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Message-ID: <20150219143113.14434.5387.stgit@localhost.localdomain>
Date: Thu, 19 Feb 2015 23:31:13 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>, namhyung@...nel.org,
Ingo Molnar <mingo@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH perf/core ] perf-probe: Check kprobes blacklist when adding
new events
Recent linux kernel provides a blacklist of the functions which
can not be probed. perf probe can now check this blacklist before
setting new events and indicate better error message for users.
Without this patch,
----
# perf probe --add vmalloc_fault
Added new event:
Failed to write event: Invalid argument
Error: Failed to add events.
----
With this patch
----
# perf probe --add vmalloc_fault
Added new event:
Warning: Skipped probing on blacklisted function: vmalloc_fault
----
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Reported-by: Arnaldo Carvalho de Melo <acme@...nel.org>
---
tools/perf/util/probe-event.c | 109 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 108 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 9dfbed9..662d454 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1903,6 +1903,95 @@ static struct strlist *get_probe_trace_command_rawlist(int fd)
return sl;
}
+struct kprobe_blacklist_node {
+ struct list_head list;
+ unsigned long start;
+ unsigned long end;
+ char *symbol;
+};
+
+static void kprobe_blacklist__delete(struct list_head *blacklist)
+{
+ struct kprobe_blacklist_node *node;
+
+ while (!list_empty(blacklist)) {
+ node = list_first_entry(blacklist,
+ struct kprobe_blacklist_node, list);
+ list_del(&node->list);
+ free(node->symbol);
+ free(node);
+ }
+}
+
+static int kprobe_blacklist__load(struct list_head *blacklist)
+{
+ struct kprobe_blacklist_node *node;
+ const char *__debugfs = debugfs_find_mountpoint();
+ char buf[PATH_MAX], *p;
+ FILE *fp;
+ int ret;
+
+ if (__debugfs == NULL)
+ return -ENOTSUP;
+
+ ret = e_snprintf(buf, PATH_MAX, "%s/kprobes/blacklist", __debugfs);
+ if (ret < 0)
+ return ret;
+
+ fp = fopen(buf, "r");
+ if (!fp)
+ return -errno;
+
+ ret = 0;
+ while (fgets(buf, PATH_MAX, fp)) {
+ node = zalloc(sizeof(*node));
+ if (!node) {
+ ret = -ENOMEM;
+ break;
+ }
+ INIT_LIST_HEAD(&node->list);
+ list_add_tail(&node->list, blacklist);
+ if (sscanf(buf, "0x%lx-0x%lx", &node->start, &node->end) != 2) {
+ ret = -EINVAL;
+ break;
+ }
+ p = strchr(buf, '\t');
+ if (p) {
+ p++;
+ if (p[strlen(p) - 1] == '\n')
+ p[strlen(p) - 1] = '\0';
+ } else
+ p = (char *)"unknown";
+ node->symbol = strdup(p);
+ if (!node->symbol) {
+ ret = -ENOMEM;
+ break;
+ }
+ pr_debug2("Blacklist: 0x%lx-0x%lx, %s\n",
+ node->start, node->end, node->symbol);
+ ret++;
+ }
+ if (ret < 0)
+ kprobe_blacklist__delete(blacklist);
+ fclose(fp);
+
+ return ret;
+}
+
+static struct kprobe_blacklist_node *
+kprobe_blacklist__find_by_address(struct list_head *blacklist,
+ unsigned long address)
+{
+ struct kprobe_blacklist_node *node;
+
+ list_for_each_entry(node, blacklist, list) {
+ if (node->start <= address && address <= node->end)
+ return node;
+ }
+
+ return NULL;
+}
+
/* Show an event */
static int show_perf_probe_event(struct perf_probe_event *pev,
const char *module)
@@ -2117,6 +2206,8 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
char buf[64];
const char *event, *group;
struct strlist *namelist;
+ LIST_HEAD(blacklist);
+ struct kprobe_blacklist_node *node;
if (pev->uprobes)
fd = open_uprobe_events(true);
@@ -2134,11 +2225,25 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
pr_debug("Failed to get current event list.\n");
return -EIO;
}
+ /* Get kprobe blacklist if exists */
+ if (!pev->uprobes) {
+ ret = kprobe_blacklist__load(&blacklist);
+ if (ret < 0)
+ pr_debug("No kprobe blacklist support, ignored\n");
+ }
ret = 0;
pr_info("Added new event%s\n", (ntevs > 1) ? "s:" : ":");
for (i = 0; i < ntevs; i++) {
tev = &tevs[i];
+ /* Ensure that the address is NOT blacklisted */
+ node = kprobe_blacklist__find_by_address(&blacklist,
+ tev->point.address);
+ if (node) {
+ pr_warning("Warning: Skipped probing on blacklisted function: %s\n", node->symbol);
+ continue;
+ }
+
if (pev->event)
event = pev->event;
else
@@ -2189,13 +2294,15 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
allow_suffix = true;
}
- if (ret >= 0) {
+ /* Note that it is possible to skip all events because of blacklist */
+ if (ret >= 0 && tev->event) {
/* Show how to use the event. */
pr_info("\nYou can now use it in all perf tools, such as:\n\n");
pr_info("\tperf record -e %s:%s -aR sleep 1\n\n", tev->group,
tev->event);
}
+ kprobe_blacklist__delete(&blacklist);
strlist__delete(namelist);
close(fd);
return ret;
--
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