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Subject[PATCH 05/30] perf probe: Skip kernel symbols which is out of .text
Date
From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

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>
---
tools/perf/util/probe-event.c | 31 ++++++++++++++++++++++++-------
1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 4265f2e..37a3a8b 100644
--- 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);
--
2.1.0


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