[lttng-dev] [PATCH v2 2/2] Implement base-address-state tracing

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Thu Nov 14 11:30:57 EST 2013


----- Original Message -----
> From: "Paul Woegerer" <paul_woegerer at mentor.com>
> To: lttng-dev at lists.lttng.org, "mathieu desnoyers" <mathieu.desnoyers at efficios.com>
> Sent: Wednesday, November 13, 2013 1:37:40 PM
> Subject: [PATCH v2 2/2] Implement base-address-state tracing
> 
> Dump the base-address state (executable and shared objects) into session
> on session-enable (per-session events).
> 
> Signed-off-by: Paul Woegerer <paul_woegerer at mentor.com>
> ---
>  include/lttng/ust-tracepoint-event.h     | 14 +++++++
>  liblttng-ust-baddr/Makefile.am           |  4 +-
>  liblttng-ust-baddr/lttng-ust-baddr.c     | 64
>  ++++++++++++++++++++++++++++++++
>  liblttng-ust-baddr/ust_baddr_statedump.c | 21 +++++++++++
>  liblttng-ust-baddr/ust_baddr_statedump.h | 60 ++++++++++++++++++++++++++++++
>  liblttng-ust/lttng-events.c              |  4 ++
>  liblttng-ust/lttng-ust-comm.c            | 62
>  +++++++++++++++++++++++++++++++
>  7 files changed, 228 insertions(+), 1 deletion(-)
>  create mode 100644 liblttng-ust-baddr/ust_baddr_statedump.c
>  create mode 100644 liblttng-ust-baddr/ust_baddr_statedump.h
> 
> diff --git a/include/lttng/ust-tracepoint-event.h
> b/include/lttng/ust-tracepoint-event.h
> index bb3a05d..be58030 100644
> --- a/include/lttng/ust-tracepoint-event.h
> +++ b/include/lttng/ust-tracepoint-event.h
> @@ -480,6 +480,18 @@ size_t
> __event_get_align__##_provider##___##_name(_TP_ARGS_PROTO(_args))      \
>  #define TP_FIELDS(...) __VA_ARGS__
>  
>  /*
> + * For state dump, check that "session" argument (mandatory) matches the
> + * session this event belongs to. Ensures that we write state dump data only
> + * into the started session, not into all sessions.
> + */
> +#undef _TP_SESSION_CHECK
> +#ifdef TP_SESSION_CHECK
> +#define _TP_SESSION_CHECK(session, csession)   (session == csession)
> +#else /* TP_SESSION_CHECK */
> +#define _TP_SESSION_CHECK(session, csession)   1
> +#endif /* TP_SESSION_CHECK */
> +
> +/*
>   * Using twice size for filter stack data to hold size and pointer for
>   * each field (worse case). For integers, max size required is 64-bit.
>   * Same for double-precision floats. Those fit within
> @@ -506,6 +518,8 @@ void
> __event_probe__##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args))	      \
>  									      \
>  	if (0)								      \
>  		(void) __dynamic_len_idx;	/* don't warn if unused */    \
> +	if (!_TP_SESSION_CHECK(session, __chan->session))		      \
> +		return;							      \
>  	if (caa_unlikely(!CMM_ACCESS_ONCE(__chan->session->active)))	      \
>  		return;							      \
>  	if (caa_unlikely(!CMM_ACCESS_ONCE(__chan->enabled)))		      \
> diff --git a/liblttng-ust-baddr/Makefile.am b/liblttng-ust-baddr/Makefile.am
> index afa9489..0d3cf28 100644
> --- a/liblttng-ust-baddr/Makefile.am
> +++ b/liblttng-ust-baddr/Makefile.am
> @@ -5,7 +5,9 @@ lib_LTLIBRARIES = liblttng-ust-baddr.la
>  liblttng_ust_baddr_la_SOURCES = \
>  	lttng-ust-baddr.c \
>  	ust_baddr.c \
> -	ust_baddr.h
> +	ust_baddr.h \
> +	ust_baddr_statedump.c \
> +	ust_baddr_statedump.h
>  liblttng_ust_baddr_la_LIBADD = \
>  	-L$(top_builddir)/liblttng-ust/.libs \
>  	-llttng-ust
> diff --git a/liblttng-ust-baddr/lttng-ust-baddr.c
> b/liblttng-ust-baddr/lttng-ust-baddr.c
> index 21c22a2..f73bf0d 100644
> --- a/liblttng-ust-baddr/lttng-ust-baddr.c
> +++ b/liblttng-ust-baddr/lttng-ust-baddr.c
> @@ -34,6 +34,7 @@
>  
>  #define TRACEPOINT_DEFINE
>  #include "ust_baddr.h"
> +#include "ust_baddr_statedump.h"
>  
>  int
>  push_baddr(void *so_base, const char *so_name)
> @@ -62,3 +63,66 @@ pop_baddr(void *so_base)
>  	tracepoint(ust_baddr, pop, so_base);
>  	return 0;
>  }
> +
> +static int
> +extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
> +{
> +	int j;
> +	int num_loadable_segment = 0;
> +
> +	for (j = 0; j < info->dlpi_phnum; j++) {
> +		char resolved_path[PATH_MAX];
> +		struct stat sostat;
> +		void *base_addr_ptr;
> +
> +		if (info->dlpi_phdr[j].p_type != PT_LOAD)
> +			continue;
> +
> +		/* Calculate virtual memory address of the loadable segment */
> +		base_addr_ptr = (void *) info->dlpi_addr
> +			+ info->dlpi_phdr[j].p_vaddr;
> +
> +		num_loadable_segment += 1;
> +		if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0)
> +				&& num_loadable_segment == 1) {
> +			/* If the iterated element is the executable itself we
> +			 * have to use Dl_info to determine its full path */

