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Commit dd975497 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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perf probe: Introduce perf_cache interfaces 



Introduce perf_cache object and interfaces to create, add entries,
commit, and delete the object.

perf_cache represents a file for the cached "perf probe" definitions on
one binary file or vmlinux which has its own build id. The probe cache
file is located under the build-id cache directory of the target binary,
as below;

  <perf-debug-dir>/.build-id/<BU>/<ILDID>/probe

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160615032830.31330.84998.stgit@devbox


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent da1b0407

tools/perf/util/probe-file.c

+331 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
 * GNU General Public License for more details.

 *

 */

#include <sys/uio.h>

#include "util.h"

#include "event.h"

#include "strlist.h"
@@ -324,3 +325,333 @@ int probe_file__del_events(int fd, struct strfilter *filter) 


	return ret;

}



/* Caller must ensure to remove this entry from list */

static void probe_cache_entry__delete(struct probe_cache_entry *entry)

{

	if (entry) {

		BUG_ON(!list_empty(&entry->node));



		strlist__delete(entry->tevlist);

		clear_perf_probe_event(&entry->pev);

		zfree(&entry->spev);

		free(entry);

	}

}



static struct probe_cache_entry *

probe_cache_entry__new(struct perf_probe_event *pev)

{

	struct probe_cache_entry *entry = zalloc(sizeof(*entry));



	if (entry) {

		INIT_LIST_HEAD(&entry->node);

		entry->tevlist = strlist__new(NULL, NULL);

		if (!entry->tevlist)

			zfree(&entry);

		else if (pev) {

			entry->spev = synthesize_perf_probe_command(pev);

			if (!entry->spev ||

			    perf_probe_event__copy(&entry->pev, pev) < 0) {

				probe_cache_entry__delete(entry);

				return NULL;

			}

		}

	}



	return entry;

}



/* For the kernel probe caches, pass target = NULL */

static int probe_cache__open(struct probe_cache *pcache, const char *target)

{

	char cpath[PATH_MAX];

	char sbuildid[SBUILD_ID_SIZE];

	char *dir_name;

	bool is_kallsyms = !target;

	int ret, fd;



	if (target)

		ret = filename__sprintf_build_id(target, sbuildid);

	else {

		target = DSO__NAME_KALLSYMS;

		ret = sysfs__sprintf_build_id("/", sbuildid);

	}

	if (ret < 0) {

		pr_debug("Failed to get build-id from %s.\n", target);

		return ret;

	}



	/* If we have no buildid cache, make it */

	if (!build_id_cache__cached(sbuildid)) {

		ret = build_id_cache__add_s(sbuildid, target,

					    is_kallsyms, NULL);

		if (ret < 0) {

			pr_debug("Failed to add build-id cache: %s\n", target);

			return ret;

		}

	}



	dir_name = build_id_cache__cachedir(sbuildid, target, is_kallsyms,

					    false);

	if (!dir_name)

		return -ENOMEM;



	snprintf(cpath, PATH_MAX, "%s/probes", dir_name);

	fd = open(cpath, O_CREAT | O_RDWR, 0644);

	if (fd < 0)

		pr_debug("Failed to open cache(%d): %s\n", fd, cpath);

	free(dir_name);

	pcache->fd = fd;



	return fd;

}



static int probe_cache__load(struct probe_cache *pcache)

{

	struct probe_cache_entry *entry = NULL;

	char buf[MAX_CMDLEN], *p;

	int ret = 0;

	FILE *fp;



	fp = fdopen(dup(pcache->fd), "r");

	if (!fp)

		return -EINVAL;



	while (!feof(fp)) {

		if (!fgets(buf, MAX_CMDLEN, fp))

			break;

		p = strchr(buf, '\n');

		if (p)

			*p = '\0';

		if (buf[0] == '#') {	/* #perf_probe_event */

			entry = probe_cache_entry__new(NULL);

			if (!entry) {

				ret = -ENOMEM;

				goto out;

			}

			entry->spev = strdup(buf + 1);

			if (entry->spev)

				ret = parse_perf_probe_command(buf + 1,

								&entry->pev);

			else

				ret = -ENOMEM;

			if (ret < 0) {

				probe_cache_entry__delete(entry);

				goto out;

			}

			list_add_tail(&entry->node, &pcache->entries);

		} else {	/* trace_probe_event */

			if (!entry) {

				ret = -EINVAL;

				goto out;

			}

			strlist__add(entry->tevlist, buf);

		}

	}

out:

	fclose(fp);

	return ret;

}



static struct probe_cache *probe_cache__alloc(void)

{

	struct probe_cache *pcache = zalloc(sizeof(*pcache));



	if (pcache) {

		INIT_LIST_HEAD(&pcache->entries);

		pcache->fd = -EINVAL;

	}

	return pcache;

}



void probe_cache__purge(struct probe_cache *pcache)

{

	struct probe_cache_entry *entry, *n;



	list_for_each_entry_safe(entry, n, &pcache->entries, node) {

		list_del_init(&entry->node);

		probe_cache_entry__delete(entry);

	}

}



void probe_cache__delete(struct probe_cache *pcache)

{

	if (!pcache)

		return;



	probe_cache__purge(pcache);

	if (pcache->fd > 0)

		close(pcache->fd);

	free(pcache);

}



struct probe_cache *probe_cache__new(const char *target)

