Re: [PATCH 07/14] tools/perf: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc

[Adrian Hunter <adrian.hunter@intel.com>]

On 15/08/2025 11:34, Athira Rajeev wrote:
> The powerpc PMU collecting Dispatch Trace Log (DTL) entries makes use of
> AUX support in perf infrastructure. The PMU driver has the functionality
> to collect trace entries in the aux buffer. On the tools side, this data
> is made available as PERF_RECORD_AUXTRACE records. This record is
> generated by "perf record" command. To enable the creation of
> PERF_RECORD_AUXTRACE, add functions to initialize auxtrace records ie
> "auxtrace_record__init()". Fill in fields for other callbacks like
> info_priv_size, info_fill, free, recording options etc. Define
> auxtrace_type as PERF_AUXTRACE_VPA_PMU. Add header file to define vpa
> dtl pmu specific details.
> 
> Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
> ---
>  tools/perf/arch/powerpc/util/Build      |   1 +
>  tools/perf/arch/powerpc/util/auxtrace.c | 122 ++++++++++++++++++++++++
>  tools/perf/util/auxtrace.c              |   2 +
>  tools/perf/util/auxtrace.h              |   1 +
>  tools/perf/util/powerpc-vpadtl.h        |  26 +++++
>  5 files changed, 152 insertions(+)
>  create mode 100644 tools/perf/arch/powerpc/util/auxtrace.c
>  create mode 100644 tools/perf/util/powerpc-vpadtl.h
> 
> diff --git a/tools/perf/arch/powerpc/util/Build b/tools/perf/arch/powerpc/util/Build
> index fdd6a77a3432..a5b0babd307e 100644
> --- a/tools/perf/arch/powerpc/util/Build
> +++ b/tools/perf/arch/powerpc/util/Build
> @@ -10,3 +10,4 @@ perf-util-$(CONFIG_LIBDW) += skip-callchain-idx.o
>  
>  perf-util-$(CONFIG_LIBUNWIND) += unwind-libunwind.o
>  perf-util-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
> +perf-util-$(CONFIG_AUXTRACE) += auxtrace.o
> diff --git a/tools/perf/arch/powerpc/util/auxtrace.c b/tools/perf/arch/powerpc/util/auxtrace.c
> new file mode 100644
> index 000000000000..ec8ec601fd08
> --- /dev/null
> +++ b/tools/perf/arch/powerpc/util/auxtrace.c
> @@ -0,0 +1,122 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * VPA support
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/types.h>
> +#include <linux/bitops.h>
> +#include <linux/log2.h>
> +#include <time.h>
> +
> +#include "../../util/cpumap.h"
> +#include "../../util/evsel.h"
> +#include "../../util/evlist.h"
> +#include "../../util/session.h"
> +#include "../../util/util.h"
> +#include "../../util/pmu.h"
> +#include "../../util/debug.h"
> +#include "../../util/auxtrace.h"
> +#include "../../util/powerpc-vpadtl.h"

It would be better to only add #includes when they are needed

> +#include "../../util/record.h"
> +#include <internal/lib.h> // page_size
> +
> +#define KiB(x) ((x) * 1024)
> +
> +static int
> +powerpc_vpadtl_parse_snapshot_options(struct auxtrace_record *itr __maybe_unused,
> +				struct record_opts *opts __maybe_unused,
> +				const char *str __maybe_unused)
> +{
> +	return 0;
> +}
> +
> +static int
> +powerpc_vpadtl_recording_options(struct auxtrace_record *ar __maybe_unused,
> +			struct evlist *evlist __maybe_unused,
> +			struct record_opts *opts)
> +{
> +	opts->full_auxtrace = true;
> +
> +	/*
> +	 * Set auxtrace_mmap_pages to minimum
> +	 * two pages
> +	 */
> +	if (!opts->auxtrace_mmap_pages) {
> +		opts->auxtrace_mmap_pages = KiB(128) / page_size;
> +		if (opts->mmap_pages == UINT_MAX)
> +			opts->mmap_pages = KiB(256) / page_size;
> +	}
> +
> +	return 0;
> +}
> +
> +static size_t powerpc_vpadtl_info_priv_size(struct auxtrace_record *itr __maybe_unused,
> +					struct evlist *evlist __maybe_unused)
> +{
> +	return 0;

	return VPADTL_AUXTRACE_PRIV_SIZE;
> +}
> +
> +static int
> +powerpc_vpadtl_info_fill(struct auxtrace_record *itr __maybe_unused,
> +		struct perf_session *session __maybe_unused,
> +		struct perf_record_auxtrace_info *auxtrace_info __maybe_unused,

