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

["Wangnan (F)" <wangnan0@huawei.com>]

On 2015/10/14 23:45, Namhyung Kim wrote:
> 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@huawei.com>
>> Signed-off-by: He Kuang <hekuang@huawei.com>
>> Acked-by: Alexei Starovoitov <ast@plumgrid.com>
>> Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
>> Cc: Daniel Borkmann <daniel@iogearbox.net>
>> Cc: David Ahern <dsahern@gmail.com>
>> Cc: Jiri Olsa <jolsa@kernel.org>
>> Cc: Kaixu Xia <xiakaixu@huawei.com>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Zefan Li <lizefan@huawei.com>
>> Cc: pi3orama@163.com
>> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Link: http://lkml.kernel.org/n/ebpf-6yw9eg0ej3l4jnqhinngkw86@git.kernel.org
>> ---
>>   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?

I think putting the sample file in this patch should be better.

In commit message I show a cmdline to utilize scriptlet compiling. If
we put the sample code into next patch, then people get to this point
have to write his/her own script to test scriptlet compiling manually.

Thank you.

> 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
>>