| Message ID | 20230717163947.4969316a@gandalf.local.home (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Masami Hiramatsu |
| Headers | show |
| Series | tracing/probes: Differentiate BTF support from start of function | expand |
On Mon, 17 Jul 2023 16:39:47 -0400 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Having a typo in the function name to trace one of the arguments using > BTF, gave me an error message that BTF was not supported by this kernel: > > ~# echo 'p:lock __raw_spin_lock lock=lock' > /sys/kernel/tracing/kprobe_events > -bash: echo: write error: Invalid argument > ~# cat /sys/kernel/tracing/error_log > [ 34.382149] trace_kprobe: error: BTF is not available or not supported > Command: p:lock __raw_spin_lock lock=lock > ^ > > I added two underscores instead of one underscore for the function > _raw_spin_lock(). But I spent too much time trying to figure out why BTF > was not supported, because in reality it was! The problem was that the > function wasn't found (this could happen if a function offset is used as > well). Thanks for reporting! > > Instead, add a new error message that gives a better description of the > problem. > > ~# echo 'p:lock __raw_spin_lock lock=lock' > /sys/kernel/tracing/kprobe_events > -bash: echo: write error: Invalid argument > ~# cat /sys/kernel/tracing/error_log > [ 45.922742] trace_kprobe: error: BTF arg can be used only on function entry > Command: p:lock __raw_spin_lock lock=lock > ^ This looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you! > Fixes: b576e09701c7d ("tracing/probes: Support function parameters if BTF is available") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > kernel/trace/trace_probe.c | 2 +- > kernel/trace/trace_probe.h | 1 + > 2 files changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index cf504efd0694..328a51b1d068 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -1023,7 +1023,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type, > default: > if (isalpha(arg[0]) || arg[0] == '_') { /* BTF variable */ > if (!tparg_is_function_entry(ctx->flags)) { > - trace_probe_log_err(ctx->offset, NOSUP_BTFARG); > + trace_probe_log_err(ctx->offset, NOFENTRY_BTFARG); > return -EINVAL; > } > ret = parse_btf_arg(arg, pcode, end, ctx); > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h > index 604d6fb9c5ff..554fe2995ca1 100644 > --- a/kernel/trace/trace_probe.h > +++ b/kernel/trace/trace_probe.h > @@ -493,6 +493,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, > C(BAD_ATTACH_ARG, "Attached event does not have this field"),\ > C(NO_EP_FILTER, "No filter rule after 'if'"), \ > C(NOSUP_BTFARG, "BTF is not available or not supported"), \ > + C(NOFENTRY_BTFARG, "BTF arg can be used only on function entry"), \ > C(NO_BTFARG, "This variable is not found at this probe point"),\ > C(NO_BTF_ENTRY, "No BTF entry for this probe point"), \ > C(BAD_VAR_ARGS, "$arg* must be an independent parameter without name etc."),\ > -- > 2.40.1 >
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index cf504efd0694..328a51b1d068 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -1023,7 +1023,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type, default: if (isalpha(arg[0]) || arg[0] == '_') { /* BTF variable */ if (!tparg_is_function_entry(ctx->flags)) { - trace_probe_log_err(ctx->offset, NOSUP_BTFARG); + trace_probe_log_err(ctx->offset, NOFENTRY_BTFARG); return -EINVAL; } ret = parse_btf_arg(arg, pcode, end, ctx); diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 604d6fb9c5ff..554fe2995ca1 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -493,6 +493,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call, C(BAD_ATTACH_ARG, "Attached event does not have this field"),\ C(NO_EP_FILTER, "No filter rule after 'if'"), \ C(NOSUP_BTFARG, "BTF is not available or not supported"), \ + C(NOFENTRY_BTFARG, "BTF arg can be used only on function entry"), \ C(NO_BTFARG, "This variable is not found at this probe point"),\ C(NO_BTF_ENTRY, "No BTF entry for this probe point"), \ C(BAD_VAR_ARGS, "$arg* must be an independent parameter without name etc."),\