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Message-ID: <77361428-5970-5031-e204-7aefcd9cbebc@arm.com>
Date:   Mon, 4 Sep 2023 12:02:10 +0100
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Subject: Re: [PATCH v1 2/3] perf tools: Revert enable indices setting syntax
 for BPF map
Content-Language: en-US
To:     Ian Rogers <irogers@google.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        "coresight@lists.linaro.org" <coresight@lists.linaro.org>
References: <20230728001212.457900-1-irogers@google.com>
 <20230728001212.457900-3-irogers@google.com>
Cc:     Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Eduard Zingerman <eddyz87@gmail.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Rob Herring <robh@kernel.org>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, Wang Nan <wangnan0@huawei.com>,
        Wang ShaoBo <bobo.shaobowang@huawei.com>,
        YueHaibing <yuehaibing@huawei.com>,
        He Kuang <hekuang@huawei.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>
From:   James Clark <james.clark@arm.com>
In-Reply-To: <20230728001212.457900-3-irogers@google.com>
Content-Type: text/plain; charset=UTF-8
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Precedence: bulk


On 28/07/2023 01:12, Ian Rogers wrote:
> This reverts commit e571e029bdbf ("perf tools: Enable indices setting
> syntax for BPF map").
> 
> The reverted commit added a notion of arrays that could be set as
> event terms for BPF events. The parsing hasn't worked over multiple
> Linux releases. Given the broken nature of the parsing it appears the
> code isn't in use, nor could I find a way for it to be used to add a
> test.
> 
> The original commit contains a test in the commit message,
> however, running it yields:
> ```
> $ perf record -e './test_bpf_map_3.c/map:channel.value[0,1,2,3...5]=101/' usleep 2
> event syntax error: '..pf_map_3.c/map:channel.value[0,1,2,3...5]=101/'
>                                   \___ parser error
> Run 'perf list' for a list of valid events
> 
>  Usage: perf record [<options>] [<command>]
>     or: perf record [<options>] -- <command> [<options>]
> 
>     -e, --event <event>   event selector. use 'perf list' to list available events
> ```
> 
> Given the code can't be used this commit reverts and removes it.
> 

Hi Ian,

Unfortunately this revert breaks Coresight sink argument parsing.

Before:

  $ perf record -e cs_etm/@tmc_etr0/ -- true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 4.008 MB perf.data ]

After:

  $ perf record -e cs_etm/@tmc_etr0/ -- true
  event syntax error: 'cs_etm/@tmc_etr0/'
                           \___ parser error

I can't really see how it's related to the array syntax that the commit
messages mention, but it could either be that the revert wasn't applied
cleanly or just some unintended side effect.

We should probably add a cross platform parsing test for Coresight
arguments, but I don't know whether we should just blindly revert the
revert for now, or work on a new change that explicitly fixes the
Coresight case.