{

	struct probe_cache *pcache = probe_cache__alloc();

	int ret;



	if (!pcache)

		return NULL;



	ret = probe_cache__open(pcache, target);

	if (ret < 0) {

		pr_debug("Cache open error: %d\n", ret);

		goto out_err;

	}



	ret = probe_cache__load(pcache);

	if (ret < 0) {

		pr_debug("Cache read error: %d\n", ret);

		goto out_err;

	}



	return pcache;



out_err:

	probe_cache__delete(pcache);

	return NULL;

}



static bool streql(const char *a, const char *b)

{

	if (a == b)

		return true;



	if (!a || !b)

		return false;



	return !strcmp(a, b);

}



static struct probe_cache_entry *

probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)

{

	struct probe_cache_entry *entry = NULL;

	char *cmd = synthesize_perf_probe_command(pev);



	if (!cmd)

		return NULL;



	list_for_each_entry(entry, &pcache->entries, node) {

		/* Hit if same event name or same command-string */

		if ((pev->event &&

		     (streql(entry->pev.group, pev->group) &&

		      streql(entry->pev.event, pev->event))) ||

		    (!strcmp(entry->spev, cmd)))

			goto found;

	}

	entry = NULL;



found:

	free(cmd);

	return entry;

}



int probe_cache__add_entry(struct probe_cache *pcache,

			   struct perf_probe_event *pev,

			   struct probe_trace_event *tevs, int ntevs)

{

	struct probe_cache_entry *entry = NULL;

	char *command;

	int i, ret = 0;



	if (!pcache || !pev || !tevs || ntevs <= 0) {

		ret = -EINVAL;

		goto out_err;

	}



	/* Remove old cache entry */

	entry = probe_cache__find(pcache, pev);

	if (entry) {

		list_del_init(&entry->node);

		probe_cache_entry__delete(entry);

	}



	ret = -ENOMEM;

	entry = probe_cache_entry__new(pev);

	if (!entry)

		goto out_err;



	for (i = 0; i < ntevs; i++) {

		if (!tevs[i].point.symbol)

			continue;



		command = synthesize_probe_trace_command(&tevs[i]);

		if (!command)

			goto out_err;

		strlist__add(entry->tevlist, command);

		free(command);

	}

	list_add_tail(&entry->node, &pcache->entries);

	pr_debug("Added probe cache: %d\n", ntevs);

	return 0;



out_err:

	pr_debug("Failed to add probe caches\n");

	probe_cache_entry__delete(entry);

	return ret;

}



static int probe_cache_entry__write(struct probe_cache_entry *entry, int fd)

{

	struct str_node *snode;

	struct stat st;

	struct iovec iov[3];

	int ret;

	/* Save stat for rollback */

	ret = fstat(fd, &st);

	if (ret < 0)

		return ret;



	pr_debug("Writing cache: #%s\n", entry->spev);

	iov[0].iov_base = (void *)"#"; iov[0].iov_len = 1;

	iov[1].iov_base = entry->spev; iov[1].iov_len = strlen(entry->spev);

	iov[2].iov_base = (void *)"\n"; iov[2].iov_len = 1;

	ret = writev(fd, iov, 3);

	if (ret < (int)iov[1].iov_len + 2)

		goto rollback;



	strlist__for_each(snode, entry->tevlist) {

		iov[0].iov_base = (void *)snode->s;

		iov[0].iov_len = strlen(snode->s);

		iov[1].iov_base = (void *)"\n"; iov[1].iov_len = 1;

		ret = writev(fd, iov, 2);

		if (ret < (int)iov[0].iov_len + 1)

			goto rollback;

	}

	return 0;



rollback:

	/* Rollback to avoid cache file corruption */

	if (ret > 0)

		ret = -1;

	if (ftruncate(fd, st.st_size) < 0)

		ret = -2;



	return ret;

}



int probe_cache__commit(struct probe_cache *pcache)

{

	struct probe_cache_entry *entry;

	int ret = 0;



	/* TBD: if we do not update existing entries, skip it */

	ret = lseek(pcache->fd, 0, SEEK_SET);

	if (ret < 0)

		goto out;



	ret = ftruncate(pcache->fd, 0);

	if (ret < 0)

		goto out;



	list_for_each_entry(entry, &pcache->entries, node) {

		ret = probe_cache_entry__write(entry, pcache->fd);

		pr_debug("Cache committed: %d\n", ret);

		if (ret < 0)

			break;

	}

out:

	return ret;

}

tools/perf/util/probe-file.h

+20 −0
Original line number Diff line number Diff line
@@ -5,6 +5,19 @@ 
#include "strfilter.h"

#include "probe-event.h"



/* Cache of probe definitions */

struct probe_cache_entry {

	struct list_head	node;

	struct perf_probe_event pev;

	char			*spev;

	struct strlist		*tevlist;

};



struct probe_cache {

	int	fd;

	struct list_head entries;

};



#define PF_FL_UPROBE	1

#define PF_FL_RW	2
@@ -18,5 +31,12 @@ int probe_file__get_events(int fd, struct strfilter *filter, 
				  struct strlist *plist);

int probe_file__del_strlist(int fd, struct strlist *namelist);



struct probe_cache *probe_cache__new(const char *target);

int probe_cache__add_entry(struct probe_cache *pcache,

			   struct perf_probe_event *pev,

			   struct probe_trace_event *tevs, int ntevs);

int probe_cache__commit(struct probe_cache *pcache);

void probe_cache__purge(struct probe_cache *pcache);

void probe_cache__delete(struct probe_cache *pcache);



#endif