Subject: Re: [PATCH v9 perf, bpf-next 5/9] perf util: handle PERF_RECORD_KSYMBOL

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Wed, 16 Jan 2019 11:22:21 -0300

Em Wed, Jan 16, 2019 at 02:12:37PM +0000, Song Liu escreveu:
> 
> 
> > On Jan 16, 2019, at 6:00 AM, Arnaldo Carvalho de Melo <[email-masked]> wrote:
> > 
> > Em Tue, Jan 15, 2019 at 04:14:06PM -0800, Song Liu escreveu:
> >> This patch handles PERF_RECORD_KSYMBOL in perf record/report.
> >> Specifically, map and symbol are created for ksymbol register, and
> >> removed for ksymbol unregister.
> >> 
> >> This patch also set perf_event_attr.ksymbol properly. The flag is
> >> ON by default.
> >> 
> >> Signed-off-by: Song Liu <[email-masked]>
> >> ---
> >> tools/perf/util/event.c   | 21 +++++++++++++++
> >> tools/perf/util/event.h   | 20 ++++++++++++++
> >> tools/perf/util/evsel.c   | 12 ++++++++-
> >> tools/perf/util/evsel.h   |  1 +
> >> tools/perf/util/machine.c | 57 +++++++++++++++++++++++++++++++++++++++
> >> tools/perf/util/machine.h |  3 +++
> >> tools/perf/util/session.c |  4 +++
> >> tools/perf/util/tool.h    |  4 ++-
> >> 8 files changed, 120 insertions(+), 2 deletions(-)
> >> 
> >> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> >> index 937a5a4f71cc..3c8a6a8dd260 100644
> >> --- a/tools/perf/util/event.c
> >> +++ b/tools/perf/util/event.c
> >> @@ -24,6 +24,7 @@
> >> #include "symbol/kallsyms.h"
> >> #include "asm/bug.h"
> >> #include "stat.h"
> >> +#include "session.h"
> >> 
> >> #define DEFAULT_PROC_MAP_PARSE_TIMEOUT 500
> >> 
> >> @@ -45,6 +46,7 @@ static const char *perf_event__names[] = {
> >> 	[PERF_RECORD_SWITCH]			= "SWITCH",
> >> 	[PERF_RECORD_SWITCH_CPU_WIDE]		= "SWITCH_CPU_WIDE",
> >> 	[PERF_RECORD_NAMESPACES]		= "NAMESPACES",
> >> +	[PERF_RECORD_KSYMBOL]			= "KSYMBOL",
> >> 	[PERF_RECORD_HEADER_ATTR]		= "ATTR",
> >> 	[PERF_RECORD_HEADER_EVENT_TYPE]		= "EVENT_TYPE",
> >> 	[PERF_RECORD_HEADER_TRACING_DATA]	= "TRACING_DATA",
> >> @@ -1329,6 +1331,14 @@ int perf_event__process_switch(struct perf_tool *tool __maybe_unused,
> >> 	return machine__process_switch_event(machine, event);
> >> }
> >> 
> >> +int perf_event__process_ksymbol(struct perf_tool *tool __maybe_unused,
> >> +				union perf_event *event,
> >> +				struct perf_sample *sample __maybe_unused,
> >> +				struct machine *machine)
> >> +{
> >> +	return machine__process_ksymbol(machine, event, sample);
> >> +}
> >> +
> >> size_t perf_event__fprintf_mmap(union perf_event *event, FILE *fp)
> >> {
> >> 	return fprintf(fp, " %d/%d: [%#" PRIx64 "(%#" PRIx64 ") @ %#" PRIx64 "]: %c %s\n",
> >> @@ -1461,6 +1471,14 @@ static size_t perf_event__fprintf_lost(union perf_event *event, FILE *fp)
> >> 	return fprintf(fp, " lost %" PRIu64 "\n", event->lost.lost);
> >> }
> >> 
> >> +size_t perf_event__fprintf_ksymbol(union perf_event *event, FILE *fp)
> >> +{
> >> +	return fprintf(fp, " ksymbol event with addr %lx len %u type %u flags 0x%x name %s\n",
> >> +		       event->ksymbol_event.addr, event->ksymbol_event.len,
> >> +		       event->ksymbol_event.ksym_type,
> >> +		       event->ksymbol_event.flags, event->ksymbol_event.name);
> >> +}
> >> +
> >> size_t perf_event__fprintf(union perf_event *event, FILE *fp)
> >> {
> >> 	size_t ret = fprintf(fp, "PERF_RECORD_%s",
> >> @@ -1496,6 +1514,9 @@ size_t perf_event__fprintf(union perf_event *event, FILE *fp)
> >> 	case PERF_RECORD_LOST:
> >> 		ret += perf_event__fprintf_lost(event, fp);
> >> 		break;
> >> +	case PERF_RECORD_KSYMBOL:
> >> +		ret += perf_event__fprintf_ksymbol(event, fp);
> >> +		break;
> >> 	default:
> >> 		ret += fprintf(fp, "\n");
> >> 	}
> >> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
> >> index eb95f3384958..018322f2a13e 100644
> >> --- a/tools/perf/util/event.h
> >> +++ b/tools/perf/util/event.h
> >> @@ -5,6 +5,7 @@
> >> #include <limits.h>
> >> #include <stdio.h>
> >> #include <linux/kernel.h>
> >> +#include <linux/bpf.h>
> >> 
> >> #include "../perf.h"
> >> #include "build-id.h"
> >> @@ -84,6 +85,19 @@ struct throttle_event {
> >> 	u64 stream_id;
> >> };
> >> 
> >> +#ifndef KSYM_NAME_LEN
> >> +#define KSYM_NAME_LEN 256
> >> +#endif
> >> +
> >> +struct ksymbol_event {
> >> +	struct perf_event_header header;
> >> +	u64 addr;
> >> +	u32 len;
> >> +	u16 ksym_type;
> >> +	u16 flags;
