perf probe: Skip kernel symbols which is out of .text

Skip the kernel symbols which is out of .text, e.g. the functions
in .inittext. Those are found in debuginfo/kallsyms, but already
freed from memory.

e.g.
  ----
  # perf probe vfs_caches_init
  vfs_caches_init+0 is out of .text, skip it.
  Probe point 'vfs_caches_init' not found.
    Error: Failed to add events.
  ----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150506124649.4961.56249.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 4265f2e3bd14ba46441c307661a2d05b405cbacf..37a3a8b04a6912687bd6767cc1a531b78bab9ffd 100644 (file)
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -557,8 +557,9 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
                                           bool uprobe)
 {
        struct ref_reloc_sym *reloc_sym;
+       u64 etext_addr;
        char *tmp;
-       int i;
+       int i, skipped = 0;
 
        if (uprobe)
                return add_exec_to_probe_trace_events(tevs, ntevs, module);
@@ -572,19 +573,29 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
                pr_warning("Relocated base symbol is not found!\n");
                return -EINVAL;
        }
+       /* Get the address of _etext for checking non-probable text symbol */
+       etext_addr = kernel_get_symbol_address_by_name("_etext", false);
 
        for (i = 0; i < ntevs; i++) {
                if (tevs[i].point.address && !tevs[i].point.retprobe) {
-                       tmp = strdup(reloc_sym->name);
-                       if (!tmp)
-                               return -ENOMEM;
+                       /* If we found a wrong one, mark it by NULL symbol */
+                       if (etext_addr < tevs[i].point.address) {
+                               pr_warning("%s+%lu is out of .text, skip it.\n",
+                                  tevs[i].point.symbol, tevs[i].point.offset);
+                               tmp = NULL;
+                               skipped++;
+                       } else {
+                               tmp = strdup(reloc_sym->name);
+                               if (!tmp)
+                                       return -ENOMEM;
+                       }
                        free(tevs[i].point.symbol);
                        tevs[i].point.symbol = tmp;
                        tevs[i].point.offset = tevs[i].point.address -
                                               reloc_sym->unrelocated_addr;
                }
        }
-       return 0;
+       return skipped;
 }
 
 /* Try to find perf_probe_event with debuginfo */
@@ -630,11 +641,14 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
                pr_debug("Found %d probe_trace_events.\n", ntevs);
                ret = post_process_probe_trace_events(*tevs, ntevs,
                                                        target, pev->uprobes);
-               if (ret < 0) {
+               if (ret < 0 || ret == ntevs) {
                        clear_probe_trace_events(*tevs, ntevs);
                        zfree(tevs);
                }
-               return ret < 0 ? ret : ntevs;
+               if (ret != ntevs)
+                       return ret < 0 ? ret : ntevs;
+               ntevs = 0;
+               /* Fall through */
        }
 
        if (ntevs == 0) {       /* No error but failed to find probe point. */
@@ -2403,6 +2417,9 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
        pr_info("Added new event%s\n", (ntevs > 1) ? "s:" : ":");
        for (i = 0; i < ntevs; i++) {
                tev = &tevs[i];
+               /* Skip if the symbol is out of .text (marked previously) */
+               if (!tev->point.symbol)
+                       continue;
                /* Ensure that the address is NOT blacklisted */
                node = kprobe_blacklist__find_by_address(&blacklist,
                                                         tev->point.address);