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perf probe: Provide clearer message permission error for tracefs access

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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@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Link: http://lore.kernel.org/lkml/162299456839.503471.13863002017089255222.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Masami Hiramatsu 2021-06-07 00:49:28 +09:00 committed by Arnaldo Carvalho de Melo
parent bde1e7d934
commit 0808b3d5b7
1 changed files with 65 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
tools/perf/util/probe-file.c
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@ -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)
{
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;
return true;
}
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;
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("%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 (err == -ENOENT) {
const char *config;
if (print_common_warning(err, readwrite))
return;
if (uprobe)
config = "CONFIG_UPROBE_EVENTS";
else
config = "CONFIG_KPROBE_EVENTS";
if (print_configure_probe_event(uprobe ? 0 : err, uprobe ? err : 0))
return;
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");
else
pr_warning("Failed to open %cprobe_events: %s\n",
uprobe ? 'u' : 'k',
str_error_r(-err, sbuf, sizeof(sbuf)));
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;
}