Re: [PATCH v4 09/16] perf tools: Enable indices setting syntax for BPF maps

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Dec 08, 2015 at 02:25:37AM +0000, Wang Nan escreveu:
> This patch introduce a new syntax to perf event parser:
> 
>  # perf record -e bpf_file.c/maps.mymap.value[0,3...5,7]=1234/ ...

Is the above example valid? Wouldn't this be "maps:mymap.value" ?

> 
> By utilizing the basic facilities in bpf-loader.c which allow setting
> different slots in a BPF map separately, the newly introduced syntax
> allows perf to control specific elements in a BPF map.
> 
> Test result:
> 
>  # cat ./test_bpf_map_3.c
>  /************************ BEGIN **************************/
>  #define SEC(NAME) __attribute__((section(NAME), used))
>  enum bpf_map_type {
>      BPF_MAP_TYPE_ARRAY = 2,
>  };
>  struct bpf_map_def {
>      unsigned int type;
>      unsigned int key_size;
>      unsigned int value_size;
>      unsigned int max_entries;
>  };
>  static void *(*map_lookup_elem)(struct bpf_map_def *, void *) =
>      (void *)1;
>  static int (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
>      (void *)6;

Can you explain the above a bit more? What are the magic 1 and 6 values?

>  struct bpf_map_def SEC("maps") channel = {
>      .type = BPF_MAP_TYPE_ARRAY,
>      .key_size = sizeof(int),
>      .value_size = sizeof(unsigned char),
>      .max_entries = 100,
>  };

>  SEC("func=hrtimer_nanosleep rqtp->tv_nsec")
>  int func(void *ctx, int err, long nsec)
>  {
>      char fmt[] = "%ld\n";
>      long usec = nsec * 0x10624dd3 >> 38; // nsec / 1000
>      int key = (int)usec;
>      unsigned char *pval = map_lookup_elem(&channel, &key);

So that "mymap.value" name doesn't needs to be specified here?

