From 0808b3d5b7514dc856178dbc509929329bbf301d Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 7 Jun 2021 00:49:28 +0900 Subject: perf probe: Provide clearer message 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 Tested-by: Arnaldo Carvalho de Melo Cc: Aneesh Kumar K.V Cc: Ian Rogers Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Ravi Bangoria Link: http://lore.kernel.org/lkml/162299456839.503471.13863002017089255222.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- 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 +#include #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; } -- cgit v1.2.3-59-g8ed1b