[PATCH 36/86] perf probe: Allow placing uprobes in alternate namespaces.

Arnaldo Carvalho de Melo
2017-07-19T14:33:46Z

From: Krister Johansen <kjlx@templeofstupid.com>

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: Krister 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: Arnaldo Carvalho de Melo <acme@redhat.com>

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-probe.txt | 9 ++++
tools/perf/arch/powerpc/util/sym-handling.c | 2 +-
tools/perf/builtin-probe.c | 43 ++++++++++++++--
tools/perf/util/namespaces.c | 13 +++++
tools/perf/util/namespaces.h | 2 +
tools/perf/util/probe-event.c | 80 +++++++++++++++++++----------
tools/perf/util/probe-event.h | 10 ++--
7 files changed, 125 insertions(+), 34 deletions(-)

diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
index 165c2b1d4317..a42aabc2b082 100644
--- a/tools/perf/Documentation/perf-probe.txt
+++ b/tools/perf/Documentation/perf-probe.txt
@@ -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]
diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
index bf9a2594572c..9c4e23d8c8ce 100644
--- a/tools/perf/arch/powerpc/util/sym-handling.c
+++ b/tools/perf/arch/powerpc/util/sym-handling.c
@@ -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;

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index cf9f9e9c2fc0..3fb98d59cd27 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -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;
diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
index fc5f398779a4..a58e91197729 100644
--- a/tools/perf/util/namespaces.c
+++ b/tools/perf/util/namespaces.c
@@ -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;
+}
diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
index f19aa41119ae..05d82601c9a6 100644
--- a/tools/perf/util/namespaces.h
+++ b/tools/perf/util/namespaces.h
@@ -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) {
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index a2670e9d652d..a80895a7e611 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -184,13 +184,19 @@ static struct map *kernel_get_module_map(const char *module)
return NULL;
}

-struct map *get_target_map(const char *target, bool user)
+struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user)
{
/* Init maps of given executable or kernel */
- if (user)
- return dso__new_map(target);
- else
+ if (user) {
+ struct map *map;
+
+ map = dso__new_map(target);
+ if (map && map->dso)
+ map->dso->nsinfo = nsinfo__get(nsi);
+ return map;
+ } else {
return kernel_get_module_map(target);
+ }
}

static int convert_exec_to_group(const char *exec, char **result)
@@ -366,7 +372,8 @@ static int kernel_get_module_dso(const char *module, struct dso **pdso)
static int find_alternative_probe_point(struct debuginfo *dinfo,
struct perf_probe_point *pp,
struct perf_probe_point *result,
- const char *target, bool uprobes)
+ const char *target, struct nsinfo *nsi,
+ bool uprobes)
{
struct map *map = NULL;
struct symbol *sym;
@@ -377,7 +384,7 @@ static int find_alternative_probe_point(struct debuginfo *dinfo,
if (!pp->function || pp->file)
return -ENOTSUP;

- map = get_target_map(target, uprobes);
+ map = get_target_map(target, nsi, uprobes);
if (!map)
return -EINVAL;

@@ -421,8 +428,8 @@ static int get_alternative_probe_event(struct debuginfo *dinfo,

memcpy(tmp, &pev->point, sizeof(*tmp));
memset(&pev->point, 0, sizeof(pev->point));
- ret = find_alternative_probe_point(dinfo, tmp, &pev->point,
- pev->target, pev->uprobes);
+ ret = find_alternative_probe_point(dinfo, tmp, &pev->point, pev->target,
+ pev->nsi, pev->uprobes);
if (ret < 0)
memcpy(&pev->point, tmp, sizeof(*tmp));

@@ -444,7 +451,7 @@ static int get_alternative_line_range(struct debuginfo *dinfo,
if (lr->end != INT_MAX)
len = lr->end - lr->start;
ret = find_alternative_probe_point(dinfo, &pp, &result,
- target, user);
+ target, NULL, user);
if (!ret) {
lr->function = result.function;
lr->file = result.file;
@@ -457,12 +464,14 @@ static int get_alternative_line_range(struct debuginfo *dinfo,
}

/* Open new debuginfo of given module */
-static struct debuginfo *open_debuginfo(const char *module, bool silent)
+static struct debuginfo *open_debuginfo(const char *module, struct nsinfo *nsi,
+ bool silent)
{
const char *path = module;
char reason[STRERR_BUFSIZE];
struct debuginfo *ret = NULL;
struct dso *dso = NULL;
+ struct nscookie nsc;
int err;

if (!module || !strchr(module, '/')) {
@@ -480,6 +489,7 @@ static struct debuginfo *open_debuginfo(const char *module, bool silent)
}
path = dso->long_name;
}
+ nsinfo__mountns_enter(nsi, &nsc);
ret = debuginfo__new(path);
if (!ret && !silent) {
pr_warning("The %s file has no debug information.\n", path);
@@ -489,6 +499,7 @@ static struct debuginfo *open_debuginfo(const char *module, bool silent)
pr_warning("Rebuild with -g, ");
pr_warning("or install an appropriate debuginfo package.\n");
}
+ nsinfo__mountns_exit(&nsc);
return ret;
}