> 
>      if (!pval)
>          return 0;
>      bpf_trace_printk(fmt, sizeof(fmt), (unsigned char)*pval);
>      return 0;
>  }
>  char _license[] SEC("license") = "GPL";
>  int _version SEC("version") = LINUX_VERSION_CODE;
>  /************************* END ***************************/
> 
> Normal case:
>  # echo "" > /sys/kernel/debug/tracing/trace
>  # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0,1,2,3...5]=101/' usleep 2
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.012 MB perf.data ]
>  # cat /sys/kernel/debug/tracing/trace | grep usleep
>            usleep-405   [004] d... 2745423.547822: : 101
>  # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0...9,20...29]=102,maps:channel.value[10...19]=103/' usleep 3
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.012 MB perf.data ]
>  # ./perf record -e './test_bpf_map_3.c/maps:channel.value[0...9,20...29]=102,maps:channel.value[10...19]=103/' usleep 15
>  [ perf record: Woken up 1 times to write data ]
>  [ perf record: Captured and wrote 0.012 MB perf.data ]
>  # cat /sys/kernel/debug/tracing/trace | grep usleep
>            usleep-405   [004] d... 2745423.547822: : 101
>            usleep-655   [006] d... 2745434.122814: : 102
>            usleep-904   [006] d... 2745439.916264: : 103
>  # ./perf record -e './test_bpf_map_3.c/maps:channel.value[all]=104/' usleep 99
>  # cat /sys/kernel/debug/tracing/trace | grep usleep
>            usleep-405   [004] d... 2745423.547822: : 101
>            usleep-655   [006] d... 2745434.122814: : 102
>            usleep-904   [006] d... 2745439.916264: : 103
>            usleep-1537  [003] d... 2745538.053737: : 104
> 
> Error case:
>  # ./perf record -e './test_bpf_map_3.c/maps:channel.value[10...1000]=104/' usleep 99
>  event syntax error: '..annel.value[10...1000]=104/'
>                                    \___ Index too large
>  Hint:	Valid config terms:
>       	maps:[<arraymap>].value<indices>=[value]
>       	maps:[<eventmap>].event<indices>=[event]
> 
>       	where <indices> is something like [0,3...5] or [all]
>       	(add -v to see detail)
>  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
> 
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Zefan Li <lizefan@huawei.com>
> Cc: pi3orama@163.com
> ---
>  tools/perf/util/parse-events.c |  5 ++-
>  tools/perf/util/parse-events.l | 13 ++++++-
>  tools/perf/util/parse-events.y | 85 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 100 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index af3d657..abdf551 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -660,9 +660,10 @@ parse_events_config_bpf(struct parse_events_evlist *data,
>  						 sizeof(errbuf));
>  			data->error->help = strdup(
>  "Hint:\tValid config terms:\n"
> -"     \tmaps:[<arraymap>].value=[value]\n"
> -"     \tmaps:[<eventmap>].event=[event]\n"
> +"     \tmaps:[<arraymap>].value<indices>=[value]\n"
> +"     \tmaps:[<eventmap>].event<indices>=[event]\n"
>  "\n"
> +"     \twhere <indices> is something like [0,3...5] or [all]\n"
>  "     \t(add -v to see detail)");
>  			data->error->str = strdup(errbuf);
>  			if (err == -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE)
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 4387728..8bb3437 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -9,8 +9,8 @@
>  %{
>  #include <errno.h>
>  #include "../perf.h"
> -#include "parse-events-bison.h"
>  #include "parse-events.h"
> +#include "parse-events-bison.h"
>  
>  char *parse_events_get_text(yyscan_t yyscanner);
>  YYSTYPE *parse_events_get_lval(yyscan_t yyscanner);
> @@ -111,6 +111,7 @@ do {							\
>  %x mem
>  %s config
>  %x event
> +%x array
>  
>  group		[^,{}/]*[{][^}]*[}][^,{}/]*
>  event_pmu	[^,{}/]+[/][^/]*[/][^,{}/]*
> @@ -176,6 +177,14 @@ modifier_bp	[rwx]{1,3}
>  
>  }
>  
> +<array>{
> +"]"			{ BEGIN(config); return ']'; }
> +{num_dec}		{ return value(yyscanner, 10); }
> +{num_hex}		{ return value(yyscanner, 16); }
> +,			{ return ','; }
> +"\.\.\."		{ return PE_ARRAY_RANGE; }
> +}
> +
>  <config>{
>  	/*
>  	 * Please update parse_events_formats_error_string any time
> @@ -196,6 +205,8 @@ no-inherit		{ return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NOINHERIT); }
>  ,			{ return ','; }
>  "/"			{ BEGIN(INITIAL); return '/'; }
>  {name_minus}		{ return str(yyscanner, PE_NAME); }
> +\[all\]			{ return PE_ARRAY_ALL; }
> +"["			{ BEGIN(array); return '['; }
>  }
>  
>  <mem>{
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index c3cbd7a..7e93b9f 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -48,6 +48,7 @@ static inc_group_count(struct list_head *list,
>  %token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
>  %token PE_ERROR
>  %token PE_PMU_EVENT_PRE PE_PMU_EVENT_SUF PE_KERNEL_PMU_EVENT
> +%token PE_ARRAY_ALL PE_ARRAY_RANGE
>  %type <num> PE_VALUE
>  %type <num> PE_VALUE_SYM_HW
>  %type <num> PE_VALUE_SYM_SW
> @@ -84,6 +85,9 @@ static inc_group_count(struct list_head *list,
>  %type <head> group_def
>  %type <head> group
>  %type <head> groups
> +%type <array> array
> +%type <array> array_term
> +%type <array> array_terms
>  
>  %union
>  {
> @@ -95,6 +99,7 @@ static inc_group_count(struct list_head *list,
>  		char *sys;
>  		char *event;
>  	} tracepoint_name;
> +	struct parse_events_array array;
>  }
>  %%
>  
> @@ -601,6 +606,86 @@ PE_TERM
>  	ABORT_ON(parse_events_term__num(&term, (int)$1, NULL, 1, &@1, NULL));
>  	$$ = term;
>  }
> +|
> +PE_NAME array '=' PE_NAME
> +{
> +	struct parse_events_term *term;
> +	int i;
> +
> +	ABORT_ON(parse_events_term__str(&term, PARSE_EVENTS__TERM_TYPE_USER,
> +					$1, $4, &@1, &@4));
> +
> +	term->array = $2;
> +	$$ = term;
> +}
> +|
> +PE_NAME array '=' PE_VALUE
> +{
> +	struct parse_events_term *term;
> +
> +	ABORT_ON(parse_events_term__num(&term, PARSE_EVENTS__TERM_TYPE_USER,
> +					$1, $4, &@1, &@4));
> +	term->array = $2;
> +	$$ = term;
> +}
> +
> +array:
> +'[' array_terms ']'
> +{
> +	$$ = $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 = malloc(sizeof(new_array.ranges[0]) *
> +				  new_array.nr_ranges);
> +	ABORT_ON(!new_array.ranges);
> +	memcpy(&new_array.ranges[0], $1.ranges,
> +	       $1.nr_ranges * sizeof(new_array.ranges[0]));
> +	memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
> +	       $3.nr_ranges * sizeof(new_array.ranges[0]));
> +	free($1.ranges);
> +	free($3.ranges);
> +	$$ = new_array;
> +}
> +|
> +array_term
> +
> +array_term:
> +PE_VALUE
> +{
> +	struct parse_events_array array;
> +
> +	array.nr_ranges = 1;
> +	array.ranges = malloc(sizeof(array.ranges[0]));
> +	ABORT_ON(!array.ranges);
> +	array.ranges[0].start = $1;
> +	array.ranges[0].length = 1;
> +	$$ = array;
> +}
> +|
> +PE_VALUE PE_ARRAY_RANGE PE_VALUE
> +{
> +	struct parse_events_array array;
> +
> +	ABORT_ON($3 < $1);
> +	array.nr_ranges = 1;
> +	array.ranges = malloc(sizeof(array.ranges[0]));
> +	ABORT_ON(!array.ranges);
> +	array.ranges[0].start = $1;
> +	array.ranges[0].length = $3 - $1 + 1;
> +	$$ = array;
> +}
>  
>  sep_dc: ':' |
>  
> -- 
> 1.8.3.4