[PATCH v2 10/12] perf tools: Add RISC-V trace PMU record capabilities
Anup Patel
apatel at ventanamicro.com
Thu Jan 1 19:52:26 PST 2026
On Fri, Nov 21, 2025 at 1:39 PM Nutty.Liu <nutty.liu at hotmail.com> wrote:
>
> On 11/1/2025 11:42 PM, Anup Patel wrote:
> > From: Mayuresh Chitale <mchitale at ventanamicro.com>
> >
> > Introduce the required auxiliary API functions allowing the perf core
> > to interact with RISC-V trace perf driver.
> >
> > Co-developed-by: Anup Patel <apatel at ventanamicro.com>
> > Signed-off-by: Anup Patel <apatel at ventanamicro.com>
> > Signed-off-by: Mayuresh Chitale <mchitale at ventanamicro.com>
> > ---
> > 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
> Seems the above comment 'page_size' is redundant.
Okay, I will update.
>
> > +#include "../../../util/auxtrace.h"
> > +#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;
> Nit: How about checking if 'err' is NULL since it's passed from other
> module ?
Other archs (ARM and x86) also don't check "err" anywhere so
to be consistent we don't check "err" here.
>
> Otherwise,
> Reviewed-by: Nutty Liu <nutty.liu at hotmail.com>
>
> Thanks,
> Nutty
Regards,
Anup
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