> >> +	char name[KSYM_NAME_LEN];
> >> +};
> >> +
> >> #define PERF_SAMPLE_MASK				\
> >> 	(PERF_SAMPLE_IP | PERF_SAMPLE_TID |		\
> >> 	 PERF_SAMPLE_TIME | PERF_SAMPLE_ADDR |		\
> >> @@ -651,6 +665,7 @@ union perf_event {
> >> 	struct stat_round_event		stat_round;
> >> 	struct time_conv_event		time_conv;
> >> 	struct feature_event		feat;
> >> +	struct ksymbol_event		ksymbol_event;
> >> };
> >> 
> >> void perf_event__print_totals(void);
> >> @@ -748,6 +763,10 @@ int perf_event__process_exit(struct perf_tool *tool,
> >> 			     union perf_event *event,
> >> 			     struct perf_sample *sample,
> >> 			     struct machine *machine);
> >> +int perf_event__process_ksymbol(struct perf_tool *tool,
> >> +				union perf_event *event,
> >> +				struct perf_sample *sample,
> >> +				struct machine *machine);
> >> int perf_tool__process_synth_event(struct perf_tool *tool,
> >> 				   union perf_event *event,
> >> 				   struct machine *machine,
> >> @@ -811,6 +830,7 @@ size_t perf_event__fprintf_switch(union perf_event *event, FILE *fp);
> >> size_t perf_event__fprintf_thread_map(union perf_event *event, FILE *fp);
> >> size_t perf_event__fprintf_cpu_map(union perf_event *event, FILE *fp);
> >> size_t perf_event__fprintf_namespaces(union perf_event *event, FILE *fp);
> >> +size_t perf_event__fprintf_ksymbol(union perf_event *event, FILE *fp);
> >> size_t perf_event__fprintf(union perf_event *event, FILE *fp);
> >> 
> >> int kallsyms__get_function_start(const char *kallsyms_filename,
> >> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> >> index dbc0466db368..a2c75aace409 100644
> >> --- a/tools/perf/util/evsel.c
> >> +++ b/tools/perf/util/evsel.c
> >> @@ -1035,6 +1035,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
> >> 	attr->mmap  = track;
> >> 	attr->mmap2 = track && !perf_missing_features.mmap2;
> >> 	attr->comm  = track;
> >> +	attr->ksymbol = track && !perf_missing_features.ksymbol;
> >> 
> >> 	if (opts->record_namespaces)
> >> 		attr->namespaces  = track;
> >> @@ -1652,6 +1653,7 @@ int perf_event_attr__fprintf(FILE *fp, struct perf_event_attr *attr,
> >> 	PRINT_ATTRf(context_switch, p_unsigned);
> >> 	PRINT_ATTRf(write_backward, p_unsigned);
> >> 	PRINT_ATTRf(namespaces, p_unsigned);
> >> +	PRINT_ATTRf(ksymbol, p_unsigned);
> >> 
> >> 	PRINT_ATTRn("{ wakeup_events, wakeup_watermark }", wakeup_events, p_unsigned);
> >> 	PRINT_ATTRf(bp_type, p_unsigned);
> >> @@ -1811,6 +1813,8 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
> >> 				     PERF_SAMPLE_BRANCH_NO_CYCLES);
> >> 	if (perf_missing_features.group_read && evsel->attr.inherit)
> >> 		evsel->attr.read_format &= ~(PERF_FORMAT_GROUP|PERF_FORMAT_ID);
> >> +	if (perf_missing_features.ksymbol)
> >> +		evsel->attr.ksymbol = 0;
> >> retry_sample_id:
> >> 	if (perf_missing_features.sample_id_all)
> >> 		evsel->attr.sample_id_all = 0;
> >> @@ -1930,7 +1934,13 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
> >> 	 * Must probe features in the order they were added to the
> >> 	 * perf_event_attr interface.
> >> 	 */
> >> -	if (!perf_missing_features.write_backward && evsel->attr.write_backward) {
> >> +	if (!perf_missing_features.ksymbol &&
> >> +		   evsel->attr.ksymbol) {
> >> +		perf_missing_features.ksymbol = true;
> >> +		pr_debug2("switching off ksymbol\n");
> >> +		goto fallback_missing_features;
> >> +	} else if (!perf_missing_features.write_backward &&
> >> +		   evsel->attr.write_backward) {
> > 
> > Please keep the existing coding style, i.e. no need to change this line
> > into two:
> > 
> > 	if (!perf_missing_features.write_backward && evsel->attr.write_backward) {
> > 
> > Just add the '} else' in front of it, ditto for the new line.
> > 
> > I'm not that strict about it, perhaps I should, to avoid my upstreamers
> > to block things due to this ;-)
> > 
> > And also this is not the only issue I found with this specific patch,
> > see below for one more functional issue.
> > 
> > I saw no issues in the previous patches (don't recall right now if there
> > where coding style minor issues), so in your next patchset version you
> > may add my:
> > 
> > Reviewed-by: Arnaldo Carvalho de Melo <[email-masked]>
> > 
> 
> Thanks Arnaldo!
> 
> Just to be sure, did you mean to add Reviewed-by to patch 1/9 through 5/9?

