Subject: Re: [PATCH v2 perf,bpf 05/11] perf, bpf: save bpf_prog_info in a rbtree in perf_env

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Fri, 15 Feb 2019 12:21:55 -0200

Em Thu, Feb 14, 2019 at 04:00:06PM -0800, Song Liu escreveu:
> bpf_prog_info contains information necessary to annotate bpf programs.
> This patch saves bpf_prog_info for bpf programs loaded in the system.
> 
> Signed-off-by: Song Liu <[email-masked]>
> ---
>  tools/perf/builtin-record.c |  2 +-
>  tools/perf/builtin-top.c    |  2 +-
>  tools/perf/util/bpf-event.c | 39 +++++++++++++----
>  tools/perf/util/bpf-event.h | 15 +++++--
>  tools/perf/util/env.c       | 83 +++++++++++++++++++++++++++++++++++++
>  tools/perf/util/env.h       | 14 +++++++
>  6 files changed, 142 insertions(+), 13 deletions(-)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 88ea11d57c6f..2355e0a9eda0 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1083,7 +1083,7 @@ static int record__synthesize(struct record *rec, bool tail)
>  		return err;
>  	}
>  
> -	err = perf_event__synthesize_bpf_events(tool, process_synthesized_event,
> +	err = perf_event__synthesize_bpf_events(session, process_synthesized_event,
>  						machine, opts);
>  	if (err < 0)
>  		pr_warning("Couldn't synthesize bpf events.\n");
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 5a486d4de56e..27d8d42e0a4d 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -1216,7 +1216,7 @@ static int __cmd_top(struct perf_top *top)
>  
>  	init_process_thread(top);
>  
> -	ret = perf_event__synthesize_bpf_events(&top->tool, perf_event__process,
> +	ret = perf_event__synthesize_bpf_events(top->session, perf_event__process,
>  						&top->session->machines.host,
>  						&top->record_opts);
>  	if (ret < 0)
> diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
> index e6dfb95029e5..ead599bc4f4e 100644
> --- a/tools/perf/util/bpf-event.c
> +++ b/tools/perf/util/bpf-event.c
> @@ -1,15 +1,13 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <errno.h>
>  #include <stdlib.h>
> -#include <bpf/bpf.h>
> -#include <bpf/btf.h>
> -#include <bpf/libbpf.h>
> -#include <linux/btf.h>

I think you need these here, since in this C file you will use the
definitions for these structs, see further comments below.

>  #include <linux/err.h>
>  #include "bpf-event.h"
>  #include "debug.h"
>  #include "symbol.h"
>  #include "machine.h"
> +#include "env.h"
> +#include "session.h"
>  
>  #define ptr_to_u64(ptr)    ((__u64)(unsigned long)(ptr))
>  
> @@ -42,7 +40,7 @@ int machine__process_bpf_event(struct machine *machine __maybe_unused,
>   *   -1 for failures;
>   *   -2 for lack of kernel support.
>   */
> -static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
> +static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
>  					       perf_event__handler_t process,
>  					       struct machine *machine,
>  					       int fd,
> @@ -52,17 +50,29 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
>  	struct ksymbol_event *ksymbol_event = &event->ksymbol_event;
>  	struct bpf_event *bpf_event = &event->bpf_event;
>  	struct bpf_prog_info_linear *info_linear;
> +	struct perf_tool *tool = session->tool;
> +	struct bpf_prog_info_node *info_node;
>  	struct bpf_prog_info *info;
>  	struct btf *btf = NULL;
>  	bool has_btf = false;
> +	struct perf_env *env;
>  	u32 sub_prog_cnt, i;
>  	int err = 0;
>  	u64 arrays;
>  
> +	/*
> +	 * for perf-record and perf-report use header.env;
> +	 * otherwise, use global perf_env.
> +	 */
> +	env = session->data ? &session->header.env : &perf_env;
> +
>  	arrays = 1UL << BPF_PROG_INFO_JITED_KSYMS;
>  	arrays |= 1UL << BPF_PROG_INFO_JITED_FUNC_LENS;
>  	arrays |= 1UL << BPF_PROG_INFO_FUNC_INFO;
>  	arrays |= 1UL << BPF_PROG_INFO_PROG_TAGS;
> +	arrays |= 1UL << BPF_PROG_INFO_JITED_INSNS;
> +	arrays |= 1UL << BPF_PROG_INFO_LINE_INFO;
> +	arrays |= 1UL << BPF_PROG_INFO_JITED_LINE_INFO;
>  
>  	info_linear = bpf_program__get_prog_info_linear(fd, arrays);
>  	if (IS_ERR_OR_NULL(info_linear)) {
> @@ -151,8 +161,8 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
>  						     machine, process);
>  	}
>  
> -	/* Synthesize PERF_RECORD_BPF_EVENT */
>  	if (opts->bpf_event) {
> +		/* Synthesize PERF_RECORD_BPF_EVENT */
>  		*bpf_event = (struct bpf_event){
>  			.header = {
>  				.type = PERF_RECORD_BPF_EVENT,
> @@ -165,6 +175,19 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
>  		memcpy(bpf_event->tag, info->tag, BPF_TAG_SIZE);
>  		memset((void *)event + event->header.size, 0, machine->id_hdr_size);
>  		event->header.size += machine->id_hdr_size;
> +
> +		/* save bpf_prog_info to env */
> +		info_node = malloc(sizeof(struct bpf_prog_info_node));
> +		if (info_node) {
> +			info_node->info_linear = info_linear;
> +			perf_env__insert_bpf_prog_info(env, info_node);
> +			info_linear = NULL;
> +		}
> +
> +		/*
> +		 * process after saving bpf_prog_info to env, so that
> +		 * required information is ready for look up
> +		 */
>  		err = perf_tool__process_synth_event(tool, event,
>  						     machine, process);
>  	}
> @@ -175,7 +198,7 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_tool *tool,
>  	return err ? -1 : 0;
>  }
>  
> -int perf_event__synthesize_bpf_events(struct perf_tool *tool,
> +int perf_event__synthesize_bpf_events(struct perf_session *session,
>  				      perf_event__handler_t process,
>  				      struct machine *machine,
>  				      struct record_opts *opts)
> @@ -209,7 +232,7 @@ int perf_event__synthesize_bpf_events(struct perf_tool *tool,
>  			continue;
>  		}
>  
> -		err = perf_event__synthesize_one_bpf_prog(tool, process,
> +		err = perf_event__synthesize_one_bpf_prog(session, process,
>  							  machine, fd,
>  							  event, opts);
>  		close(fd);
> diff --git a/tools/perf/util/bpf-event.h b/tools/perf/util/bpf-event.h
> index 7890067e1a37..11e6730b6105 100644
> --- a/tools/perf/util/bpf-event.h
> +++ b/tools/perf/util/bpf-event.h
> @@ -3,19 +3,28 @@
>  #define __PERF_BPF_EVENT_H
>  
>  #include <linux/compiler.h>
> +#include <bpf/bpf.h>
> +#include <bpf/btf.h>
> +#include <bpf/libbpf.h>
> +#include <linux/btf.h>