Thanks
James

> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  tools/perf/util/parse-events.c |   8 +--
>  tools/perf/util/parse-events.l |  11 ---
>  tools/perf/util/parse-events.y | 122 ---------------------------------
>  3 files changed, 1 insertion(+), 140 deletions(-)
> 
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 02647313c918..0e2004511cf5 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -800,13 +800,7 @@ parse_events_config_bpf(struct parse_events_state *parse_state,
>  
>  			parse_events_error__handle(parse_state->error, idx,
>  						strdup(errbuf),
> -						strdup(
> -"Hint:\tValid config terms:\n"
> -"     \tmap:[<arraymap>].value<indices>=[value]\n"
> -"     \tmap:[<eventmap>].event<indices>=[event]\n"
> -"\n"
> -"     \twhere <indices> is something like [0,3...5] or [all]\n"
> -"     \t(add -v to see detail)"));
> +						NULL);
>  			return err;
>  		}
>  	}
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 99335ec586ae..d7d084cc4140 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -175,7 +175,6 @@ do {							\
>  %x mem
>  %s config
>  %x event
> -%x array
>  
>  group		[^,{}/]*[{][^}]*[}][^,{}/]*
>  event_pmu	[^,{}/]+[/][^/]*[/][^,{}/]*
> @@ -251,14 +250,6 @@ non_digit	[^0-9]
>  		}
>  }
>  
> -<array>{
> -"]"			{ BEGIN(config); return ']'; }
> -{num_dec}		{ return value(yyscanner, 10); }
> -{num_hex}		{ return value(yyscanner, 16); }
> -,			{ return ','; }
> -"\.\.\."		{ return PE_ARRAY_RANGE; }
> -}
> -
>  <config>{
>  	/*
>  	 * Please update config_term_names when new static term is added.
> @@ -302,8 +293,6 @@ r0x{num_raw_hex}	{ return str(yyscanner, PE_RAW); }
>  {lc_type}-{lc_op_result}	{ return lc_str(yyscanner, _parse_state); }
>  {lc_type}-{lc_op_result}-{lc_op_result}	{ return lc_str(yyscanner, _parse_state); }
>  {name_minus}		{ return str(yyscanner, PE_NAME); }
> -\[all\]			{ return PE_ARRAY_ALL; }
> -"["			{ BEGIN(array); return '['; }
>  @{drv_cfg_term}		{ return drv_str(yyscanner, PE_DRV_CFG_TERM); }
>  }
>  
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index 454577f7aff6..5a90e7874c59 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -64,7 +64,6 @@ static void free_list_evsel(struct list_head* list_evsel)
>  %token PE_LEGACY_CACHE
>  %token PE_PREFIX_MEM
>  %token PE_ERROR
> -%token PE_ARRAY_ALL PE_ARRAY_RANGE
>  %token PE_DRV_CFG_TERM
>  %token PE_TERM_HW
>  %type <num> PE_VALUE
> @@ -108,11 +107,6 @@ static void free_list_evsel(struct list_head* list_evsel)
>  %type <list_evsel> groups
>  %destructor { free_list_evsel ($$); } <list_evsel>
>  %type <tracepoint_name> tracepoint_name
> -%destructor { free ($$.sys); free ($$.event); } <tracepoint_name>
> -%type <array> array
> -%type <array> array_term
> -%type <array> array_terms
> -%destructor { free ($$.ranges); } <array>
>  %type <hardware_term> PE_TERM_HW
>  %destructor { free ($$.str); } <hardware_term>
>  
> @@ -127,7 +121,6 @@ static void free_list_evsel(struct list_head* list_evsel)
>  		char *sys;
>  		char *event;
>  	} tracepoint_name;
> -	struct parse_events_array array;
>  	struct hardware_term {
>  		char *str;
>  		u64 num;
> @@ -878,121 +871,6 @@ PE_TERM
>  
>  	$$ = term;
>  }
> -|
> -name_or_raw array '=' name_or_legacy
> -{
> -	struct parse_events_term *term;
> -	int err = parse_events_term__str(&term, PARSE_EVENTS__TERM_TYPE_USER, $1, $4, &@1, &@4);
> -
> -	if (err) {
> -		free($1);
> -		free($4);
> -		free($2.ranges);
> -		PE_ABORT(err);
> -	}
> -	term->array = $2;
> -	$$ = term;
> -}
> -|
> -name_or_raw array '=' PE_VALUE
> -{
> -	struct parse_events_term *term;
> -	int err = parse_events_term__num(&term, PARSE_EVENTS__TERM_TYPE_USER, $1, $4, false, &@1, &@4);
> -
> -	if (err) {
> -		free($1);
> -		free($2.ranges);
> -		PE_ABORT(err);
> -	}
> -	term->array = $2;
> -	$$ = term;
> -}
> -|
> -PE_DRV_CFG_TERM
> -{
> -	struct parse_events_term *term;
> -	char *config = strdup($1);
> -	int err;
> -
> -	if (!config)
> -		YYNOMEM;
> -	err = parse_events_term__str(&term, PARSE_EVENTS__TERM_TYPE_DRV_CFG, config, $1, &@1, NULL);
> -	if (err) {
> -		free($1);
> -		free(config);
> -		PE_ABORT(err);
> -	}
> -	$$ = term;
> -}
> -
> -array:
> -'[' array_terms ']'
> -{
> -	$$ = $2;
> -}
> -|
> -PE_ARRAY_ALL
> -{
> -	$$.nr_ranges = 0;
> -	$$.ranges = NULL;
> -}
> -
> -array_terms:
> -array_terms ',' array_term
> -{
> -	struct parse_events_array new_array;
> -
> -	new_array.nr_ranges = $1.nr_ranges + $3.nr_ranges;
> -	new_array.ranges = realloc($1.ranges,
> -				sizeof(new_array.ranges[0]) *
> -				new_array.nr_ranges);
> -	if (!new_array.ranges)
> -		YYNOMEM;
> -	memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
> -	       $3.nr_ranges * sizeof(new_array.ranges[0]));
> -	free($3.ranges);
> -	$$ = new_array;
> -}
> -|
> -array_term
> -
> -array_term:
> -PE_VALUE
> -{
> -	struct parse_events_array array;
> -
> -	array.nr_ranges = 1;
> -	array.ranges = malloc(sizeof(array.ranges[0]));
> -	if (!array.ranges)
> -		YYNOMEM;
> -	array.ranges[0].start = $1;
> -	array.ranges[0].length = 1;
> -	$$ = array;
> -}
> -|
> -PE_VALUE PE_ARRAY_RANGE PE_VALUE
> -{
> -	struct parse_events_array array;
> -
> -	if ($3 < $1) {
> -		struct parse_events_state *parse_state = _parse_state;
> -		struct parse_events_error *error = parse_state->error;
> -		char *err_str;
> -
> -		if (asprintf(&err_str, "Expected '%ld' to be less-than '%ld'", $3, $1) < 0)
> -			err_str = NULL;
> -
> -		parse_events_error__handle(error, @1.first_column, err_str, NULL);
> -		YYABORT;
> -	}
> -	array.nr_ranges = 1;
> -	array.ranges = malloc(sizeof(array.ranges[0]));
> -	if (!array.ranges)
> -		YYNOMEM;
> -	array.ranges[0].start = $1;
> -	array.ranges[0].length = $3 - $1 + 1;
> -	$$ = array;
> -}
>  
>  sep_dc: ':' |
>