small nit: multi line comments should be like this:

/*
 * Comment..
 * continue....
 */

(throughout the patch)

> +			Dl_info dl_info = { 0 };
> +			if (!dladdr(base_addr_ptr, &dl_info))
> +				return 0;
> +			if (!realpath(dl_info.dli_fname, resolved_path))
> +				return 0;
> +		} else {
> +			/* For regular dl_phdr_info entries we have to check if
> +			 * the path to the shared object really exists */
> +			if (!realpath(info->dlpi_name, resolved_path)) {
> +				/* Found vDSO, put the 'path' into brackets */
> +				snprintf(resolved_path, PATH_MAX - 1, "[%s]",
> +						info->dlpi_name);
> +			}
> +		}
> +
> +		if (stat(resolved_path, &sostat)) {
> +			sostat.st_size = 0;
> +			sostat.st_mtime = -1;
> +		}
> +
> +		tracepoint(ust_baddr_statedump, soinfo,
> +				(struct lttng_session *) data, base_addr_ptr,
> +				resolved_path, sostat.st_size, sostat.st_mtime);
> +
> +		/* We are only interrested in the base address (lowest virtual

interrested -> interested

> +		 * address associated with the memory image), skip the rest */

Ah that makes the "break" much clearer now :)

> +		break;
> +	}
> +	return 0;
> +}
> +
> +int
> +baddr_statedump(struct lttng_session *session)
> +{
> +	/* Iterate through the list of currently loaded shared objects and
> +	 * generate events for loadable segments using extract_soinfo_events */
> +	dl_iterate_phdr(extract_soinfo_events, session);
> +	return 0;
> +}
> diff --git a/liblttng-ust-baddr/ust_baddr_statedump.c
> b/liblttng-ust-baddr/ust_baddr_statedump.c
> new file mode 100644
> index 0000000..75f74ca
> --- /dev/null
> +++ b/liblttng-ust-baddr/ust_baddr_statedump.c
> @@ -0,0 +1,21 @@
> +/*
> + * Copyright (C) 2013  Paul Woegerer <paul_woegerer at mentor.com>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
> USA
> + */
> +
> +#define TRACEPOINT_CREATE_PROBES
> +#define TP_SESSION_CHECK
> +#include "ust_baddr_statedump.h"
> diff --git a/liblttng-ust-baddr/ust_baddr_statedump.h
> b/liblttng-ust-baddr/ust_baddr_statedump.h
> new file mode 100644
> index 0000000..77a9af4
> --- /dev/null
> +++ b/liblttng-ust-baddr/ust_baddr_statedump.h
> @@ -0,0 +1,60 @@
> +#undef TRACEPOINT_PROVIDER
> +#define TRACEPOINT_PROVIDER ust_baddr_statedump
> +
> +#if !defined(_TRACEPOINT_UST_BADDR_STATEDUMP_H) ||
> defined(TRACEPOINT_HEADER_MULTI_READ)
> +#define _TRACEPOINT_UST_BADDR_STATEDUMP_H
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +/*
> + * Copyright (C) 2013  Paul Woegerer <paul_woegerer at mentor.com>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> copy
> + * of this software and associated documentation files (the "Software"), to
> deal
> + * in the Software without restriction, including without limitation the
> rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included
> in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
> OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> THE
> + * SOFTWARE.
> + */
> +
> +#include <stdint.h>
> +#include <unistd.h>
> +#include <lttng/ust-events.h>
> +
> +#define LTTNG_UST_BADDR_STATEDUMP_PROVIDER
> +#include <lttng/tracepoint.h>
> +
> +TRACEPOINT_EVENT(ust_baddr_statedump, soinfo,
> +	TP_ARGS(struct lttng_session *, session, void *, baddr, const char*,
> sopath, int64_t, size, int64_t, mtime),
> +	TP_FIELDS(
> +		ctf_integer_hex(void *, baddr, baddr)
> +		ctf_string(sopath, sopath)
> +		ctf_integer(int64_t, size, size)
> +		ctf_integer(int64_t, mtime, mtime)
> +	)
> +)
> +
> +#endif /* _TRACEPOINT_UST_BADDR_STATEDUMP_H */
> +
> +#undef TRACEPOINT_INCLUDE
> +#define TRACEPOINT_INCLUDE "./ust_baddr_statedump.h"
> +
> +/* This part must be outside ifdef protection */
> +#include <lttng/tracepoint-event.h>
> +
> +#ifdef __cplusplus
> +}
> +#endif
> diff --git a/liblttng-ust/lttng-events.c b/liblttng-ust/lttng-events.c
> index 26601a6..65ae320 100644
> --- a/liblttng-ust/lttng-events.c
> +++ b/liblttng-ust/lttng-events.c
> @@ -86,6 +86,8 @@ void lttng_session_sync_enablers(struct lttng_session
> *session);
>  static
>  void lttng_enabler_destroy(struct lttng_enabler *enabler);
>  
> +void _lttng_ust_sockinfo_session_enabled(struct lttng_session
> *session_enabled);
> +
>  /*
>   * Called with ust lock held.
>   */
> @@ -293,6 +295,8 @@ int lttng_session_enable(struct lttng_session *session)
>  	/* Set atomically the state to "active" */
>  	CMM_ACCESS_ONCE(session->active) = 1;
>  	CMM_ACCESS_ONCE(session->been_active) = 1;
> +
> +	_lttng_ust_sockinfo_session_enabled(session);
>  end:
>  	return ret;
>  }
> diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
> index a6e4ba3..3968804 100644
> --- a/liblttng-ust/lttng-ust-comm.c
> +++ b/liblttng-ust/lttng-ust-comm.c
> @@ -34,6 +34,7 @@
>  #include <time.h>
>  #include <assert.h>
>  #include <signal.h>
> +#include <dlfcn.h>
>  #include <urcu/uatomic.h>
>  #include <urcu/futex.h>
>  #include <urcu/compiler.h>
> @@ -106,6 +107,7 @@ struct sock_info {
>  
>  	char wait_shm_path[PATH_MAX];
>  	char *wait_shm_mmap;
> +	struct lttng_session *session_enabled;

OK

>  };
>  
>  /* Socket from app (connect) to session daemon (listen) for communication */
> @@ -122,6 +124,8 @@ struct sock_info global_apps = {
>  	.notify_socket = -1,
>  
>  	.wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
> +
> +	.session_enabled = NULL,

If have this NULL field spelled out (not strictly needed, but I understand that we're already putting them = 0 for other fields) for global_apps, we also need it for local_apps (just below).

