Re: [PATCH 09/31] perf tools: Compile scriptlets to BPF objects when passing '.c' to --event

[Namhyung Kim]

On Wed, Oct 14, 2015 at 12:41:20PM +0000, Wang Nan wrote:
> This patch provides infrastructure for passing source files to --event
> directly using:
> 
>  # perf record --event bpf-file.c command
> 
> This patch does following works:
> 
>  1) Allow passing '.c' file to '--event'. parse_events_load_bpf() is
>     expanded to allow caller tell it whether the passed file is source
>     file or object.
> 
>  2) llvm__compile_bpf() is called to compile the '.c' file, the result
>     is saved into memory. Use bpf_object__open_buffer() to load the
>     in-memory object.
> 
> Introduces a bpf-script-example.c so we can manually test it:
> 
>  # perf record --clang-opt "-DLINUX_VERSION_CODE=0x40200" --event ./bpf-script-example.c sleep 1
> 
> Note that '--clang-opt' must put before '--event'.
> 
> Futher patches will merge it into a testcase so can be tested automatically.
> 
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
> Acked-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: David Ahern <dsahern@xxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Zefan Li <lizefan@xxxxxxxxxx>
> Cc: pi3orama@xxxxxxx
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Link: http://lkml.kernel.org/n/ebpf-6yw9eg0ej3l4jnqhinngkw86@xxxxxxxxxxxxxx
> ---
>  tools/perf/tests/bpf-script-example.c | 44 +++++++++++++++++++++++++++++++++++
>  tools/perf/util/bpf-loader.c          | 17 ++++++++++++--
>  tools/perf/util/bpf-loader.h          |  5 ++--
>  tools/perf/util/parse-events.c        |  5 ++--
>  tools/perf/util/parse-events.h        |  3 ++-
>  tools/perf/util/parse-events.l        |  3 +++
>  tools/perf/util/parse-events.y        | 15 ++++++++++--
>  7 files changed, 83 insertions(+), 9 deletions(-)
>  create mode 100644 tools/perf/tests/bpf-script-example.c
> 
> diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
> new file mode 100644
> index 0000000..410a70b
> --- /dev/null
> +++ b/tools/perf/tests/bpf-script-example.c

Shouldn't it be a part of the next patch?

