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: 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>

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 @@ found:
 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 @@ end:
         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 @@ out:
         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);