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Date:   Wed, 16 Jan 2019 14:12:37 +0000
From:   Song Liu <songliubraving@...com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     lkml <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>,
        "dsahern@...il.com" <dsahern@...il.com>
Subject: Re: [PATCH v9 perf, bpf-next 5/9] perf util: handle
 PERF_RECORD_KSYMBOL



> On Jan 16, 2019, at 6:00 AM, Arnaldo Carvalho de Melo <acme@...nel.org> 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 <songliubraving@...com>
>> ---
>> 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 <acme@...hat.com>
> 

Thanks Arnaldo!

Just to be sure, did you mean to add Reviewed-by to patch 1/9 through 5/9?

> 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

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