auxtrace_info is not __maybe_unused

> +		size_t priv_size __maybe_unused)
> +{
> +	auxtrace_info->type = PERF_AUXTRACE_VPA_PMU;
> +
> +	return 0;
> +}
> +
> +static u64 powerpc_vpadtl_reference(struct auxtrace_record *itr __maybe_unused)
> +{
> +	return 0;
> +}
> +
> +static void powerpc_vpadtl_free(struct auxtrace_record *itr)
> +{
> +	free(itr);
> +}
> +
> +struct auxtrace_record *auxtrace_record__init(struct evlist *evlist __maybe_unused,

evlist is not __maybe_unused

> +						int *err)
> +{
> +	struct auxtrace_record *aux;
> +	struct evsel *pos;
> +	char *pmu_name;
> +	int found = 0;
> +
> +	evlist__for_each_entry(evlist, pos) {
> +		pmu_name = strdup(pos->name);
> +		pmu_name = strtok(pmu_name, "/");
> +		if (!strcmp(pmu_name, "vpa_dtl")) {

pmu_name is leaked but strstarts() could be used instead
of above

> +			found = 1;
> +			pos->needs_auxtrace_mmap = true;
> +			break;
> +		}
> +	}
> +
> +	if (!found)
> +		return NULL;
> +
> +	/*
> +	 * To obtain the auxtrace buffer file descriptor, the auxtrace event
> +	 * must come first.
> +	 */
> +	evlist__to_front(pos->evlist, pos);
> +
> +	aux = zalloc(sizeof(*aux));
> +	if (aux == NULL) {
> +		pr_debug("aux record is NULL\n");
> +		*err = -ENOMEM;
> +		return NULL;
> +	}
> +
> +	aux->parse_snapshot_options = powerpc_vpadtl_parse_snapshot_options;

Doesn't look like snapshot mode is supported, so
powerpc_vpadtl_parse_snapshot_options() is not needed

> +	aux->recording_options = powerpc_vpadtl_recording_options;
> +	aux->info_priv_size = powerpc_vpadtl_info_priv_size;
> +	aux->info_fill = powerpc_vpadtl_info_fill;
> +	aux->free = powerpc_vpadtl_free;
> +	aux->reference = powerpc_vpadtl_reference;

reference is optional.  powerpc_vpadtl_reference() stub is not needed

> +	return aux;
> +}
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index ebd32f1b8f12..f587d386c5ef 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -55,6 +55,7 @@
>  #include "hisi-ptt.h"
>  #include "s390-cpumsf.h"
>  #include "util/mmap.h"
> +#include "powerpc-vpadtl.h"

Isn't needed yet

>  
>  #include <linux/ctype.h>
>  #include "symbol/kallsyms.h"
> @@ -1393,6 +1394,7 @@ int perf_event__process_auxtrace_info(struct perf_session *session,
>  	case PERF_AUXTRACE_HISI_PTT:
>  		err = hisi_ptt_process_auxtrace_info(event, session);
>  		break;
> +	case PERF_AUXTRACE_VPA_PMU:
>  	case PERF_AUXTRACE_UNKNOWN:
>  	default:
>  		return -EINVAL;
> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
> index f001cbb68f8e..1f9ef473af77 100644
> --- a/tools/perf/util/auxtrace.h
> +++ b/tools/perf/util/auxtrace.h
> @@ -50,6 +50,7 @@ enum auxtrace_type {
>  	PERF_AUXTRACE_ARM_SPE,
>  	PERF_AUXTRACE_S390_CPUMSF,
>  	PERF_AUXTRACE_HISI_PTT,
> +	PERF_AUXTRACE_VPA_PMU,

Everything else is called some variation of vpa dtl, so
PERF_AUXTRACE_VPA_DTL would seem a more consistent name

>  };
>  
>  enum itrace_period_type {
> diff --git a/tools/perf/util/powerpc-vpadtl.h b/tools/perf/util/powerpc-vpadtl.h
> new file mode 100644
> index 000000000000..625172adaba5
> --- /dev/null
> +++ b/tools/perf/util/powerpc-vpadtl.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * VPA DTL PMU Support
> + */
> +
> +#ifndef INCLUDE__PERF_POWERPC_VPADTL_H__
> +#define INCLUDE__PERF_POWERPC_VPADTL_H__
> +
> +#define POWERPC_VPADTL_NAME "powerpc_vpadtl_"
> +
> +enum {
> +	POWERPC_VPADTL_TYPE,
> +	VPADTL_PER_CPU_MMAPS,

VPADTL_PER_CPU_MMAPS is never used

> +	VPADTL_AUXTRACE_PRIV_MAX,
> +};
> +
> +#define VPADTL_AUXTRACE_PRIV_SIZE (VPADTL_AUXTRACE_PRIV_MAX * sizeof(u64))
> +
> +union perf_event;
> +struct perf_session;
> +struct perf_pmu;
> +
> +int powerpc_vpadtl_process_auxtrace_info(union perf_event *event,
> +				  struct perf_session *session);

None of these definitions are used in this patch, although probably
VPADTL_AUXTRACE_PRIV_SIZE should be.
It would be better to add definitions only when they are needed.

> +
> +#endif