3 files changed, 29 insertions, 17 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 93bd2ff001fb..d9dd47885218 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -326,7 +326,7 @@ try_again:
                                 goto try_again;
                         }
                         printf("\n");
-                        error("perfcounter syscall returned with %d (%s)\n",
+                        error("sys_perf_event_open() syscall returned with %d (%s).  /bin/dmesg may provide additional information.\n",
                                         fd[nr_cpu][counter][thread_index], strerror(err));
 
 #if defined(__i386__) || defined(__x86_64__)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index b3e568ffad27..970a7f2a083d 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -153,9 +153,9 @@ struct stats			walltime_nsecs_stats;
          attrs[counter].config == PERF_COUNT_##c)
 
 #define ERR_PERF_OPEN \
-"Error: counter %d, sys_perf_event_open() syscall returned with %d (%s)\n"
+"counter %d, sys_perf_event_open() syscall returned with %d (%s).  /bin/dmesg may provide additional information."
 
-static int create_perf_stat_counter(int counter)
+static int create_perf_stat_counter(int counter, bool *perm_err)
 {
         struct perf_event_attr *attr = attrs + counter;
         int thread;
@@ -171,11 +171,14 @@ static int create_perf_stat_counter(int counter)
                 for (cpu = 0; cpu < nr_cpus; cpu++) {
                         fd[cpu][counter][0] = sys_perf_event_open(attr,
                                         -1, cpumap[cpu], -1, 0);
-                        if (fd[cpu][counter][0] < 0)
-                                pr_debug(ERR_PERF_OPEN, counter,
+                        if (fd[cpu][counter][0] < 0) {
+                                if (errno == EPERM || errno == EACCES)
+                                        *perm_err = true;
+                                error(ERR_PERF_OPEN, counter,
                                          fd[cpu][counter][0], strerror(errno));
-                        else
+                        } else {
                                 ++ncreated;
+                        }
                 }
         } else {
                 attr->inherit = !no_inherit;
@@ -186,12 +189,15 @@ static int create_perf_stat_counter(int counter)
                 for (thread = 0; thread < thread_num; thread++) {
                         fd[0][counter][thread] = sys_perf_event_open(attr,
                                 all_tids[thread], -1, -1, 0);
-                        if (fd[0][counter][thread] < 0)
-                                pr_debug(ERR_PERF_OPEN, counter,
+                        if (fd[0][counter][thread] < 0) {
+                                if (errno == EPERM || errno == EACCES)
+                                        *perm_err = true;
+                                error(ERR_PERF_OPEN, counter,
                                          fd[0][counter][thread],
                                          strerror(errno));
-                        else
+                        } else {
                                 ++ncreated;
+                        }
                 }
         }
 
@@ -332,6 +338,7 @@ static int run_perf_stat(int argc __used, const char **argv)
         int status = 0;
         int counter, ncreated = 0;
         int child_ready_pipe[2], go_pipe[2];
+        bool perm_err = false;
         const bool forks = (argc > 0);
         char buf;
 
@@ -390,12 +397,15 @@ static int run_perf_stat(int argc __used, const char **argv)
         }
 
         for (counter = 0; counter < nr_counters; counter++)
-                ncreated += create_perf_stat_counter(counter);
-
-        if (ncreated == 0) {
-                pr_err("No permission to collect %sstats.\n"
-                       "Consider tweaking /proc/sys/kernel/perf_event_paranoid.\n",
-                       system_wide ? "system-wide " : "");
+                ncreated += create_perf_stat_counter(counter, &perm_err);
+
+        if (ncreated < nr_counters) {
+                if (perm_err)
+                        error("You may not have permission to collect %sstats.\n"
+                              "\t Consider tweaking"
+                              " /proc/sys/kernel/perf_event_paranoid or running as root.",
+                              system_wide ? "system-wide " : "");
+                die("Not all events could be opened.\n");
                 if (child_pid != -1)
                         kill(child_pid, SIGTERM);
                 return -1;
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index dd625808c2a5..3d2b47d5121a 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1214,7 +1214,9 @@ try_again:
                         int err = errno;
 
                         if (err == EPERM || err == EACCES)
-                                die("No permission - are you root?\n");
+                                die("Permission error - are you root?\n"
+                                        "\t Consider tweaking"
+                                        " /proc/sys/kernel/perf_event_paranoid.\n");
                         /*
                          * If it's cycles then fall back to hrtimer
                          * based cpu-clock-tick sw counter, which
@@ -1231,7 +1233,7 @@ try_again:
                                 goto try_again;
                         }
                         printf("\n");
-                        error("perfcounter syscall returned with %d (%s)\n",
+                        error("sys_perf_event_open() syscall returned with %d (%s).  /bin/dmesg may provide additional information.\n",
                                         fd[i][counter][thread_index], strerror(err));
                         die("No CONFIG_PERF_EVENTS=y kernel support configured?\n");
                         exit(-1);