@@ -516,7 +527,7 @@ static struct debuginfo *debuginfo_cache__open(const char *module, bool silent)
goto out;
}

- debuginfo_cache = open_debuginfo(module, silent);
+ debuginfo_cache = open_debuginfo(module, NULL, silent);
if (!debuginfo_cache)
zfree(&debuginfo_cache_path);
out:
@@ -531,14 +542,18 @@ static void debuginfo_cache__exit(void)
}

-static int get_text_start_address(const char *exec, unsigned long *address)
+static int get_text_start_address(const char *exec, unsigned long *address,
+ struct nsinfo *nsi)
{
Elf *elf;
GElf_Ehdr ehdr;
GElf_Shdr shdr;
int fd, ret = -ENOENT;
+ struct nscookie nsc;

+ nsinfo__mountns_enter(nsi, &nsc);
fd = open(exec, O_RDONLY);
+ nsinfo__mountns_exit(&nsc);
if (fd < 0)
return -errno;

@@ -582,7 +597,7 @@ static int find_perf_probe_point_from_dwarf(struct probe_trace_point *tp,
ret = -EINVAL;
goto error;
}
- ret = get_text_start_address(tp->module, &stext);
+ ret = get_text_start_address(tp->module, &stext, NULL);
if (ret < 0)
goto error;
addr += stext;
@@ -659,7 +674,7 @@ post_process_offline_probe_trace_events(struct probe_trace_event *tevs,

/* Prepare a map for offline binary */
map = dso__new_map(pathname);
- if (!map || get_text_start_address(pathname, &stext) < 0) {
+ if (!map || get_text_start_address(pathname, &stext, NULL) < 0) {
pr_warning("Failed to get ELF symbols for %s\n", pathname);
return -EINVAL;
}
@@ -676,7 +691,8 @@ post_process_offline_probe_trace_events(struct probe_trace_event *tevs,
}

static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
- int ntevs, const char *exec)
+ int ntevs, const char *exec,
+ struct nsinfo *nsi)
{
int i, ret = 0;
unsigned long stext = 0;
@@ -684,7 +700,7 @@ static int add_exec_to_probe_trace_events(struct probe_trace_event *tevs,
if (!exec)
return 0;

- ret = get_text_start_address(exec, &stext);
+ ret = get_text_start_address(exec, &stext, nsi);
if (ret < 0)
return ret;

@@ -715,7 +731,7 @@ post_process_module_probe_trace_events(struct probe_trace_event *tevs,
if (!module)
return 0;

- map = get_target_map(module, false);
+ map = get_target_map(module, NULL, false);
if (!map || debuginfo__get_text_offset(dinfo, &text_offs, true) < 0) {
pr_warning("Failed to get ELF symbols for %s\n", module);
return -EINVAL;
@@ -802,7 +818,8 @@ static int post_process_probe_trace_events(struct perf_probe_event *pev,
int ret;

if (uprobe)
- ret = add_exec_to_probe_trace_events(tevs, ntevs, module);
+ ret = add_exec_to_probe_trace_events(tevs, ntevs, module,
+ pev->nsi);
else if (module)
/* Currently ref_reloc_sym based probe is not for drivers */
ret = post_process_module_probe_trace_events(tevs, ntevs,
@@ -825,7 +842,7 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
struct debuginfo *dinfo;
int ntevs, ret = 0;

- dinfo = open_debuginfo(pev->target, !need_dwarf);
+ dinfo = open_debuginfo(pev->target, pev->nsi, !need_dwarf);
if (!dinfo) {
if (need_dwarf)
return -ENOENT;
@@ -945,7 +962,7 @@ static int __show_line_range(struct line_range *lr, const char *module,
char sbuf[STRERR_BUFSIZE];

/* Search a line range */
- dinfo = open_debuginfo(module, false);
+ dinfo = open_debuginfo(module, NULL, false);
if (!dinfo)
return -ENOENT;

@@ -1021,14 +1038,18 @@ static int __show_line_range(struct line_range *lr, const char *module,
return ret;
}

-int show_line_range(struct line_range *lr, const char *module, bool user)
+int show_line_range(struct line_range *lr, const char *module,
+ struct nsinfo *nsi, bool user)
{
int ret;
+ struct nscookie nsc;

ret = init_probe_symbol_maps(user);
if (ret < 0)
return ret;
+ nsinfo__mountns_enter(nsi, &nsc);
ret = __show_line_range(lr, module, user);
+ nsinfo__mountns_exit(&nsc);
exit_probe_symbol_maps();

return ret;
@@ -1111,7 +1132,7 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
if (ret < 0)
return ret;