Are you sure you'll need all of these headers here? Perhaps just some
forward declarations will do?

In fact the only bpf or btf structure here seems to be
bpf_prog_info_linear, which needs ust a forward declaration.

Avoiding these includes reduces the build time, and since the build-test
target does many builds and I want to build this in many containers, we
should try to reduce the build time by using just what is needed in each
header and C file. Also during development it helps with not rebuilding
tons of things when something unrelated changes in a header, etc.

- Arnaldo

> +#include <linux/rbtree.h>
>  #include "event.h"
>  
>  struct machine;
>  union perf_event;
>  struct perf_sample;
> -struct perf_tool;
>  struct record_opts;
>  
> +struct bpf_prog_info_node {
> +	struct bpf_prog_info_linear	*info_linear;
> +	struct rb_node			rb_node;
> +};
> +
>  #ifdef HAVE_LIBBPF_SUPPORT
>  int machine__process_bpf_event(struct machine *machine, union perf_event *event,
>  			       struct perf_sample *sample);
>  
> -int perf_event__synthesize_bpf_events(struct perf_tool *tool,
> +int perf_event__synthesize_bpf_events(struct perf_session *session,
>  				      perf_event__handler_t process,
>  				      struct machine *machine,
>  				      struct record_opts *opts);
> @@ -27,7 +36,7 @@ static inline int machine__process_bpf_event(struct machine *machine __maybe_unu
>  	return 0;
>  }
>  
> -static inline int perf_event__synthesize_bpf_events(struct perf_tool *tool __maybe_unused,
> +static inline int perf_event__synthesize_bpf_events(struct perf_session *session __maybe_unused,
>  						    perf_event__handler_t process __maybe_unused,
>  						    struct machine *machine __maybe_unused,
>  						    struct record_opts *opts __maybe_unused)
> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
> index 4c23779e271a..665b6fe3c7b2 100644
> --- a/tools/perf/util/env.c
> +++ b/tools/perf/util/env.c
> @@ -8,10 +8,86 @@
>  
>  struct perf_env perf_env;
>  
> +void perf_env__insert_bpf_prog_info(struct perf_env *env,
> +				    struct bpf_prog_info_node *info_node)
> +{
> +	__u32 prog_id = info_node->info_linear->info.id;
> +	struct bpf_prog_info_node *node;
> +	struct rb_node *parent = NULL;
> +	struct rb_node **p;
> +
> +	down_write(&env->bpf_info_lock);
> +	p = &env->bpf_prog_infos.rb_node;
> +
> +	while (*p != NULL) {
> +		parent = *p;
> +		node = rb_entry(parent, struct bpf_prog_info_node, rb_node);
> +		if (prog_id < node->info_linear->info.id) {
> +			p = &(*p)->rb_left;
> +		} else if (prog_id > node->info_linear->info.id) {
> +			p = &(*p)->rb_right;
> +		} else {
> +			pr_debug("duplicated bpf prog info %u\n", prog_id);
> +			up_write(&env->bpf_info_lock);
> +			return;
> +		}
> +	}
> +
> +	rb_link_node(&info_node->rb_node, parent, p);
> +	rb_insert_color(&info_node->rb_node, &env->bpf_prog_infos);
> +	up_write(&env->bpf_info_lock);
> +}
> +
> +struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
> +							__u32 prog_id)
> +{
> +	struct bpf_prog_info_node *node = NULL;
> +	struct rb_node *n;
> +
> +	down_read(&env->bpf_info_lock);
