From 87f918685a452be514d060a09eeb4e0c91422e86 Mon Sep 17 00:00:00 2001 From: Ramkumar Ramachandra Date: Fri, 4 Oct 2013 10:47:31 +0530 Subject: [PATCH] perf trace: Improve the error messages Currently, execution of 'perf trace' reports the following cryptic message to the user: $ perf trace Couldn't read the raw_syscalls tracepoints information! Typically this happens because the user does not have permissions to read the debugfs filesystem. Also handle the case when the kernel was not compiled with debugfs support or when it isn't mounted. Now, the tool prints detailed error messages: $ perf trace Error: Unable to find debugfs Hint: Was your kernel was compiled with debugfs support? Hint: Is the debugfs filesystem mounted? Hint: Try 'sudo mount -t debugfs nodev /sys/kernel/debug' $ perf trace Error: No permissions to read /sys/kernel/debug//tracing/events/raw_syscalls Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/' Signed-off-by: Ramkumar Ramachandra Cc: David Ahern Cc: Ingo Molnar Link: http://lkml.kernel.org/r/1380863851-14460-1-git-send-email-artagnon@gmail.com [ Added ready to use commands to fix the issues as extra hints, use the current debugfs mount point when reporting permission error, use strerror_r instead of the deprecated sys_errlist, as reported by David Ahern ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 19ddcab..5496546 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1590,17 +1590,13 @@ static int trace__run(struct trace *trace, int argc, const char **argv) } if (perf_evlist__add_newtp(evlist, "raw_syscalls", "sys_enter", trace__sys_enter) || - perf_evlist__add_newtp(evlist, "raw_syscalls", "sys_exit", trace__sys_exit)) { - fprintf(trace->output, "Couldn't read the raw_syscalls tracepoints information!\n"); - goto out_delete_evlist; - } + perf_evlist__add_newtp(evlist, "raw_syscalls", "sys_exit", trace__sys_exit)) + goto out_error_tp; if (trace->sched && - perf_evlist__add_newtp(evlist, "sched", "sched_stat_runtime", - trace__sched_stat_runtime)) { - fprintf(trace->output, "Couldn't read the sched_stat_runtime tracepoint information!\n"); - goto out_delete_evlist; - } + perf_evlist__add_newtp(evlist, "sched", "sched_stat_runtime", + trace__sched_stat_runtime)) + goto out_error_tp; err = perf_evlist__create_maps(evlist, &trace->opts.target); if (err < 0) { @@ -1717,6 +1713,29 @@ out_delete_evlist: out: trace->live = false; return err; +out_error_tp: + switch(errno) { + case ENOENT: + fputs("Error:\tUnable to find debugfs\n" + "Hint:\tWas your kernel was compiled with debugfs support?\n" + "Hint:\tIs the debugfs filesystem mounted?\n" + "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'\n", + trace->output); + break; + case EACCES: + fprintf(trace->output, + "Error:\tNo permissions to read %s/tracing/events/raw_syscalls\n" + "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", + debugfs_mountpoint, debugfs_mountpoint); + break; + default: { + char bf[256]; + fprintf(trace->output, "Can't trace: %s\n", + strerror_r(errno, bf, sizeof(bf))); + } + break; + } + goto out_delete_evlist; } static int trace__replay(struct trace *trace) -- 2.7.4