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Date: Mon, 7 Jun 2021 00:49:28 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
Jiri Olsa <jolsa@...nel.org>, linux-kernel@...r.kernel.org,
aneesh.kumar@...ux.ibm.com, Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>
Subject: [PATCH v2] perf/probe: Report permission error for tracefs access
Report permission error for the tracefs open and rewrite
whole the error message code around it.
You'll see a hint according to what you want to do with
perf probe as below.
$ perf probe -l
No permission to read tracefs.
Please try 'sudo mount -o remount,mode=755 /sys/kernel/tracing/'
Error: Failed to show event list.
$ perf probe -d \*
No permission to write tracefs.
Please run this command again with sudo.
Error: Failed to delete events.
This also fixes -ENOTSUP checking for mounting tracefs/debugfs.
Actually open returns -ENOENT in that case and we have to check
it with current mount point list. If we unmount debugfs and tracefs
perf probe shows correct message as below.
$ perf probe -l
Debugfs or tracefs is not mounted
Please try 'sudo mount -t tracefs nodev /sys/kernel/tracing/'
Error: Failed to show event list.
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
Changes in v2:
- Rewrite whole the error message for the tracefs access.
---
tools/perf/util/probe-file.c | 95 +++++++++++++++++++++++++++++-------------
1 file changed, 65 insertions(+), 30 deletions(-)
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 52273542e6ef..f9a6cbcd6415 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -22,6 +22,7 @@
#include "symbol.h"
#include "strbuf.h"
#include <api/fs/tracing_path.h>
+#include <api/fs/fs.h>
#include "probe-event.h"
#include "probe-file.h"
#include "session.h"
@@ -31,44 +32,78 @@
/* 4096 - 2 ('\n' + '\0') */
#define MAX_CMDLEN 4094
-static void print_open_warning(int err, bool uprobe)
+static bool print_common_warning(int err, bool readwrite)
{
- char sbuf[STRERR_BUFSIZE];
+ if (err == -EACCES)
+ pr_warning("No permission to %s tracefs.\nPlease %s\n",
+ readwrite ? "write" : "read",
+ readwrite ? "run this command again with sudo." :
+ "try 'sudo mount -o remount,mode=755 /sys/kernel/tracing/'");
+ else
+ return false;
- if (err == -ENOENT) {
- const char *config;
+ return true;
+}
- if (uprobe)
- config = "CONFIG_UPROBE_EVENTS";
- else
- config = "CONFIG_KPROBE_EVENTS";
+static bool print_configure_probe_event(int kerr, int uerr)
+{
+ const char *config, *file;
+
+ if (kerr == -ENOENT && uerr == -ENOENT) {
+ file = "{k,u}probe_events";
+ config = "CONFIG_KPROBE_EVENTS=y and CONFIG_UPROBE_EVENTS=y";
+ } else if (kerr == -ENOENT) {
+ file = "kprobe_events";
+ config = "CONFIG_KPROBE_EVENTS=y";
+ } else if (uerr == -ENOENT) {
+ file = "uprobe_events";
+ config = "CONFIG_UPROBE_EVENTS=y";
+ } else
+ return false;
- pr_warning("%cprobe_events file does not exist"
- " - please rebuild kernel with %s.\n",
- uprobe ? 'u' : 'k', config);
- } else if (err == -ENOTSUP)
- pr_warning("Tracefs or debugfs is not mounted.\n");
+ if (!debugfs__configured() && !tracefs__configured())
+ pr_warning("Debugfs or tracefs is not mounted\n"
+ "Please try 'sudo mount -t tracefs nodev /sys/kernel/tracing/'\n");
else
- pr_warning("Failed to open %cprobe_events: %s\n",
- uprobe ? 'u' : 'k',
- str_error_r(-err, sbuf, sizeof(sbuf)));
+ pr_warning("%s/%s does not exist.\nPlease rebuild kernel with %s.\n",
+ tracing_path_mount(), file, config);
+
+ return true;
+}
+
+static void print_open_warning(int err, bool uprobe, bool readwrite)
+{
+ char sbuf[STRERR_BUFSIZE];
+
+ if (print_common_warning(err, readwrite))
+ return;
+
+ if (print_configure_probe_event(uprobe ? 0 : err, uprobe ? err : 0))
+ return;
+
+ pr_warning("Failed to open %s/%cprobe_events: %s\n",
+ tracing_path_mount(), uprobe ? 'u' : 'k',
+ str_error_r(-err, sbuf, sizeof(sbuf)));
}
-static void print_both_open_warning(int kerr, int uerr)
+static void print_both_open_warning(int kerr, int uerr, bool readwrite)
{
- /* Both kprobes and uprobes are disabled, warn it. */
- if (kerr == -ENOTSUP && uerr == -ENOTSUP)
- pr_warning("Tracefs or debugfs is not mounted.\n");
- else if (kerr == -ENOENT && uerr == -ENOENT)
- pr_warning("Please rebuild kernel with CONFIG_KPROBE_EVENTS "
- "or/and CONFIG_UPROBE_EVENTS.\n");
- else {
- char sbuf[STRERR_BUFSIZE];
- pr_warning("Failed to open kprobe events: %s.\n",
+ char sbuf[STRERR_BUFSIZE];
+
+ if (kerr == uerr && print_common_warning(kerr, readwrite))
+ return;
+
+ if (print_configure_probe_event(kerr, uerr))
+ return;
+
+ if (kerr < 0)
+ pr_warning("Failed to open %s/kprobe_events: %s.\n",
+ tracing_path_mount(),
str_error_r(-kerr, sbuf, sizeof(sbuf)));
- pr_warning("Failed to open uprobe events: %s.\n",
+ if (uerr < 0)
+ pr_warning("Failed to open %s/uprobe_events: %s.\n",
+ tracing_path_mount(),
str_error_r(-uerr, sbuf, sizeof(sbuf)));
- }
}
int open_trace_file(const char *trace_file, bool readwrite)
@@ -109,7 +144,7 @@ int probe_file__open(int flag)
else
fd = open_kprobe_events(flag & PF_FL_RW);
if (fd < 0)
- print_open_warning(fd, flag & PF_FL_UPROBE);
+ print_open_warning(fd, flag & PF_FL_UPROBE, flag & PF_FL_RW);
return fd;
}
@@ -122,7 +157,7 @@ int probe_file__open_both(int *kfd, int *ufd, int flag)
*kfd = open_kprobe_events(flag & PF_FL_RW);
*ufd = open_uprobe_events(flag & PF_FL_RW);
if (*kfd < 0 && *ufd < 0) {
- print_both_open_warning(*kfd, *ufd);
+ print_both_open_warning(*kfd, *ufd, flag & PF_FL_RW);
return *kfd;
}
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