Thanks,
Namhyung


> @@ -0,0 +1,44 @@
> +#ifndef LINUX_VERSION_CODE
> +# error Need LINUX_VERSION_CODE
> +# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
> +#endif
> +#define BPF_ANY 0
> +#define BPF_MAP_TYPE_ARRAY 2
> +#define BPF_FUNC_map_lookup_elem 1
> +#define BPF_FUNC_map_update_elem 2
> +
> +static void *(*bpf_map_lookup_elem)(void *map, void *key) =
> +	(void *) BPF_FUNC_map_lookup_elem;
> +static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
> +	(void *) BPF_FUNC_map_update_elem;
> +
> +struct bpf_map_def {
> +	unsigned int type;
> +	unsigned int key_size;
> +	unsigned int value_size;
> +	unsigned int max_entries;
> +};
> +
> +#define SEC(NAME) __attribute__((section(NAME), used))
> +struct bpf_map_def SEC("maps") flip_table = {
> +	.type = BPF_MAP_TYPE_ARRAY,
> +	.key_size = sizeof(int),
> +	.value_size = sizeof(int),
> +	.max_entries = 1,
> +};
> +
> +SEC("func=sys_epoll_pwait")
> +int bpf_func__sys_epoll_pwait(void *ctx)
> +{
> +	int ind =0;
> +	int *flag = bpf_map_lookup_elem(&flip_table, &ind);
> +	int new_flag;
> +	if (!flag)
> +		return 0;
> +	/* flip flag and store back */
> +	new_flag = !*flag;
> +	bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
> +	return new_flag;
> +}
> +char _license[] SEC("license") = "GPL";
> +int _version SEC("version") = LINUX_VERSION_CODE;
> diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
> index aa784a4..ba6f752 100644
> --- a/tools/perf/util/bpf-loader.c
> +++ b/tools/perf/util/bpf-loader.c
> @@ -12,6 +12,7 @@
>  #include "bpf-loader.h"
>  #include "probe-event.h"
>  #include "probe-finder.h" // for MAX_PROBES
> +#include "llvm-utils.h"
>  
>  #define DEFINE_PRINT_FN(name, level) \
>  static int libbpf_##name(const char *fmt, ...)	\
> @@ -33,7 +34,7 @@ struct bpf_prog_priv {
>  	struct perf_probe_event pev;
>  };
>  
> -struct bpf_object *bpf__prepare_load(const char *filename)
> +struct bpf_object *bpf__prepare_load(const char *filename, bool source)
>  {
>  	struct bpf_object *obj;
>  	static bool libbpf_initialized;
> @@ -45,7 +46,19 @@ struct bpf_object *bpf__prepare_load(const char *filename)
>  		libbpf_initialized = true;
>  	}
>  
> -	obj = bpf_object__open(filename);
> +	if (source) {
> +		int err;
> +		void *obj_buf;
> +		size_t obj_buf_sz;
> +
> +		err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
> +		if (err)
> +			return ERR_PTR(err);
> +		obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);
> +		free(obj_buf);
> +	} else
> +		obj = bpf_object__open(filename);
> +
>  	if (!obj) {
>  		pr_debug("bpf: failed to load %s\n", filename);
>  		return ERR_PTR(-EINVAL);
> diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
> index a8f25ee..ccd8d7f 100644
> --- a/tools/perf/util/bpf-loader.h
> +++ b/tools/perf/util/bpf-loader.h
> @@ -18,7 +18,7 @@ typedef int (*bpf_prog_iter_callback_t)(struct probe_trace_event *tev,
>  					int fd, void *arg);
>  
>  #ifdef HAVE_LIBBPF_SUPPORT
> -struct bpf_object *bpf__prepare_load(const char *filename);
> +struct bpf_object *bpf__prepare_load(const char *filename, bool source);
>  
>  void bpf__clear(void);
>  
> @@ -34,7 +34,8 @@ int bpf__foreach_tev(struct bpf_object *obj,
>  		     bpf_prog_iter_callback_t func, void *arg);
>  #else
>  static inline struct bpf_object *
> -bpf__prepare_load(const char *filename __maybe_unused)
> +bpf__prepare_load(const char *filename __maybe_unused,
> +		  bool source __maybe_unused)
>  {
>  	pr_debug("ERROR: eBPF object loading is disabled during compiling.\n");
>  	return ERR_PTR(-ENOTSUP);
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 5087023..4849dbd 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -626,11 +626,12 @@ errout:
>  
>  int parse_events_load_bpf(struct parse_events_evlist *data,
>  			  struct list_head *list,
> -			  char *bpf_file_name)
> +			  char *bpf_file_name,
> +			  bool source)
>  {
>  	struct bpf_object *obj;
>  
> -	obj = bpf__prepare_load(bpf_file_name);
> +	obj = bpf__prepare_load(bpf_file_name, source);
>  	if (IS_ERR(obj) || !obj) {
>  		char errbuf[BUFSIZ];
>  		int err;
> diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
> index fbb16c7..8f17c83 100644
> --- a/tools/perf/util/parse-events.h
> +++ b/tools/perf/util/parse-events.h
> @@ -123,7 +123,8 @@ int parse_events_add_tracepoint(struct list_head *list, int *idx,
>  				struct list_head *head_config);
>  int parse_events_load_bpf(struct parse_events_evlist *data,
>  			  struct list_head *list,
> -			  char *bpf_file_name);
> +			  char *bpf_file_name,
> +			  bool source);
>  /* Provide this function for perf test */
>  struct bpf_object;
>  int parse_events_load_bpf_obj(struct parse_events_evlist *data,
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 5e5d31a..eeea4e1 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -116,6 +116,7 @@ group		[^,{}/]*[{][^}]*[}][^,{}/]*
>  event_pmu	[^,{}/]+[/][^/]*[/][^,{}/]*
>  event		[^,{}/]+
>  bpf_object	.*\.(o|bpf)
> +bpf_source	.*\.c
>  
>  num_dec		[0-9]+
>  num_hex		0x[a-fA-F0-9]+
> @@ -161,6 +162,7 @@ modifier_bp	[rwx]{1,3}
>  
>  {event_pmu}	|
>  {bpf_object}	|
> +{bpf_source}	|
>  {event}		{
>  			BEGIN(INITIAL);
>  			REWIND(1);
> @@ -267,6 +269,7 @@ r{num_raw_hex}		{ return raw(yyscanner); }
>  
>  {modifier_event}	{ return str(yyscanner, PE_MODIFIER_EVENT); }
>  {bpf_object}		{ return str(yyscanner, PE_BPF_OBJECT); }
> +{bpf_source}		{ return str(yyscanner, PE_BPF_SOURCE); }
>  {name}			{ return pmu_str_check(yyscanner); }
>  "/"			{ BEGIN(config); return '/'; }
>  -			{ return '-'; }
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index 497f19b..ad37996 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -42,7 +42,7 @@ static inc_group_count(struct list_head *list,
>  %token PE_VALUE PE_VALUE_SYM_HW PE_VALUE_SYM_SW PE_RAW PE_TERM
>  %token PE_EVENT_NAME
>  %token PE_NAME
> -%token PE_BPF_OBJECT
> +%token PE_BPF_OBJECT PE_BPF_SOURCE
>  %token PE_MODIFIER_EVENT PE_MODIFIER_BP
>  %token PE_NAME_CACHE_TYPE PE_NAME_CACHE_OP_RESULT
>  %token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
> @@ -55,6 +55,7 @@ static inc_group_count(struct list_head *list,
>  %type <num> PE_TERM
>  %type <str> PE_NAME
>  %type <str> PE_BPF_OBJECT
> +%type <str> PE_BPF_SOURCE
>  %type <str> PE_NAME_CACHE_TYPE
>  %type <str> PE_NAME_CACHE_OP_RESULT
>  %type <str> PE_MODIFIER_EVENT
> @@ -461,7 +462,17 @@ PE_BPF_OBJECT
>  	struct list_head *list;
>  
>  	ALLOC_LIST(list);
> -	ABORT_ON(parse_events_load_bpf(data, list, $1));
> +	ABORT_ON(parse_events_load_bpf(data, list, $1, false));
> +	$$ = list;
> +}
> +|
> +PE_BPF_SOURCE
> +{
> +	struct parse_events_evlist *data = _data;
> +	struct list_head *list;
> +
> +	ALLOC_LIST(list);
> +	ABORT_ON(parse_events_load_bpf(data, list, $1, true));
>  	$$ = list;
>  }
>  
> -- 
> 1.8.3.4
> 
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