1/9 to 4/9, 5/9 is this one and we're still going thru it, so not
finished yet, right?

- Arnaldo
 
> > To those.
> > 
> >> 		perf_missing_features.write_backward = true;
> >> 		pr_debug2("switching off write_backward\n");
> >> 		goto out_close;
> >> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> >> index 82a289ce8b0c..4a8c3e7f4808 100644
> >> --- a/tools/perf/util/evsel.h
> >> +++ b/tools/perf/util/evsel.h
> >> @@ -168,6 +168,7 @@ struct perf_missing_features {
> >> 	bool lbr_flags;
> >> 	bool write_backward;
> >> 	bool group_read;
> >> +	bool ksymbol;
> >> };
> >> 
> >> extern struct perf_missing_features perf_missing_features;
> >> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> >> index 143f7057d581..c8f6daac9d2d 100644
> >> --- a/tools/perf/util/machine.c
> >> +++ b/tools/perf/util/machine.c
> >> @@ -681,6 +681,61 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
> >> 	return 0;
> >> }
> >> 
> >> +static int machine__process_ksymbol_register(
> >> +	struct machine *machine,
> >> +	union perf_event *event,
> >> +	struct perf_sample *sample __maybe_unused)
> >> +{
> >> +	struct symbol *sym;
> >> +	struct map *map;
> >> +
> >> +	map = map_groups__find(&machine->kmaps, event->ksymbol_event.addr);
> >> +	if (!map) {
> >> +		map = dso__new_map("bpf_prog");
> > 
> > Humm, why not use event->ksymbol_event.name as the name of the map as
> > well? Otherwise we may end up thinking its all the same map "bpf_prog",
> > when we have lots.
> 
> I will fix this in next version. 
> 
> Song
> 
> > 
> >> +		if (!map)
> >> +			return -ENOMEM;
> >> +
> >> +		map->start = event->ksymbol_event.addr;
> >> +		map->pgoff = map->start;
> >> +		map->end = map->start + event->ksymbol_event.len;
> >> +		map_groups__insert(&machine->kmaps, map);
> >> +	}
> >> +
> >> +	sym = symbol__new(event->ksymbol_event.addr, event->ksymbol_event.len,
> >> +			  0, 0, event->ksymbol_event.name);
> >> +	if (!sym)
> >> +		return -ENOMEM;
> >> +	dso__insert_symbol(map->dso, sym);
> >> +	return 0;
> >> +}
> >> +
> >> +static int machine__process_ksymbol_unregister(
> >> +	struct machine *machine,
> >> +	union perf_event *event,
> >> +	struct perf_sample *sample __maybe_unused)
> > 
> > Please follow the existing style, the above should be:
> > 
> > static int machine__process_ksymbol_unregister(struct machine *machine,
> > 					       union perf_event *event,
> > 					       struct perf_sample *sample __maybe_unused)
> > 
> >> +{
> >> +	struct map *map;
> >> +
> >> +	map = map_groups__find(&machine->kmaps, event->ksymbol_event.addr);
> >> +	if (map)
> >> +		map_groups__remove(&machine->kmaps, map);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +int machine__process_ksymbol(struct machine *machine __maybe_unused,
> >> +			     union perf_event *event,
> >> +			     struct perf_sample *sample)
> > 
> > This one follows the existing style, great.
> > 
> >> +{
> >> +	if (dump_trace)
> >> +		perf_event__fprintf_ksymbol(event, stdout);
> >> +
