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Commit 544abd44 authored by Krister Johansen's avatar Krister Johansen Committed by Arnaldo Carvalho de Melo
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perf probe: Allow placing uprobes in alternate namespaces. 



Teaches perf how to place a uprobe on a file that's in a different mount
namespace.  The user must add the probe using the --target-ns argument
to perf probe.  Once it has been placed, it may be recorded against
without further namespace-specific commands.

Signed-off-by: default avatarKrister Johansen <kjlx@templeofstupid.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
[ PPC build fixed by Ravi: ]
Link: http://lkml.kernel.org/r/1500287542-6219-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
[ Fix !HAVE_DWARF_SUPPORT build ]
Link: http://lkml.kernel.org/r/1499305693-1599-4-git-send-email-kjlx@templeofstupid.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent bf2e710b

tools/perf/Documentation/perf-probe.txt

+9 −0
Original line number Diff line number Diff line
@@ -130,6 +130,11 @@ OPTIONS 
--max-probes=NUM::

	Set the maximum number of probe points for an event. Default is 128.



--target-ns=PID:

	Obtain mount namespace information from the target pid.  This is

	used when creating a uprobe for a process that resides in a

	different mount namespace from the perf(1) utility.



-x::

--exec=PATH::

	Specify path to the executable or shared library file for user
@@ -264,6 +269,10 @@ Add probes at malloc() function on libc 


 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc



Add a uprobe to a target process running in a different mount namespace



 ./perf probe --target-ns <target pid> -x /lib64/libc.so.6 malloc



SEE ALSO

--------

linkperf:perf-trace[1], linkperf:perf-record[1], linkperf:perf-buildid-cache[1]

tools/perf/arch/powerpc/util/sym-handling.c

+1 −1
Original line number Diff line number Diff line
@@ -126,7 +126,7 @@ void arch__post_process_probe_trace_events(struct perf_probe_event *pev, 
	struct rb_node *tmp;

	int i = 0;



	map = get_target_map(pev->target, pev->uprobes);

	map = get_target_map(pev->target, pev->nsi, pev->uprobes);

	if (!map || map__load(map) < 0)

		return;

tools/perf/builtin-probe.c

+39 −4
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ static struct { 
	struct line_range line_range;

	char *target;

	struct strfilter *filter;

	struct nsinfo *nsi;

} params;



/* Parse an event definition. Note that any error must die. */
@@ -80,6 +81,9 @@ static int parse_probe_event(const char *str) 
		params.target_used = true;

	}



	if (params.nsi)

		pev->nsi = nsinfo__get(params.nsi);



	/* Parse a perf-probe command into event */

	ret = parse_perf_probe_command(str, pev);

	pr_debug("%d arguments\n", pev->nargs);
@@ -189,7 +193,7 @@ static int opt_set_target(const struct option *opt, const char *str, 


		/* Expand given path to absolute path, except for modulename */

		if (params.uprobes || strchr(str, '/')) {

			tmp = realpath(str, NULL);

			tmp = nsinfo__realpath(str, params.nsi);

			if (!tmp) {

				pr_warning("Failed to get the absolute path of %s: %m\n", str);

				return ret;
@@ -208,6 +212,34 @@ static int opt_set_target(const struct option *opt, const char *str, 
	return ret;

}



static int opt_set_target_ns(const struct option *opt __maybe_unused,

			     const char *str, int unset __maybe_unused)

{

	int ret = -ENOENT;

	pid_t ns_pid;

	struct nsinfo *nsip;



	if (str) {

		errno = 0;

		ns_pid = (pid_t)strtol(str, NULL, 10);

		if (errno != 0) {

			ret = -errno;

			pr_warning("Failed to parse %s as a pid: %s\n", str,

				   strerror(errno));

			return ret;

		}

		nsip = nsinfo__new(ns_pid);

		if (nsip && nsip->need_setns)

			params.nsi = nsinfo__get(nsip);

		nsinfo__put(nsip);



		ret = 0;

	}



	return ret;

}





/* Command option callbacks */



#ifdef HAVE_DWARF_SUPPORT
@@ -299,6 +331,7 @@ static void cleanup_params(void) 
	line_range__clear(&params.line_range);

	free(params.target);

	strfilter__delete(params.filter);

	nsinfo__put(params.nsi);

	memset(&params, 0, sizeof(params));

}
@@ -554,6 +587,8 @@ __cmd_probe(int argc, const char **argv) 
	OPT_BOOLEAN(0, "cache", &probe_conf.cache, "Manipulate probe cache"),

	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",

		   "Look for files with symbols relative to this directory"),

	OPT_CALLBACK(0, "target-ns", NULL, "pid",

		     "target pid for namespace contexts", opt_set_target_ns),

	OPT_END()

	};

	int ret;
@@ -634,15 +669,15 @@ __cmd_probe(int argc, const char **argv) 
			pr_err_with_code("  Error: Failed to show event list.", ret);

		return ret;

	case 'F':

		ret = show_available_funcs(params.target, params.filter,

					params.uprobes);

		ret = show_available_funcs(params.target, params.nsi,

					   params.filter, params.uprobes);

		if (ret < 0)

			pr_err_with_code("  Error: Failed to show functions.", ret);

		return ret;

#ifdef HAVE_DWARF_SUPPORT

	case 'L':

		ret = show_line_range(&params.line_range, params.target,

				      params.uprobes);

				      params.nsi, params.uprobes);

		if (ret < 0)

			pr_err_with_code("  Error: Failed to show lines.", ret);

		return ret;

tools/perf/util/namespaces.c

+13 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include "event.h"

#include <sys/types.h>

#include <sys/stat.h>

#include <limits.h>

#include <sched.h>

#include <stdlib.h>

#include <stdio.h>
@@ -233,3 +234,15 @@ void nsinfo__mountns_exit(struct nscookie *nc) 
		nc->newns = -1;

	}

}



char *nsinfo__realpath(const char *path, struct nsinfo *nsi)

{

	char *rpath;

	struct nscookie nsc;



	nsinfo__mountns_enter(nsi, &nsc);

	rpath = realpath(path, NULL);

	nsinfo__mountns_exit(&nsc);



	return rpath;

}

tools/perf/util/namespaces.h

+2 −0
Original line number Diff line number Diff line
@@ -49,6 +49,8 @@ void nsinfo__put(struct nsinfo *nsi); 
void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc);

void nsinfo__mountns_exit(struct nscookie *nc);



char *nsinfo__realpath(const char *path, struct nsinfo *nsi);



static inline void __nsinfo__zput(struct nsinfo **nsip)

{

	if (nsip) {