>  };
>  
>  /* TODO: allow global_apps_sock_path override */
> @@ -176,6 +180,7 @@ static const char *cmd_name_mapping[] = {
>  
>  static const char *str_timeout;
>  static int got_timeout_env;
> +static void *ust_baddr_handle;
>  
>  extern void lttng_ring_buffer_client_overwrite_init(void);
>  extern void lttng_ring_buffer_client_overwrite_rt_init(void);
> @@ -235,6 +240,51 @@ void print_cmd(int cmd, int handle)
>  }
>  
>  static
> +void *lttng_ust_baddr_handle(void)
> +{
> +	if (!ust_baddr_handle) {
> +		ust_baddr_handle = dlopen(
> +			"liblttng-ust-baddr.so.0", RTLD_NOW | RTLD_GLOBAL);
> +		if (ust_baddr_handle == NULL)
> +			ERR("%s", dlerror());
> +	}
> +	return ust_baddr_handle;
> +}
> +
> +static void __attribute__((destructor))
> +lttng_ust_baddr_handle_fini(void);
> +static void
> +lttng_ust_baddr_handle_fini(void)
> +{
> +	if (ust_baddr_handle) {
> +		int ret = dlclose(ust_baddr_handle);
> +		if (ret)
> +			ERR("%s", dlerror());
> +	}
> +}

Rather than adding another destructor to the same file (which can be executed in any order wrt other destructors), could you instead make lttng_ust_exit() call this teardown function ?

> +
> +static
> +int lttng_ust_baddr_statedump(struct lttng_session *session)
> +{
> +	static
> +	int (*lttng_ust_baddr_init_fn)(struct lttng_session *);
> +
> +	if (!lttng_ust_baddr_init_fn) {
> +		void *baddr_handle = lttng_ust_baddr_handle();
> +		if (baddr_handle) {
> +			lttng_ust_baddr_init_fn = dlsym(baddr_handle,
> +				"baddr_statedump");
> +			if (lttng_ust_baddr_init_fn == NULL)
> +				ERR("%s", dlerror());
> +		}
> +		if (!lttng_ust_baddr_init_fn)
> +			return -1;
> +	}
> +
> +	return lttng_ust_baddr_init_fn(session);
> +}
> +
> +static
>  int setup_local_apps(void)
>  {
>  	const char *home_dir;
> @@ -1143,6 +1193,13 @@ restart:
>  			ret = handle_message(sock_info, sock, &lum);
>  			if (ret) {
>  				ERR("Error handling message for %s socket", sock_info->name);
> +			} else {
> +				struct lttng_session *session =
> +					global_apps.session_enabled;

This does not handle local_apps (per-user sessiond).

What you want here is e.g.:

struct lttng_session *session = sock_info->session_enabled;

> +				if (session) {

sock_info->session_enabled = NULL;
lttng_ust_baddr_statedump(session);

> +					global_apps.session_enabled = NULL;
> +					lttng_ust_baddr_statedump(session);
> +				}
>  			}
>  			continue;
>  		default:
> @@ -1456,3 +1513,8 @@ void ust_after_fork_child(sigset_t *restore_sigset)
>  	ust_after_fork_common(restore_sigset);
>  	lttng_ust_init();
>  }
> +
> +void _lttng_ust_sockinfo_session_enabled(struct lttng_session
> *session_enabled)
> +{
> +	global_apps.session_enabled = session_enabled;
> +}

void _lttng_ust_sockinfo_session_enabled(struct sock_info *sock_info, struct lttng_session *session_enabled)
{
    sock_info->session_enabled = session_enabled;
}

Thanks,

Mathieu

> --
> 1.8.4.2
> 
> 

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com



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