> >> +	if (event->ksymbol_event.flags & PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER)
> >> +		return machine__process_ksymbol_unregister(machine, event,
> >> +							   sample);
> >> +	return machine__process_ksymbol_register(machine, event, sample);
> >> +}
> >> +
> >> static void dso__adjust_kmod_long_name(struct dso *dso, const char *filename)
> >> {
> >> 	const char *dup_filename;
> >> @@ -1812,6 +1867,8 @@ int machine__process_event(struct machine *machine, union perf_event *event,
> >> 	case PERF_RECORD_SWITCH:
> >> 	case PERF_RECORD_SWITCH_CPU_WIDE:
> >> 		ret = machine__process_switch_event(machine, event); break;
> >> +	case PERF_RECORD_KSYMBOL:
> >> +		ret = machine__process_ksymbol(machine, event, sample); break;
> >> 	default:
> >> 		ret = -1;
> >> 		break;
> >> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> >> index a5d1da60f751..4ecd380ce1b4 100644
> >> --- a/tools/perf/util/machine.h
> >> +++ b/tools/perf/util/machine.h
> >> @@ -130,6 +130,9 @@ int machine__process_mmap_event(struct machine *machine, union perf_event *event
> >> 				struct perf_sample *sample);
> >> int machine__process_mmap2_event(struct machine *machine, union perf_event *event,
> >> 				 struct perf_sample *sample);
> >> +int machine__process_ksymbol(struct machine *machine,
> >> +			     union perf_event *event,
> >> +			     struct perf_sample *sample);
> >> int machine__process_event(struct machine *machine, union perf_event *event,
> >> 				struct perf_sample *sample);
> >> 
> >> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> >> index 5456c84c7dd1..2efa75bb0c0a 100644
> >> --- a/tools/perf/util/session.c
> >> +++ b/tools/perf/util/session.c
> >> @@ -376,6 +376,8 @@ void perf_tool__fill_defaults(struct perf_tool *tool)
> >> 		tool->itrace_start = perf_event__process_itrace_start;
> >> 	if (tool->context_switch == NULL)
> >> 		tool->context_switch = perf_event__process_switch;
> >> +	if (tool->ksymbol == NULL)
> >> +		tool->ksymbol = perf_event__process_ksymbol;
> >> 	if (tool->read == NULL)
> >> 		tool->read = process_event_sample_stub;
> >> 	if (tool->throttle == NULL)
> >> @@ -1305,6 +1307,8 @@ static int machines__deliver_event(struct machines *machines,
> >> 	case PERF_RECORD_SWITCH:
> >> 	case PERF_RECORD_SWITCH_CPU_WIDE:
> >> 		return tool->context_switch(tool, event, sample, machine);
> >> +	case PERF_RECORD_KSYMBOL:
> >> +		return tool->ksymbol(tool, event, sample, machine);
> >> 	default:
> >> 		++evlist->stats.nr_unknown_events;
> >> 		return -1;
> >> diff --git a/tools/perf/util/tool.h b/tools/perf/util/tool.h
> >> index 56e4ca54020a..9c81ca2f3cf7 100644
> >> --- a/tools/perf/util/tool.h
> >> +++ b/tools/perf/util/tool.h
> >> @@ -53,7 +53,9 @@ struct perf_tool {
> >> 			itrace_start,
> >> 			context_switch,
> >> 			throttle,
> >> -			unthrottle;
> >> +			unthrottle,
> >> +			ksymbol;
> >> +
> >> 	event_attr_op	attr;
> >> 	event_attr_op	event_update;
> >> 	event_op2	tracing_data;
> >> -- 
> >> 2.17.1
> > 
> > -- 
> > 
> > - Arnaldo

-- 

- Arnaldo