlist, tracking_evsel);
+
+ tracking_evsel->core.attr.freq = 0;
+ tracking_evsel->core.attr.sample_period = 1;
+ evsel__set_sample_bit(tracking_evsel, TIME);
+
+ return 0;
+}
+
+static u64 rvtrace_reference(struct auxtrace_record *itr __maybe_unused)
+{
+ return rdtsc();
+}
+
+static void rvtrace_recording_free(struct auxtrace_record *itr)
+{
+ struct rvtrace_recording *ptr =
+ container_of(itr, struct rvtrace_recording, itr);
+
+ free(ptr);
+}
+
+static struct auxtrace_record *rvtrace_recording_init(int *err, struct perf_pmu *rvtrace_pmu)
+{
+ struct rvtrace_recording *ptr;
+
+ if (!rvtrace_pmu) {
+ *err = -ENODEV;
Otherwise,
Reviewed-by: Nutty Liu <nutty.liu@xxxxxxxxxxx>
Thanks,
Nutty