> +	n = env->bpf_prog_infos.rb_node;
> +
> +	while (n) {
> +		node = rb_entry(n, struct bpf_prog_info_node, rb_node);
> +		if (prog_id < node->info_linear->info.id)
> +			n = n->rb_left;
> +		else if (prog_id > node->info_linear->info.id)
> +			n = n->rb_right;
> +		else
> +			break;
> +	}
> +
> +	up_read(&env->bpf_info_lock);
> +	return node;
> +}
> +
> +/* purge data in bpf_prog_infos tree */
> +static void purge_bpf_info(struct perf_env *env)
> +{
> +	struct rb_root *root;
> +	struct rb_node *next;
> +
> +	down_write(&env->bpf_info_lock);
> +
> +	root = &env->bpf_prog_infos;
> +	next = rb_first(root);
> +
> +	while (next) {
> +		struct bpf_prog_info_node *node;
> +
> +		node = rb_entry(next, struct bpf_prog_info_node, rb_node);
> +		next = rb_next(&node->rb_node);
> +		rb_erase_init(&node->rb_node, root);
> +		free(node);
> +	}
> +	up_write(&env->bpf_info_lock);
> +}
> +
>  void perf_env__exit(struct perf_env *env)
>  {
>  	int i;
>  
> +	purge_bpf_info(env);
>  	zfree(&env->hostname);
>  	zfree(&env->os_release);
>  	zfree(&env->version);
> @@ -38,6 +114,12 @@ void perf_env__exit(struct perf_env *env)
>  	zfree(&env->memory_nodes);
>  }
>  
> +static void init_bpf_rb_trees(struct perf_env *env)
> +{
> +	env->bpf_prog_infos = RB_ROOT;
> +	init_rwsem(&env->bpf_info_lock);
> +}
> +
>  int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
>  {
>  	int i;
> @@ -59,6 +141,7 @@ int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
>  
>  	env->nr_cmdline = argc;
>  
> +	init_bpf_rb_trees(env);
>  	return 0;
>  out_free:
>  	zfree(&env->cmdline_argv);
> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
> index d01b8355f4ca..a6d25e91bc98 100644
> --- a/tools/perf/util/env.h
> +++ b/tools/perf/util/env.h
> @@ -3,7 +3,10 @@
>  #define __PERF_ENV_H
>  
>  #include <linux/types.h>
> +#include <linux/rbtree.h>
>  #include "cpumap.h"
> +#include "rwsem.h"

You don't need the following header, just use a forward declaration for
the sole struct you use with a pointer:

struct bpf_prog_info_node;

> +#include "bpf-event.h"
>  
>  struct cpu_topology_map {
>  	int	socket_id;
> @@ -64,6 +67,13 @@ struct perf_env {
>  	struct memory_node	*memory_nodes;
>  	unsigned long long	 memory_bsize;
>  	u64                     clockid_res_ns;
> +
> +	/*
> +	 * bpf_info_lock protects bpf rbtrees. This is needed because the
> +	 * trees are accessed by different threads in perf-top
> +	 */
> +	struct rw_semaphore	bpf_info_lock;
> +	struct rb_root		bpf_prog_infos;

Please group this into a structure, i.e.:

	struct {
		struct rw_semaphore lock;
		struct rb_root	    infos;
	} bpf_progs;

>  };
>  
>  extern struct perf_env perf_env;
> @@ -80,4 +90,8 @@ const char *perf_env__arch(struct perf_env *env);
>  const char *perf_env__raw_arch(struct perf_env *env);
>  int perf_env__nr_cpus_avail(struct perf_env *env);
>  
> +void perf_env__insert_bpf_prog_info(struct perf_env *env,
> +				    struct bpf_prog_info_node *info_node);
> +struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
> +							__u32 prog_id);
>  #endif /* __PERF_ENV_H */
> -- 
> 2.17.1