- dinfo = open_debuginfo(pevs->target, false);
+ dinfo = open_debuginfo(pevs->target, pevs->nsi, false);
if (!dinfo) {
ret = -ENOENT;
goto out;
@@ -1155,6 +1176,7 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,

int show_line_range(struct line_range *lr __maybe_unused,
const char *module __maybe_unused,
+ struct nsinfo *nsi __maybe_unused,
bool user __maybe_unused)
{
pr_warning("Debuginfo-analysis is not supported.\n");
@@ -2703,6 +2725,7 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
struct probe_trace_event *tev = NULL;
struct probe_cache *cache = NULL;
struct strlist *namelist[2] = {NULL, NULL};
+ struct nscookie nsc;

up = pev->uprobes ? 1 : 0;
fd[up] = __open_probe_file_and_namelist(up, &namelist[up]);
@@ -2729,7 +2752,9 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
if (ret < 0)
break;

+ nsinfo__mountns_enter(pev->nsi, &nsc);
ret = probe_file__add_event(fd[up], tev);
+ nsinfo__mountns_exit(&nsc);
if (ret < 0)
break;

@@ -2805,7 +2830,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
int ret, i, j, skipped = 0;
char *mod_name;

- map = get_target_map(pev->target, pev->uprobes);
+ map = get_target_map(pev->target, pev->nsi, pev->uprobes);
if (!map) {
ret = -EINVAL;
goto out;
@@ -3345,13 +3370,16 @@ int apply_perf_probe_events(struct perf_probe_event *pevs, int npevs)
void cleanup_perf_probe_events(struct perf_probe_event *pevs, int npevs)
{
int i, j;
+ struct perf_probe_event *pev;

/* Loop 3: cleanup and free trace events */
for (i = 0; i < npevs; i++) {
+ pev = &pevs[i];
for (j = 0; j < pevs[i].ntevs; j++)
clear_probe_trace_event(&pevs[i].tevs[j]);
zfree(&pevs[i].tevs);
pevs[i].ntevs = 0;
+ nsinfo__zput(pev->nsi);
clear_perf_probe_event(&pevs[i]);
}
}
@@ -3409,8 +3437,8 @@ int del_perf_probe_events(struct strfilter *filter)
return ret;
}

-int show_available_funcs(const char *target, struct strfilter *_filter,
- bool user)
+int show_available_funcs(const char *target, struct nsinfo *nsi,
+ struct strfilter *_filter, bool user)
{
struct rb_node *nd;
struct map *map;
@@ -3421,7 +3449,7 @@ int show_available_funcs(const char *target, struct strfilter *_filter,
return ret;

/* Get a symbol map */
- map = get_target_map(target, user);
+ map = get_target_map(target, nsi, user);
if (!map) {
pr_err("Failed to get a map for %s\n", (target) ? : "kernel");
return -EINVAL;
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 5812947418dd..078681d12168 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -4,6 +4,7 @@
#include <linux/compiler.h>
#include <stdbool.h>
#include "intlist.h"
+#include "namespaces.h"

/* Probe related configurations */
struct probe_conf {
@@ -92,6 +93,7 @@ struct perf_probe_event {
struct perf_probe_arg *args; /* Arguments */
struct probe_trace_event *tevs;
int ntevs;
+ struct nsinfo *nsi; /* Target namespace */
};

/* Line range */
@@ -163,10 +165,12 @@ int show_perf_probe_event(const char *group, const char *event,
struct perf_probe_event *pev,
const char *module, bool use_stdout);
int show_perf_probe_events(struct strfilter *filter);
-int show_line_range(struct line_range *lr, const char *module, bool user);
+int show_line_range(struct line_range *lr, const char *module,
+ struct nsinfo *nsi, bool user);
int show_available_vars(struct perf_probe_event *pevs, int npevs,
struct strfilter *filter);
-int show_available_funcs(const char *module, struct strfilter *filter, bool user);
+int show_available_funcs(const char *module, struct nsinfo *nsi,
+ struct strfilter *filter, bool user);
void arch__fix_tev_from_maps(struct perf_probe_event *pev,
struct probe_trace_event *tev, struct map *map,
struct symbol *sym);
@@ -180,7 +184,7 @@ int e_snprintf(char *str, size_t size, const char *format, ...) __printf(3, 4);
int copy_to_probe_trace_arg(struct probe_trace_arg *tvar,
struct perf_probe_arg *pvar);

-struct map *get_target_map(const char *target, bool user);
+struct map *get_target_map(const char *target, struct nsinfo *nsi, bool user);

void arch__post_process_probe_trace_events(struct perf_probe_event *pev,
int ntevs);
--
2.9.4